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Recent changes in grasslands of eastern Nebraska and north-central Kansas

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MANUSCRIPT THESIS
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RECENT GHANGf.CS IN GRASSLANDS
OB* EASTERN NEBRASKA AND
NORTH-CENTRAL KANSAS
by
R o b ert L. F o w le r
A THESIS
P r e se n te d t o th e F a c u lty o f
The G ra d u ate C o l l e g e i n t h e U n i v e r s i t y o f N eb rask a
In P a r t i a l F u l f i l m e n t o f R eq u irem en ts
F o r t h e D egree o f D o c t o r o f P h i l o s p h y
D ep artm en t o f B otany
L i n c o l n , N e b r a sk a
A p r i l , 1941
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UMI Number: DP13748
UMI*
U M I Microform D P 1 3 7 4 8
Copyright 2 0 0 6 by P roQ uest Information and Learning C om pany.
All rights reserved. This microform edition is protected against
unauthorized copying under Title 17, United States C ode.
ProQ uest Information and Learning C om pany
3 0 0 North Z e e b R oad
P .O . Box 1346
Ann Arbor, M l 4 8 1 0 6 -1 3 4 6
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TABLE OF COJimTS
Page
INTRODUCTION
......................................................................................................
GENERAL, DESCRIPTION OF THE AREA
1
..................................
4
CONDITIONS FOR PLANT DEVELOPMENT............. . .....................................
3
LOCATION «AD DESCRIPTION OF PRAIRIES,............................................
I1ETH0D3 AND PROCEDURE..............................
BLUE3TE1.1 PRAI LIES
8
(iCp
................................................
12
J a m a ic a P r a i r i e ...........................................................
12
C o m p o s it io n "before t h e D r o u g h t ...........................................
12
E a r ly C hanges r e s u l t i n g frora Drought*
13
Re c e n t Cha a g e s .....................
13
The L i n c o l n G r o u p ,
* .......................................
........................................................
16
C o m p o s it io n b e f o r e t h e D r o u g h t ...........................................
E a r ly Changes r e s u l t i n g from D r o u g h t , , *
L o c o •it o
L
V a lp a ra iso P r a ir ie
n
.
T
i
g
.
16
.............
o
s
16
IT
....................................................
C o m p o s itio n b e f o r e t h e D r o u g h t
22
.............................
E a r ly C hances r e s u l t i n g from D r o u g h t . . . . . .......................
22
22
R o cen t C h a n g es .....................................................
Hebron P r a i r i e *
23
...........................................
■Composition b e f o r e t h e D r o u g h t . * . . . . . .................................
E a r ly Change a r e s u l t i n g from D r o u g h t
•«««,,*•
26
26
26
R e c e n t C h a n g e s . . . . ....................................................
B e lle v ille
P r a ir ie
2?
.....................................................
C o m p o s it io n b e f o r e t h e D r o u g h t
30
...........................
E a r ly Changes r e s u l t i n g from D r o u g h t . . . ............................
30
30
383721
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Pag©
30
R e c e n t C h an g es.
•iH£AT0'KA3S PRAIRIES
33
» * » * • # «
Olay C e n te r P r a i r i e
33
C o m p o s it io n b e f o r e t h e Drought
r •
*
*
•
•
•
■*»“V
JJ
E a rly C hanges r e s u l t i n g ; from D rought
33
K eeeu t Changes
34
.......... .....................
38
b e f o r e t h e D r o u g h t .. . . . .
38
C a rleto n P r a i r i e
Ccrcpooit.lo:
E a r ly C hanges r e s u l t i n g from Drought
38
R o een t w h on go s. . . . . . . . . . . . . . . . . . . . . .
39
............................ ......................
42
C o m p o s it io n ‘b e f o r e t h e D r o u g h t . . . . . *
42
E a r ly C hanges r e s u l t i n g from Drought
42
R ecent C h a n g es.
.............
43
Liontronn •*r & x r l e . . . . . . . . . . . . . . . . . . . . . .
46
C o m p o s it io n b e f o r e t h e D r o u g h t . . . . . .
46
E a r ly Changes r e s u l t i n g from D rought
46
. '.oc*v'it . -xmngeo. . . . . . . . . . . . . . . . . . . . . .
47
N e lso n P r a i r i e
RESULTS PRCM ALL P R A IR IE S
50
DI S CUS S I ON. . . . . . . . . . . . . . .
58
S U M M A R Y . . . , ......................................
64
LITERATURE CITED ,
70
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RECENT CHANGES IN GRASSLANDS OF
EASTERN NEBRASKA AND NORTH-CENTRAL KANSAS
INTRODUCTION
The c o m p o s i t i o n o f t h e g r a s s l a n d s o f e a s t e r n Neb­
r a s k a and n o r t h - c e n t r a l K ansas h a s b e e n g r e a t l y m o d if i e d by
d rou gh t.
F o r m erly t h e p r a i r i e s w ere composed o f v e g e t a t i o n
w h ic h was i n c l o s e a d j u s t m e n t w i t h i t s
en v iro n m en t.
There
were no g r e a t w aves o f e m i g r a t i o n , n e i t h e r w ere t h e r e
i m m i g r a t i o n s , f o r t h e p r a i r i e was a c l o s e d community and
i n v o d e r s , w i t h r a r e e x c e p t i o n s , were e x c l u d e d (W eaver and
F lo r y , 19 3 ^ ).
R e c u r r in g d r o u g h ts d u r i n g t h e p a s t s e v e n y e a r s
h a v e u n b a la n c e d t h i s h i g h d e g r e e o f e q u i l i b r i u m .
I t h as
r e s u l t e d i n h i g h m o r t a l i t y o f b o t h d o m in a n t and subdom i­
n a n t s p e c i e s , and t h i s h a s b een f o l l o w e d by an enormous
in c r e a se in w eeds.
Even d e e p l y r o o t e d f o r b s h a v e b een
r e d u ced i n n u m b ers, o f t e n t o o n e - t h i r d o f t h e i r fo rm er
a bundance (W eaver and A l b e r t s o n , 1 9 3 9 ) •
T h ese p h en om en al c h a n g e s h a v e a r o u s e d u n u s u a l i n t e r e s t
and h a ve s t i m u l a t e d much e c o l o g i c a l I n v e s t i g a t i o n th r o u g h ­
o u t t h e r e g i o n d o m in a ted by g r a s s e s .
fo lk
(1937)
E l l i s o n and Wool-
r e p o r t t h a t t h e r a n g e s o f s o u t h e a s t e r n Montana
w ere damaged beyond t h e i r a b i l i t y
to reco v er in 1935.
Ranges o f t h e Upper Snake R iv e r l i k e w i s e s u s t a i n e d h ea vy
lo sse s
(P echanec e t a l . ,
1 9 3 7 )*
R e g a r d in g t h e r a n g e s o f
U t a h , S t e w a r t and Young ( 1 9 3 9 ) s t a t e t h a t t h e n a t i v e p e r e n -
R ep ro d u ced with p erm ission o f th e copyright ow ner. Further reproduction prohibited w ithout perm ission.
2
n l a l s p e c i e s w h ic h f o r m e r e l y c o v e r e d t h e f o o t h i l l s h av e b een
r e p l a c e d l a r g e l y by Bromus t e c t o r u m . t h u s r e d u c i n g f o r a g e
p r o d u c tio n .
I n t h e d r y d e s e r t v a l l e y s , however,- S a l s o l a
n e s t l f e r has been th e in v a d e r (S tew a rt e t a l . , 1 9 4 0 ).
Bromus t e c t o r u m h a s a l s o
I n c r e a s e d i n abundance i n N eva d a ,
e a s t e r n Oregon and W a sh in g to n and i n p a r t s o f Montana, a t
t h e e x p e n s e o f t h e weakened p e r e n n i a l s p e c i e s .
R anges o f e a s t e r n Wyoming d i d n o t s u f f e r much from
t h e d r o u g h t ( B e a t h , 1 9 3 5 )> h u t t h o s e o f e a s t e r n C olo ra d o
w ere dam aged.
A llr e d (1935)
s t a t e s th a t th e fo r a g e g r a s s e s ,
c h i e f l y B o u t e l o u a g r a c i l i s and B u c h lo e d a c t v l o i d e s . w ere
r e d u c e d 40 p e r c e n t .
Even w e ll- m a n a g e d r a n g e s w ere d e p l e t e d
a s much a s 39 p e r c e n t ( N e l s o n and W a s se r , 1 9 4 0 ) .
D esp ite
h i g h m o r t a l i t y o f t h e s e g r a s s e s , t h e s u r v i v i n g p l a n t s were
r a t h e r u n i f o r m l y d i s t r i b u t e d and s h o u l d r e c o v e r u n d er
f a v o r a b l e m o i s t u r e r e l a t i o n s h i p s ( S a v a g e , 1 9 3 7 )*
In K a n s a s , u n g r a z e d p r a i r i e s o f t h e w e s t - c e n t r a l p a r t
s u f f e r e d t h e g r e a t e s t d e t e r i o r a t i o n , a v e r a g i n g a p p r o x im a t e ly
8 5 p e r c e n t o f t h e b a s a l c o v e r ( l e a v e r and A l b e r t s o n , 1 9 3 6 ) .
T h i s g r e a t l o s s was n o t p erm a n en t; A l b e r t s o n ( 1 9 3 9 )
rep orts
t h a t t h e Im p o r ta n t p e r e n n i a l g r a s s e s h a v e I n c r e a s e d somewhat
in b a sa l cover, as a r e s u lt o f l e s s severe c lim a tic co n d itio n s.
The p r a i r i e s o f w e s t e r n Io?/a w ere unharmed, b u t t h o s e
o f s o u t h e a s t e r n N e b r a s k a w ere g r e a t l y I n j u r e d .
The m ost
i m p o r t a n t c h a n g e s r e c o r d e d I n N eb rask a w ere t h e e x t e n s i v e
r e p l a c e m e n t o f Andropor.on f u r c a t u s and e s p e c i a l l y A.
s c o n a r l u s by A gropyron s m l t h l l . t h e t h i n n i n g o f t h e p l a n t
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
.
3
c o v e r , t h e l o s s o f t h e u n d e r s t o r y , and t h e r a p i d sp rea d o f
w eeds.
Weeds w ere o f t e n s o abundant t h a t t h e p r a i r i e s f r e ­
q u e n t l y a p p e a r e d more l i k e abandoned f i e l d s t h a n g r a s s l a n d s
(W eaver and A l b e r t s o n , 1 9 3 6 ) .
F u r t h e r d e t e r i o r a t i o n o c c u r r e d i n s o u t h e a s t e r n Neb­
r a s k a f o l l o w i n g t h e d r o u g h t o f 1936 ( R o b e r t s o n , 1 9 3 9 ;
Weaver and A l b e r t s o n , 1 9 3 9 , 1 9 4 0 ) .
P e r e n n ia l g r a s s e s as a
g ro u p w e r e r e d u c e d 22 p e r c e n t i n abundance w h i l e p e r e n n i a l
f o r b s w ere d e c r e a s e d 10 p e r c e n t .
A n n u a ls , p a r t i c u l a r l y
Bromus t e c t o r u m . Kedeoma h l s n l d a . and P l a n t a g o p u r s h i l .
w ere from t h r e e t o s i x t im e s a s ab u n d an t i n 1 9 3 7 a s d u r in g
th e p r eced in g y e a r .
By 1 9 3 9 , p e r e n n i a l g r a s s e s had r e c o v ­
e r e d t h e l o s s e s o f 1937» b u t p e r e n n i a l f o r b s and annual
g r a s s e s and f o r b s f u r t h e r d e c r e a s e d ( w e a v e r , R o b ertso n
F o w l e r , 194-0) •
The p r e s e n t i n v e s t i g a t i o n i s a c o n t i n u a t i o n o f t h e
r e s e a r c h c o n d u c t e d by R o b e r tso n from 1936 t o 1 9 3 7 , and by
Weaver i n 1 9 3 8 .
The i n t e r p r e t a t i o n s o f t h e r e s u l t s a r e b a s e d
upon t h e c o m p r e h e n s iv e r e p o r t s o f Weaver and F i t z p a t r i c k
(1934)
on t r u e p r a i r i e , t h e s t u d i e s o f Weaver ( 1 9 1 9 , 192 0)
and Nedrow ( 1 9 3 7 )
on r o o t d e v e lo p m e n t and a c t i v i t i e s o f
n a t i v e p l a n t s , t o g e t h e r w i t h t h e s t u d i e s o f d r o u g h t by
R ob ertson ( 1 9 3 9 ) ,
Weaver and A l b e r t s o n ( 1 9 3 6 , 1 9 3 9 , and
1 9 4 0 ) , and t h o s e o f Weaver, R o b e r tso n and F o w le r ( 1 9 4 0 ) .
G r a t e f u l a ck n o w led g em en t i s made t o Dr. J . E. Weaver
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
4
f o r o u t l i n i n g t h e p rob lem and f o r v a l u a b l e s u g g e s t i o n s
th rou ghou t th e i n v e s t i g a t i o n .
GtSNKKAL DESCRIPTION OF TKK AREA
The t w e l v e p r a i r i e s o f known p r e v i o u s h i s t o r y , on w hich
c h a n g e s w ore r e c o r d e d , a r e l o c a t e d I n s o u t h e a s t e r n .Nebraska
and n o r t h - c e n t r a l K a n s a s .
They a r e i n S a u n d e r s , L a n c a s t e r ,
T h a y e r , C l a y , and N u c k o l l s c o u n t i e s In N e b r a s k a , and J e w e l l
and R e p u b l i c c o u n t i e s i n K ansas ( F i g , 1 ) ,
T h is r e g i o n was f o r m e r ly c o v e r e d w i t h t r u e - p r a l r l e
v e g e t a t io n o f th e m id -g r a s s ty p o .
The m ajor d o m in a n ts w ere
And ron oaon s c o n a r lu g - . f t Inn s o a r t e a . S o o r o b o lu s h e t e r o l e n l s .
K o e l e r l a o r l o t a t a . B o u t e l o u a c u r b l o e n d u i a and S n o r o b o lu s
asper.
I n m o i s t p l a c e s t h e mid g r a s s e s gav e way t o & p o s t -
c l im a x o f t a l l g r a s s e s d o m in ated by AndronoKOn f u r o & t u s .
Sorgho a trues n u t a n s . P s.nlcum v l m a t u m . and Elymu& c a n a d e n s i s .
The fo r m e r c o m p o s i t i o n , h o w e v e r , h a s b e e n m ark ed ly changed
by d r o u g h t .
much d e p l e t e d
A lth o u g h many o f . t h e s t a t i o n s m a in t a in e d a
co v er o f.fo r m e r p r a ir ie g r a s s e s , c h ie f ly
s p e c i e s o f b l u e s terns ( And ro n o r o n ) , o t h e r s h a v e become
d o m in a ted by w e s t e r n w h e a t g r a s a ( A nroovron a m i t h l l ) .
T h e s e g r o u p s a r e h e r e a f t e r d e s i g n a t e d a s t h o b lu e a te m and
w estern w h eatgraea p r a i r i e s .
The t o p o g r a p h y i s g e n e r a l l y r o l l i n g , a l t h o u g h n e a r l y
l e v e l a t tw o o f t h e s t a t i o n s , and t h e a v e r a g e e l e v a t i o n i s
about 1 ,5 0 0 f e e t .
The s o i l s h a v e d e v e l o p e d from l o e s s ,
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
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P i g . 1 . — Map o f p o r t i o n o f e a s t e r n Hebr t .s k a and n o r t h - c e n t r a l K an sas s h o w in g
l o c a t io n o f th e p r a ir ie s
(X) and t h e
tow n s ( 0 ) n e a r w h ic h t h e y l i e .
o f p r a i r ie a t V a lp a ra iso i s
L o ca tio n
i n d i c a t e d by
th e arrow .
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
5
e x c e p t t h o s e on g l a c i a l d r i f t ancj a llu v iu m *
fe r tile ,
fiiic -te x tu r e d
c a p a c ity .
silt
They a r e
3Guns o f h ig h - w a t e r - h o l d i n g
R o o ts o f upland, g r a s s e s p e n e t r a t e t o a depth, o f two t o
o v e r f i v e f e e t and t h o s e o f t h e lo w la n d a b o u t t h r o e t o t e n
f o o t (W ea v er, 1 9 1 9 , 1 9 2 0 ) .
■ CONDITIONS FOR PLANT DEVELOPMENT
4
B e f o r e t h e g r e a t d r o u g h t , mean a n n u a l r a i n f a l l
v a r ie d
from a p p r o x i m a t e l y 25 i n c h e s a t t h e w e s t e r l y s t a t i o n s
t o a b o u t 28 a t t h o s e f a r t h ^ e s t e a s t .
N e a r ly 80 p e r c e n t
o f t h e a n n u a l p r e c i p i t a t i o n f e l l d u r i n g t h e g r o w in g s e a s o n .
P e r i o d s o f d r o u g h t o c c u r r e d a t any t i m e , e s p e c i a l l y a f t e r
midsummer.
Water c o n t e n t i n t h e s u r f a c e s o i l and s u b s o i l
-was r a r e l y r e d u c e d t o t h e p o i n t o f n o n a v a i l a b i l i t y ^
A l­
t h o u g h t h e a v e r a g e day a i r t e m p e r a t u r e s some tim e s' r e a c h e d
9 0 ° P . , t h e y u s u a l l y ranged b e tw e e n 7 5 ° and 8 5 ° .
The
a v e r a g e day h u m id it y was u s u a l l y b e tw e e n 50 and 8 0 p e r
c e n t d u rin g y e a r s o f g r e a t e r r a i n f a l l b u t f e l l
a lly
t o 40 p er cen t d u rin g d r i e r y e a r s .
was n e a r l y c o n s t a n t and s o m e t im e s h i g h .
o e a sa ia n ­
Wind movement
E v a p o r a t io n from
p o r o u s cup a t m o a e t e r o r a r e l y f a l l b e lo w an a v e r a g e w e e k ly
l o s s o f 10 c c . p e r day (W eaver and Hlramel, 1 9 3 1 ) .
The p r a i r i e s h a v e e x p e r i e n c e d g r e a t e x t r e m e s i n w e a t h e r
d u rin g th e p a s t sev en y e a r s .
I n t e r m itt e n t p erio d s o f
s e v e r e d r o u g h t a cco m p a n ie d by h i g h t e m p e r a t u r e s , h i g h
^ T o t a l w a t e r c o n t e n t o f s o i l m in u s t h e h y g r o s c o p i c c o e f f i c i e n t
( w h ic h was d e t e r m in e d f o r e a c h s o i l d e p t h a t e a c h s t a t i o n )
d e s i g n a t e d as w a t e r a v a i l a b l e f o r g r o w t h .
R ep ro d u ced with p erm ission o f th e copyright ow ner. Further reproduction prohibited w ithout perm ission.
is
6
e v a p o r a t i o n r a t e s , u n u su a l h i g h wind movement, and low
r e l a t i v e h u m id it y h a ve p r e v a i l e d .
The y e a r 1939 was c h a r a c t e r i z e d by h i g h a v e r a g e
t e m p e r a t u r e s and l o n g p e r i o d s o f d r o u g h t ,
A p r i l and May
w ere u n s e a s o n a b l y dry w it h a b n o rm a lly h i g h t e m p e r a t u r e s .
The a v e r a g e d e p a r t u r e from t h e normal ( 5 9 . 3 ° F . ) was + 7 « 8 ° .
J u n e and J u l y were h o t w it h d e p a r t u r e s a s g r e a t a s +■ 7 °
a b o v e n o r m a l, w h i l e t e m p e r a t u r e s d u r in g August w ere a p p r o x i ­
m a te ly n o r m a l.
T em p era tu res a s h i g h a s 1 0 8 ° t o 1 1 2 ° F ,
o c c u r r e d d u r in g J u l y and were accom p an ied by s t r o n g , d e s ­
i c c a t i n g , h o t w in d s.
R a i n f a l l was d e f i c i e n t a t m o st o f
t h e p r a i r i e s t a t i o n s from A p r i l t o Sep tem b er; t h e a v e r a g e
d e f i c i t was 6 . 8 i n c h e s .
The b e g i n n i n g o f th e g ro w in g s e a s o n o f 1940 was
s lig h tly
year.
c o o l e r and e v en d r i e r th a n t h a t o f t h e p r e c e d i n g
D u rin g May, t e m p e r a t u r e s were n o r m a l, b u t r a i n f a l l
was d e f i c i e n t .
The months o f J u n e , J u l y , and A u gu st w ere '
a l s o warm and d r y ; maximum t e m p e r a t u r e s ran ged b etw een
1 0 0 ° and 1 1 6 ° F . l a t e i n J u l y .
R a in le ss p e r io d s o f v a ry in g
l e n g t h w ere o f f r e q u e n t o c c u r r e n c e .
The a v e r a g e a c c u m u la t i v e
r a i n f a l l d e f i c i t from A p r i l t o S ep tem b er was 4 . 9 I n c h e s w i t h
a minimum o f 4 . 0 and a maximum o f 5*8 i n c h e s .
The w a t e r c o n t e n t o f b o t h s o i l and s u b s o i l was g r e a t e r
i n t h e b l u e s t e m p r a i r i e s th a n i n t h e w h e a t g r a s s g r o u p .
I n A p r i l , an a v a i l a b l e w a t e r s u p p ly o f 2 t o 20 p e r c e n t
o r more o c c u r r e d i n t h e s u r f a c e 24 i n c h e s a t a l l o f t h e
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
7
b lu e ste m p r a i r i e s , e x c e p t B e l l e v i l l e ,
Kansas .
S u b so il
m o i s t u r e was a v a i l a b l e , u s u a l l y i n amounts o f 2 t o 5 p a r
c e n t , t o a d ep th o f 6 f e e t a t th e b lu estem s t a t i o n
( F i g . 2).
A f t e r A p r i l , t h e m o is t u r e c o n t e n t o f t h e s u r f a c e 24 i n c h e s
was red u c e d t o t h e p o i n t o f n o n a v a i l a b i l i t y a t some l e v e l
one o r more t i m e s .
A s i n g l e e x c e p tio n occurred a t th e
N e l s o n s t a t i o n where w a t e r was c o n t i n u o u s l y a v a i l a b l e .
B elow
a d e p t h o f t h r e e f e e t , h o w e v e r , m o is t u r e was a lw a y s a v a i l a b l e
a t e a c h s t a t i o n e x c e p t H ebron.
•cater was c o n t i n u o u s l y a v a i l a b l e a t t h e w h e a t g r a s s
s t a t i o n s i n t h e s u r f a c e f o o t o n ly a t C a r l e t o n ; a t t h e o t h e r
s t a t i o n s i t was red u c e d t o t h e p o i n t o f n o n a v a i l a b i l i t y o v e r
lo n g p e r io d s ( F ig . 3 )«
At 1 - 2 f e e t i n d e p t h , s m a l l amounts
o f m o i s t u r e w ere c o n t i n u o u s l y a v a i l a b l e o n ly a t Clay C e n t e r .
B elow 2 f e e t w a te r was p r e s e n t i n amounts o f l e s s th a n 2
p e r c e n t a t n e a r l y a l l l e v e l s a t Clay C e n t e r , a t 5 - 6
f e e t i n d e p t h a t C a r l e t o n , b u t was n o t a v a i l a b l e a t any
l e v e l a f t e r A p r il a t M ontrose.
R a i n f a l l d u r i n g t h e g r o w in g s e a s o n o f 194-0 was n o t
s u f f i c i e n t t o m a in t a i n a c o n t in u o u s s u p p ly o f s o i l m o is ­
tu re. ^
.-Hater was u s u a l l y a v a i l a b l e f o r g row th i n t h e
s u r f a c e 24 i n c h e s a t a l l b lu e s t e m and w h e a t g r a s s s t a t i o n s
from A p r i l t o J u n e , i n c l u s i v e .
A f t e r J u n e , m o is t u r e was
I n f o r m a t i o n a s t o s o i l m o i s t u r e c o n d i t i o n s i n 1940 was
o b t a i n e d from Dr. J . S . l e a v e r .
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
Reproduced
with permission
CLAY CENTER 25.5
CARLETON 26.9
MONTROSE 25.0
0.5'
LINCOLN 2 7 .9
HEBRON 2 7 .3
N ELSO N 2 0 . 8
B ELLEV ILLE 2 6 .2
of the copyright owner.
Further reproduction
1.7
1.6
2.8
2.6
2.0 2 .7
6.8 3 .3
4 .8
1.8
1.9
5.5
3.1
prohibited without permission.
Fig.
1939.
2 %
2.2 4.3 2.4 3.8
2.2
3.1
\z~
"-"I
5 0 /0 T 0
2 0 % OR MORE
3.3 6.0 4.5 i3.4
B 10% TO 1 9 .9 %
1 0 % TO 1 9 . 9 %
N O N -A V A ILA B LE
L E S S THA N
2.3
LESS
THAN
2%
2 0 % OR MORE
2 (left).— Available soil moisture to depth of 6 feet at Nebraska-Kansas bluestem stations in
Mean annual precipitation at each station follows the name, and total current monthly rainfall is
given at the foot of each column^-.
Fig. 3
( r i g h t M e a n annual precipitation, current monthly precipitation, and available soil
moisture at Nebraska-Kansas wheatgrass stations in 1939^.
1
From weaver and Albertson, 1940a.
8
c o n t i n u o u s l y a v a i l a b l e o n ly a t t h e L i n c o l n s t a t i o n ;
at th e
o t h e r p r a i r i e s , a s w e l l a s t h e w h e a t g r a s s g r o u p , t h e r e w ere
l o n g p e r i o d s when w a t e r was n o n a v a i l a b l e .
B elow t h r e e f e e t
a c o n t i n u o u s s u p p ly o f w a t e r was m a in t a in e d i n t h e s p r i n g
o n ly a t L in c o ln
and B e l l e v i l l e .
