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Phytophagous insects on the ashnola bighorn sheep range Maynard, Richard John 1972

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PHYTOPHAGOUS INSECTS ON THE ASHNOLA BIGHORN SHEEP RANGE by RICHARD JOHN MAYNARD B.Sc.  (Agric),  U n i v e r s i t y o f B r i t i s h Columbia, 1968  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Plant Science  We accept t h i s t h e s i s as conforming to the r e q u i r e d standard.  THE UNIVERSITY OF BRITISH COLUMBIA September 1972  In presenting the  this thesis in partial fulfillment  r e q u i r e m e n t s f o r an  advanced degree at the  of B r i t i s h Columbia, I agree t h a t it  the  f r e e l y a v a i l a b l e f o r r e f e r e n c e and  agree t h a t  permission for extensive  t h e s i s f o r s c h o l a r l y p u r p o s e s may o f my  D e p a r t m e n t o r by  understood that for  financial  written  University  L i b r a r y s h a l l make study.  I  copying of g r a n t e d by  his representatives.  gain  s h a l l not  be  allowed without  of  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  O^tjrfe*- 3  J  /J?Z.  Columbia  further this the  Head  It is  copying or p u b l i c a t i o n of t h i s  permission.  Department  Date  be  of  thesis my  i  ABSTRACT  There a r e c o n f l i c t i n g  statements  i n the literature  c o n c e r n i n g t h e e f f e c t s o f p h y t o p h a g o u s i n s e c t s on r a n g e l a n d grass y i e l d s .  T h i s p r e l i m i n a r y s t u d y was i n t e n d e d t o  asses t h e use o f range f o r a g e by i n s e c t s , grasshoppers.  especially  The s t u d y a r e a s w e r e t w o s o u t h - f a c i n g  s l o p e s a t a b o u t 5500 f e e t e l e v a t i o n i n t h e A s h n o l a Resources  Management A r e a i n S o u t h  Central British  Columbia.  A p l a n t community a n a l y s i s was made t o d e t e r m i n e which  g r a s s e s a n d f o r b s w e r e most numerous and w h i c h  p r o v i d e d most g r o u n d - c o v e r  i n selected areas.  The commun-  i t i e s under s t u d y were c h a r a c t e r i z e d by v a r i o u s of f o u r prominent (Agropyron Kentucky (Stipa  combinations  g r a s s s p e c i e s : Bluebunch Wheatgrass  spicatum), Junegrass  Bluegrass  (Koeleria  (Poa p r a t e n s i s ) ,  cristata),  and C o l u m b i a  Needlegrass  columbiana).  I n s e c t g r a z i n g damage t o g r a s s e s was e s t i m a t e d b y random s a m p l i n g  of i n d i v i d u a l grass blades.  The " p r e f e r r e d "  ( m o s t - u t i l i z e d ) s p e c i e s were K o e l e r i a c r i s t a t a , Poa  s e c u n d a , and S t i p a c o l u m b i a n a ,  s p i c a t u m was n o t v i s i b l y  Poa p r a t e n s i s ,  i n that order.  Agropyron  utilized.  G r a s s h o p p e r numbers were e s t i m a t e d i n s e v e r a l w a y s ; t h e most common s p e c i e s were C a m n u l a p e l l u c i d a , and  Melanoplus  sanguinipes.  