At o t h e r s t a t i o n s , i n c l u d i n g
th e w h eatgrass p r a i r i e s , i t
was n o n a v a i l a b l e a t some l e v e l
o ver lo n g p e r io d s o f tim e .
A f t e r June t h e s u b s o i l i n t h e
b l u e s t e m grou p u s u a l l y c o n t a in e d s m a l l amounts o f m o i s t u r e ,
but in th e w h eatgrass s t a t i o n s ,
save fo r s e v e r a l l e v e l s a t
Clay C e n t e r and C a r l e t o n , i t was n e v e r a v a i l a b l e .
LOCATION AND DESCRIPTION OF PRAIRIES
The p r a i r i e s w ere a l l w i t h i n 110 m i l e s o f L i n c o ln
a n d , w it h one e x c e p t i o n , th e y occurred upon u p la n d .
u n g r a z e d b u t ha4
They w ere
g e n e r a l l y b e e n ../owed i n t h e f a l l .
A ll
w ore unburned e x c e p t t h e e a s t e r n h a l f o f t h e p r a i r i e a t
iu on trose.
D e s c r ip tio n o f th e predrought v e g e t a t io n at
each p r a i r i e i s
d isc u sse d .
g i v e n when i t s p o s t d r o u g h t b e h a v i o r i s
L o c a tio n ,
size,
s o i l t y p e , and o t h e r d a t a
r e g a r d i n g t h e p r a i r i e s a r e shown i n T a b le 1 ,
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
9
Table 1,
Pertinent data regarding each of the twelve p rairies
where permanent p lots were located.
Prairie^
Jamaica
Lincoln group
Belmont
Crete
Emerald
Lincoln
Approximate
s i z e , (acres)
10
60
140
30
320
S o il
Grass
type
Topography
Wabash s i l t loam Bluestem
Lowland, le v e l
Carrington s i l t
loam
Bluestem
Upland, r o llin g
Valparaiso
35
Shelby s i l t loam Bluestem
Upland, r o llin g
Hebron
30
Shelby fin e sandy Bluest an
loam and Nuckolls
s i l t loam
UpLand, r o llin g
B ellev ille2
30
Crete s i l t loam
Bluest an
Upland, r o llin g
Clay Center
10
Hastings s i l t
loam
Wheatgrass Upland, r o llin g
Carleton
35
Crete s i l t loam
Wheatgrass Upland, s li g h t l y
rol lin g
Nelson
30
Crete s i l t loam
Yiheatgrass Upland, r o llin g
Montrose^
80
Hastings s i l t
loam
Wheatgrass Upland, moderately
rol. lin g
Each p rairie bears the name of the nearest town,
2
Located in Kansas,
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
10
METHODS AID PKOCK0URB
O ne-hundred perm anent p l o t s , u s u a l l y one s q u a r e m e te r
i n a r e a , w ere s t u d i e d In d e t a i l *
Those w ere t h e p l o t s
e s t a b l i s h e d by R o b e r ts o n i n 1936*
A c e n s u s o f ther^ u s i n g
t h e s t e a i - c o u n t m e th o d , was t a k e n i n 133 6 and 1 9 3 7 by R o b e r t­
s o n and i n 1938 by l e a v e r .
T h is c e n s u s was c o n t i n u e d by t h e
w r i t e r d u r in g 1939 sad 1 9 4 0 , and t h e number o f p r a i r i e s was
i n c r e a s e d from n i n e t o t w e l v e *
B ecause o f In c rea sed w o ed ln eo s, p o r t io n s o f th e
s e v e r a l p r a i r i e s had b een p low ed and t w e n t y - f i v e o f t h e
o r i g i n a l p l o t s were d estro y ed *
2nough p l o t s w ere l o c a t e d t o
i n c r e a s e t h e number t o t h e o r i g i n a l o n e -h u n d r e d *
Stem c o u n t s
o f B u c h lo e d a c t v l o l d e o and F e s t u c a o c t o f l o r a w ere n o t mad©
d u r i n g t h e p a s t two y e a r s .
I n s t e a d , th e b a s a l c o v e r o f
B u c h lo e was d e t e r m in e d and t h e number o f sou&re d e c i m e t e r
u n i t s o c c u p i e d by F e s t u c a wore r e c o r d e d *
S e v e r a l a l t e r n e a o f A^ropvron a m l t h l l on t h e p r a i r i e s
a t V a l p a r a i s o and B elm ont w ere mapped e a c h summer by means
o f a p l a n e - t a b l e , and t h e i r a r e a s were d e t e r m in e d from t h e
map by e p l a n l m e t e r *
In t h i s manner s e a s o n a l c h a n g e s i n
t h e a r e a o f e a c h a l t e r n e were o b t a i n e d .
ra ts,
F i g h t c h a r t quad­
e a c h one s q u a r e ice t e r i n a r e a , and t h r e e t r a n s e c t s ,
two by f i v e m e te r s In a r e a , w ere p i e c e d i n t h e t e n s i o n zo n e
a t t h e e d g e o f t h e a l t e r n e a , i n 1 9 3 8 , i n o r d e r t o o b t a in
c h a n g e s i n p o s i t i o n s o f boundary and t h e b e h a v i o r o f t h e
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
11
p e r e n n ia l g r a s s e s .
S e v e r a l bare a r e a s t o t a l i n g 5 ,1 2 2 squ are
f e e t i n a d e n s e s t a n d o f A g ro p yron s m i t h 5.1 w ere a l s o mapped
a t C la y C e n te r and c h a n g e s i n t h e i r s i z e a s c e r t a i n e d .
The b e h a v i o r o f p e r e n n i a l f o r b s was s t u d i e d i n s l t # s
c o n t r o l l e d by A g ro p yron s m i t h ! 1 . S tem c o u n t s o f a l l f o r b s
woro made a n n u a l l y w i t h i n p erm an en t c i r c t i l a r p l o t s , e a c h
"
o
7 , 8 5 0 s q u a r e f e e t i n a rea #
Two o f t h e s e p l o t s w ere l o c a t e d on
each o f th e f o ll o w i n g p r a i r i e s i
1~
M o n t r o s e , C la y C e n t e r , C a r l e t o n ,
and H eb ron .
C hanges i n c o m p o s i t i o n o f v e g e t a t i o n r o s u l t i n g from
s l o p e e x p o s u r e w ere s t u d i e d on t h e p r a i r i e s a t E m era ld , L i n c o l n ,
and C r e t e .
Two t r a n s e c t s ,
e a c h o n e m e t e r i n w i d t h , wore l o c a t e d
a t E m erald o n a s o u t h w e s t s l o p s .
. o t h e r 41 m e t e r s .
One was 54 m e t e r s l o n g and t h e
They w ere c h a r t e d i n 1 9 3 9 and a g a i n i n 1 9 4 0 .
f o u r t e e n b e s a l - a r e a q u a d r a t s w ere l o c a t e d on l o n g , s o u t h w e s t
s l o p e s on t h e C r e t e and L i n c o l n p r a i r i e s .
T h ey , t o o , w ere
a n a ly z e d each y e a r .
A lt h o u g h r e c o r d s o f s e e d l i n g c o u n t s w ere o b t a i n e d from
e a c h p erm an en t p l o t , f u r t h e r s t u d i e s were- c o n d u c t e d on t h e
C rete p r a i r i e ,
w here i n 1S 3 8 n i n e c i r c u l a r p l o t s ,
to ta lin g
17b s q u a r e f e e t i n a r e a , -wore l o c a t e d i n s i t e s d o m in a te d by
S t l p a s p a r t a n and S p o r o b o lu s a s p e r .
to 1940, I n c lu s iv e )
D u r in g e a c h y e a r (1 9 3 8
a c e n s u s was t a k e n o f a l l s e e d l i n g s o f
f i r s t o r seco n d y e a r * s grow th .
D e t a i l e d m ea su rem en ts w ere s u p p le m e n t e d by c a r e f u l
s tu d y o f t h e c o m p o s i t i o n and d e v e lo p m e n t o f t h e . v e g e t a t i o n
383721
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
o v er each o f th e
p r a ir ie s.
The- t w e l v e p r a i r i e s have b e e n s e p a r a t e d I n t o two
g r o u p s — b l u e s t e m and w h e a t g r a s s — on t h e b a s i s o f t h e dom­
in a n t v e g e t a tio n .
The b lu estern g ro u p i s
com posed o f t h e
p r a i r i e a t J a m a ic a , f o u r n e a r L i n c o l n , and o n e e a c h a t
V a l p a r a i s o , H eb ron , and B e l l e v i l l e ;
t h e w h e a t g r a s s grou p
I n c l u d e s t h e r e m a in d e r .
BLUE3T&K PKAIRIKS
T h is g ro u p o f p r a i r i e s n o t o n l y had t h e p l a n t c o v e r
g r e a t l y o p en ed by t h e l o s s o f t h e u n d e r s t o r y b u t a l s o
s u f f e r e d more o r l e s s
c o m p le te d e s t r u c t i o n o f b o t h l a r g o
and s m a l l p a t c h e s o f v e g e t a t i o n t h r o u g h o u t .
It s t ill
r e t a i n e d i t s m a jo r p a t t e r n o f t h e b l u e s t c m e and damage was
s m a l l on t h e m ost p r o t e c t e d s l o p e s and i n r a v i n e s ,
J a m a ica P r a i r i e
C o m p o s itio n
b e f o r e t h e D rought
The J a m a ica P r a i r i e
o c c u r s on l o w l a n d .
drought o f 1 9 3 4 , i t
P r io r to th e
was d om in ated by A n d rp roton f u r c a t u s .
Thin g r a s s a l o n e f u r n i s h e d from 6 0 t o 9 0 p e r c e n t o f t h e
c o v e r ( l e a v e r and A l b e r t s o n , 1 9 3 6 ) .
a l s o was v e r y a b u n d a n t, p a r t i c u l a r l y
it
Androoo; on s c o o a r l u s
:>n t h e u p l a n d s , where
form ed a s much a s 25 p e r c e n t o f t h e c o v e r .
o ra t e n s I s and Sorrh.astrum
X-oa
n u ta n s w ere w i d e l y d i s t r i b u t e d ,
w h i l e d n o r o b o lu s a s o o r o c c u r r e d o n ly i n a few a l t c r n e s .
R ep ro d u ced with p erm ission o f the copyright ow ner. Further reproduction prohibited w ithout p erm ission.
13
B o u t e l o u a c u r t i n e n d u l a was common on t h e h i l l s i d e s .
A g roovron s m l t h l i . B u c h lo e d a c t v l o l d e s . and B o u telo .u a
g r a c i l i s w ere r e s t r i c t e d t o a few l o c a l d e p r e s s i o n s .
L a y er­
i n g was w e l l d e v e lo p e d and f o r b s were v e r y ab u n d an t b o t h i n
s p e c i e s and i n number o f p l a n t s .
A s t e r m u l t i f l o r u s and
S o l l d a g o relaberrlm a w ere among t h e m ost i m p o r t a n t f o r b s .
E a r ly Changes r e s u l t i n g from D rought
G r e a t ch a n g es i n t h e s t r u c t u r e o f t h e p r a i r i e became
ap p aren t a f t e r th e drought o f 1 934.
I m p o r ta n t c h a n g e s w h ich
o c c u r r e d b e t w e e n 1935 and 1938 w ere t h e r e p l a c e m e n t o f t h e
c h i e f d o m in a n t, Androoogon f u r c a t u s . by A gronvron s m l t h l i .
t h e d i s a p p e a r a n c e o f l a y e r i n g , and an i n c r e a s e i n S p o r o b o lu a
h e t e r o l e o l s . 3 t l n a s p a r t e a . K o e l e r l a c r l s t a t a . and A s t e r
m u ltiflo r u s .
A nnuals becam e v e r y common, r e a c h i n g t h e i r
maximum abundance i n 1 9 3 7 .
The n o r t h e r n p o r t i o n o f t h e p r a i r i e was p l a c e d u n d er
c u l t i v a t i o n i n 1938 b e c a u s e o f i n c r e a s e d w e e d i n e s s .
T h is
r e d u c e d t h e t o t a l number o f p l o t s from 13 t o 5 .
R e c e n t Changes
P e r e n n i a l g r a s s e s a s a group I n c r e a s e d 3 5 p e r c e n t In
number o f s te m s from 1938 t o 1 9 3 9 , d e s p i t e a l o s s o f 56 p e r
c e n t by A gropyron s m l t h l i and 88 p e r c e n t by S t i o a s n a r t e a
(T a b le 2 ) .
The c h i e f g a i n s among mid g r a s s e s w ere t h o s e o f
Andropogon f u r c a t u s (1 2 8 p e r c e n t ) , S p o r o b o lu s h e t e r o l e p l a
( 1 5 7 p e r c e n t ) , and S. a s p e r ( 8 7 8 p e r c e n t ) .
In te r stitia l
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R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
15
g r a s s ob a l s o mad© l a r g e g a in s *
Panlcura o crib n o rla n u ro and
Poa p r a te , ria ls in c r e a s e d 556 arid 6 4 p e r c e n t , r e s p e c t i v e l y *
C o n v e r s e ly , forb® and a n n u a ls , w ith few e x c e p t i o n s , s u s t a in e d
h ea v y l o s s e s *
Growth d u r in g 1 9 4 0 was h in d e r e d by u n fa v o r a b le m o is t u r e
c o n d itio n s .
Only a few s p e c i e s flo w e r e d a b u n d a n tly .
f o r b s w ith l a r g e , u n d erg ro u n d
s t o r a g e o r g a n s w ere a b u n d an t
a s th o y w ere a l s o d u r in g p r e c e d in g d ry y e a r s .
o n e s w ere M i l UR m u ta b lle } ...
C e r ta in
Im p o rta n t
T r a r te s c a n tla b r a c t e a t a . S ene-olo
o l a t t e n s l s . and D elp h in iu m v i r o s c e n a *
*^eoda, a lth o u g h n o t
a b u n d a n t, w ere r e s t r i c t e d t o t h e a i t e m e a o f Agroovron. s m i t h ! i ,
Only t h r e e , O a p a e lla b u r s a - n a s t o r l a . Humex a c e t o s e l a . and
L a c tu c a s c a r l o l a jWere I m p o r ta n t.
P e r e n n ia l g ra sn e® a s a g r o u p wore red u ced 30 p e r c e n t
i n abu n d an ce i n 1940*
Among t h e im p o r ta n t s p e c i e s s u s t a i n i n g
l o s s e s w ere A ndrooogon f u r e a t u n . B u oh loe d e c t v 1 o l d e n .
hfiTQV'Yro o am lth.3,.i. ar.d Ppa n r a te n s.l.n .
o n ly t h r e e s p e c i e s ,
S t ln a a n a r t e a , Carex s p p . and Androno^on a c o o a r i u s . o&do
g a in s .
P e r e n n ia l f o r b s s u f f e r e d l o s s e s r a n g in g from 16 p e r
e< .-.t ( A s t e r m u l t i f l o r u s ? t o 100 p e r c e n t ( Q x& lis a t r l c t a and
d o lld a r .o g la b o r r im a ) •
A n n u als w ere n e a r ly t w ic e a s ab u n d an t
i n l ' :;4 0 a s In 1 9 3 9 , b u t t h e i r ab u n d an ce i n 1940 was J u s t
about o n e -tw e n tie th o f th a t in 1 9 3 0 .
B roau s te c to r u m
r e a c h e d u n u su a l ab u n d an ce i n 1938* b u t d is a p p e a r e d c o m p le t e ly
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
16
from t h e p l o t s i n 1939 and d id n o t r e a p p e a r In 194-0.
The a v e r a g e number o f s p e c i e s p er p l o t d e c r e a s e d from
14 in 193 8 t o 9 in 1939 and 1 9 4 0 .
The a v e r a g e number o f
b a r e d , o o u a r e - d e c im e t e r u n i t s p e r p l o t in c r e a s e d from 4
i n 1938 t o 5 and 6 , r e s p e c t i v e l y , i n 1939 and 1 9 4 0 .
Th" t o t a l
c o u n ts f o r s e e d l i n g s i n 1939 and 1940 w ere
18 and 5 3 i r e s p e c t i v e l y .
S p e c ie s p r o d u c in g s e e d l i n g s i n 1940
w ere Andropogon f u r c a t u s . A gropvron s a l t h l l . S t f p a s o a r t e a ,
and O x a lls a t r l c t a *
The L in c o ln Group
The L in c o ln grou p i n c l u d e s t h e B elm on t,.
E m erald,
L i n c o l n , and C re te p r a i r i e s w h ich a r e o n ly 15 m il e s a p a r t .
B e c a u se o f s i m i l a r i t y i n v e g e t a t i o n , to p o g r a p h y , and s o i l
th e y a r e t r e a t e d
to g e th e r .
C o m p o sitio n b e f o r e t h e D rought
T h ese s t a t i o n s w ore c l a s s i f i e d
(1 9 3 4 )
a s h lu e s t e m p r a i r i e s .
by w eaver and F i t z p a t r i c k
The v e g e t a t i o n was com posed
o f a h ig h p e r c e n t a g e o f A ndronogon seen :, r i u n . D tio a s r > a r te a .
S o o r o b o lu s h c t e r o l e r i s . D o u te lo u a g r a c i l i s . arid B .
c u r tl-
p e n d u la on t h e s l o p e s and r i d g e s , and a p red o m in a n ce o f
A ndrooo^on f u r c a t u a i n t h e r a v i n e s .
E a r ly Changes r e s u l t i n g from D rought
Marked c h a n g e s a p p e a r e d i n th e p r a i r i e c o v e r a f t e r
th e drought o f 1934.
The m ost e o n a p lc lo u s w ere r e d u c t io n
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
17
i n ab u n d an ce o f Andropogon s p p . , p a r t i c u l a r l y A, s c o p a r lu a :
t h e d is a p p e a r a n c e o f th e u n d e r s t o r y , and th e i n c r e a s e in
b o th x e r i c p e r e n n i a l s and a n n u a ls .
The tw o f o l l o w i n g y e a r s p ro d u ced f u r t h e r d e t e r i o r a t i o n .
L ess x e r ic s p e c ie s , p a r t ic u la r ly
Andropo.ro n s c o o a r l u s .
a g a in s u s t a in e d h ea v y l o s s e s , w h ile t h e more x e r i c o n es
in c r e a s e d .
P e r e n n ia l f o r b s d id n o t ch an ge a p p r e c ia b ly In
ab und ance.
The m oat c o n s p ic u o u s c h a n g e , h o w e v e r , was t h e
enorm ous i n c r e a s e in a n n u a l p l a n t s , e s p e c i a l l y L ep ld lu m
d e n s lflo r u m .
R ecen t Changes
An a n a l y s i s o f th e o r i g i n a l s e v e n p l o t s showed t h a t
p e r e n n i a l g r a s s e s in c r e a s e d 27 p e r c e n t from 1938 t o
1939 (T a b le 3 ) .
Im p o rta n t s p e c i e s m aking g a in s w ere
B o u t e lo u a c u r t l p e n d u l a . S p o r o b o lu s h e t e r o l e o l s . and
Andrononon f u r c a t u s .
A gron vron s m l t h l l .
The o n ly s p e c i e s t h a t d e c r e a s e d was
D e e p -r o o te d f o r b s l i k e
Amoroha
c a n e s c e n s d id n o t ch an ge a p p r e c ia b ly i n a b u n d a n ce, b u t
s h a l l o w - r o o t e d s p e c i e s s u f f e r e d h eavy l o s s e s .
A ste r
m u l t l f l o r u s was t h e o n ly fo r b t h a t i n c r e a s e d .
The p l a n t c o v e r rem ain ed open
d e s p i t e an in c r e a s e
I n p e r e n n i a l g r a s s e s and c e r t a i n f o r b s .
The a v e r a g e number
o f b a r e d u n i t s was 1 0 , com pared w ith 6 i n 1 9 3 8 .
T h ese
u n i t s w e re In v a d e d by h o r d e s o f a n n u a ls , th e m ost lm~
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 3*
Lincoln P r a ir ie s.
Number of stems o f most important s p e c ie s , percentage change
with permission
in abundance, and number o f square decim eters entered or vacated from 1938 to 1940.
S pecies
Humber o f stems
Percentage
change
of the copyright owner.
Further reproduction
prohibited
without permission.
1938
1939
1940
Agropyron sraith ii
654
346
498
47.1
Andropogon furcatus
328
495
429
50.9
-
13.3
+
Andropogon scoparius
174
218
248
25.2
+
13.8
Bouteloua curtipendula
478
717
475
50.0
-
33.8
Bouteloua g r a c ilis
802
1118
1020 ¥ 3 9 .4
-
8.8
Carex spp.
186
398
323
¥
114.0
-
46
69
98
+
50.0
' 204
232
Poa p ra ten sis
130
134
28
1-
Sporobolus asper
194
224
257
*
Sporobolus h etero lep is
253
406
S tip a spartea
103
167
Other sp ecies
64
58
3616
4582
14
14
1938-1939 1939-1940 1938-1940
square
Number o f
decimet*-r u n its
entered or () vacated
1940
1939
Perennial gra sses
K oeleria c r is ta ta
Panicum virgatum
Total
5(12)
8( 1) ■
30.8
3( 10)
7(3)
+
42.5
0( 0)
0( 1)
-
0.6
2( 8)
8( 6)
+
27.2
1( 0)
1( 0)
18.8
<► 73.7
4 (1 )
4 (D
42.0
¥
113.0
0( 1)
1( 0)
-
4 .7
¥
8 .3
0( 0)
1( 2)
3 .1
-
7 9 .1
-
78.5
1( 1)
0( 0)
15.5
+
14.7
+
32.5
2( 2)
4 (1 )
326 + 6O.5
-
19.7
¥
28.9
0 (3 )
4 (1 )
mm
45.5
mm
11.7
0( 1)
1 (3 )
0 .0
—
9 .4
1 (2 )
0 (1)
1 1 .1
¥
12.6
19(41
39(20)
2 8.6
mm
28.6
0( 1)
0( 0)
¥
221 +> 13.7
91
+
62.1
mm
9 .4
4072 ¥
26.7
10
0 .0
43.9
-
23.9
.
Perennial forbs
Araorpha canescens
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
with permission
+■ 14.7
+
32.5
2( 2)
4 (1 )
-
19.7
¥
28.9
0 (3 )
4 (1 )
62.1
mm 45.5
-
11.7
0( 1)
1 (3 )
58 _ 9 .4
58
3616 4582 4072 4* 26.7
0.0
9 .4
1( 2)
0( 1)
¥
Sporobolus asper
194
224
257
Sporobolus h ete ro lep is
253
406
326 + 60.5
S tip a spartea
103
167
Other sp ecies
Total
91
¥
15.5
..... 64
of the copyright owner.
Further reproduction
-
11.1
¥
12.6
19(41
39(20)
0,0
-
28,6
mm
28.6
0( 1)
0( 0)
238 ¥
3 .7
-
47.5
-
45.5
15(13)
10(19)
-
7 6 .9
1( 2)
6( 0)
50.8
1(16)
17(32)
11( 2)
27( 21)
Perennial forbs
10
prohibited without permission.
Araorpha canescens
14
14
A ster m u ltiflo r u s
437
453
13
10
3
-
2 3 .1
-
70.1
118
30
58
_
7 4 .6
+
582
507
309
mm
93.3
39.1
Brornus tectorum
19
151
829
¥ 694.7
¥ 449.0
♦ 426.3
3 (0 )
0 (3)
Erigeron ramosus
83
111
94
+
33.7
-
15.3
+
1 3 .3
1( 10)
1( 1)
Pectuca o c to flo r a l
65
6
15
-
9 0.8
+ I 50.0
-
7 6 .9
0(10)
2 (0 )
Hedeoma hisp id a
42
13
62
-
6 9 .0
+ 376.9
4- 47.6
0 (3 )
9 (0 )
2
0
168
+
4-8300.0
0( 0)-
25(0)
54
2
¥
8 0 .0
_ ? 6 .3 .
• --93.3
329
1155
¥
86.9
+
25I . I
¥ 560.0
0( 0)
4( 23)
2 (0 )
T otal
?°
176
39(4)
Grand T otal
4374
5418
5536
¥
23.9
+
2 .2
40(96)
105(45)
Solidago glaberrirna
Other sp ecies
Total
12.9
-
-
46.9
Annuals
Lepidfow dens’-fkrvm
Other sp ecies
- 100.0
^Number o f square decim eter u n its in v/hich sp e c ie s occurred*
+
2 6 .6
...
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
19
p o r t a n t o f w h ich w ere E r ig e r o n ram osua and Bromua
t e c to r u m ,
P e r e n n ia l g r a s s e s w ere -redu ced o v e r 11 p e r c e n t in
1 9 4 0 , n o t w it h s t a n d in g an a v e r a g e g a in o f 29 p e r c e n t hy
A grooyron s m l t h i l . A ndropogon s c o n a r lu s . K o e le r la c r l s t a t a .
and S p o r o b o lu s a s p e r .
O th er s p e c i e s w ere red u ced 5 t o 79
per c e n t.
P e r e n n ia l f o r b s l o s t 39 p e r c e n t b e c a u s e o f d e c r e a s e
i n w a te r c o n t e n t o f s o i l .
.Even th e d e e p ly r o o te d Axaornha
c a n e 3 c e a s s u s t a in e d a l o s s o f 29 p e r c e n t .
The d e a th o f t h e p e r e n n i a l s p e c i e s p rod u ced new b a r e d
u n i t s w h ich w ere q u ic k ly in v a d e d by Bromua te c to r u m and
o t h e r a n n u a ls .
T h ese p l a n t s becam e f o u r t o f i v e t im e s more
ab u n d an t th a n i n t h e p r e c e d in g y e a r , r e d u c in g th e a v e r a g e
number o f b a re d u n i t s from 10 t o 6 .
i n a l l p l o t s , h o w e v e r , i n c r e a s e d from
The number o f s p e c i e s
26 t o 3 4 , a n e t g a in
of 8.
S e e d l i n g s w ere n o t ab u n d an t e i t h e r y e a r o f th e s t u d y .
S u p p lem en ta ry s t u d i e s o f s e e d l i n g s co n d u cted on th e C rete
p r a i r i e show ed t h a t 33 p e r c e n t o f t h e f i r s t y e a r s e e d l i n g s
o f S p o r o b o lu s a s p e r s u r v iv e d t h e w in t e r o f 1 9 4 0 , and t h a t
75 p o r c e n t o f t h o s e one ye<*r aid o r o ld e r s u r v iv e d .
The s u r ­
v i v a l o f y e a r - o l d s e e d l i n g s o i o t l o a s p a r t e a was l e s s , b e in g
23 p e r c e n t , b u t t h a t o f t h e o ld e r o n es was g r e a t e r , 83 p e r
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
20
c e n t*
S ix p e r e n n ia l s p e c i e s ,
In vad ed th o p l o t s In 1 9 4 0 .
f o u r g r a s s e s and two f o r b e ,
One p l o t , a b o u t t h r e e s q u a r e f e e t
I n a r e a , was b a r e In 1 9 3 9 b u t c o n t a in e d 13 s e e d l i n g s t h e
next y ea r.
T h o se s e e d l i n g s w ere S p o r o b o lu s s a n e r . ban 1 cuts
scr.lbnerlnn.uCT. O r a lis o t r l c t a . and K rin ero n ra m o su s.
The i n s t a b i l i t y
o f th e p r a i r i e s p e c i e s p ro d u ced im ­
p o r t a n t c h a n g e s i n t h e p e r c e n t a g e c o m p o s it io n o f th o p l a n t
cover.
D ata from 14 b a s a l - a r o a q u a d r a t s , l o c a t e d on l o n g ,
s o u t h w e s t s l o p e s on th e C r e te and L in c o ln p r a i r i e s , a r e
sum m arised i n T a b le 4 ,
T a b lo 4 .
t o 1940
P e r c e n ta g e ch a n g e in p la n t c o v e r
from 1939
in 14 m e te r q u a d r a ts on th o c o u th s l o p e o f p r a i r i e s
a t L in c o ln and C r e t e .
S p e c ie s
P er1' c e n t o f cKartKO
tto q cr s lo p e L ld d le s io n e Lower s i o n e
Andropogon f u r c a t u s
*
Arud ro p o g o n &c o p a r iu s
- 1 8 .5
+ 4 2 .8
+ 1 0 0 .0
+
1*8
- 2 9 .3
B o u t e lo u a c u r t ip o n d u la
+ 2 0 .5
+ 4 5 .0
- 4 7 .1
Q arex s p p .
+ 1 1 .1
-
3 .6
-
K o e le r ia c r l s t a t a
— 4 6 .0
+
5 »0
+ 4 3 .4
Poa p r a t e n s i s
+ 2 0 .4
- 2 6 ,7
+ 1 0 .8
S p o r o b o lu s a s p e r
+ 5 6 6*7
- 1 2 .5
- 6 6 .7
S p o r o b o lu s h e t o r o l e p i s
- 1 1 .7
+ 1 8 .3
- 1 4 .1
3 tip a . s p s r t e a
- 2 6 .7
+ 4 1 .3
0 0 .0
F o rb s
- 2 5 .5
- 4 6 .0
- 3 5 .4
0 .9
7 .3
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
21
A ndropogon a c o p a r l u s . Poa p r a t e n a l s . and S p o r o b o lu s
a s p e r becam e more Im p o r ta n t on t h e u p p er s l o p e .
S o u t e lo u a
c u r t l p e n d u l a . S p o r o b o lu s h e t e r o l e p l s . and S t lp a s p a r t e a
in c r e a s e d i n im p o r ta n c e on t h e m id - s lo p e , w h ile Andropogon
f u r c a t u s and K o e le r la c r l s t a t a becam e more im p o r ta n t o n ly
on t h e lo w e r s l o p e ,
A g ro o v ro n s m l t h l l c o n tin u e d t o sp r e a d i n t h e B elm ont
p r a i r i e d e s p i t e an a v e r a g e r e d u c t io n o f
number o f s t e m s .
26 p e r c e n t in th e
The a r e a o f an a l t e r n e , mapped i n 1 9 3 8 ,
in c r e a s e d 11 p e r c e n t by 1939 and n e a r ly 15 p e r c e n t by
1940 ( F i g , 4 ) .
G r e a t e s t ch an ge i n boundary o c c u r r e d on th e
s o u t h and w e s t s i d e s w h ich 'were a d j a c e n t t o a r a v i n e .
A n a ly s is o f a t r a n s e c t l o c a t e d a c r o s s t h e s o u th w e s te r n
boundary o f t h e a l t e r n e
m ig r a te d 16 i n c h e s .
showed t h a t A gronvron s m l t h l l
T h is g r a s s f u r n is h e d o n ly 1 p e r c e n t
o f th e p la n t c o v e r i n t h e t r a n s e c t in 1 9 3 8 , 4 i n 1 9 3 9 , and
14 p e r c e n t i n 1 9 4 0 .
Pan1 cum v lr g a tu m and Panlcum s c r l b -
n erla n u m w ere c o m p le t e ly r e p la c e d w h ile Poa p r a t e n a ls and
A ndropogon f u r c a t u s s u f f e r e d l o s s e s o f 60 t o 86 p e r c e n t .
B a s a l a r e a d e c r e a s e d 50 p e r c e n t d u r in g t h e s e tw o y e a r s .
S t u d ie s c o n d u c te d a t Em erald r e v e a le d t h a t B o u te lo u a
g r a c i l i s was t h e o n ly s p e c i e s t o I n c r e a s e i t s
( F i g . 5 )»
te r r ito r y ,
A s t e r r o u l t l f l o r u s . S t l p a s p a r t e a . A groovron
s m l t h l i . and A ndropogon f u r c a t u s
w ere red u ced i n
a r e a 7 , 1 1 , 1 2 , and 22 p e r c e n t , r e s p e c t i v e l y .
S p o r o b o lu s
a a n e r . B o u t e lo u a c u r t l p e n d u l a . and Andropogon s c o p a r iu s
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
\
iV
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X
--------------
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y
\
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'
/
I
1
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I
1
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yi
1
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s
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j
s
X
- x .
X
—"
\
X
\
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\
\
—
——
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X
■
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r \
•*
S
.
F i g , 4 0— iiap sh o w in g s u c c e s s i v e c h a n g e s i n s i z e and sh a p e
o f a p o r t i o n o f an a l t e r n e o f A&ropyron s r a l t h i i a t B elm o n t,
The a n n u a l ch a n g e i n b o u n d a r y , a s A grop yron s p r e a d from th e
t o p t o b o tto m otlttem *?, i s i n d i c a t e d f o r 1 9 3 8 b y lo n g d a s h e s ,
f o r 1 9 3 9 by s h o r t d a s h e s , and f o r 19 4 0 b y a s o l i d l i n e .
I n c r e a s e I n a r e a d u r in g t h e t h r e e y e a r s was 1 4 * 5 p e r c e n t ,
Each squ are- r e p r e s e n t s an a r e a o f n i n e f e e t .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
with permission
VO
M
VO
VO
Hilltop
of the copyright owner.
B-
O
-3 0 .1
+40.0
“16.9
-1 0 .9
+225.0 “6 .9
-1 2 .5
-1 1 .9
Further reproduction
F ig . 6*—A b e lt tra n sect one meter vdde and 41 meters long a t Bnerald, extending from
th e top o f a h i l l to lower slope; per cent o f increase or decrease in area i s shov.n by fig u r e s .
prohibited without permission.
V ertica l iiatch, Agropyron sraith ii; dotted, Andropogon fu rca tu s; bare, Aster xau ltifloru s;
h orizon tal broken l i n e s , Bouteloua g r a c i l i s ; l e f t hatch, S tlp a sp a rtea . and crosshatch,
mixture o f S tip a spartea and Sporobolus h e te r o lo p is.
ho
22
in c r e a s e d i n a b u n d a n c e .
V a lp a r a is o P r a i r i e
C o m p o sitio n b e f o r e th e D rou ght
T h is a r e a was d e s c r ib e d i n 1930 a s a l i t t l e
b lu e s t e m
p r a i r i e w it h a good a d m ix tu r e o f A ndropogon f u r c a t u s .
Poa
p r a t e n a l s . S o rh h a stru m n u t a n s . B o u te lo u a c u r t l p e n d u l a . and
3 . A r a c l l l a o c c u r r e d o n ly i n s m a ll a m o u n ts.
A lt e r n e s o f
p r a i r i e d r o p s e e d w ere common on th e d r i e r r i d g e s .
E a r ly C hanges r e s u l t i n g from D rou gh t
N o tic e a b le ch an ges occu rred a f t e r th e drought o f
1934,
B a s a l c o v e r on th e u p p er s lo p e was red u ced 4 5 p e r
cen t.
The l e s s x e r i c g r a s s e s , p a r t i c u l a r l y Poa p r a t e n a l s ,
Panlcum s c r lb n e r la n u m . P . w llc o x la n u m . and A ndropogon
s c o p a r lu s and A. f u r c a t u s ; s u f f e r e d h ea v y l o s s e s .
C e r ta in
x e r i c s p e c i e s su c h a s B o u t e lo u a g r a c i l i s , Arcronvron s m l t h l l .
and A s t e r m u l t l f l o r u s . s p r e a d r a p i d l y .
S e e d lin g s o f K o c le r ia
c r l s t a t a . E r lg e r o n r a m o su s. an d~K uhnla g l u t i n o s a w ere
a b u n d a n t.
By 1 9 3 8 , b a s a l c o v e r had b e e n f u r t h e r r e d u c e d .
A l t e r n e s o f Ag.ro p yron s m l t h l i and B o u t e lo u a c u r t lp e n d u la
w ere common.
R e l i c t p a t c h e s o f A ndropogon f u r c a t u s o c c u r r e d
o n ly in t h e l o w e s t p l a c e s .
Amorpha c a n e s c e n s and A s t e r
m u l t l f l o r u s w ere t h e d o m in a n t f o r b s .
A n n u a ls, e s p e c i a l l y
Hedeoma h l s p l d a and L eo ld lu m d e n s i f l o r u m . w ere v e r y a b u n d a n t.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
R e ce n t Changes
S ev e n p erm an en t p l o t s w ere p la c e d on t h e p r a i r i e a t
V a lp a r a is o i n 1938 and a c e n s u s was ta k e n d u r in g e a c h y e a r
th e r e a fte r .
The a v e r a g e i n c r e a s e o f p e r e n n i a l g r a s s e s from
193 8 t o 193 9 was 4 0 p e r c e n t (T a b le 5 )♦
G r e a te st p e rcen ta g e
g a i n s w ere made by Ag;rony ron s m l t h l l (2 0 2 ) , Andronov on f u r ­
c a tu s
( 1 0 1 ) , and S p o r o b o lu s c r y p ta n d r u s ( 2 6 4 ) .
Only one
s p e c i e s , K o e l e r l a c r l s t a t a . was red u c e d i n a b u n d a n ce.
P e r e n n ia l f o r b s , e x c e p t Amorpha c a n e s c e n a and O x a lls s t r l c t a .
w ere r e d u c e d i n a b u n d a n c e,
Amorpha i s v e r y d e e p ly r o o t e d
an<* Q x a lls s t r l c t a made a s m a ll I n c r e a s e b e c a u s e o f i t s
e a r l y g r o w th .
A n n u a ls s u f f e r e d a l o s s o f 9 7 p e r c e n t .
Two
s p e c i e s , Hedeoma h i s o I d a and L en ld lu m d e n s l f l o r u a . w ere
e x c e e d l i n g l y a b u n d a n t i n 1938 b u t d is a p p e a r e d c o m p le te ly
from t h e p l o t s i n 1939*
Chenopodlum album and S a l s o l a
p e s t l f e r . b o t h s h a l l o w l y r o o t e d , becam e n o t o n ly '’abundant
b u t a l s o w id e ly d i s t r i b u t e d .
The a v e r a g e number o f b a r e d u n i t s was n e a r ly t r e b l e d
In 1 9 3 9 , and t h e t o t a l number o f s p e c i e s was red u ced from
31 to 2 3 , a n et lo s s o f 8 .
P e r e n n ia l g r a s s e s w ere red u ced SLI p e r c e n t d e s p i t e an
a v e r a g e I n c r e a s e o f 4 1 p e r c e n t by Ap;rooyron s m l t h l l and
o t h e r n o r t h e r n s p e c i e s in 1 9 4 0 .
G r a s s e s o f summer g r o w th ,
p a r t i c u l a r l y B o u t e lo u a c u r t lp e n d u la and S p o r o b o lu s a s n e r .
s u s t a in e d l o s s e s o f 3 t o 80 p e r c e n t .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 5«
V alparaiso P r a ir ie .
Number o f stems o f most important s p e c ie s , percentage,-change
with permission
in abundance, and number o f square decim eters entered or vacated from 1938 to 1940*
Sp ecies
Number o f stems
change
Percental;e
of the copyright owner.
1938-1939 1939-1940 1938-1940
Number o f new square
decim eter u n its
Entered or ( ) vacated
1940
1939
Further reproduction
prohibited without permission.
1938
1939
1940
Agropyron s m ith ii
130
392
553
4 201.5
4
4 1 .1
+ 325.4
2( 1)
11( 1)
Andropogon furcatus
173
348
638
4 101.2
4
8 3 .3
4
268.8
6(3)
5(0)
Bouteloua curtlpendula
971
2140
1649
4
169.8
22.9
4
69.8
6(9)
18(2)
7155
8540
658I
4
1 9 .4
-
2 2 .9
-
8.0
0(4)
17(3)
Carex app.
96
225
179
+ 134.4
-
20,4
4
86,5
5(1)
6( 0)
K oeleria c r is ta t a
95
51
53
-
46.3
4
13.7
-
38.9
0( 0)
0( 0)
0
34
33
4
-
2 .9
4
0( 2)
1( 0)
'36
114
23
4
Sporobolus cryptandrus
33
120
90
Sporobolus h e te ro lep is
11
21
26
S tip a spartea
2
226
Other sp e c ie s
119
224
0
+
88.2
8821 12435
9875
4
4 0 .4
P erennial g rasses
Bouteloua g r a c i l i s
Poa p ra ten sis
Sporobolus asper
T otal
mm
7 9 .8
-
36.1
2 (0)
2(0)
4 263.6
-
2 5 .0
4
172.7
0(0)
1 (0 ) .
+
90.9
4
23.8
4
136.4
0(0)
0(0)
45 +11200.0
-
80.1
42150.0
0( 0)
3(0)
100.0
- 100.0
0( 0)
216.7
—
2 0 .5 “
4
13.5
21(20)
.
0( 1)
64(7)
P erennial forbs
Amorpha canescens
8
8
4
A ster m u ltlflo ru s
529
222
260
-
a .0
mm
50.0
-
50.0
0 (0 )
0(0)
58.0
4
1 7 .1
-
50.9
8(24)
18(2)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
4
with permission
of the copyright owner.
0
34
33
Sporobolus asper
36
114
23
Sporobolus cryptandrus
33
120
Sporobolus h e te ro le p is
n
21
S tip a spartea
2
226
Other sp e c ie s
119
224
0
+
8821 12435
9875
+
Poa p ra ten sis
T otal
Further reproduction
+
ou;
no;
36.1
2 (0 )
2 (0 )
2 5 .0
+ 172,7
0( 0)
1( 0)
4
23.8
+ 136.4
0(0)
0 (0 )
-
8 0 .1
+2150.0
0 (0 )
3 (o)
88.2
- 100.0
- 100.0
...........0( 0)
0( 1)
40*4
-
2 0 .5
+
13.5
21(20)
64(7)
0.0
-
50.0
-
50.0
0 (0 )
0(0)
+
1 7 .1
-
50.9
8(24)
18(2)
0(0)
5(0)
-0i23)._
1( 0)
-
2 .9
+ 216.7
-
79.8
-
90
4 263.6
-
26
+
90.9
45 +11200.0
.
P eren n ial forbs
prohibited
without permission.
Amorpha canescens
8
8
4
A ster m u ltiflo ru s
529
222
260
58.0
Qxalia s t r ic t a
8
11
91
+ 37.5
4 727.3
+1037.5
Other sp e c ie s
96
1
42
93.9
+4100.0
- . 56.3
641
242
397
62.2
4 64.4
-
20
38
300
90 .0
4 689.5
Hedeoma h isp id a
684
0
767
- 100.0
Lepidiwin c/tnji/Zoro m
837
0
1422
100.0
2
12
265
5
W
55
3199
T otal
-
3 8 .0
.-
8(47)
24(2)
+1400.0
0 (2 )
49(0)
+
4 12.1
0(77)
52( 0)
4
+
0(72)
97(0)
Annuals
Chenopodium album
S a lso la p e s t if e r
Other sp e c ie s
Total
Grand T otal
1584
IO546 12732 1347/
69.9
500.0
+2108.3
+13150.0
6(1)
44(0)
87.8
48800.0
+ 985.3
0 (5 )
32(0)
-
96.5
+5716.1
+ 102.4
6(157) 274(0)
+
21.7
+
+
+
4 .9
27.7
35(224) 362(9)
_
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
P e r e n n ia l f o r b s p r o f i t e d by th o d e c r e a s e I n p e r e n n i a l
g r a s s e s and i n c r e a s e d 6 # p e r c e n t ,
Amornha canoecerrn was th o
o n ly s p e c i e s w h ic h d id n o t I n c r e a s e .
Two a l t o m e s o f Ar.ropyron s m l t h l l ware c h a r te d d u r in g
ea c h summer*
They showed an a v e r a g e g a in i n a r e a (1 9 3 8 t o
1 9 3 9 ) o f a b o u t 50 p e r c e n t ( F i g . 6 ) .
T h ese g a i n s wore made
a t t h e e x p e n s e o f B o u te lo u a cu r t 1nend u l a *
D ata from a s e r i e s
o f q u a d r a ts l o c a t e d w it h in th o a l t e r n e s show ed t h a t Ar.ronvron
sk i 1 th 11
in c r e a s e d 80 p e r c e n t and a l s o red u ced tit© number o f.
b a red u n i t s 8 0 p e r c e n t .
A n n u a ls, p a r t i c u l a r l y
r o o te d w e e d s , w ore v e r y a b u n d an t o n ly In 1940*
s h a llo w The d r y in g
o f th e s o i l by A groovron s m l t h l l c a u s e d h eavy l o o s e s t o
K o e lo r la c r i s t a t e and B o u te lo u a o u r t lo e n d u la ( F i g . ? ) •
Dead crow n s o f B o u te lo u a w ere q u i t e common.
D e e p -r o o te d
f o r b s l i k e w i s e s u f f e r e d h ea v y l o s s e s a s may be soon in T a b le 6 .
T a b le 6*
V a r i a t i o n I n abun dan ce o f Im p o rta n t d e e p -
r o o t e d f o r b s from 1939 t o 1940 a t V a lp a r a i s o # N ebraska*
S p e c ie s
1940
P er cen t
chantse
B u n d ie s Stem s B unches Stem s Bunches Stem s
1939
K uhnla g l u t l n o o a
20
270
4
89
- 8 0 .0
-6 7 .0
L ia t r lo p u n c ta ta
7
18
6
30
— 1 4 .2
+ 6 6 .7
16
30
10
18
- 3 7 .5
-4o*0
1
4
0
0
- 1 0 0 .0
-100.0
Hosa a rk a n o a n a
S a lv ia p ltc h e r l
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
i
i
!
i
i
I
— \
\
•
- .
.
■
'■
»
■• ■
F i g . o • — A lt e r n e o f Agrop;?ron s m l t h l l a t V a lp a r a is o sh o w in g
c h a n g e s I n a r e a from 193B ( l o n g b ro k e n l i n e s )
k en l i n o s )
and t o 1 9 4 0 ( s o l i d l i n e ) *
t o 1 9 3 9 ( s h o r t b ro­
I n c r e a s e i n a r e a fro ® 1 9 3 8
t o 1 9 3 9 w as 3*8 p e r c e n t , and t h a t fr o ® 19 3 9 t o 194.0 was 5 3 .1 p ar
c e n t*
B ach s q u a r e r e p r e s e n t s an a r e a o f f o u r sq u a r e f e e t *
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
2£&
!
*
*
F i g , 7 * — M eter q u a d ra t on h i l l t o p
a t V a lp a r a is o
sh o w in g d e a t h o f B o u te lo u a c u r t lp e n d u l a and in v a s io n
o f. AK ropyron s m l t h l l a s a r e s u l t o f d r o u g h t .
f i r s t c h a r t ! n g , Junes, 1 9 2 9 ( l e f t ) ,
The
show s t h a t Boute**
lo u a c u r t l p e n d u l a ( l e f t h a t c h ) o c c u p ie d a b o u t 3 $ p er
c e n t o f th e p l o t .
I n d i v i d u a l s te m s o f A grop yron a r e
r e p r e s e n t e d by + •
B a red a r e a s a r e u n h a tc h e d .
By
J u n e , 1 9 4 0 ( r i g h t ) , A&ropyron h ad in v a d e d a l l b u t
a b o u t 4 2 p e r cirnt of. t h e t e r r i t o r y f o r m e r ly o c c u p ie d
by B o u t e lo u a .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
26
None o f t h e many s e e d l i n g s o f B o u te lo u a c u r t lp o n d u la
o b s e r v e d i n 1939 s u r v iv e d th e w in t e r o f 19^0*
H ebron P r a i r i e
C o m p o sitio n b e f o r e th e D rou gh t
The H ebron p r a i r i e w as d om in ated in 1931 by Androppgon
s c o p a r lu s on t h e h i l l t o p , by Andropogon s c o p a r lu s and
A, f u r c a t u s on th e m id s lo p e , and by A. f u r c a t u s a lo n e on
t h e lo w e r s l o p e and b o tto m la n d ,
K o e le r la c r l s t a t a was
w id e ly d i s t r i b u t e d th r o u g h o u t th e p r a i r i e .
B o u te lo u a
c u r t lp e n d u la and B . g r a c i l i s w ere ab u n d an t o n ly on th e
s lo p e s .
S t fp a a p a r t e a was r e s t r i c t e d t o th e S h e lb y f i n e
san d y loam s o i l o f t h e n o r t h e a s t e r n o n e - f o u r t h o f t h e
p r a ir ie .
E a r ly C hanges r e s u l t i n g from D rou gh t
E a r ly i n th e summer o f 1 9 3 5 , la r g e q u a n t i t i e s o f d u s t
from a d j a c e n t c u l t i v a t e d f i e l d s w ere b low n o v e r th e w e s te r n
h a lf o f th e p r a ir ie .
w ere c o m p le t e ly k i l l e d
rod s.
N e a r ly a l l o f t h e p e r e n n ia l s p e c i e s
o r b a d ly damaged o v e r many sq u a re
The e s t im a t e d l o s s e s r e s u l t i n g from b o th d ro u g h t and
d u s t d e p o s i t s v a r ie d from 95 p e r c e n t on u p p er and m id d le
s l o p e s o f s o u t h f a c i n g h i l l s t o 10 p e r c e n t n e a r t h e i r
f o o t (W eaver and A l b e r t s o n , 1 9 3 6 ) .
The o p e n in g o f t h e p l a n t c o v e r , p a r t i c u l a r l y on
s l o p e s , p e r m it t e d t h e in v a s i o n o f n a t iv e a n n u a ls and w e e d s .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
27
The l a t t e r becam e s o ab u n d an t t h a t b u r n in g was used a s a m ethod
o f c o n tr o l.
The m ost r em a rk a b le i n v a s i o n , h o w e v e r , was made
b y Ap:ropyron s m l t h l l .
Sy 19 3 6 t h i s s p e c i e s , v/hich fo r m e r ly
o c c u r r e d o n ly s p a r i n g l y , was i n c o m p le te p o s s e s s i o n o f two
l a r g e a r e a s w h ich had b ee n c o v e r e d w ith d e p o s i t s o f d u s t .
S u b se q u e n t s t u d i e s h a v e shown t h a t th e wave r e a ch ed i t s p eak
in 1939.
M u e lle r (194-1) p o i n t s o u t t h a t r e c e n t g a in s in
a r e a made by t h i s s p e c i e s a r e due t o i t s a b i l i t y
a d j u s t m e n t s and m a in ta in v i a b i l i t y
of it s
t o make
rh izo m es u n d er
s o i l d e p o s i t s o f g r e a t d e p th s a s w e l l a s th r o u g h lo n g
p e r io d s o f d e s i c c a t i o n .
B o u t e lo u a g r a c i l i s had a lw a y s o c c u r r e d i n s m a ll
am ounts i n t h e p r a i r i e .
A f t e r th e d ro u g h t o f 1 9 3 6 , i t
b eg a n t o s p r e a d u n t i l 1 9 3 9 , a f t e r w h ich i t
(F ig . 8 ) .
l o s t h e a v ily
B . c u r t lp e n d u la a l s o in v a d e d th e n ew ly b a r e d
a r e a s , r e a c h in g maximum ab u n d an ce i n 1 9 3 9 .
D u rin g t h i s
y e a r a few d i s e a s e d p l a n t s -were o b s e r v e d b u t by 1940
a b o u t f i v e p e r c e n t o f th e b u n ch es w ere a f f e c t e d .
The
n a t u r e and e x t e n t o f t h i s d i s e a s e h ave b e e n d i s c u s s e d
e ls e w h e r e ( F o w le r and W eaver, 1 9 4 0 ) .
R e c e n t C hanges
An a n a l y s i s o f 13 p erm anent p l o t s r e v e a le d t h a t
p e r e n n i a l g r a s s e s I n c r e a s e d 28 p e r c e n t in abundance from
193 8 t o 1939 ( T a b le 7 ) .