on t h e c l i m a x A g r o p y r o n  Grasshoppers  spicatum  C. x a n t h i p p u s ,  were l e a s t  numerous  c o m m u n i t y where o n l y 21%  ii  of  t h e t o t a l g r a s s was  of the four p r e f e r r e d  where o n l y 32% o f t h e g r o u n d  was  c o v e r e d by  H i g h e s t numbers o f g r a s s h o p p e r s w e r e f o u n d Poa c o m m u n i t y , where 90% o f t h e g r a s s was s p e c i e s , and where t h e g r o u n d  was  62%  species,  and  vegetation. on a  of a  "disclimax" preferred  covered.  Experiments to determine the e f f e c t s of grasshoppers on g r a s s y i e l d s u s e d e x c l o s u r e c a g e s p l a c e d on t h r e e d i f f e r e n t communities Poa)  i n 1969  and  ( S t i p a - Agropyron,  1970.  Poa - S t i p a ,  I n a l l a r e a s t h e mean g r a s s  y i e l d s were h i g h e r i n s i d e t h e cages, b u t t h e were n o t s t a t i s t i c a l l y to  and  significant.  t h o s e o f o t h e r w o r k e r s who  differences  This result  have a t t e m p t e d t o  i s similar demonstrate  e f f e c t s o f g r a s s h o p p e r s on r a n g e l a n d g r a s s y i e l d s ; . w h i l e g r a s s h o p p e r s consume a f a i r l y appear t o have l i t t l e  effect  l a r g e amount o f g r a s s , t h e y on t h e t o t a l s t a n d i n g y i e l d  g r a s s , as d e t e r m i n e d by an e n d - o f - s e a s o n G r a s s h o p p e r s may  clip  dominated  by s u c c u l e n t g r a s s e s ,  where t h e y c o n g r e g a t e on s p o t s w h i c h h a v e b e e n t r a m p l e d , g r a z e d by l i v e s t o c k ,  of  absence  o f o v e r g r a z i n g by l i v e s t o c k ,  since their grazing i s distributed healthy, intact plants.  In  e v e n h i g h numbers  p e r m a n e n t damage,  o v e r a l a r g e number o f  The m a t u r e g r a s s l a n d ,  s p i c a t u m , seems t o be r e l a t i v e l y  dramatic developments  clipped,  or otherwise disturbed.  g r a s s h o p p e r s p r o b a b l y c a n do l i t t l e  by A g r o p y r o n  of vegetation.  be a t t r a c t e d t o m o i s t a r e a s , f o r  example p l a n t communities  the  of  i n insect populations.  dominated immune t o  iii  TABLE OF CONTENTS PAGE ABSTRACT  i  TABLE OF CONTENTS  i i i v  LIST OF TABLES LIST OF FIGURES  . . .  vi  ACKNOWLEDGMENTS  vii  1.  INTRODUCTION  1  2.  DESCRIPTION OF STUDY AREA  4  3.  MATERIALS AND METHODS  6  3.1  6  Measurement o f c l i m a t i c and edaphic variables  3.2  6  7  Sampling f o r grasshoppers 7  3.2.1  Sweep net  3.2.2  Thrown t r a p s  7  7  3.2.3  Dropping cage  3.2.4  Convergence  .  on a spot by two people  7  3.3  Sampling, other i n s e c t s  7  3.4  Sampling, s o i l i n v e r t e b r a t e s  3.5  Sampling, v e g e t a t i o n  8  3.5.1  Community a n a l y s i s  g.  3.5*2  Insect, use of p l a n t communities  ............  8 r  ...  3.5.2.1  Grazed, blade  3.5.2.2  Wind t u n n e l  3.5.2.3  E x c l o s u r e cages  3.5.2.4  Insect grazing observations...  g. 8g  .  g ]_  0  iv  PAGE  4.  5.  OBSERVATIONS AND RESULTS 4.1  Environment  4.2  Sampling, grasshoppers  13  4.3  Sampling,  15  4.4  Sampling, s o i l i n v e r t e b r a t e s  15  4.5  Sampling, v e g e t a t i o n  16  4.5.1  Community a n a l y s i s  16  4.5.2  I n s e c t use of p l a n t communities  ,  ...  other i n s e c t s  ...  