A l l s p e c i e s e x c e p t Androoogon
f u r c a t u s and Poa p r a t e n s l s made g a i n s .
T h is o c c u r r e d
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
274
i»
'
F i g . -8 * —- I n v a s io n o f B o u t e lo u a g r a c i l i s
(lig h t)
i n t o A ndropogon f u r c a t u s (d a r k ) a t H eb ron , A u g u st
17, 1940.
P h o to g ra p h ed b y J . E» W eaver.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 7 ,
Hebron P r a ir ie .
Number o f stems o f most important s p e c ie s , percentage change in
with permission
abundance, and number o f square decim eters entered or vacated from 1938 t o 1940.
Number o f steins
S p ecies
Percentage
of the copyright owner.
Further reproduction
1938
1939
1940
953
1148
1112 4 20,5
Andropogon furcatus
2157
1?/,/,
736
-
Andropogon scoparius
1049
1280
Bouteloua curtipendula
1239
Bouteloua g r a c ilis
Number c f
square
decim eter u n its
entered or ( ) vacated
change
1938-1939 1939-1940 1938-1940
1939
1940
Perennial g ra sses
Agropyron s m ith ii
prohibited without permission.
4
16.7
0( 0)
0(0)
40.8
mm
65.9
6(8)
2(5)
-
61.9
mm
53.5
0 (0 )
0( 1)
4 57.1
-
30.5
4
9 .2
6 (4 )
2(1)
4 125.3
-
50,9
i
9 .6
1 (1 )
1( 0)
4
192.5
-
86.3
-
59.9
7(0)
0 (1 )
396
4
80.5
-
53.4
-
15.9
0 (0 )
0( 0)
35
4
169.0
-
77.6
-
39.7
0 (0 )
0( 0)
378 4
0 ,5
—
64.4
-
64.2
0 (6 )
0 (1 )
- 100.0
0( 0)
0 (1 )
-
0(0)
0(0)
0( 0)
0 (0 )
415400.0
0 (0 )
0(0)
8 6 .2
0(0)
0(0)
-
3 .1
42.3
-
488
4 2 2 ,0
1946
1353
1588
3547
l? a
Bouteloua h irsu ta
252
737
101
Carex spp.
471
85O
58
156
Flymus canadensis
K oeleria c r is ta ta
.
IO56 1061
48
74
0
4
54.2
- 100.0
Panicum virgatum
194
341
169
4
75.8
-
50.4
Sporobolus asper
0
30
19
4
-
'36.7
Sporobolus cryptandrus
3
111
465
4
360.0
S tip a apartea
218
315
30
4
44.5
-
Other sp e cie s
3
b
0
4
33.3
- 100.0
mm
100.0
0 ( 1)
0 (0 )
9305 12840 7023
4
27.5
-
<m
24.5
20(20)
5(10)
Panicura scribnerianuni
T otal
4 318.9
90.5
43.5
1 2 ,9
4
-
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Sporobolus cryptan drus
with permission
3
111
465
S tip a spartea
218
315
30
Other sp e c ie s
3
4
0
9305 12840
Total
+ 360.0
+ 318.9
4
-
44.5
90.5
H 5 4 0 0 .0
-
0 (0 )
0 (0 )
8 6 .2
0 (0 )
0(0)
o(0
0 ( 0)
of the copyright owner.
4 -33*3
- 100.0
- 100.0
7023
4
27*5
-
43.5
-
24.5
20( 20)
5(10)
«•
38.8
-
18.3
-
50.0
0(2 )
1( 0)
-
8 7 .0
-
71.4'
-
96.3
0( 0)
1( 0)
- 100*0
0( 0)
0 (0 )
3(0)
Perennial forbe
Further reproduction
prohibited
without permission.
Amorpha canescens
116
71
58
Aster m u ltiflo ru s
54
7
2
6
2
0
50.0
- 100.0
10
25
74.4
4
1 5 0 .u
~
35.9 •
Total
3?
215
90
85
58.1
-
5 .6
-
60*5
0( 1)
0( 3)
Bromus tectorum
1998
1129
2245
43.5
4
98.8
4
1 2 ,4
0 (2 )
2 (0)
781
270
194
-
65.4
— 28.1
- * 7 5 .2
3(21)
13(1)
45
34
331
-
2 4 .4
+ 873.5
4-6356.0
2 (4 )
12(1)
202
534
213
+ 164*4
-
+
1 5 .4
0 (1 )
1(0)
1
3
199
4 2.00,0
+ 653.3
+19800.0
1 (1 )
5(0)
Plant ado jiu’s h ii
53
63
S a lso la p e s t iie r
4
80
103
0
O xalis s tr ic t a
Other sp e cie s
-
5(0)
Annuals
Festuea o c to flo ra 1
Kedeorna hispida
Hordetun puMllum
Lepidiui d*rt*i /torum
Other sp e c ie s
T otal
Grand Total.
60.1
252 + 18.9
+
300.0
+-'375.5
3 (0)
9(0)
34
4-1900,0
-
57.5
4 750.0
7 (0 )
3 (0)
76
—
-
0 (1 )
3(0)
100.0
4
26.2
1843 :3350
+
23*4
4
81,0
4- 39.2
16(30)
48(2)
11929 14773 10459
4
15.9
-
28.5
-
36(53)
58(12)
240?
Number o f square decim eter u n its in v'hich co ecies occurred.
17.7
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
29
d e s p i t e t h e f a c t t h a t 1939 was th e t h ir d h o t t e s t y e a r on
r e c o r d and t h a t p e r io d s o f d r o u g h t w ere o f f r e q u e n t o c c u r r e n c e .
In f a c t , t h e r e was a lw a y s a v a i l a b l e w a te r In th e s o i l and
s u b s o i l t o a d e p th o f 6 f e e t .
P e r e n n ia l f o r b s w ere r ed u ced i n 1939 t o 58 p e r c e n t
o f t h e ir 1938 ab u n d an ce.
Amornha c a n e s e e a s . A s t e r m u lt i-
f l o r u s f and O x a lls s t r l o t a s u s t a in e d t h e h e a v i e s t l o s s e s .
A n n u a ls a s a g ro u p in c r e a s e d 23 p e r c e n t in 1939♦
Hordeum p u s l l l u m . L ep ld iu m d e n s if lo r u x n . F la n t a g o n u r s h l l . and
S a l s o l a n e s t l f e r w ere among t h e im p o r ta n t s p e c i e s m aking
g a i n s , w h i l e Bromus t e c t o r u m . F e s t u c a o c t o f l o r a . and
Hedeoma h l a o l d a w ere among t h o s e s u f f e r i n g l o s s e s .
The c o n t i n u a t i o n o f th e d r o u g h t In 194-0 r e s u l t e d i n
fu r th e r changes in th e p la n t c o v e r .
Dead crow ns o f Andro-
p ogon f u r c a t u s and 3 o u t e lo u a c u r t lo e a c lu la w ere o b s e r v e d
e v e r y w h e r e b u t w ere ' e s p e c i a l l y
common on s l o p e s .
A fte r
c a r e f u l r e c o n n a i s s a n c e , d r o u g h t l o s s e s o f B o u te lo u a
c u r t i p e n d u l a w ere fou n d n o t t o e x c e e d 10 p e r c e n t ; t h o s e
o f Andropo^on s c o p a r lu s w ere a b o u t 5 p e r c e n t , and t h o s e o f
A . f u r c a t u s w ere a p p r o x im a te ly
15 p e r c e n t .
*
In l o c a l
a r e a s , h o w e v e r , t h e l o s s o f A. f u r c a t u s was f r e q u e n t l y
a s h ig h a s 80 p e r c e n t .
N ew ly b a red u n i t s w ere in v a d e d by
Hedeoma h l s p l d a . Hordeum p u s l l l u m . P la n t a g o p u r s h l l . and
F e stu c a o c t o f lo r a .
A l l p e r e n n ia l and a n n u a l s p e c i e s w ere
red u c ed i n h e i g h t and w ith th e e x c e p t i o n o f B o u te lo u a
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
30
g r a c i l i s . f lo w e r e d s p a r i n g l y .
B e l l e v i l l e P r a ir ie
C o m p o sitio n b e f o r e th e D rou gh t
B e f o r e t h e d r o u g h t o f 1 9 3 4 , th e B e l l e v i l l e p r a i r i e
was d o m in a ted on t h e u p la n d s by Andronogon s c o p a r lu s and
K o e le r la c r l s t a t a .
m ost partjvdth
The lo w la n d s w ere c o v e r e d , f o r th e
A ndroporon f u r c a t u s
w h ich w it h o t h e r t a l l
g r a s s e s ^ aa filvm us c a n a d e n s is and Pan!cum Y irg n tu ctj o c c u p ie d
th e w e tte r a r e a s .
B u c h lo e d a c t v l o l d e s and B o u te lo u a
g r a c i l i s , e i t h e r i n p u re o r m ixed p a t c h e s , o c c u r r e d on th e
s t e e p s lo p e s t o g e t h e r w i t h S p o r o b o lu s a s p e r . Q p u n tla
h u m lf u s a . P I a n ta r o p u r s h l l . and Hedeoma h l s p l d a .
B o u te lo u a
c u r t lp e n d u la was w id e ly d i s t r i b u t e d th r o u g h o u t th e p r a i r i e , ,
b u t A grop yron s m i t h l l was r e s t r i c t e d t o a s t e e p - s i d e d
h o llo w i n t h e n o r t h e a s t c o r n e r .
E a r ly Changes r e s u l t i n g from D rought
T h ree s u c c e s s i v e y e a r s o f d ro u g h t p ro d u ced g r e a t
c h a n g e s i n th e c o m p o s it io n o f th e v e g e t a t i o n .
A gronvron
s m i t h l l com posed 65 p e r c e n t o f th e c o v e r and Androporeon
f u r c a t u s m ost o f th e r e m a in d e r .
t a l l - g r a s s w as k i l l e d .
A bout 9 3 p e r c e n t o f t h e
Andropogon s c o p a r lu s s u s t a in e d th e
h e a v i e s t l o s s e s , e s p e c i a l l y on s l o p e s w here o n ly a t r a c e
r e m a in e d .
B o u te lo u a c u r t lp e n d u la in c r e a s e d l a abundance
and becam e w id e ly d i s t r i b u t e d .
B u ch lo e d a c t v l o l d e s and
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
u r v le r s to r y d is a p p e a r e d c o m p l e t e l y » and a n n u a ls becam e v e r y
common.
D e f i c i e n c y o f s o i l m o is t u r e , p r e v a le n c e o f h ig h
t e m p e r a t u r e s , and l o c a l c o v e r a g e by d u s t a l l c o n t r ib u t e d
t o t h o s e c h a n g e s i n p la n t p o p u la t io n *
R ec en t C hanges
A c e n s u s o f t h e perm an ent p l o t s i n 1939 show ed t h a t
a l l n a t iv e p e r e n n ia l o p o c io s b u t one I n c r e a s e d in abundance
(T a b le 8 }*
The s i n g l e e x c e p t i o n »vas t h a t o f Ataoroha c a n e s c e n a
w h ich l o s t 11 p e r c e n t ( F ig * 9 ) *
A n n u als w ere red u ced 1 p o r
c e n t d e s p i t e th e enorm ous i n c r e a s e i n P ia n ta ^ o n u r s h l i *
Among p e r e n n i a l s , Andropov.on s c o p a r lu s mad© th o l a r g e s t g a i n s
(1 1 3 p o r c e n t ) vihil© o t h e r g r a s s e s , in c l u d i n g A. f u r c a t u s .
b o u t e lo u a o u r t i n m d u i a . B . r r a s i l l s . and S p o r o b o lu s a s n o r ,
mad© an a v e r a g e i n c r e a s e o f 6 4 p e r c e n t *
P e r e n n ia l fo r b o
a s a grou p in c r e a s e d 36 p e r c e n t in a b u n d a n ce.
An-Irono ••on s c o p a r lu s and A. f u r c a t u s wore t h e o n ly
im p o r ta n t s p e c i e s t o make g a i n s in 1 9 4 0 ; o t h e r s s u s t a in e d
l o s s e s o f 3 t o 58 p e r c e n t w it h a mean l o s s o f 22 p o r c e n t .
A n n u a ls w ore re d u ced 43 p e r c e n t i n abun dan ce d e s p i t e t h e
g a i n s o f Hordeum n u a iilu m and L co ld lu m d c n s lf lo r u m *
R o b e r tso n (1 9 3 9 )
th o p l o t s i n 1 9 3 6 .
to 3 1 .
reco rd ed a t o t a l o f 54 s p e c ie s in
By 1 9 4 0 , t h i s number had b een red u c e d
D u rin g th e f i r s t y e a r o f t h i s s t u d y , t h e number o f
s p e c i e s p o r p l o t was re d u c ed from 1 4 , 4 t o 1 3 * 5 , and. d u r in g
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
3lA
i
P i g . 9 . — Amorpha c a n e s e e n s l a t h e m ost ab un dan t
and m ost w id e ly d i s t r i b u t e d o f a l l f o r b s a t B e l l e v i l l e .
P h o to g r a p h e d b y J . E . W eaver#
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 8*
Beleville Prairie*
Number of stems of most important species, percentage change in
with permission
abundance, and number of square decimeters entered or vacated from 1938 to 1940,
Sp ecies
Number o f stems
Percentage
of the copyright owner.
Further reproduction
1928
19?9
1940
906
1215
971
4
34.1
mm
.845
1365
1474
4
61.5
30
64
134
Bouteloua curtlpendula
2721
4544
2724
Bouteloua g r a c i l i s
6604 10662
Number of
square
decim eter u n its
entered or () vacated
change
1938-1939 1939-1940 1938-1940
1939
1940
Perennial grasses
Agropyron sm ith ii
Andropogon furcatus
Andropogon scoparius
Buchloe dactyloides^
20.1
4
7 .1
0 (1 )
0(3)
4
8 .0
4
7 4 .4
1 (0 )
0(0)
+ 113.3
4
109.4
4
346.7
0 (0)
0 (0 )
4
67.0
-
4 0 .1
4
0 .1
0 (0 )
0 (2)
9191
4
6 1 .4
-
13.8
4
39.2
1(0)
0 (1)
15.05 15.50 13.32
4
3 .0
«•»
1 4 .1
-
11,5
0 (0 )
o(o)
prohibited
without permission.
199
304
277
4
52.8
-
8 .9
4
39.2
0 (0 )
0 (1 )
• 326
428
281
4
31.3
-
34.3
-
13.8
0(0)
0 (0 )
Panicum virgatum
219
268
267
4
22.4
-
0 .4
4
21.9
0 (0 )
0(0)
Sporobolus asper
446
686
553
4
53.8 . -
1 9 .4
4
23.9
0 (0 )
0(0)
Sporobolus cryptandrus
120
202
175
4
68,3
1 3 .4
4
45.8
2 (0 )
0(1)
24
200
107
4
733.3
4.6*5
4
345.8
0 (0 )
0 (1 )
12440 19938 16154
4
60.3
•m
1 9 .0
+
30.0
4 (1 )
0 (9)
10.5
-
2 .9
-
13.2
1 (0)
0(0)
0 .0
4 200.0
2 (0 )
0(0)
Carex spp.
K oeleria c r is ta t a
Other sp ecie s
Total
-
Perennial forb s
Amorpha canescens
38
34
33
-
Aster m u ltiflo r a s
4
12
12
4 200.0
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
*
Reproduced
with permission
Sporobolus asper
446
686
553
Sporobolus cryptandrus
120
202
24
200
w
\ v/
23.9
0( 0)
0( 0)
53.8
-
1 9 .4
175
68,3
-
1 3 .4
45.8
2( 0)
0( 1)
107
733.3
-
4 6.?
345*8
0( 0)
0( 1)
12440 19938 16154
6O.3
-
19.0
30.0
4 (1 )
0(9)
10.5
-
Other sp e cie s
Total
/
v»*t
+
+
Perennial forb s
of the copyright owner.
Further reproduction
Araorpha canescens
38
34
33
rtster m u ltiflo ru s
4
12
12
200.0
L ia tr is punctata
3
10
7
+ 233.3
1?
V-
T otal
64
87
Bromus tectorum
651
Festuca octoflora^
Other species
-
-
2 .9
-
13.2
1( 0)
0( 0)
0.0
+
200.0
2( 0)
0( 0)
+ 133.3
0( 0)
0( 0)
31.6
1,6
2( 0)
0( 0)
5(0)
0( 0)
30.0
+
61.2
65
t
35.9
-
2 5.3
455
265
-
30.1
-
41.8
-
59.3
10(3)
2( 4)
606
469
124
-
22.6
-
73.6
-
79.5
6 (3 )
5(10)
62
7
9
mm
88.7
+
28.6
-
85.5
0( 0)
1( 0)
0
5
57
+
0( 0)
0(1)
44
124
0( 0)
0( 2)
24
200
107
+
733.3
0 (0 )
0( 1)
781
791
448
+
1 .3
42.6
16(6)
8(18)
13285 20816 16667
+
56.7
25.5
-25(7)
8(27)
58.1
..
—
Annuals
prohibited
Hordeum puc ilium.
without permission.
Plantago p u rsh ii
Lepicium densif/ot-Um
.
Other sp e c ie s
T otal
Grand T otal
+
10 + 181.8
+1040.0
-
91.9
mm
7 7 .2
46.5
+
3 45.8
-
4 3 .4
-
-
19.9
Estimated cover in per cent
2
Number of square decimeter units in which species occurred
.
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
t h e s e c o n d y e a r i t was f u r t h e r red u ced t o 1 1 . 8 .
The l a r g e s t
number o f b a r e u n i t s p e r p l o t ( 1 . 7 ) was r e c o r d e d In 1 9 3 9 ,
w h ile t h e s m a l l e s t number ( 0 . 4 ) was fou n d in 1 9 4 0 .
S e e d l i n g s o f p e r e n n i a l g r a s s e s w ere n o t common e i t h e r
year.
T h ose o f S p o r o b o lu s a s n o r , B o u te lo u a g r a c i l i s ^ K o e le r la
c r l s t a t a . w ere t h e o n ly o n e s o b s e r v e d .
WHEATGRASS PRAIRIES
F o u r p r a i r i e s a r e I n c lu d e d i n t h i s g r o u p .
lo c a t e d
They a r e
n e a r C lay C e n te r , C a r le t o n , and N e ls o n , N eb rask a,
and M o n tr o se , K a n sa s, r e s p e c t i v e l y .
C lay C e n te r P r a i r i e
C o m p o sitio n b e f o r e t h e D rou gh t
The C lay C e n te r p r a i r i e was c h a r a c t e r iz e d in 1931
by W eaver and A lb e r t s o n (1 9 3 6 )
p r a ir ie .
as a t y p ic a l l i t t l e
b lu e s te m
A ndropogon s c o p a r lu s o f b o th sod and bunch ty p e
u s u a l l y f u r n is h e d a s much a s 9 3 p e r c e n t o f t h e c o v e r b u t
in p l a c e s
f u r c a t u s f r e q u e n t l y c o n s t i t u t e d 25 p e r c e n t o f
th e v e g e ta tio n .
In d r i e r p a r t s o f t h e p r a i r i e , B u n h loe
d a c t v l o l d e s . B o u t e lo u a g r a c i l i s . and K o e le r la c r l s t a t a were
a b u n d a n t.
S p o r o b o lu s c r v n t a n d r u s . F e s tu c a o c t o f l o r a . and
A grop yron s m i t h l l o c c u r r e d in s m a ll am ounts o n l y ,
Amoroha
c a n e s c e h a was t h e m ost im p o r ta n t f o r b .
E a r ly C hanges r e s u l t i n g from D rought
In t h e s p r in g o f 1935 much o f t h e p r a i r i e was c o v e r e d
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
34
w ith a l a y e r o f d u s t tw o o r more in c h e s t h i c k w h ich b lew
In from a d j a c ’-'f t c u l t i v a t e d
fie ld s .
The e m o o tb e r in g c a u se d
by t h e b la n k e t o f d u s t c o u p le d w ith th e e f f e c t s
d e s t r o y e d n e a r ly o i l
o f th e d r o u g h t,
o f A ndrooocon f u r c a t u s and A. o c o n a r iu s
a s w e l l a s many o f t h e more x e r l c s p e c i e s ( F i g . 1 0 ) .
B o u te lo u a .wrncl 11 s and A x ro rtv ro n sm ith i t
w ere th e
m ost im p o r ta n t s p e c i e s t h a t s u r v iv e d th e b u r i a l .
T h u s, in
a tw e lv e -m o n th p e r i o d , a t h r i v i n g c lim a x p r a i r i e had by
d r o u g h t and d u s t d e p o s i t b e e n a l l buy d e s t r o y e d ( l e a v e r and
A lb e r t s o n , 1 9 3 6 ) .
Agrroovron s m i t h l l sp r e a d o v e r m ost o f t h e p r a i r i e by
1 9 3 7 , and l a r g e , w e l l d e v e lo p e d b u n c h e s o f B o u te lo u a g r a c i l i s
w ere q u i t e c o n s p ic u o u s ( R o b e r t s o n , 1 9 3 9 )*
A n n u a ls, p a r t i c ­
u l a r l y Bromus t.e c to r u fi,. I,e elB lu m d cm sl H o rum. and D s l s o l a
p e a t l f e r . w ere v e r y common.
ab u n d a n t i n a s w a l e .
B roau s te c to r u m was t h e m oat
D e s p it e I n c r e a s e s o f A s t e r m u lt i f l o r a s
and Amo noha c a n e o c e n s . p e r e n n ia l f o r b s a s a gro u p w ere
red u c e d in a b u n d a n c e .
R ecen t Changes
An a n a l y s i s o f th e 11 p erm anent p l o t s show ed t h a t
p e r e n n ia l g r a s s e s had i n c r e a s e d in ab u n d an ce 7 4 p e r c e n t
from 1936 t o 1939 (T a b le 9 ) .
T h is i n c r e a s e was made p o s s i b l e
by t h e som ewhat f a v o r a b le g r o w in g s e a s o n o f 1 9 3 8 .
t h e r a p id s p r e a d o f Ap.ron vron s m i t h l l rea c h e d i t s
A p p a r e n tly
peak by
1 9 3 8 , s i n c e i n 1 9 3 9 and 1 9 4 0 t h i s s p e c i e s d e c r e a s e d in
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
F i g . 1 0 .— S u r v i v a l o f A ndropogon f u r c a t u s i n s o i l
c o v e r e d w it h a d e p o s i t o f d u s t a t C la y C e n t e r .
o t h e r p l a n t s w e r e .b u r i e d .
A ll
P h o to June 2 3 , 1 9 3 8 , by
J . S . W eaver.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
with permission
Table 9 .
Clay Center P y a ir ie .
Number o f steins of most important s p e c ie s , percentage change in
abundance, and number o f square decim eters entered or vacated from 1938 to 1940*
of the copyright owner.
Percentage
Number of stems
SpecieB
1^8
1939
19 Ip
1938-1939 1939-1940 1939-1940
-1939
1940
-
Perennial grasses
0 .6
-
21.7
-
22.2
43(2)
12(4)
544 + 192*3
-
56.6
+
27.2
15(0)
4(1)
539
168
4 186;, 7
-
68.8
-
10.6
0 (0 )
0(0)
817
1730
621
* 111.8
— 64*1
- . 2 4 .0 '
24(0)
7(2)
Bouteloua gracilis
4171
8982
5785
4 115.3
-
+
38.7
6 (2 )
7 (0 )
Buchloe dactyloides^-
1.72 27.45
0
+1495.9
- 100.0
- 100.0
2 (0 )
0 (1 )
Carex spp*
1573
3263
1296
+ 107.4
-
60.3
-
17.6
15( 0)
4(1)
101
8
0
-
92.1
- 100.0
mm
100.0
0 (0 )
0 (0 )
Panicum scribnerianum
97
137
0
♦
41.2
- 100.0
- 100,0
4 (3 )
0(0)
Panicum vdlcoxianum
77
26
O «■» 66.2
- 100.0
- 100,0
0(1)
0( 0)
'350
386
2
10.3
-
99.5
m 9 9 .4
1 (0 )
0( 0)
1548
2502
14
61.6
-
9 9 .0
mm
99.2
0 (0 )
9(0)
38
153
157
+ 302.6
•+
2 .6
+ 313.1
3(0)
0(1)
333
484
545
■i* 45.3
*»
+
63.7
5(0)
0
0
0
0 .0
3416
3394
Andropogon furcatus
426
1254
Andropogon scoparlus
188
Bouteloua curtipendula
Agropyron sroithii
Further reproduction
prohibited without permission.
Koeleria cristata
Poa pratensis
Schedonnardus paniculatus
Sporobolus asper
•
Number of
square
decimeter units
entered or () vacated
change
Sporobolus; cryptondrus
♦
Other so e c ie s
Total
*
*
2659
13135 22858 11791
-
+
+
74.0
35.6
12,6
*
+
o.O
—
48.4-
0.0
_
t0 .2
*
2 (0 )
.........0 ( o ) ... . -.0.(0)
118(8)
36 (10 )
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
with permission
33
153
157
4 302.6
4
2*6
333
484
«
0
545
+
45.3
*•
0 .0
+
12.6
4
74.0
**
Sporobolus asper
*
Sporobolus cryptandrus
#,
*
0
Other sp e c ie s
TQUal
0
13135 2235$ 11791
4
5(0)
63.7
9
0 .0
:
_ .0 L Q l_ .
43. 4^ - 1 0 .2
,
118(8)
...... Q,o_
0( 1)
3(0)
4 313.1
2 (0 )
-4k
0(0)
. 36(10)
P erennial forbs
of the copyright owner.
Further reproduction
prohibited without permission.
Amorpha canescens
13
20
22
4
53.8
.4 10.0
4
6 9 .2
4 (0 )
0(0)
Aster m u ltiflo ru s
72
86
59
♦
1 9 .4
“
-
1 8 .1
1 (0 )
0(0 )
Artem isia gnaphalodes
13
21
31
4
61.5
4 47.6
4 138.5
4(0)
1 (2 )
C allirhoe a lc eo id e s
9
11
7
4
18.2
- 364.0
-
2 (0 )
0( 0)
Solidago glaberrima
13
13
0
0 .0
- 100.0
-
10C.0
2(0)
0 (0)
Other sp e c ie s
19
37
26
4
?4*7
-
29.7
4
36.8
1( 0)
T otal
139
138
135
4
35.3
-
28.2
-
2 .9
3 (1 )
' 16(1)
2 (2 )
Bromus tectorum
5390
500 1891 -
90.7
4 278.2
-
64.9
0(6)
6(0)
44525.0
45681.3
1( 0)
15(0)
4 614.3
0 (0)
0( 0)
41960.0
4 132.7
0 (2)
10(0)
8.4
4 151.0
120(18)
35(3)
4 244.3
-
3 0 .4
121(26)
66(3)
-
-
1 6 .4
255(31)
31.4
22.2 *
Annuals
16
20
925
4
25.0
7
0
50
-
100.0
le D id iu m d e n s i ihrurri
254
3
591
-
98.8
Other sp e cie s
294
681
738
4 131.6
5954
1204
4145
79.8
Chenopodium album
2
Festuca o c to flo r a
Total
t
4
>
Grand Total
1922S 24250 16071
4. 2 6 .1 .
33.7
Estimated cover in per cent.
2
Number of square decimeter units in v.hich species occurred,
104(15) .
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
abundance*
The
g r a s s e s o f s o u th e r n o r i g i n , w it h few
e x c e p t i o n s , had o v e r t w i c e a s m any. ste m s i n 1939 a s In
1938*
G r a s s e s o f n o r th e r n e x t r a c t i o n , h o w e v e r , u s u a lly
w ere re d u c ed I n abundance*
The e f f e c t s o f in c r e a s e d w a te r d e f i c i t became q u it e
e v i d e n t in 1 9 4 0 .
h o t o n ly w ere a l l o f t h e p l a n t s red u ced
i n s t a t u r e , h u t few s p e c i e s f lo w e r e d .
Sven in t h e m oat
f a v o r a b le p l a c e s n o t more th a n t h r e e p e r c e n t o f th e ste m s
o f Ag.ropyron s s l t h l l b o r e f l o w e r s .
Dead crow n s o f B o u te lo u a
c u r t lp e n d u la and A ndropogon f u r c a t u s w ere common.
d e p r e s s io n s
Bven in
B o u te lo u a c u r t ip e n d u la s u s t a in e d a l o s s o f
15 'per c e n t , e ls e w h e r e th e l o s s was 30 t o 40 p e r c e n t .
L o s s e s o f A ndropogon f u r c a t u s d id n o t e x c e e d 15 p e r c e n t .
A n a l y s i s o f th e q u a d r a ts In 1940 show ed t h a t p e r e n n ia l
g r a s s e s s u s t a in e d a l o s s o f 4 8 p e r c e n t .
Only two s p e c i e s ,
S p o r o b o lu s c r y p ta n d r u s and S . a s e e r . in c r e a s e d In a b u n d a n ce.
B u c h lo e d a c t v l o i d e B . K o e l e r l a c r l s t a t a . &ad t h e two I n t e r s t l t l a l g r a s s e s j P an icu m s c r lb n e r ia m m and P . w llc o x la n u m .^
d is a p p e a r e d c o m p le t e ly from t h e p l o t s .
P e r e n n i a l •f o r b s a s
a grou p were- r ed u c ed 28 p o r c e n t d e s p i t e g a in s o f 10 and
4 8 p e r c e n t by Atsoroha o a n e s c e n s and A r t e m is ia g .n a o h a lo d e s .
r e s p e c tiv e ly .
A n n u als I n c r e a s e d more th a n t h r e e f o l d .
A o ln g .le s q u a r e f o o t o f s o i l n o t uncommonly s u p p o r te d more
th a n 100 p l a n t s o f .Ghennnndinm album &T p e r h a p s 500 o f
Bromus tr-n toru in .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
37
A l l p e r e n n i a l s and a n n u a l© , w ith few e x c e p t i o n s ,
e n t e r e d s e v e r a l b a r e u n i t s d u r in g 1939 and 1 9 4 0 .
few bar© a r e a s w ere p rod u ced b y t h e i r a b s e n c e .
Only a
As a r e s u l t ,
t h e a v e r a g e number o f b o re u n i t s p e r p l o t was red u ced from
5* 3 i n 193 9 t o 1 * 2 p e r p l o t i n 1940*
D e s p it e g a in s iri
ab u n d an ce o f a n n u a ls , th e t o t a l number o f s p e c i e s o c c u r r in g
i n t h e p l o t s was r ed u c ed from 36 t o 32 in 194-0.
S e e d l i n g c o u n ts w ere low e a c h y e a r .
B o u te lo u a g r a c i l i s
was t h e o n ly im p o r ta n t s p e c i e s p r o d u c in g s e e d l i n g s b o th
y e a r s , and S p o r o b o lu s a s n r r , A groovron s m i t h l l . and A s t e r
m u l t i f l o r u s w ere r e p r e s e n t e d by s e e d l i n g s o n ly i n 1939*
Two l a r g e b a r e a r e a s , t o t a l i n g 3 ,1 2 3 s q u a r e f e e t , 'were
mapped i n J u n e , 1939 and 1940*
The d a t a show t h a t Agromrron
s m i t h l l in v a d e d t h o s e a r e a s , d e c r e a s in g t h e t o t a l b a re
sp ace ab ou t 3 p e r c e n t ( F ig . 1 1 } .
The tw o b a r e a r e a s
c o n t a in e d a t o t a l o f 19 s p e c i e s o f p e r e n n ia l g r a s s e s , f o r b s ,
and w eed s in 193 9 b u t o n ly 15 in 1 9 4 0 .
Andropogon f u r c a t u s
was re d u c e d from 9 6 t o 51 b u n c h e s; B o u te lo u a c u r t lp e n d u la
from 75 t o 4 0 , and Amornha c a n e s c e n a from 55 t o 41 b u n c h e s .
B o u te lo u a g r a c i l i s , h o w e v e r , in c r e a s e d from 3 b u n ch es t o 1 0 . .
F u r th e r in fo r m a t io n w it h r e f e r e n c e t o rc-n-.-onas o f
f o r b s t o d r o u g h t was o b t a in e d from an a n n u a l c e n s u s o f a i l .
f o r b s I n two c i r c u l a r p l o t s t o t a l i n g 1 5 ,7 0 6 sq u a r e f e e t .
A s tu d y o f t h e d a t a in 1940 r e v e a le d t h a t o n ly 4 o f th e
14 s p e c i e s in c lu d e d i n th e p l o t s in c r e a s e d i n a b u n d a n ce.
They w ere S o lld & g o m o l l i s ,
w h ich show ed an i n c r e a s e o f
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
57A
"\
I
P ig * 1 1 . —- I n v a s io n o f A g ro p y ron s a i t h i i i n t o b a r e d s o i l a t
C lay C e n te r r e s u l t i n g i n a r e d u c t io n o f 3 * 0 p e r c e n t i n i t s
a r e a from 1 9 3 9 (b r o k e n l i n e )
to 1940 ( s o l i d lin o ) *
Each
s q u a r e r e p r e s e n t s an a r e a o f f o u r sq u a r e f e e t .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
38
5^ 8 s te m s ) , h a lv a s tr u m co c o in e u m ( 1 7 2 ) , Amomha o a n e s c e n e
( 1 3 ) , and I.Vi:;odesmla .lu n cea (1 5 s t e m s ) .
The r e m a in in g
s p e c i e s w ere r e d u c e d from 1 t o 18 p l a n t s ea ch *
C a r le t o n P r a i r i e
C o m p o sitio n h e f o r e t h e D rou gh t
The v e g e t a t i o n o f t h e C a r le t o n p r a i r i e w as c h a r a c t e r ­
i s e d In 1 9 3 1 b y d o m in a n ce o f Andropo^on
s c o p s
r lu s . except
i n s w a le s w h ere d o m in a n ce was s h a r e d w i t h A. f u r c a t u s and
Ag.ro n vron s m i t h ! ! .
A lth o u g h n o t a b u n d a n t, K o e le r la c r i s t a t e
was w id e ly d i s t r i b u t e d *
S m e ll s l t e r n o s o f B uchlo© d a c t v l o l d e s
and B o u t e lo u a g r a c i l i s o c c u r r e d in t h e d r i e s t p l a c e s .
Among
t h e m o st im p o r ta n t f o r b s w ere E rlftoron ram os u s . A s t e r m u l t i f l o r u s . G a l l l r h o e a l c e o l d c s . and Amomha c a n e e c e n s .
E a r ly C hanges r e s u l t i n g fro ® D rou gh t
The d e s t r u c t i v e i n f l u e n c e o f t h e d r o u g h t had p rod u ced
c o n s p i c l o u s c h a n g e s i n t h e p l a n t c o v e r by 1933*
Androppgon
s c e n a r i o s and A. f u r c a t u s no lo n g e r com posed m o st o f t h e
v e g e t a t i o n ; th e y had b e e n r e p la c e d i n d om in an ce by a,y ro p y ro n
s m i t h ! ! w h ic h now c o n t r o l l e d o v e r h a l f o f t h e p r a i r i e and
c o n s titu te d about
( F ig * 1 2 ) .
50 p e r c e n t o f t h e c o v e r o f t h e re m a in d e r
B o u t e lo u a g r a c i l i s and B u c h lo e d a c t v l o l d e s a l s o
in c r e a s e d i n a b u n d a n c e , f r e q u e n t l y fo r m in g an u n d e r s t o r y t o
A nropyron s a l t h l i .
p r o t o n s I s was r a r e .
K o e lo r la c r l a t a t a ' w as common b u t Poa
A s t e r m u l t i f l o r u s in c r e a s e d en o rm o u sly
i n a b u n d a n ce w h i l e K uhnla g l u t l n o s a and Amomha c a n e a c e n s
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
58 a
3
i
•
’
*
F ig * 1 2 * — P r a i r i e a t C a r le t o n sh o w in g r e l i c t p a tc h
o f A n d roooron f u r o a tu a a l t e r n a t i n g w it h B u o h lo e
d a c t y l a i d e s 1 ( f o r e g r o u n d ) and Agropyron. s m l t h l l
i n t h e b ack grou n d *
P h o to g ra p h ed b y J . E . Weaver*
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
made s m a l l .g a i n s *
D u rin g th© d ry y e a r s o f 1936 and 1337 a l l p e r e n n ia l
g r a s s e o , e x c e p t A groovron s m l t h l l and B o u te lo u a c u r t i p c n d u l a .
w ere r ed u ced 3 t o 93 p e r c e n t .
P e r e n n ia l f o r b s w ere red u c e d
36 p e r c e n t , A s t e r m u l t i f l o r a s and Amornha c a n e g e e a s s u s ­
t a in in g th e h e a v ie s t lo o s e s .
n in g o f t h e p l a n t c o v e r .
a b u n d a n c e.
A n n u als p r o f i t e d by th e t h i n ­
They I n c r e a s e d 6 t o 26 tim e s i n
Lcroldlum d e n s ! f l o r a s and Hedeoma M a n ia s, wore
th© m ost a b u n d a n t among a n n u a ls .
R e c e n t Changes
D rou gh t c o n d i t i o n s w ore l o s s s e v e r e i n 1 9 3 8 .
D u rin g
1939 and 1 9 ^ 0 , h o w e v e r , t h e w e a th e r was warmer and d r i e r th a n
norm al w it h a n a c c u m u la te d r a i n f a l l d e f i c i t o f 9 .5 I n c h e s .
A n a l y s i s o f 13 p l o t s e s t a b l i s h e d i n 1936 showed t h t
a l l p e r e n n ia l g r a s s e s , e x c e p t P a n ic u s vlrftatu m and S t lp a
a p n r t c a , i n c r e a s e d In ab u n d an ce from 1938 t o 1939 (T a b le 1 C ).
The l a r g e s t g a in was made by B o u te lo u a K r a c l l l s .
f o r b s a l s o show ed i n c r e a s e s .
s p e c ie s , how ever, v a r ie d .
P e r e n n ia l
The r e s p o n s e o f i n d i v i d u a l
A s t e r y u l t l f l o r u s g a in e d 30 p e r
c e n t w h ile Amorpha c a n e s c o n s l o s t 23 p e r a e 'n t.
A n n u a ls,
w it h few e x c e p t i o n s , w ere red u ced from 63 t o 100 p e r c e n t .
E f f e c t s o f th e d rou gh t' upon t h e p la n t c o v e r were more
p ro n o u n ced In 19^0 th a n In th e p r e v io u s y e a r .
Dead b u n ch es
o f B o u te lo u a c u r t l o e n d u l a and A ndroooron f u r c a t u s w ere common.
As many a s 60 dead crow n s o f B o u te lo u a c u r t lo e n d u la w ere
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 10*
Carleton P r a ir ie ,
Number o f stems of most important s p e c ie s , percentage change
with permission
in abundance, and number o f square decim eters entered or vacated from 1932 to 1940,
Species
Number of stems
of the copyright owner.
1933
1939
Percentage
1940
Number of
square
decimeter units
entered or () vacated
change
1933-1939 1939-1940 1938-1940
1939
1940
'V
Perennial grasses
39IO 3474 5015.
Agropyron smithii
■f 28.3
19.5
*
3 5 .1
M 90.2
-
7 .3
5(5)
8( 4)
86.8
0( 0)
0 (4 )
•
Further reproduction
prohibited without permission.
Andropogon furcatus
700 1054
Andropogon scoparius
214
345
25
*
61.2
-
92.8
-
88.3
0( 0)
0(0)
2226
3309
1268
+
48.7
-
61.7
-
4 3.0
4(0)
1( 0)
347
2460
1532
+ 603.9
-
37.7
+• 34.5
0(0 )
0 (1 )
«•
9*1
0 (0 )
0( 0)
Bouteloua curtlpendula
Bouteloua gracilis
33.98 33.12
Buchloe dactyloides
103
30.9C
12.2
430
540
25O + 25.6
92
147
102
Panicum virgatum
266
242
95
Poa pratensis
265
317
46
Sporobolus asper
251
410
118
80
70
13
71
264
212
Carex spp.
Koeleria cristata
Stipa spartea
Other species
C
M
Total
-
M
l 18.9
-
53.7
-
41.9
KD
0 (2 )
4* 59.8
-
30.6
+
10.9
0 (0 )
0 (0 )
9 .0
.
60.7
«» 64.3
0 (1 )
1( 0)
19.6
-
85.5
•» 82.6
0(2)
0 (0 )
+
63.3
-
71.2
-
53.0
0 (0 )
0( 0)
-
12.5
-
8 1 .4
-
8 3 .0
0 (0 )
0 (1 )
4- 198.6
0( 0)
0( 1)
1 ,7
10(9)
10(13)
12.5
0 (0 )
0( 1)
r
+ 271.8
•
19.7
A
t
8932 13332 '8779
+
54.9
*
22* 5
36,5
•e
12.9
-
Perennial forbu
Amor aa 'canescens
l‘r-J
35
•f
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
with permission
of the copyright owner.
-
60.7
-
64.3
0( 1)
1( 0)
4 19.6
-
85.5
— 8 2 .6
0 (2 )
0 (0 )
118
+
63.3
-
71.2
-
53.0
0( 0)
0( 0)
70
13
M*
12.5
*» 8 1 .4
-
8 3 .0
0 (0 )
0 (1 )
264
212
4 271.8
-
19.7
4 198.6
0( 0)
0 (1 )
+
54.9
~
36.5 * -
-
22.5
4
12.9
Panicutn virgatum
266
242
95
T
Poa p ra ten sis
265
317
46
Sporobolua asper
251
410
S tip a spartea
80
Other sp e c ie s
&
Si
T otal
71
8932 13832
Perennial forbo
8779
9 .0
1 .7
10(9)
10( 13)
12.5
0( 0)
0(1)
- 100.0
0( 0)
0( 0)
•
**7
Further reproduction
Amorpha canescens
40
^|ster rrm ltiflorus
10
13
100
I?!
T otal
150
175
Bromus tectorura
363
95
Festuca o c to flo r a 2
863
80
8
Hordeum pusillum
35
0 + 3 0 .0
- 100.0
-
4
31.0
-
74.0
•
6 6 .0
0 (0 )
......0 ( 0 ) _
+
16.7
— 60.6
-
54.0
0(0)
0 (1)
«*
73.8
4 287.4
+
1 .4
0(2)
0(0)
93
-
9 0 .4
4
-
88.9
0(8)
0 (1 )
3
149
-
62.5
+4866.6
+1762.5
0( 0)
1 (0 )
337
5
138
w*
98.5
42660.0
-
0( 1)
2(0)
Plantago p u rsh il
1
16
103 + 1500.0
4 543.8
+10200.0
0(0)
1 (0 )
S a lso ia p o s tife r
4
0
42
♦ 950.0
0( 1)
0( 0)
Other sp e c ie s
0
30
258
0(0 )
4 (0 )
Total
713
149
Grand T otal
9795
Other sp e c ie s
69
Annuals
prohibited without permission.
Hedeoraa hisp id a
- 100.0
4
4 760.0
IO53 -
14156 9906
16.3
+
4
7 9 .1
4 610.1
4
48.4
0(12)
8 (1 )
44.5
-
30.0
4
1 .1
0 (2 )
18(15)
Estimated cover in per cen t.
o
59.1 '
Number o f square decim eter u n its in vdiich sp ecies occurred.
.
t
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
41
o b s e r v e d in a p l o t o f tw o -s q u a r e snotere*
L o sses to t h is
s p e d o s w ere f r e q u e n t l y a s much a s 80 p e r c e n t in a r e a s o f
AgroDvron s t n i t h i l b u t d id n o t e x c e e d 10 p e r c e n t w here b l u e ­
st©® p r e v a i le d *
L o s s e s o f A ndropogon f u r e a t u a and Sn.orobol.us
a o n e r w ere a b o u t 15 p e r c o a t*
tin n y dead b u n c h e s o f Amornha
o a n e s e e n s -and R osa a r k a n sa n a w ere o b s e r v e d , i n d i c a t i n g t h a t
e v e n sera© d e e p - r o o t e d fo r b a had succum bed*
D ata o b t a in e d
from a. c e n s u s o f f o r b s in tw o c i r c u l a r p l o t s t o t a l i n g J.5*708
sq u are f e e t ,
r e v e a le d t h a t Amoroha c a n e s e e n a was red u ced
from 803 t o 6 7 6 sterns i n 1 9 4 0 , a d e c r e a s e o f 16 p e r c e n t*
Rosa a r k a n sa n a was r ed u c ed from 294 t o 30 s t e m s , a ch an ge
o f 90 p e r c e n t *
f o lia
A s t e r m u l t i f l o r u s and A c e r a t e s a n .- u e t l-
w ere r e d u c e d 86 and 100 p e r c e n t , r e s p e c t i v e l y , i n
194c.
A n a ly s is o f tem p orary p l o t s r e v e a le d t h a t i n t h e
A r r o w ron s i n l t h l l a r e a s , A gronvron f u r n is h e d 83 p e r c e n t
o f t h e c o v e r , B o u te lo u a c u r t lo o n d u la 3 , 3.* g .r a c ^ Ilq 1 3 ,
and f o r b s o n ly 1 p e r c e n t ,
t h e r e b lu e st,e m s p r e d o m in a te d ,
33 p e r c e n t o f t h e c o v e r was f u r n is h e d by Andropogon f u r ­
c a t e s . 27 by B o u t e lo u a c u r t l n e n d u l a . 25 by Carox p erm a v lv a n l c a . 14 by K o s l e r l a o r l s t a t a and 1 p e r c e n t by f o r b s .
A n a l y s i s o f th e p erm an en t p l o t s i n 1940 r e v e a le d
t h a t b o t h p e r e n n i a l g r a s s e s and fo r b a w ere red u ced i n
abundance.
O nly two s p e c i e s , A nrooyron otai t h i l and
Amomha ca n e s c o n s made s m a ll g a i n s .
O th e r s w ere red u ced
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
1 9 t o 1 0 0 p e r c e n t In ab u n d an ce , w it h t h e s te a ic g r a s s e s
s u f f e r i n g m oat*
A nnual p l a n t s , h o w e v e r , made phenom enal
I n c r e a s e s f o l l o w i n g t h e d e s t r u c t i o n o f n a t i v e p e r e n n ia ls *
G r e a t e s t i n c r e a s e s » e r « made by P l a n t a / o o u r o h i l . liodeoiaa
h l a n l d a . and Hordeum o u s t H u m .
The t o t a l num ber o f s p e c i e s i n a l l t h e p l o t s was
r e d u ce d d u r in g t h r e e y e a r s from 33 t o 2 6 , a n o t l o s s o f 7 .
The a v e r a g e number o f b a r e u n i t s was l e s s
th a n 1 e a c h y e a r .
N e ls o n P r a i r i e
C o m p o sitio n b e f o r e t h e D rou gh t
The N e ls o n P r a i r i e i n 1931 was d e s c r ib e d by w eaver
and A lb e r t s o n (1 9 3 6 ) a s a f i n e l i t t l e
b lu o a t e n p r a i r i e w ith
o n e - t h i r d o f th© a r e a sh a r e d e q u a l ly w it h b i g b lu o s t e u u
'.Veeds w ere a b s e n t*
E a r ly C hanges r e s u l t i n g from D rought
D u rin g t h e s p r i n g o f 1 9 35 h a l f o f t h i s p r a i r i e was
c o v e r e d w it h a l a y e r o f d u s t t o a d e p th o f a b o u t o n e h a l f in c h *
As a r e s u l t many o f t h e n a t iv e g r a s s e s ,
p a r t i c u l a r l y A n d roocron a c o m r l u a . w ere d e s tr o y e d *
D eep ly
r o o t e d f o r b s su c h a s Amoroha cA n cscen a w ere n o t i n j u r e d .
Ap.ropvron s mi t h i l in v a d e d w h ere t h e d u s t d e p o s i t was a b o u t
an in c h d e e p and c e r t a i n o t h e r p l a c e s
Dromuo .la p o n lc u su
w ere p o p u la te d by
The r e m a in in g h a l f o f th© p r a i r i e was
d o m in a te d by An d ro p o g o n f u r e a t u a w it h a good a d m ix tu r e o f
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
43
o f F e stu c a o c t o f l o r a *
The d e s t r u c t i v e e f f e c t o f th e d r o u g h ts o f 1936 and
1 9 3 7 p ro d u ced f u r t h e r c h a n g e s .
Ad o ng t h e s e w ere th e r e d u c t io n
o f A ndropogon f u r e a t u a and A_. on ora r f up t o a b o u t 58 p e r c e n t ;
t h e a lm o s t t o t a l d isa p p ea r® n c© o f Amronvron o t a l t h l l and th©
i n c r e a s e i n t h e t h r e e s p e c i e s o f B o u t e lo u a .
P e r e n n ia l f o r b s ,
e x c e p t Amornha c& n ea cen a . becam e l e s s num erous b u t a n n u a ls
and w eed s becam e more ab u n d an t*
R ecen t C hanges
C o n d it io n s f o r g ro w th wore g r e a t l y im p roved in 1 9 3 8 .
w it h th e e x c e p t i o n o f d u l y , r a i n f a l l was a d e q u a te f o r good
pl&v-t d e v e lo p m e n t d u r in g e a c h month o f tn e g r o w in g s e a s o n .
The sufficer o f 1939» h o w e v e r , was c h a r a c t e r i s e d by h ig h
t e m p e r a t u r e s , o c c a s i o n a l d e s i c c a t i n g h o t w in d s , and lo n g
p e r io d s o f d r o u g h t.
Only in J u ly was p r e c i p i t a t i o n in
e x c e s s o f n o r m a l.
A n a l y s i s o f 6 perm anent p l o t s e s t a b l i s h e d i n 1936
show ed th a n p e r e n n i a l g r a s s e s had in c r e a s e d n e a r ly 100 p e r
c e n t i n ab u n d an ce i n 1 9 3 9 , w h ile p e r e n n ia l f o r b s and a n n u a ls
had d e c r e a s e d 24 and 9 8 p e r c e n t , r e s p e c t i v e l y (T abic 1 1 ) .
A l l I m p o r ta n t a n n u a ls d is a p p e a r e d c o m p le t e ly fro® t h e
p l o t s i n 1 9 3 9*
“i t h
th e e x c e p t io n o f t h e tw o s p e c i e s o f
Androno ~ort. a l l p e r e n n i a l g r a s s e s in c r e a s e d from 1 7 t o
o v e r 3 0 0 p e r c e n t i n abundance w ith an a v e r a g e I n c r e a s e o f
1 4 5 p e r c e n t*
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 11,
Nelson P r a ir ie .
Number o f stems o f most important s p e c ie s , percentage change
with permission
in abundance, and number o f square decim eters entered or vacated from 1938 to 1940.
Species
Number o f s teras
Percentage
change
of the copyright owner.
Further reproduction
prohibited without permission.
1938
1939
1940
1938-1949 1939-1940 1938-1940
Agropyron s m ith ii
447
791
1078
+
Andropogon furcatus
511
470
255
Andropogon scoparius
105
71
8
Bouteloua curtipendula
2252
3863
Bouteloua g r a c ilis
.570
Bouteloua h ir su te
Carex app.