11  16  4.5.2.1  Grazed blade  16  4.5.2.2  Wind t u n n e l  18  4.5.2.3  E x c l o s u r e cages  18  DISCUSSION  20  5 .1  Background  20  5.2  E f f e c t s of temperature and s o i l moisture on i n s e c t s and g r a s s  6.  11  •  22  5.3  I n s e c t sampling  24  5.4  Community a n a l y s i s  26  5.5  E f f e c t s of grasshoppers on g r a s s y i e l d  5.6  G r a z i n g mammals  31  5.7  Wind t u n n e l  33  SUMMARY  ...  27  35  LITERATURE CITED  37  APPENDICES  56  V  L I S T OF TABLES TABLE NUMBER 1.  PAGE  E l e v a t i o n , aspect, of each study  s l o p e , and s o i l  classes  area  41  2A, C l i m a t i c d a t a f o r J u n i p e r S l o p e 2B. C l i m a t i c d a t a f o r S o u t h S l o p e  1969.,.  1969...  42 43  3.  Grasshopper phenology, J u n i p e r Slope,  1970  44  4.  Common p h y t o p h a g o u s i n s e c t s o f t h e A s h n o l a .  45  5.  Vegetation: basal h i tanalysis  46  6.  Vegetation:  7.  Insect grazing of grasses  47  cover h i t a n a l y s i s on J u n i p e r  s l o p e , 1970 8.  Grasses grazed  48 by i n s e c t s :  consolidated  estimates 9.  Carryover  4  on t h e J u n i p e r slope  Poa-Stipa  c o m m u n i t y , 14 May 1970 10. E x c l o s u r e  9  c a g e r e s u l t s : Mean g r a s s  50 yields  f r o m t h r e e c o m m u n i t i e s i n I969 and 1970..  5 1  vi  LIST OF FIGURES  PAGE FIGURE 1.  S o i l moisture at a depth of 30 on two communities  cms  on J u n i p e r  Slope, 1970 FIGURE 2.  52  Grasshopper numbers i n r e l a t i o n t o grass phenology on J u n i p e r Slope r i d g e community  FIGURE 3«  5 3  A i r and s o i l temperatures, J u n i p e r Slope 1970  FIGURE 4 .  (A and B)  54 Changes i n abundance of  i n s e c t s on seven communities,  1970,....,.  5 5  vii  ACKNOWLEDGMENTS  I  am e x t r e m e l y g r a t e f u l t o D r . B r i n k f o r g i v i n g me s o  much h e l p . My w i f e , J e n n i f e r , h e l p e d t h r o u g h o u t a r a t i n g samples, Bruce and  the project,  sep-  p a c k i n g h o r s e s , p r o o f r e a d i n g and t y p i n g ,  Begg, my f i e l d a s s i s t a n t , was a n e x c e l l e n t c o m p a n i o n  worker.  Due t o h i s i n g e n i o u s S o u t h  able t o l i v e  i n comfort.  S l o p e Shower we w e r e  Bud T i l l o t s o n ,  pilot  f o r Okanagan  Helicopters, kindly flew i n supplies during h i s training flights.  Tuke a n d M a r g a r e t  and R o b e r t ,  cannot  M e n n e l l , as w e l l as Susan,  be t h a n k e d  d u r i n g o u r Keremeos  enough f o r t h e i r k i n d n e s s t o u s  stopovers.  D r . S c u d d e r and M i s s K a t h l e e n S t e w a r t ogical information.  D r . R. H. W r i g h t  t h e Lyman E n t o m o l o g i c a l Museum, M c G i l l  identified  the Orthoptera.  provided  o f B. C.  k i n d l y a l l o w e d me t o u s e h i s w i n d t u n n e l . of  Wilfrid,  entomol-  Research  D r . V, R. V i c k e r y , University,  -1-  1.  INTRODUCTION  "The l a n d i s as t h e Garden o f Eden b e f o r e them, and b e h i n d them a d e s o l a t e w i l d e r n e s s , y e a , and n o t h i n g s h a l l escape them." ( J o e l 2s2  Reference t o grasshopper plagues)  Some i n s e c t s have brought f e a r and famine t o e v e r y c o n t i n e n t a t one time o r a n o t h e r . man's e a r l i e s t the  I n N o r t h America, s i n c e  a g r i c u l t u r e i n s e c t s have d e s t r o y e d c r o p s .  