Number o f
square
decim eter u n its
entered or ( ) vacated
1940
1939
P erennial gra sses
7 7 .0
4
36.3
+
41.2
0 (8 )
8(0)
-
8 .0
am
45.7
-
50.1
0( 4)
2(3)
-
32.4
88.7
-
9 2 .4
0( 0)
0( 0)
952
4
71.5
-
7 5 .4
am
57.7
0 (5 )
7 (1 )
2582
738
+ 353.0
-
7 1 .4
4
29.5
0( 1)
2 (0 )
147
172
130
+
17.0
-
24.4
-
11.6
0 (0 )
0(0 )
192
466
180
+ 142.7
-
61.4
-
6 .3
0(2 )
1 (1 )
. 25
47
14
+ .8 0 .0 - -
70.2
-
4 4 .0
0( 0)
2 (0 )
40
122
71
+■ 205.0
-
41.8
+
77.5
0( 0)
1( 0)
8
2
_
-
6 0 .0
—
5
1 S .0
0 (2 )
Q io)
4297
8589
3428
99.9
*
60.0
-
20.2
0(22)
Araorpha canescens
332
275
227
-
17.2
-
17.5
-
31.6
0( 0)
0( 0)
L ia tr is punctata
6
4
8
-
33.3
•t
+
33.3
0( 0)
1( 0)
Other species
31
?
0
100.0
0(0)
... 0 (0 )
349
282
235
36.3
0 (0 )
1 (0 )
K oeleria c r is ta ta
Sporobolus cryptandrus
Other sp e cie s
T otal
3 7 -6
2 3 (5 )
Perennial forbs
T otal
100. 0
90.3
-
23.6
100.0
-
16.7
am
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
122
71
4
*
5
2
4297
8589
3428
332
275
40
Other sp e cie s
with permission
Total
8
V
\
Reproduced
Sporobolus cryptandrus
0.
T , OUfV
0
•
k
&
f
.
*
+
f
—
f v.n.
v \v /
+
77.5
—
7^.0
of the copyright owner.
-
41.8
~
6 0 .0
99.9
-
60.0
~
227
«•» 17.2
-
17.5
100.0
?
4
7
. 6
0 (0 )
1(0)
......_ .0(21..
0 (0 )
20.2
0(22)
2 3 (5 )
-
31.6
0(0)
0 (0 )
4
33.3
0 (0 )
1 (0 )
P erennial forbs
Araorpha caneacens
Further reproduction
prohibited without permission.
L ia tr ls punctata
6
4
8
33.3
i
Other sp e cie s
31
3
0
90.3
r 100.0
— 100.0
0(0)
...... 0(0)
T otal
349
28?
235
23.6
-
-
36.3
0(0)
1(0)
Bromus tectorum
123
0
7
-
94.3
0 (3 )
1(0)
Festuca o c to flo r a
491
0
4 2 .0
0(63)
Hedeoaa hisp id a
11
Hordeura pusillum
Lepidium c/ens’if/orwirj
—
16.7
Annuals
Plantago purahii
S a lso la p e s tif e r
Other sp e c ie s
.
•m
100.0
4
285
-
100,0
4*
0
43
-
100.0
4
4
53
0
21
-
100.0
+
«■»
55
0
150
-
100.0
f
4
75
0
30
-
100.0
4
-
13
0
12
-
100.0
4
-
0
6
0
Total
330
6
263
Grand T otal
4996
8877
3926
“K
-
100.00
2?(0)
290.9
0 (0 )
7(0)
60,4
0(0)
2(0)
172.7
0(1)
16(0)
60.0
0(2)
2(0)
7.7
0(2)
1 (0 )
0 .0
0(0)
0(0)
-
98.2
4 4 2 8 .3
-
20.3
0(71)
5(0)
4
7 7 .7
-
55.S
-
21.4
0(93)
80(5)
Number o f square decim eter u n its in which sp e cie s occurred.
_
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
45
D e s p i t e t h e i n c r e a s e s in p e r e n n ia l g r a s s e s , t h e a v e r a g e
number o f b a r e u n i t s p e r p l o t in c r e a s e d from 0 * 2 i n 1938 t o
11*0 I n 1939*
The number o f s p e c i e s p e r p l o t , h o w e v e r ,
d e c r e a s e d from 12 t o 6 i n 1939* & l o s s w h ich may b e a t t r i b u t e d
t o t h e d is a p p e a r a n c e o f a n n u a ls*
The i n c r e a s e i n B o u te lo u a c u r t ln e n f lu la was accom p an ied
b y t h e o c c u r r e n c e and i n c r e a s e o f a w id e ly s p r e a d d i s e a s e d
c o n d i t i o n ( F o w le r and W eaver, 1 9 4 0 } *
In 1939 B o u te lo u a
c u r t i r e n d u l a f u r n is h e d 6 0 p e r c e n t o f t h e b a s a l c o v e r b u t
a p p r o x im a t e ly 30 p e r c e n t o f t h e p l a n t s w ere d i s e a s e d .
By
1 9 4 0 , d i s e a s e d p l a n t s had in c r e a s e d t o 4 0 p e r c e n t*
A t t h e s e c o n d q u a d r a t t i n g , i n 1 9 4 0 , i t was fou nd t h a t
d r o u g h t h ad p rod u ced g r e a t e r d e s t r u c t i o n ,
P e r e n n ia l g r a s s e s
and f o r b s w ere r e d u c ed In ab u n d an ce 6 0 and 1 ? p e r c e n t , r e s ­
p e c tiv e ly .
P it h t h e e x c e p t i o n o f A gronvron a n i l t h l i and
L i a t r l s p u n c t a t a . a l l s p e c i e s s u s t a in e d l o s s e s r a n g in g from
18 t o 89 p e r c e n t*
Dead crow n s o f B o u t e lo u a c u r t ln o n d u la
and A ndropogon f u r c a t u s w ore common.
F lo w e r in g s te m s w ere
p ro d u ced o n ly In r a v i n e s and f a v o r a b le p la c e 's by t h e d r o u g h ts tr ik c n g r a s s e s .
The num erous l a r g e b a r e a r e a s r e s u l t i n g from t h e
d e a t h o f p e r e n n i a l s w ere In v a d ed by h o r d e s o f a n n u a ls*
C h ie f among t h e s e w ore H edeoaa h l s n l d a . P l a n t a i n p u r a h l l .
L en id iu m d e n e l f l o r u r e . and S a l s o l a n e o t l f s r ,
The t o t a l
number o f s p e c i e s I n c r e a s e d , w it h t h e a p p e a r a n c e o f a n n u a ls ,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
46
from 19 I n 1 9 3 9 t o 23 i n 1940.,
The a v e r a g e number o f b a r e
u n i t s , h o w ev er, d e c r e a se d 73 p er c e n t .
S e e d lin g s o f p e r e n n ia l
n a t i v e s p e c i e s w ere n o t common d u r in g e i t h e r y e a r o f t h e
s tu d y *
M o n tro se P r a i r i e
C o m p o sitio n b e f o r e th e D rou gh t
The M o n tro se g r a s s l a n d was c h a r a c t e r i s e d In 1931 a s a
little
b lu a s t e n i p r a i r i e * ' AndronoRon a c o o a .r iu s . r e p r e s e n t e d
b o t h by t h e so d and b u n ch t y p e , d o m in a te d t h e u p la n d , w h ile
A* T u r n s tu s m ixed w it h lo re.h a stru m n u ta n s was t h e m ost
ab u n d an t g r a s s i n r a v i n e s and s w a l e s ,
K o a le r la c r l c t a t a
and B o u te lo u a c u r t ln e n d u la w ere r e s t r i c t e d t o t h e d r i e r
s l o p e s , a s w ore a l s o th e few s c a t t e r e d p a t c h e s o f 3 . . g r a c i l i s
and D u eh lo e d a c t v l o l d e s *
A groovron s m l t h l l was r e p r e s e n t e d
o n ly by a few stem s*
E a r ly C hanges r e s u l t i n g from D rou gh t
S t u d i e s I n J u n e . 1935» by l e a v e r and A lb e r t s o n show ed
t h a t t i l l s p r a i r i e had s u f f e r e d much damage*
F u lly 75 p e r
c e n t o f t h e f o r s ie r v e g e t a t i o n had b oon d e s t r o y e d .
D e s tr u c tio n
o f A nd roooron s c o n a r lu s a l o n e had b oon a p p r o x im a te ly 9 9 p e r
c e n t.
L o s s e s o f A. f u r e a t u a . h o w e v e r , w ere l e s s .
B u o h lo e
d a c t v i o l d e s and B o u te lo u a g r a c i l i s h ad I n c r e a s e d t h e i r
te r r ito r y *
A gron vron s m l t h .i l . l i k e w i s e , had in c r e a s e d In
a b u n d a n c e , p a r t i c u l a r l y on a r e a s w here s o i l had d r i f t e d .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
47
C o n v e r s e ly , - f o r b s had b e e n r ed u ced m a r k e d ly .
C e r t a in a n n u a ls
and s h a l l o w - r o o t e d w eed s had becom e v e r y common.
D u rin g t h e d ry y e a r s o f 1936 end 1937 th e t o t a l number
o f p e r e n n i a l g r a s s s te m s d id n o t ch a n g e a p p r e c i a b l y .
L o sses
t o D o o ic s p e c i e s w ere b a la n c e d by in c r e a s e ®
in x e r ic g r a s se s *
P e r e n n ia l f o r b s w ere re d u c e d In, abu nd an ce*
A n n u als c o n tin u e d
t o i n c r e a s e , b ec o m in g a b o u t 1C t im e s .a s ab u n d an t i n 15*37 a s
in 1 9 3 6 .
R e c e n t C hanges
A n a l y s i s o f t h e 0 p l o t s e s t a b l i s h e d in. 1936 showed
t h a t p e r e n n i a l g r a s s e s i n c r e a s e d o n ly 2 p e r c e n t i n abu nd ance
b e tw e e n 1 9 3 6 and 1939 ( T a b le 1 2 ) .
R u ch lo e d a c t v lo l d e a
c o m p le t e ly d is a p p e a r e d from t h e p l o t s i n 1 9 3 8 b u t r e a p p e a r e d
in 1 9 3 9 .
P e r e n n ia l f o r b s and a n n u a ls- w ere red u c e d i n
ab u n d an ce 5 4 and
96 p e r c e n t , r e s p e c t i v e l y .
Bromus tc c to r u m
c o m p le t e ly d is a p p e a r e d front th e p lo t s ' in 1 9 3 5 .
F i r e from an a d j o i n i n g s t u b b l e f i e l d
ra n th r o u g h
t h e n o r t h e a s t h a l f o f t h e p r a i r i e e a r l y in J u l y , 1939
(F ig . 1 3 ).
ground.
The g r a s s e s w e r e s o dry t h a t a l l burn ed t o th e
O b s e r v a t io n s t h e n e x t summer r e v e a le d a v e r y open
c o v e r and an a b s e n c e o f d e b r i s on t h e b u rn ed t r a c t .
B o u te lo u a
c u r t lp o n d u la and A ndropogon f u r e a t u a woro r e d u c e d i n
ab u n d an ce a b o u t 3 0 p e r c e n t .
h o w ev er, in c r e a s e d u n t i l i t
S o o r o b o lu s c r v n t a n d r u s .
c o n t r ib u t e d a t l e a s t 1 p e r c e n t
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
P i g . 1 3 . — P r a i r i e a t M o n tro se, K an sas sh ow in g th e
r e s u l t s o f f i r e w h ic h s p r e a d i n t o d r y A gropyron
s r a i t h l i from a d j o in i n g w h e a t - s t u b b le f i e l d on J u ly 1 ,
1959.
P h oto J u ly 1 5 , 1 9 3 9 , b y J . E . W eaver.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 12.
Montrose P r a ir ie .
Number of stems o f most important s p e c ie s , percentage change
with permission
in abundance, and number of square decim eters entered or vacated from 1938 to 1940.
of the copyright owner.
S p ecies
Number o f 3tems
Percentage
Number o f square
decim eter u n its
entered or ( ) vacated
change
Further reproduction
prohibited without permission.
lft38
1?39
1940
1938-1939 1939-1940 1938-1940
3343
2553
2412
mm
23.6
-
5.5
568
655
818
+
15.3
+
24.9
3665
5026
4226
37.1
-
15.9
972
556
2763
42,8
+ 396.9
0
0.43
3.12
218
143
151
-
34.4
+
3?
4
11
•
88.6
1940
1939
Perennial tr a s s e s
Agropyron sm ith ii
Andropogon furcatus
Bouteloua curtipendula
Bouteloua g r a c ilis
Buchloe d actyloides^
Carex spp.
Other sp ecies
T otal
8801
mm
+
-
2 7 .8
.
6(3 )
4 (4 )
4* 44.0
0( 1)
0 (1 )
+
15*3
5(1)
2 (3 )
+ 184.3
0(0 )
0 (0 )
«•
0( 0)
0(0)
30.7
0(0 )
0( 0)
+ 175\0
- 100.0
1 (0 )
0 (0 )
+ 625.6
5*6
-
8937 10381
+
1 .5
+
1 6 .0
+
17.8
12(5)
6 (8)
mm
43.9
-
13.0
-
51.2
0 (0 )
0( 0)
66.7
- 100.0
- 100.0
0( 0)
0 (0 )
-_73_.3__ - 100.0
- 100.0
0 (0 )
33.3
-
69.2
0( 0)
0(0)
+
-
97.2
0(0 )
0(0)
-
66.5
1(3 )
0( 1)
P erennial forb s
Amorpha canescens
41
23
20
Aster m u ltiflo ru s
9
3
0
-
15
0
mm
20
-
53.9
Other so e c ie s
T otal
65
4
30
Broraus tectorum.
10?
0
3
-
100.0
Festuca octoflora^
573
52
192
-
90.9
-
_
0( 0)
Annuals
t 269.2
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Bouteloua curtipendula
Bouteloua g r a c ilis
Buchloe d actyloides^
with permission
Carex spp.
Other sp e c ie s
Total
3665
5026
4226
+
37.1
-
972
556
2763
-
42.8
+ 396.9
0
0*43
3*12
218
143
151
??
4
11
8801
8937 10381
+
-
+
15.9
+
15.3
5(1)
2 (3 )
+ 184.3
0 (0 )
0(0)
+
0( 0)
0( 0)
30.7
0 (0 )
0 (0)
1( 0)
0 (0 )
4 625.6
5.6
-
of the copyright owner.
3 4 .4
+
88.6
+ n S .o
«•» 100.0
1 .5
4
1 6 .0
+
17.8
12(5)
6 (8 )
43.9
-
13,0
-
51.2
0 (0 )
0 (0 )
66.7
«“ 100,0
wm 100.0
0 (0 )
0(0)
- 100.0 • m. 100.0
_____ 0( 0)
Perennial forb s
Further reproduction
prohibited
without permission.
Araorpha canescens
41
23
20
A ster rau ltifloru s
9
3
0
-
. 15
4
0
_
T otal
65
30
20
J3A - 53.9
Bromus tectorum
107
0
3
- 100.0
Festuca o c to flo r a 2
573
52
192
-
90.9
Hedeoma h isp id a
718
26
303
-
' H
6
137
T otal
839
32
443
Grand T otal
9705
8999 10844
Other sp e cie s
0 (0 ).....
33.3
-
69.2
0 (0 )
0(0)
+
-
97.2
0( 0)
0 (0 )
t 269.2
m 66.5
1(3)
0 (1 )
96.4
+1065.4
-
0 (2 )
1(0)
57.1
+2183.3
+ 878.6
0( 0) ....
1(0 )
-
96.2
+1284.4
•
47.2
1( 5)
2 (1 )
-
7 .3
+
4
11.6
13(10)
8 (9 )
-
Annuals
Other sp e c ie s
Estinsated cover in per cent
2Number o f square decim eter u n its in which sp e c ie s occurred
2 0 .4
57.8
_ -
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
49
o f th e b a sa l c o v e r .
.P e r e n n ia l f o r b s w ere few a/nd s c a t t e r e d ,
b u t a n n u a ls w ere a b u n d a n t.
B o u te lo u a r . r a c l l i s wan th e o n ly
n a t i v e s p e c i e s t o sp r e a d and f lo w e r abundar x t l y .
The o ld p l a n t c o v e r o f th e unburned a n d . unmoved p o r t io n
o f t h e p r a i r i e was t h i c k end d e b r is was abu nd an t#
L o sses to
B ou t© lou a .cu rt l a c nau.la and A ndronoson f u r e a tu a d id n o t e x c e e d
10 p e r c e n t#
A c o m p a r iso n o f th e c o m p o s it io n o f t h e p l a n t
c o v e r i n th e burn ed and unburned a r e a s r e v e a le d t h a t A groovron
s m i t h i l form ed 11 and 3 2 p e r c e n t o f t h e c o v e r , r e s p e c t i v e l y .
C over f u r n is h e d by B ou te 1 oua t~ .r a c ll ls was
60 and 12 p e r c e n t?
t h a t o f B . c u r t ln e n d u la 23 and 4 6 p e r c e n t , and t h a t o f t h e
fe r b n "m s, 1 and 3 p e r c e n t , r e s p e c t i v e l y .
A c e n s u s o f t h e p l o t s i n 194 0 show ed t h a t p e r e n n ia l
g r a s s e s I n c r e s s o d 16 p e r c e n t .
Hid g r a s s e s , e u ch a s
Agrronvron g m ith .il and B o u te lo u a c u r t l o e n d u l s , w ere red u ced on
an a v e r a g e a b o u t 11 p e r c e n t i n a b u n d a n c e , b u t B . g r a c i l i s
and P u c h lo e d a o t v l o l d c s mad© g a in s o f o v e r 100 p e r ce n t*
P e r e n n ia l f o r b s w ere r e d u c e d o n e - t h ir d i n a b u n d a n ce, b u t
a n n u a l p l a n t s becam e 14 t im e s a s ab u n d an t a s f o r m e r ly .
P o n tu c a o c t o f l o r a and Hod coma h i an Ida -wore m ost a b u n d a n t.
F u r th e r d a t a on t h e r e s p o n s e o f f o r b s t o t h e d ro u g h t
w e re o b t a in e d from an a n n u a l c e n s u s o f tw o c i r c u l a r p l o t s ,
t o t a l i n g 1 5 * 7 0 8 e p u a r e f e e t in a r e a .
S o lld a n o m o l l i s and
Lvrvodescila lu n n ca in c r e a s e d 202 and 75 p e r c e n t , r e s p e c t i v e l y ,
Amoroha c a n e s c c n g and Ace r o t os a n p u s t i f o l i a . s u s t a in e d l o s s e s
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
50
o f 4 ? and 5 6 p e r c a n t , b u t Kuhrila g l u t l n o a a sms red u ced
o n ly 2 p e r c e n t*
A lth o u g h t h e a v e r a g e number o f s p e c i e s p e r p l o t i n ­
c r e a s e d from 7 * 4 I n 1 9 3 9 t o 8 . 8 i n 1 9 4 0 , t h e t o t a l number
o f s p e c i e s rem a in ed 2 0 ,
The a v e r a g e number o f b a r e u n i t s
d id n o t ch a n g e a p p r e c ia b ly i n c i t h e r 1939 o r 1940 b u t r e ­
m ained a p p r o x im a t e ly o n e - h a l f u n i t p e r p l o t *
RESULTS FROM ALL, PR/; I HIES
The a v e r a g e i n c r e a s e o f p e r e n n ia l g r a s s e s on a l l
o f t h e p r a i r i e s from 1938 t o 1 9 3 9 w as 7 7 p e r c e n t
( T a b le 1 3 ) .
T a b le 13*
Number o f s te m s i n e a c h o f th e grou p s
o f p l a n t s a t a l l t w e lv e p r a i r i e s and p e r c e n t a g e ch an ge
i n a b u n d a n ce from 1 9 3 8 t o 1940*
Group
P e r c e n ta g e
in c r e a s e or d ecrea se
8 umber o f ste m s
193.8. .1.93.9....1940 1 9 3 8 -3 0 1 9 3 9 -4 0 1 9 3 8 -4 0
P e r e n n ia l t r u s s e s 6 3 0 9 3 1 1 1 6 5 3 8 1 3 5 0
+ 7 7 .0
- 2 7 .1
+ 2 0 .9
P e r e n n ia l f o r b s
..3 3 3 5 ...... 18.20.......1 491 .. - 4 5 . 4 .. - ...1 8 ,1
- 5 5 .3
A nnual o l a n t s
.15564.
T o ta l
81992 120481
_ 7 0 0 8 1 3 8 5 5 ...- 5 5 . 0 .
96696
+ 4 6 .9
+ 9 .1 ,1 .... - 1 0 ,9
- 1 9 .7
+ 17»9
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
A firop yron a m l t h l l . B o u te lo u a c u r t l r e n d u l a . B . g r a c i l i s .
and S n o r o b o lu a c r y p ta n d p u s p rod u ced a t l e a s t TO p e r c e n t
o f t h e t o t a l number o f ste m s e a c h y e a r and w ere m o s tly
r e s p o n s ib le f o r th e g a ln o .
The g r e a t e s t ch an ge i n popu­
l a t i o n o c c u r r e d i n t h e b lu e s t e m p r a i r i e s ,
h ere th e in ­
c r e a s e i n ab u n d an ce wac 105 p e r c e n t a s com pared w it h 55
p e r c e n t i n t h e w h o a tg r a sa g ro u p ( T a b le s 14 and 1 5 ) •
A ll
s p e c i e s , e x c e p t O u ch lo e d & c t v l o i d e s . i n t h e b lu e st© ©
s t a t i o n s rirde g a in s r a n g in g fro© 17 t o 264 p e r c e n t *
C h ie f
among t h e s e w ere A nd rooo-on a c o m r t u s (1 4 3 p e r c e n t ) ,
S n o r o b o lu s o r y o te n d r u a ( 2 5 2 ) , ,3. h c t e r o l e n l n
p r a t e ess i s
( 1 3 ^ , and B o u te lo u a g r a c i l i s
( 2 6 4 ) , Poa .
(1 9 8 p e r c e n t ) *
A ll
o f t h e s e s p e c i e s , b u t o n e , ‘w ere d o m in a n ts o f t h e p r a i r i e
b e f o r e . t h e d r o u g h t*
The s i n g l e e x c e p t i o n i s
c r v o t a n d r u s w h ich i s
a r e c e n t in v a d e r *
t n o r o b o lu s
K o c lc r la c r i s t a t a * S t l r a s o a r t e a and Panlcura a o r lb n e r la n u ©
w ere t h e o n ly s p e c i e s w h ich f a i l e d t o i n c r e a s e i n abundance
in th e w h e a tg r a ss p r a i r i e s ,
G a in s o f t h e o t h e r s , e x c e p t
B o u t e lo u a g r a c i l i s w h ich i n c r e a s e d 141 p e r c e n t , ra n g ed fro©
3 t o 9 7 p e r c e n t*
S p o r o b o lu s h o t e r o l c o l s made t h e l a r g e s t i n d i v i d u a l
g a i n , 2 6 4 p e r c e n t , o f any s p e c i e s i n e i t h e r grou p o f
p r a ir ie s *
T h is x e r l c bunch g r a s s i s
b lu e st© © p r a i r i e s w h ere i t
r e s tr ic te d
t o th e
fo rm s a d i s t i n c t ty p e on t h e
d r i e s t h i l l t o p s and u p p er s l o p e s .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 14.
Blueotem p r a ir ie s .
Number o f at erne, percentage change i n abundance, and number o f
with permission
&ach
p lo ts in which sp ecies occurred from 1938 to
A
1940.
of the copyright owner.
Further reproduction
Number of sterna
Per cent inc reaoe or decrease
1938
1939
1940
1938-1939 1939-1940 1938-1940
Agropyron s m ith li
3248
3852
3724
+
Andropogon furcatus
3417
4310
4110 +> 26.1
Andropogon scoparius
651
I 584
Boutelous curtipenaula
5017
9347
Bouteloua g r a c i l i s
7999 23867 19916
Buchloe dactyloid ss^
73.2
Species
Number o f p lo ts i n which
each s p e cie s occurred
1938
1939
1940
Perennial grasses
390
18.60
* 143.3
prohibited
-
3,3
14 .7
19
21
23
-
4 .6
20.3
30
32
28
-
7 5 .4
40.1
17
14
10
5.7
■f 97 .0
30
30
29
16.6
* 149.0
18
18
18
-
15.6
4
3
4
50.1
2?
30
25
9883 4» 86.3
* 198.4
without permission.
5.5
-
20 .0
I 885 1301
«• 117.4
-
30.9
1383
1620
320
+
17.1
-
49.4
-
40.7
18
19
12
Panieuia spp.
718
1161
842
+
61,7
.
27.5
+
X7.3 .
15
14
11
Poa p raten sis
2222
5165
2274
■f 132.5
-
56.0
•h
2 ,3
5
5
7
Sporobolus asper
685
1098
949
*• 60,3
mm 13.6
38.5
12
17
15
Sporobolus eryptandrus
123
433
730
+
252.O
+
68,6
* 493.5
3
7
7
Sporobolus h e tero lep is
201
732
610
+• 264.2
-
16.7
+
203,5
6
7
6
S tp ia spartea
596
741
575
*
24.3
-
22.4
-
3.5
12
12
10
Other s p e c ie s
819
1572
339
+
91.9
—
78.4
46463 + 105.3
-
1 0 .0
Carex spp.
867
Koeleria c r i s t a t a
Total
77.2
27946 57367
61.8
+
£ 8 .6
+
66.3
,
.
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Total
58.6
339
91.9
«■» 7 8.4
27946 57367 46463
+ 105.3
10.0
+
66.3
819
Other species
1572
with permission
Perennial forbe
12?
102 -
19.6
mm 19.7
-
35.4
32
31
26
22
6
2 -
72.7
-
66.7
-
90.9
5
1
3
1844
810
60S
-
56.1
-
24.9
-
67.0
29
23
18
Oxalis stricta
63
80
96
+
27.0
+
20.0
+
52.4
13
11
6
Solidago glaberrima
25
12
3
mm
52.0
-
75.0
M
B
88.0
6
77
1
451
109
220
mm
75.8
+
101.8
2563
1144
. 55.4
1032 ■M
3284
1735
3342
22
38
161
129
114
1336
757
Hedeoraa hispida
748
Hordeum pusillum
Lepidium d t m i f b r u m
Artemisia gnaphalodes
of the copyright owner.
Further reproduction
158
Araorpha canescens
Aster multiflorus
Other species
Total
mm
51.2
9 .8
-
59.7
92.6
+
1.8
24
16
29
+1268.2
8
11
30
Annual plants
Bromus tectorum
47*2
301 + 72.7
+
692.1
«• 19*9
«■»
11.6
mm
29.2
13
6
7
452
-
43.3
-
40.3
-
66.2
49
21
46
79
1208
-
8 9 .4
+1429.1
+
61.5
42
25
48
267
541
231
+
102.6
57.3
mm
13.5
14
6
21
843
13
1863
-
93.5
121.0
10
6
37
Plantago purshii
57
418
264
+ 633.3
T
36.8
+ 363.2
12
12
25
Salsola pestifer
14
94
298
571.4
+
217.0
+2028.6
14
12
30
2?2? 2571
325
87.4
86.1
5618
7940
Chenopodium album
prohibited without permission.
Erigeron ramosus
Festucs octoflora
Other species
Total
1
-
2
7725
Estimated cover In per cen t.
i
-
+14230.5
10.4
27.3
+
41 .4
+
2 .9
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
Table 15.
Wheatgrass Prairies*
Number of steins* percentage change in abundance, and number
with permission
f i ac h
of plots in which^Epecies occurred from 1938 to 1940.
Species
of the copyright owner.
Number o f stems
Per cent in crease or decreaso
1938
1938-1939 1939-1940 1939-1940
1939
1940
Number o f p lo t s in which
each sp e cie s occurred
1938
1939
1940
Perennial g rasses
Agropyron sm ith ii
Andropogon furcatus
Further reproduction
Andropogon scoparius
11116
11164
2285
3433
507
955
4
2. 7' -
2 .2
+
0 .4
31
33
33
1720 + 50.2
-
49.9
-
24.7
32
30
24
701 4
88*4
-
26.6
+
38.3
14
9
6
21.1
31
35
30
prohibited
without permission.
Boubeloua crutipendula
8960 13928
7067
+
55.5
-
49.3
Bouteloua g r a c i l i s
6060 14580 10818
+
140.6
-
2 5.8
4
78.5
16
13
16
Buchloe dactyloides^
35*7
66.0
34.0
+
84 .9
-
48.5
•m
4 .7
3
3
3
Carex spp*
2413
4412
1877
4
8 2.8
-
57.5
-
22.2
25
27
24
Koeleria c r i s t a t a
247
202
116
-
18 ,2
-
42.6
-
53.0
9
7
5
Panicum spp.
447
415
95
7 .2
-
7 7 .1
«a»
78,8
6
7
2
Poa p raten sis
615
703
62
14.3
-
9 1 .2
-
89.9
5
6
3
Sporobolus asper
291
574
277
97 .3
wm
51.7
-
4 .8
7
11
9
Sporobolus cryptandrus
383
616
622
60.8
4
1 .0
4
62.4
13
12
11
Stipa spartea
80
70
13
12.5
-
8I .4
-
83.8
1
1
1
Other s p e cie s
1743
2986
255
4 71.3
.8 5 .4
O
0
O
35147 54286 34787
+ 54.5
Total
Perennial forba
+
-
91.5
-
35.9
-
O .l
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced
73
Stipa spartea
80
70
13
-
12.5
-
8 1 .4
-
83.8 |
1
Other sp e cie s
1743
2936
255
+
71.3
-
J?l*5
"
8$_.4__
O
35147 54286 34737
+
54.5
~
35.9
-
0 .1
304 -
1 8 .1
-
1 2 .9
-
28.6
16
16
14
3
“
5
q.
with permission
a
T3
-5
§■
C/)
O
Total
1
D
JL
D
Perennial Torbs
426
349
q
Aster laultiflorua
93
103
59
-
10*8
-
4 2 .7
-
36.6
10
7
ro
O
O
5
Artemisia gnaphalodes
13
21
31
+
61.5
+
47 .6
+ 138.5
2
1
4
6
1
*
50*0
-
83*3
-
75 .0
2
5
1
13
13
0
0-0
_
-
100.0
5
3
0
223
184
64
-
1 7 .4
-
65.2
-
71.3
772
676
459
-
12*5
-
32.1
-
40.5
5983
595
2266
-
90*1
+ 280*8
-
62.1
10
4
15
17
25
934
+
4 7 .1
+3636.0
+5394.1
2
6
17
1907
132
620
-
93.1
+ 369.7
-
67.5
28
7
25
of the copyright owner.
Amorpha cane seen a
o
S
®
Oxalis s t r i c t a
Solidago glaberrima
Other sp ecies
Further reproduction
?
Total
100.0
3
C
D
^
Annual plants
"
D
q
.
s
z
2;
§
Bromus tectoruia
Chenopodium album
prohibited
Festuca o o to flo ra 2
S.
Hedeoma hispid#
754
31
523
-
95.9
+1587.1
-
30.6
20
9
24
Hordeum pueillum
390
5
159
-
98.7
+3O8O.O
-
59.2
6
1
14
Lepidium cfenst{forum
309
3
919
-
9 9 .0
+30533.3
+ 197.4
1
Plantago pursiiii
78
16
133
-79.5
+
70.5
5
3
13
S a ls o la pesfcifer
58
0
+
+
325.9
9
3
22
249
715
1 .8
+ 192.4
7838
1390
without permission.
§;
<
g1
■
g
-5
3
Other sp e cie s
Total
+ 731.3
247 - 100,0
728
+ 187.2
5909 - - - 82*-3
+
t .325.1 ...-
Estimated cover i n per cen t.
Miitr-i’.ro " n f
d e n tm w tfir
u n i t s i n w h ic h s D e c ie s o c c u r r e d .
2 4 .5
0
6
R eproduced with permission of the copyright owner. Further reproduction prohibited without permission.
The a v e r a g e r e d u c t i o n o f p e r e n n i a l g r a s s e e on a l l o f
t h e p r a i r i e s was 2? p e r c e n t i n 1 9 4 0 .
e x c e p tio n s,
A l l s p e c i e s , w i t h few
s u s t a i n e d l o s s e s o f 2 t o 91 p e r c e n t .
H ea v iest
l o s s e s were r e c o r d e d a t t h e w h e a tg r a a s s t a t i o n s where s u b s o i l
m o i s t u r e t o a d e p t h o f 6 f e o t was c o n s i s t e n t l y
l e s s th a n 2
p e r c e n t and u s u a l l y n o n a v a i l a h l e d u r in g t h e g r o w in g s e a s o n .
Andropogon s c o n a r l u s . w h ich was f o r m e r l y t h e m ost
im p o rta n t s p e c i e s i n t h i s r e g io n ,
i n c r e a s e d 54 p e r c e n t
but
on a l l p r a i r i e s i n 1 9 3 9 A was red u c e d 57 p e r c e n t t h e f o l l o w ­
in g year*
le ss;
it
Changes i n ab u n d an ce o f . Andropogon f u r c a t u s were
i n c r e a s e d 36 p e r c e n t d u r in g t h e f i r s t y e a r , h u t
hy 1 9 4 0 i t was r e d u c e d 25 p e r c e n t .
S p o r o b o lu s c r v n t a n d r u s a l o n e made c o n s i s t e n t g a i n s
in b o th groups o f p r a i r i e s each y e a r .
I n c r e a s e i n abundance
o f t h i s I n v a d e r was due t o I t s p r o l i f i c s e e d i n g h a b i t and t o
an e x c e l l e n t r o o t s y s t e m .
I t h a s now e n t e r e d many o f t h e
p r a i r i e s and a l s o become one o f t h e c h i e f p a s t u r e g r a s s e s
o f e a s te r n N ebraska,
(W eaver and H a n sen , 1 9 3 9 , 1 9 4 1 ) .
A gron vron s r o l , / n l l . B o u t e lo u a c u r f c lp e n d u la . and B .
g r a c i l i s w ere f a v o r e d by t h e k i l l i n g
o f th e le s s x e r ic
g r a s s , and i n c r e a s e d en o rm o u sly i n a b u n d a n c e .
Apcroovron
s r n i t h i i was o f m in o r im p o r ta n c e b e f o r e t h e d r o u g h t , o c c u r r i n g
o n ly i n d i s t u r b e d a r e a s , and on c la y p a n s o i l s .
But f o llo w in g
t h e d r o u g h t o f 1 9 3 4 , i t i n c r e a s e d r a p i d l y and becam e one o f
t h e d o m in a n t p r a i r i e g r a s s e s
1938.
A p p a r e n t ly i t
a t t h e w e s t e r l y s t a t i o n s by
r e a c h e d i t s p eak i n o r a b o u t 1 9 3 8 ,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
f o r d a t a o b t a i n e d d u r i n g t h i s s t u d y s h o w e d .a g a i n o f 6 p e r
c e n t i n 1939 and &. l o s s o f 2 p e r c e n t i n t h e f o l l o w i n g y e a r .
T h is s m a l l l o s s may h e a t t r i b u t e d t o i t s
n orth ern o r ig in .
A gron vron ren ew s g r o w th In M arch, u s u a l l y 4 t o 6 weeks b e f o r e
t h e b lu e s t e r a s and o t h e r s p e c i e s o f s o u t h e r n e x t r a c t i o n , t h u s
t a k i n g a d v a n ta g e - o f any e a r l y s p r i n g r a i n f a l l .
I t rem a in s
dorm ant a f t e r h e a d i n g i n J u n e b u t r esu m es g r o w th i n l a t e
summer.
B e c a u s e o f t h i s g r o w th h a b i t , A nroovron a m l t h l l
may he c o n s i d e r e d a d r o u g h t - e v a d i n g r a t h e r t h a n a d r o u g h t r e s is tin g sp e c ie s.
The wave o f A groo vron s m l t h l l was c l o s e l y
one o f B o u t c l o u a c u r t l o e n d u l a .
f o l l o w e d by
T h is d r o u g h t - r e e ls t in g
s p e c i e s , w h ich c o n s t i t u t e d a b o u t 1 p e r c e n t o f t h e p r a i r i e
c o v er b e fo r e th e d ro u g h t, has soraad so w id ely t h a t i t
now one o f t h e m o st i m p o r t a n t p r a i r i e g r a s s e s .
o f B» c u r t i o e r . d u l a was due i n p a r t t o i t s
The i n c r e a s e
p r o l i f i c se e d in g
h a b i t and i n p a r t t o p r o p a g a t i o n by s h o r t r h i z o m e s .
of
is
R eco rd s
1939 showed f u r t h e r i n c r e a s e s o f t h i s s p e c i e s i n b o t h
g r o u p s o f p r a i r i e s , h u t t h e f o l l o w i n g y e a r i t made g a i n s
o n ly a t th e b lu e ste m s t a t i o n s .
H ere t h e number o f s t e m s ,
doc p i l e t h e d r a u g h t , was 6 p e r c e n t g r e a t e r t h a n t h e p r o 'c e e d in g y e a r .
A v era g e l o o s a t t h e w h e s t g r a s s s t a t i o n s
was 49 p e r c e n t *
Dead crow n s w ere q u i t e common, e s p e c i a l l y
on d r i e r s l o p e s .
The r e d u c t i o n o f t h i s s p e c i e s h a s b een
t h e r e s u l t o f an e a r l y e x h a u s t i o n o f s o i l m o i s t u r e by
Aftronvroa s m l t h l l and t o i n s u f f i c i e n t summer r a i n f a l l .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
B o u te lo u a g r a c i l i s a l s o in c r e a s e d i t s t e r r i t o r y as a
r e s u l t o f th e r e c u r r e n t d rou gh t.
I t had a lw a y s b een a
com ponent o f t h e p l a n t c o v e r , e s p e c i a l l y on h i l l t o p s and
d r y r i d g e s , b u t was h o l d i n c h e c k by t h e mid and t a l l g r a s s e s .
A f t e r ' t h o i r d e s t r u c t i o n , t h i s s p e c i e s b e g a n t o s p r e a d , fa r m in g
a l t o r n e s a t s e v e r a l s t a t i o n s and an u n d e r s t o r y t o w h e a t g r a s a
at oth ers.
R eco rd s o b t a i n e d i n 1939 r e v e a l e d t h a t i t macl©
g a i n s w e l l o v e r 100 p e r c e n t a t e a c h -group o f s t a t i o n s .
The a v e r a g e l o s s i n 1940 on a l l p r a i r i e s was 20 p e r c e n t .
Aarorvvrcn s m i t h ! 1 was t h e o n ly s p e c i e s t o s u s t a i n s m a l l e r
r e d u c tio n s.
Pan!curs w llc o x la n u m 'was t h e o n ly s p e c i e s t o s u f f e r
lo o s e s each y e a r in b o th groups o f p r a i r i e s .
D e c r e a s e In
t h i s s p e c i e s i s a t t r i b u t e d t o d e a t h o f t a l l and mid g r a s s e s
o p e n i n g t h e c o v e r and p e r m i t t i n g d i r e c t i n s o l a t i o n on
p l a n t s t h a t w ere p r o b a b ly s h a l l o w l y r o o t e d ,
N a t i v e p e r e n n i a l f o r b s f o r m e r ly formed a c o n s p i c u o u s
p a r t o f t h e c o v e r b u t have b o o n g r e a t l y r e d u c e d i n ab u n d an ce
u n t i l now t h e y a r e v e r y i n c o n s p i c u o u s .
Data o b t a i n e d i n
1 9 3 9 from a l l o f t h e p r a i r i e s r e v e a l e d & f u r t h e r r e d u c t i o n
o f 45 p er c e n t .
w ere 18 p e r c e n t .
e x c e p tio n s.
D u rin g t h e f o l l o w i n g y e a r t h e i r l o s s e s
D eep -ro o ted s p e c i e s c o n s t i t u t e d no
A s t e r mul t l f l o r n a . S o l I d o
g, 1nbe r rlsna. and
Amornha c a n e s c e n a s u f f e r e d , t h e h e a v i e s t l o s s e s .
The
g r e a t e s t r e d u c t i o n i n abundance o f f o r b s was r e c o r d e d i n
th e b lu e e te m p r a i r i e s
i n 1 9 3 9 , and a t t h e w h e a t g r a s s s t a t i o n s
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
57
I n 1940*
Q x a l l s s t r l c t a was t h e o n ly s p e c i e s t o make g a i n s
e a c h y e a r In t h e bluestcun p r a i r i e s , w h i l e A r t e m i s i a
g n a o h n lo d e s a l o n e i n c r e a s e d In t h e w h e a t g r a s s g r o u p .
The b e h a v i o r o f a n n u a l p l a n t s d u r in g t h e d r o u g h t
d i f f e r e d , g r e a t l y from t h a t o f p e r e n n i a l s p e c i e s •
C o in c i d e n t
w i t h t h e l a r g e i n c r e a s e I n p e r e n n i a l s i n 1939* a n n u a ls were
r e d u c e d 53 p e r c e n t on a l l p r a i r i e s .
In 1 9 4 0 , h o w e v e r ,
t h e c o n v e r s e o f t h e above r e l a t i o n s h i p e x i s t e d .
D esp ite a
g a i n o f 97 p e r c o a t , a n n u a ls s t i l l w ere 8 'per c e n t l o s s i n
ab u n d an ce th a n I n 1 9 5 8 .
T h e i r phenom enal g a i n In 1940
was made p o s s i b l e by e a r l y s p r i n g r a i n s and f a v o r a b l e tem­
p era l u r e s .
31 t h t h e o p e n in g o f t h e c o v e r , a s a r e s u l t o f
d e a t h o f p e r e n n i a l s p e c i e s ' , l a r g e numbers o f s e e d s
g erm in a ted .
to t h is g a in .
T w e n ty - fo u r s p e c i e s o f a n n u a l s c o n t r i b u t e d
Compared w it h t h e t o t a l In 1 9 3 9 , t h i s I s a
«
red u c tio n o f 4 s p e c ie s .
S h a l l o w l y r o o t e d an n u al w e e d s , e s p e c i a l l y
S a lso la
• o e o t i f c r and Chenooodluia a lb u m , became v e r y common, i n ­
c r e a s i n g 2 t o 20 t im e s i n a b u n d a n c e ,
Hedcocm h l s o l d a
and i,o n lS lu m d o n o lf lo r u t a a l s o mad© marked g a i n s .
C e r t a i n a n n u a l s , p a r t i c u l a r l y Bromua t e c t o r u a and
arid Chenonodlum a lb u m ^have t h e c a p a c i t y t o w i t h s t a n d crowd­
in g .
As many a s 7 0 0 p l a n t s o f Bromus t e c to r u m o r 12 5 o f
Chenooodlum album may o c c u r on a s i n g l e s o u a r e - f o o t o f
s o il.
T h is d e n s e cro w d in g r e s u l t e d i n a r e d u c t i o n i n
b o t h h e i g h t and s e e d p r o d u c t io n o f t h e i n d i v i d u a l p l a n t s .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
I n g e n e r a l , t h e r e was g r e a t e r f l u c t u a t i o n I n t h e popu­
l a t i o n o f a n n u a ls I n t h e w hentgr& ss p r a i r i e © th a n i n t h e
'b lu estem group*
DISCUSSION
T h is r e s e a r c h r e p o r t s c h a n g e s In t h e p o p u l a t i o n o f
t h e t r u e p r a i r i e o v e r a p e r i o d o f tw o y e a r s *
The w r i t e r was
g r e a t l y i m p r e s s e d by t h e h i g h l y d i s t u r b e d c o n d i t i o n o f a
c l i m a x v e g e t a t i o n when he f i r s t o b s e r v e d I t i n 1938*
T hat
g r e a t d i s t u r b a n c e had o c c u r r e d was c l e a r l y shown by t h e
a b u n d a n ce o f bar© or* n e a r l y b a red s p a c e s o f a l l s h a p e s and
s i z e s on t h e v a r i o u s s l o p e s and h i l l t o p s , and e v e n on lo w
ground.
The march o f d e a t h d e a l i n g d r o u g h t was a l s o shown
by t h e dead crowns and stem b a s e s .
Many o f t h e s e were
c l e a r l y e v i d e n t , a lth o u g h p a r t i a l l y d is in t e g r a te d *
Here
was e v i d e n c e o f a c a t a s t r o p h e s u c h a s h ap p en s o n ly a t
l o n g i n t e r v a l s and one w hich had n e v e r b e f o r e b e e n stu d ie d ,
and r e c o r d e d b y modern e c o l o g i c a l m e th o d s .
The f l o r a was new t o t h e w r i t e r , who came from t h e
w e s t e r n c o a s t , b u t h e g r a d u a l l y became f o m i l a r w i t h i t
th rou gh f i e l d
t r i p s and c a r e f u l s tu d y o f t h e h i s t o r y o f
v e g e t a t i o n , p r e c e d in g th e g r e a t drought o f 1 9 3 4 .
Few, i f
a n y , m a jo r g r a s s l a n d a r e a s h a v e had t h e e x t e n d e d d e s c r i p t i v e
s t u d y , t h e e x t e n s i v e r e c o r d o f e n v ir o n m e n t a l f a c t o r s , arid
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
59
t h e g r e a t amount o f e x p e r i m e n t a l I n v e s t i g a t i o n t h a t t h i s
r e g io n has had.
The e x c e p t i o n a l v a l u e o f l o n g - t i m e s t u d y
and e x p e r i m e n t a t i o n a r e t h u s b e i n g r e a l i s e d .
The w r i t e r u n d e r t o o k t h i s
o f Dr. J .
resea rch a t th e su g g e stio n
E. l e a v e r , o n l y a f t e r s e r v i n g an a p p r e n t i c e s h i p
i n 1 93 0» i n q u a d r a t t i n g and i n d i e c o v e r i n g and r e c o r d i n g
c h a n g e s i n t h e s e same p r a i r i e s i n c o m p a n io n s h ip w i t h D r,
J . H. R o b e r t s o n .
T h i s e x p e r i e n c e form ed a b a ck gro u n d f o r
fu rth cr procedure•
The s t e m - e o u n t method -was u sed i n quad r a t t i n g and h a s
p r o v e n t o be w e l l a d a p t e d i n r e c o r d i n g c h a n g e s .
S in ce th e
o r i g i n a l p l a n was t o c o n t i n u e t h e r e c o r d i n g o f t h e v e g e t a t i o n
on t h e s e same p l o t s o v e r a p e r i o d o f t e n y e a r s , o r a t l e a s t
u n t i l c lim a x v e g e t a t i o n was r e e s t a b l i s h e d , t h i s method
p e r m i t s a minimum o f e r r o r due t o . c h a n g e i n p e r s o n n e l .
An ar.clersta ru lin g o f t h e p l a c e o f t h i s much d e t e r i o r a t e d
w e s t e r n edge o f t r u e p r a i r i e i n r e l a t i o n t o t h e u n d i s t u r b e d
t r u e p r a i r i e E a stw a rd and t h e m ixed p r a i r i e on t h e w e s t ,
w h i l e n o t a part, o f t h i s t h e s i s ,
i s necessary i n i n t e r p r e t i n g
th e changes t h a t have o c c u r r e d .
By a c c o m p a n y in g Dr. J .
l e a v e r , whose f i e l d
o f d r o u g h t s tu d y e x t e n d s from
h.
central
Iowa t o t h e Rocky f o u n t a i n s , ' t h e w r i t e r h o 0 n o t o n ly s e e u
h i s own
fie ld
a b l e t o more l u l l }
in i t s
p roper s e t t i n g but has been
u n d erstan d i t s
s ig n ific a n c e .
The
e a s tw a r d a d v a n c e o f A fr o o v r o n s m i t h ! 1 . B o u t e l o u a c . r a c l l l s .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
60
and S p o r o b o l u s c r v o t a n d r u e , s a d t h a t o f Such loo. d a o t v l o l d e e
in grazed p r a i r i e s , r e p e a ts th e g r e a t resp on se to c lim a t ic
c h a n g e s t h a t m ust h a v e o c c u r r e d i n t h e p a o t and p o r t e n d s
w h a t may o c c u r s t i l l morn c o m p l e t e l y w i t h c o n t in u e d d e s i c ­
c a tio n .
B e c a u s e o f l o c a l d i f f e r e n c e s i n amount and tim e o f
p r e c i p i t a t i o n , b e h a v i o r o f t h e v e g e t a t i o n was n o t t h e same
on a l l p r a i r i e s .
P e r e n n ia l g r a s s e s in c r e a s e d a t a l l s t a t i o n s
d u r i n g 1939# u s u a l l y from 25 t o ICC p e r c e n t .
During 1 9 4 0 ,
l o s s e s o f 10 t o 60 p e r c e n t o c c u r r e d on a l l p r a i r i e s e x c e p t
i ' o n t r o s c , w here t h e r e was a m o d era te g a in *
T o ta l g a in s
o v e r t h e t w o - y e a r p e r i o d o c c u r r e d on t h r e e b lu e ste r n p r a i r i e s
and a t one w h c a tg r a o a s t a t i o n .
per c e n t.
T h o se w ere o n l y 13 t o 30
C o n v e r s e ly , l o s s e s o f a p p ro x im a tely eq u al
m a g n itu d e o c c u r r e d a t two b l u e s t e m and t h r e e w h e a t g r a s s
sta tio n s.
T h ree o f t h e b e s t d r o u g h t e v a d i n g o r d r o u g h t e n d u r in g
s p e c i e s o f g r a s s e s w ere Areronvron s m i t h 1 1 » B o u t o lo u a g r a c i l i s ,
and jS. c u r t l p e r . d u l a .
A# ropy ron s m l t h l ! had a p p a r e n t l y
reached, i t s maximum d e v e lo p m e n t on two b l u e s tem p r a i r i e s
and two o f w h e a t g r a s s , w h e r e , l o s s e s o f 1 t o 5 6 p e r c e n t
o c c u r r e d i n 1939*
F u rth er l o s s e s occu rred a t a l l bu t fo u r
s t a t i o n s i n 1 9 4 0 , and t h e y u s u a l l y showed a t w o - y e a r d e c r e a s e
o f 25 p e r c e n t o r m ore.
At t h e r e m a in in g s t a t i o n s , g a i n s
p r o f ir'/c .s
In 19 3 9 w ere f o l l o w e d i n s e v e r a l l y
d ecreases.
The tw o -
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
y e a r p e r i o d , h o w e v e r , r e s u l t e d i n g a i n s r a n g in g from 7 t o
3 2 5 p e r c e n t on s i x o f t h e n i n e p r a i r i e s o r g r o u p s ,
B o u t e lo u a a r a o . l l l s mad© g a i n s o f 39 t o 3 41 p e r c e n t'
during, th e two y e a r s i n t h e w h e a t-g r a s © p r a l r i o s , and s m a l l e r
o n e s In a l l b u t one o f t h e b l u e s t e m g r o u p s »
showed g a i n s o f
B* c u r t ln o r id u la
50 t o 170 p e r c e n t a t a l l s t a t i o n s t h e f i r s t
y e a r b u t a lm o st e q u a l l y h ig h l o s s e s th e seco n d .
Only t h r e e
o f t h e p r a i r i e s had s m a ll t w o - y e a r g a i n s o f t h i n s p e c i e s .
B e h a v io r o f S p o r o b o lu s a s o e r was v a r i a b l e ; t h i s
s p e c i e s i n c r e a s e d on m ost o f t h e p r a i r i e s w here i t o c c u r r e d ,
S . h c t e r o l o n i s o c c u r r e d a t o n ly a few o f th e s t a t i o n s i n
th e e a s t e r n edge o f th e t e r r i t o r y .
I t In c rea sed in every
p r a i r i e i n w h ich i t o c c u r r e d , g a i n s o f t e n a m ou ntin g t o more
t h a n 100 p e r c e n t .
v a r ia b le .
B e h a v i o r o f d t i o a s n a r t e a was somewhat
I t i n c r e a s e d w h e r e v e r i t was ab u n d an t b e f o r e t h e
d ro u g h t,
The b e h a v i o r o f t h e b lu e a t e m s i s o f s p e c i a l i n t e r e s t ,
s i n c e b e f o r e t h e d r o u g h t Andropogon s o o n o r i u s was b e l i e v e d
t o b e more d r o u g h t r e s i s t a n t t h a n t h e more d e e p ly r o o t e d
£ • f u r c a t u s . w h ich u s u a l l y o c c u r r e d on lo w e r g ro u n d .
Androoo .:o.n s c o p a r l u s showed g a i n s o f 22 t o 167 p e r c e n t a t
a l l b u t one s t a t i o n i n 1 9 3 9 ,
L o s s e s a m o u n tin g t o 60 p e r
c e n t o r more wore r e c o r d e d on a l l o f t h e w h e a t g r a s s p r a i r i e s
( where i t o c c u r r e d ) d u r in g 19 40 and a t t h e end o f t h e t w o year stu d y .
C o n v e r s e l y , g a i n s were made e a c h y e a r and t o t a l
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
g a i n s i n 194 0 o f 4 3 t o 347 p e r c e n t a t t h r e e o f f o u r b l u e ­
s t csn p r a i r i e s .
Good g a ln n wore r e c o r d e d f o r Andropogon
f u r e a t u s a t a l l b u t two
o f th e s t a t i o n s In 1 9 3 9 , h u t f u r th e r
g a l n c were made a t o n ly
t h r e e i n 1 9 4 0 . A l l b lu e e te m
e x c e p t o n e , and h a l f o f
t h e whe&tgr&ss p r a i r i e s y i e l d e d t w o -
y e a r g a i n s o f 31 t o 269
per c e n t.
p r a ir ie s,
The c h i e f p e r e n n i a l forfcs a t t h e s e v e r a l s t a t i o n s
i n c l u d e d A s t e r raul t i f l o r u a . Ox a ,1.1 a s t r l e t a . l o ld a r .o r.la b o rr lta a
L l a t r l s p u n c t a t a . Amornhn c a n e s c a n s . and A r t e m ia la fen ash alod oa
T h e s e w ere s u r v i v o r s o f th e p r e v i o u s y e a r s o f d r o u g h t .
At
t h e w h e a t g r a s s s t a t i o n s l o s s e s i n t h i s grou p ran ged from
3 to
69 p e r c e n t d u r in g t h e two y e a r s , and from 38 t o 83
p e r ce n t in th e b lu e s t e n p r a i r i e s .
th e B e l l e v i l l e
An I n c r e a s e o c c u r r e d a t
s t a t i o n o n l y , and t h i s was s l i g h t .
C h ie f a n n u a ls were Broiaue t o c t o r u t a . :Crln.oron r a m o su s .
F e s t u o a o c t o f l o r a . h en ld lum d o n s l f lorurn. Hedeoaa h l s o l d a .
Chenopodlun a lb u m . S a l s o l a nos L i f e r and Pic, n ta e o marsh i i .
T h ese i n c r e a s e d a t m ost s t a t i o n s i n 1 9 4 0 , when c o n d i t i o n s
f o r g ro w th o f t h e c o m p etin g p o r o n n i a l o w ere l e s s f a v o r a b l e .
G a in s o f t e n amounted t o s e v e r a l h u ndred p e r c e n t .
The r e s p o n s e o f t h e v a r i o u s s p e d
00 o f f o r b s and
g r a s s e s t o i n c r e a s e d d e s i c c a t i o n h a s p e r m i t t e d an u n d e r s t a n d ­
i n g o f t h e i r a u t o c o l o g y and o f community r e l a t i o n s h i p s t h a t
c o u l d n e v e r h a v e b e e n had s a v e f o r t h e d r o u g h t .
The
c o m p le t e s t o r y o f t h e b r e a k i n g down o f t h e g r a s s l a n d s u n d er
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
63
t h e Impact of d r o u g h t , the s h i f t l a g s of t h e p l a n t popu­
l a t i o n s , and t h e r o e s t a b l i s f t m a n t o f t h e s t a b i l i s e d c l i m a x
f o l l o w i n g t h i s c a t a s t r o p h e , w i l l c o n s t i t u t e a c l a s s i c In
th e stu d y o f g r a s s l a n d .
The p r e s e n t p a p e r c o n t r i b u t e s a
s m a l l p a r t t o t h i s s t o r y d u r in g t h e tw o y e a r s , 1939 and
1940*
U n fo r tu n a te ly , sin g le u n r e la te d s t u d i e s o f drought
e f f e c t I n v a r i o u s o t h e r p o r t i o n s o f t h e g r a s s l a n d f o rm a tio n
c o n s t it u t e th e s o le record*
The p r e s e n t r e p o r t i s
c lo se ly
r e l a t e d to what has gone b e f o r e at id th e permanent reco rd ■
and t h e perm anent ftu a d r a ts a r e now p a s s e d on t o a n o t h e r
I n v e s t i g a t o r who w i l l c o n t in u e the work*
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
SUMMARY
Changes i n t h e c o m p o s i t i o n o f n a t i v e g r a s s l a n d s i n s e v e n
c o u n t i e s i n - e a s t e r n ?«ebraaka and n o r t h - c e n t r a l Kansas w ere
r e c o r d e d i n 100 me.tor c u a d r a t s and numerous l a r g e r p l o t s i n
12 w i d e l y s e p a r a t e d p r a i r i e s from 19 3 8 t o 1 9 4 0 .
The g r o w in g s e a s o n o f 1939 was e x t r e m e l y dry w it h
u n s e a s o n a b ly h i g h t e m p e r a t u r e s .
A v a ila b le w ater con ten t
o f s o i l was o f t e n n e a r l y e x h a u s t e d i n t h e f i r s t two .
feet
a t a l l t h e s t a t i o n s , b u t e s p e c i a l l y i n t h o s e d om inated
by A nropyron a m l t h l l .
The f o l l o w i n g y e a r a l s o was c o n ­
s i d e r a b l y d r i e r th a n n orm al b u t mean t e m p e r a t u r e s were
n e a r l y n o r m a l.
S o i l m o i s t u r e c o n d i t i o n s were much l e s s
f a v o r a b l e i n 1 9 4 0 , no w a t e r b e i n g a v a i l a b l e f o r grow th t o
5 f e e t i n d e p t h a t any s t a t i o n d u r i n g c e r t a i n p e r i o d s .
T h is g r a s s l a n d was f o r m e r l y t r u e - p r a i r l e v e g e t a t i o n
o f th e m id -g r a ss t y p e .
The c h i e f d o m in a n ts w ere AnclroppKon
s c o o a r l u s . w h ich a l o n e f r e q u e n t l y c o n s t i t u t e d 70 p e r c e n t
o f t h e c o v e r , S t l n a s n a r t e a . S p o r o b o lu s h e t e r o l e p i s . K o e l e r l a
c r l s t a t a ; and D o u t e lo u a c u r t l n e n d u l a .
d o m in a te d t h e l o w l a n d s .
Andropogon f u r c a t u s
A s s o c i a t e d w i t h i t were S o m h a str u m
n u t a n s . Panicum v lr fta tu m ,a n d Elvmus c a n a d e n s i s .
N o t ic e a b le changes occu rred i n th e s tr u c tu r e o f th e
v e g e t a t i o n soon a f t e r th e drought o f 1 9 3 4 .
AndronoKOn
s c o p a r l u s was g r e a t l y r e d u c e d i n ab u n d an ce a t many s t a t i o n s
and a t o t h e r s was c o m p l e t e l y r e p l a c e d a s t h e c h i e f dom inant
by Afiropyron s m l t h i l .
Andropogon f u r c a t u s a l s o s u s t a i n e d
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
o5
h ea v y l o s s e s .
F ou r o f t h e 12 p r a i r i e s , m o s t ly t h o s e f a r t h b r e s t w e s t ,
became d o m in a te d by A gronvron s m i t h ! 1 : i n t h e r em a in d e r
Andropogon r e t a i n e d dom inance o v e r much o f t h e a r e a .
The u n d e r s t o r y I n a l l p r a i r i e s d i s a p p e a r e d c o m p le t e l y
and b a s a l a r e a was much r e d u c e d .
X erlc s p e c i e s ,
s u c h a s B o u t e lo u a g r a c i l i s . B. c u r t l -
n e n d u la and B u c h lo e d a c t v l o l d e a . i n c r e a s e d i n a b u n d a n ce.
F o r b s w ere u n u s u a l l y red u c e d i n num bers.
h o w e v e r , made l a r g e g a i n s .
e s p e c ia lly
In 1 9 3 7 .
A ster m u ltlflo r u a .
A nnuals became v e r y common,
Most Im p o rta n t o n e s w ere F e s t u c a
o c t o f l o r a . Bromus t c c t o r u m . Hedeoiaa h l s n l d a . and P i s n t a g o
p u r sh ll.
F u r t h e r c h a n g e s o c c u r r e d i n t h e n a t i v e v e g e t a t i o n from
1 9 3 8 t o 194-0.
T h ese c h a n g e s , h o w e v e r , w ere n o t s o c o n s p i c u o u s
a s w ere t h e e a r l i e r o n e s .
As In p r e v i o u s s t u d i e s , th e y were
r e c o r d e d m a in ly by means o f perm anent l i s t q u a d r a t s , b u t
a l s o by t r a n s e c t s , b a s a l a r e a q u a d r a ts , and by m apping.
Changes o c c u r r i n g i n a l l t h e p l o t s on any p r a i r i e
o r grou p o f s i m i l a r p r a i r i e s h a v e b een t a b u l a t e d s e p a r a t e l y .
T h u s, t h e b e h a v i o r o f e a c h Im p o r ta n t p e r e n n i a l g r a s s o r f o r b
o r a n n u a l may be s t u d i e d s e p a r a t e l y , a s may a l s o a l l c h a n g e s
on t h e p a r t i c u l a r p r a i r i e .
The a v e r a g e i n c r e a s e o f p e r e n n i a l g r a s s e s on t h e
p r a i r i e s i n 1939 was
76 p e r c e n t o v e r t h e i r 1 9 3 8 ab u n d a n ce.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
D u r in g t h e f o l l o w i n g y e a r t h e y d e c r e a s e d 27 p e r c e n t .
A p p r o x im a te ly 70 p e r c e n t o f t h e maximum number o f
s te m s o f p e r e n n i a l g r a s s e s f o r e a c h y e a r w ere p ro d u ced by
A grop vron s m l t h l l . B o u t e l o u a g r a c i l i s . 3 . c u r t l p e n d u l a . and
S p o r o b o lu s c r v p t a n d r u s .
Only one s p e c i e s , S p o r o b o lu s c r v p t a n d r u s . made g a i n s
b o t h y e a r s ; a l l o t h e r s , w i t h few e x c e p t i o n s , i n c r e a s e d o n ly
d u r i n g one y e a r , u s u a l l y 1939*
C h ie f among t h o s e m aking g a i n s i n 1939 w ere g r a s s e s of s o u th e r n
o r ig in ,
ouch a s Andropogon s c o n a r i u s . S p o r o b o lu s h e t e r o l e p l s .
3 . c r v p t a n d r u s . and B o u t e l o u a g r a c i l i s .
The n e x t y e a r ,
h o w e v e r , t h e s e g r a s s e s s u f f e r e d g r e a t l y from t h e d r o u g h t .
S p e c i e s o f n o r t h e r n o r i g i n w ere more s t a b l e .
S p o r o b o lu s h e t e r o l e p l s . a x e r l c b unch g r a s s r e s t r i c t e d
t o t h e b lu e ste m p r a i r i e s ,
(264 p e r c e n t)
made t h e g r e a t e s t i n d i v i d u a l g a i n
d u r in g t h i s s t u d y .
P e r e n n i a l f o r b s on a l l o f t h e p r a i r i e s were s u c c e s s i v e l y
r e d u c e d i n 19 3 9 and 19 4 0 t o 45 and 56 p e r c e n t o f t h e i r
1 938 a b u n d a n c e .
A s t e r m u l t l f l o r u s . S o l l d a g o g l a b e r r l i n a . and
Amorpha c a n e s c e n s s u f f e r e d t h e h e a v i e s t l o s s e s .
O x a lls
s t r l c t a was t h e o n l y s p e c i e s t o make a n e t g a i n e a c h y e a r .
S u p p lem en ta ry s t u d i e s o f f o r b s c o n d u c te d i n 8 l a r g e
c i r c u l a r p l o t s d o m in a ted by A grop vron s m l t h l l r e v e a l e d t h a t
l o s s e s o f Amorpha c a n e s c e n a . A s t e r m u l t l f l o r u s . A c e r a t e s
a n R u s t l f o l l a ». , and Rosa a r k a n sa n a ran ged from 16 t o 100
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
67
per ce n t.
S o H d a ^ o m o l l i s . Mai v a s t rum c o c c l n e u m . and
L y^ o d esm ia
l u n c e a . h o w e v e r , made l a r g e g a i n s .
T h ese f o r b s
a r e I m p o r t a n t s p e c i e s o f t h e m ixed p r a i r i e and have r e c e n t l y
in v a d e d t h e t r u e p r a i r i e .
A n n u a ls d e c r e a s e d 5 5 p e r c e n t from 1938 t o 1 9 3 9 , b u t
i n c r e a s e d 98 p e r c e n t from 1939 t o 194-0.
P la n ta r .o n u r s h i l
and tw o r u d e r a l i n v a d e r s , S a l s o l a n e s t i f e r and C h e n o n o d l u m
a lb u m , w ere t h e o n l y s p o c i e s w h ic h i n c r e a s e d i n abundance
in 1939.
By t h e n e x t y e a r n e a r l y a l l a n n u a l s had become
v e r y common, i n c r e a s i n g 2 t o 20 t im e s i n a b u n d a n c e .
The
m ost im p o r t a n t a n n u a l s w ere L epjdlum d e n s l f l o r u m . Hedeoroa
h l s p l d a . and Chenonodium a lb u m .
F lu c tu a tio n s, in g e n e r a l,
•t H&
w ere g r e a t e r i n t h e b l u e s t e m p r a i r i e s t h a n i n ^ w h e a t g r a s s
group.
The t o t a l number o f s p e c i e s on a l l o f t h e p r a i r i e s
was r e d u c e d from 90 i n 1938 t o 8 1 i n 1939 and by 1940 i t
had b e e n r e d u c e d t o 7 5 •
p l o t i n 1938 ( 1 3 .6 )
The a v e r a g e number o f s p e c i e s p e r
d e c r e a se d to 1 0 .3 i n
1939, b u t i n c r e a s e d
t o 1 1 .6 th e f o llo w in g y e a r .
The a v e r a g e number o f s q u a r e d e c i m e t e r u n i t s p e r p l o t
d e v o i d o f v e g e t a t i o n i n c r e a s e d i n 1939 and d e c r e a s e d t h e
fo llo w in g y e a r .
T h ere w ere 6 b a r e u n i t s p e r p l o t t h e f i r s t
y e a r b u t o n ly 2 t h e s e c o n d .
F o r b s , a s a g r o u p , w ere q u i t e s t a b l e ;
117 b a r e u n i t s and v a c a t e d 1 1 0 .
u n sta b le .
th e y in v a d e d
P e r e n n i a l g r a s s e s were
They I n v a d e d 4 4 0 u n i t s w h i l e v a c a t i n g 2 2 4 .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
58
A n n u als In v a d e d 5 7 8 u n i t s and p ro d u ced 363 new o n e s .
Peren­
n i a l s p e c i e s o f a l l k in d s were t h e im p o r t a n t i n v a d e r s i n
1939
when a n n u a l s w ere f e w , w h erea s a n n u a ls w ere m ost im p o r t a n t
in 1940.
A grop vron s m l t h l l was th e m ost u n s t a b l e among p e r e n n i a l
grasses;
it
in v a d e d 125 u n i t s and v a c a t e d 6 3 .
S im ila r
numbers from Andropogon f u r c a t u s w ere 54 and 4 7 ; B o u t e lo u a
c u r t i p e n d u l a in v a d e d 9 2 and v a c a t e d 4 4 , b u t Andropogon
s c o p a r l u s in v a d e d none o f t h e p l o t s and l e f t o n l y on e b a r e .
A s t e r m u l t l f l o r u s was t h e o n ly u n s t a b l e f o r b .
in v a d e d 4 9 b a r e u n i t s w h i l e v a c a t i n g 6 1 .
It
A n n u a ls , su c h a s
F e s t u c a o c t o f l o r a . P l a n t a g o p u r s h l i . and L epldlum d e n s l f l o r u m .
a l s o w ere u n s t a b l e .
A rea s d o m in a te d by e a c h o f s i x s p e c i e s were mapped
e a c h y e a r on a p r a i r i e a t S m era ld .
The r e s u l t s showed t h a t
o n ly o n e , B o u t e l o u a g r a c i l i s . i n c r e a s e d i t s
o th ers,
t e r r i t o r y , th e
Andropogon f u r c a t u s . A s t e r m u l t l f l o r u s . S t l o a
s p a r t e a . S p o r o b o lu s a s p e r and A gropvron s m l t h l l . decrec^sed
i n a r e a from 7 t o 30 p e r c e n t .
A gron vron s m l t h l l i n c r e a s e d 50 p e r c e n t o r more i n
a r e a a t C lay C e n t e r , V a l p a r a i s o , and B e lm o n t.
T h ese
I n c r e a s e s w ere made a t t h e e x p e n s e o f o t h e r p e r e n n i a l
g r a s s e s and f o r b s w h ich were r e d u c e d a b o u t 75 p e r c e n t i n
abundance.
Changes I n p e r c e n t a g e c o m p o s i t i o n o f p l a n t c o v e r on
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
p r a i r i e s a t C r e te and L i n c o l n i n 1940 I n c lu d e d an i n c r e a s e
o f 43 p e r c e n t o f Andropogon f u r c a t u s on lo w e r s l o p e s , 1 p e r
c e n t on u p p e r s l o p e s , b u t a d e c r e a s e o f 19 p e r c e n t on m id s lo p e s .
A ndroperon s c o p a r l u s i n c r e a s e d 100 p e r c e n t on
u p p e r s l o p e s , 2 p e r c e n t on t h e m id d le o n e s , b u t d e c r e a s e d
29 p e r c e n t on t h e lo w e r s l o p e s .
B o u t e l o u a c u r t l p e n d u l a . S t l o a s p a r t e a . and S p o r o b o lu s
h e t e r o l e p l s became more im p o r t a n t o n ly on t h e m id d le e l o p e s
a t C r e t e , w h i l e Carex p e n n s v l v a n l c a i n c r e a s e d in im p o r ta n c e
o n l y on t h e u p p er s l o p e s .
The b a s a l a r e a on e a c h s l o p e was
r e d u c e d a b o u t 50 p e r ce n t.S e e d l i n g s o f n a t i v e p e r e n n i a l s p e c i e s were f e w .
T otal
number o f s e e d l i n g s i n t h e 1 0 0 p l o t s i n 1 9 3 9 . was 131 and i n
1 9 4 0 i t was 1 6 8 ,
The h i g h o s t c o u n t s w ere f o r B o u t e lo u a
c u r t l n e n d u l a . Panloum s c r l b n e r i a n u m . S p o r o b o lu s a s n e r .
A s t e r m u l t l f l o r u s . and O x a l l s s t r i c t a i n t h e o r d e r named.
B u c h lo o d a c t v l o i d e s . Panicmm v i i v a t u m . and S p o r o b o lu s
h e t e r o l e p l s prod u ced no s e e d l i n g s d u r in g t h i s s t u d y .
A y e a r ly
p r a ir ie ,
c e n s u s o f p e r e n n i a l s e e d l i n g s on t h e C r e te
r e v e a l e d a h i g h m o r t a l i t y among t h o s e o f S t l p a
s n a r t o a and S p o r o b o lu s a s n e r .
The p e r c e n t a g e s u r v i v a l o f
f i r s t - y e a r p l a n t s ’was 23 and 33 p e r c e n t ,
r e sp e c tiv e ly ,
and t h a t o f y e a r - o l d o r o l d e r s e e d l i n g s was ‘83 and 75 p e r
cen t.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
70
LITERATURE CITED
A l b e r t s o n , F , W.
K ansas.
1959,
P r a ir ie s tu d ie s in w e st-c e n tr a l
T r a n s . K an s. A cad . S c i .
A l l r e d , B . W.
19S5.
The s t a t u s o f g r a s s a f t e r t h e d r o u g h t.
N a t . Wool Grower 2 5 :
B e a t h , 0 . A.
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E llis o n , L .,
4 2 :9 7 -1 0 7 .
(9) 24.
E f f e c t o f t h e d r o u g h t on Wyoming
Nat* Wool Grower 25s ( 8 ) 1 4 - 1 6 .
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on v e g e t a t i o n n e a r M ile s C i t y , M ontana.
E c o l. 18:
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F o w le r , R. L . ,
and J . E. W eaver.
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1940.
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B u l l . T o r r e y B o t , C}.ub
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M u eller, I .
1941.
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c e r ta in p r a ir ie p la n ts .
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1937.
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S t u d i e s on t h e e c o l o g y o f r o o t s .
E c o l. 18: 4 0 -4 3 .
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1940.
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managed r a n g e s a r e d e p l e t e d b y d r o u g h t s i n c e 1 9 3 1 .
C o l o . Farm B u l l .
2: 3 - 4 .
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and G. S t e w a r t .
1937.
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t h e u p p e r Snake R i v e r P l a i n s ,
Idaho*
E c o l . 18*
490-505*
R o b e r t s o n , J* H.
19 3 9*
A q u a n t i t a t i v e s tu d y o f t r u e -
p r a i r i e v e g e t a t i o n a f t e r t h r e e . y e a r s o f e x tr e m e
d r o u g h t*
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:v eo l. Donas* 9 : 4 3 1 - 4 9 2 .
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s p e c i e s I n t h e c e n t r a l and s o u t h e r n G ro a t P l a i n s ,
1935.
U. S . D e p t . A gr.j T e c h .
S t e w a r t , G. and A* E, Young*
1939*
B u ll. 549.
The h a z a r d o f b a s i n g
p erm an en t g r a z i n g c a p a c i t y on Byomua t e c t o r u c u
Jour*
Ataer. S o n . A g ro n . 3 1 s 1 0 0 2 -1 0 1 5 *
S tew a rt, G ,,
? . C o tta s ), and S . 8 . H u tc h in g s *
1940.
I n f l u e n c e o f u n r e s t r i c t e d g r a z i n g on n o r t h e r n s a l t
d e s e r t p la n t a s s o c i a t i o n in w e s te r n U tah .
Jour.
A g r. R e s . 6 0 : 2 8 9 - 3 1 6 .
J e a v e r , J * U. 1 9 1 9 .
The e c o l o g i c a l r e l a t i o n s o f r o o t s .
C a r n e g ie I n s t . D a s h ., P u b . 2 8 6 : 1 - 1 8 .
le a v e r , J .
E.
1920.
fo r m a tio n .
le a v e r , J .
Root d e v e lo p m e n t In t h e g r a s s l a n d
C a r n e g ie I n s t .
.Vaah., P u b . 2 9 2 .
S . , and F* v;„ A l b e r t s o n .
1936.
A f f e c t s o f th e
g r e a t d r o u g h t on t h e p r a i r i e s o f I o w a , N e b r a s k a , and
K ansas.
Jeevor, J .
' .c o l. 1?: 567-639*
and F* n # A l b e r t s o n .
1939*
k a j o r changes
i n g r a s s l a n d a s a r e s u l t o f c o n t in u e d d r o u g h t*
H o t.
G a s. 1 0 0 : 5 7 6 - 9 1 .
le a v e r , J .
S . , and F*
A lb e r tso n .
o f m id w e sto m r a n g e s ,
1940.
D e te r io r a tio n
E c o l. 21: 2 1 6 -3 6 .
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W eaver, J» K , , and F . E, A l b e r t s o n ,
1 9 40 a#
D e te r io r a tio n
o f g r a s s l a n d from s t a b i l i t y
to d en u d a tio n tfith
d e c r e a s e in s o i l m o is tu r e .
B o t , G a s, 10 1 : 5 9 8 - 6 2 4 *
W eaver, J . ;£♦, and T* J . F i t z p a t r i c k #
1934,
The p r a i r i e .
E c o l . Monog, 4 : 1 0 9 -2 9 5 #
W eaver, J .
K ,, and S, L# F lo r y #
1934*
S t a b i l i t y o f c lim a x
and some e n v ir o n m e n t a l c h a n g e s r e s u l t i n g fr o © b r e a k ­
in g *
W eaver, J .
E c o l. 15:
333-47.
EV, and sr. '$•
.
Hansen*
1939*
I n c r e a s e o f S p o r o b o lu s
c r v o t a n d r u s i n p a s t u r e s o f e a s t e r n N eb ra sk a ,
E co l* 20s 3 7 4 - 8 1 .
W eaver, J .
E *f and if. '.’u
Hansen#
p astu res; th e ir o r ig in ,
1941*
Natives s i d v / e o t e m
.-o m p o s itio n , arid d e g e n e r a t i o n .
U n i v . Neb. C on s, and 3 u r v . D l v . B u l l . 2 2 .
W eaver, J .
E . , and w, J .
th e p r a i r i e .
ninunel.
1931*
The e n v ir o n m e n t o f
U n iv . Web. Cons, and S u r v . D i v , B u l l .
W eaver, J • E , , J . H, R o b e r t s o n , and B, L. F ow ler*
5.
1940.
C hanges i n t r u e - p r a l r i e v e g e t a t i o n d u r i n g d ro u g h t a s
d e t e r m i n e d by l i s t
q u a d ra ts.
E col* 2 1 : 3 5 7 - 6 2 ,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
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