On  n a t i v e g r a s s l a n d s a major f a c t o r compounding t h e problems  of i n s e c t damage i s o v e r g r a z i n g by l i v e s t o c k .  I n Oklahoma  S m i t h ( 1 9 4 0 ) found t h a t t h e t o t a l p o p u l a t i o n o f i n s e c t s on o v e r g r a z e d mixed g r a s s p r a i r i e s was about f o u r t i m e s as l a r g e as normal on m o d e r a t e l y g r a z e d l a n d s .  Taylor (1935)  found 7 8 2 , 0 0 0 i n s e c t s p e r a c r e on o v e r g r a z e d l a n d compared w i t h 1 8 6 , 0 0 0 on m o d e r a t e l y used r a n g e . I n N o r t h America l i f e - h i s t o r y and e c o l o g i c a l d a t a a r e generally not available f o r grassland insect herbivores w i t h t h e e x c e p t i o n o f some s p e c i e s o f g r a s s h o p p e r s 1969).  (Blocker  However damage and consumption by g r a s s h o p p e r s has  been i n v e s t i g a t e d by some r e s e a r c h e r s .  Using the data of  Barnes ( 1 9 W , P f a d t ( 1 9 ^ 9 ) , Anderson and Wright Harper ( 1 9 5 2 ) ,  (1952),  and Putnam ( 1 9 6 2 ) , B u l l e n ( 1 9 6 6 ) determined  t h a t on N o r t h American r a n g e l a n d s g r a s s h o p p e r s a t d e n s i t i e s of 20 p e r square y a r d cause, on t h e average, a l o s s o f 7 pounds o f v e g e t a t i o n p e r a c r e p e r d a y . He f e l t  that  -2-  i n f e s t a t i o n s at t h i s l e v e l f o r three months d u r i n g  the  summer would consume a t l e a s t 600 pounds per acre, i . e . e q u i v a l e n t to the e n t i r e p r o d u c t i o n of t y p i c a l prairie.  shortgrass  says t h a t " d e n s i t i e s as low as 3  He  grasshoppers  per square yard on poor g r a z i n g land can d e s t r o y more than 50% of the v e g e t a t i o n , the maximum permitted i n good range p r a c t i c e , so t h a t any f e e d i n g by c a t t l e impoverishes  the  range". I n other p a r t s of the world  i t i s the l o c u s t r a t h e r  than the grasshopper which i s f e a r e d . locusts  In A f r i c a i n I887  ( S h i s t o c e r c a g r e g a r i a ) were r e p o r t e d to have swarmed  over 2000 l i n e a r m i l e s .  The migratory  locust  (Locusta  m i g r a t o r i a ) has a wider range than any other A c r i d i d ; i t i s found  i n g r a s s l a n d s and  savannah of A f r i c a , most of E u r a s i a  south of the T a i g a f o r e s t , E a s t I n d i a , t r o p i c a l and New  Zealand.  The  Australia,  extent of range w i t h i n these  countries  v a r i e s g r e a t l y , s u b j e c t t o temperature, burning of g r a s s l a n d s , f l o o d s , e t c . ; w i t h i d e a l c o n d i t i o n s t h e r e i s overcrowding and  p r o d u c t i o n of the g r e g a r i o u s phase (Davey and  1956).  The  s m a l l e r I t a l i a n and Moroccan l o c u s t s  Johnston (Calliptamus  h a l i c u s and D o c i o s t a u r u s maroccanus) do much i n j u r y i n the Mediterranean  area (Dempster 195^-48).  In Canada and U. S. A. i n the 18?0's the Rocky Mountain l o c u s t or l e s s e r m i g r a t o r y grasshopper (Melanoplus  mexicanus  phase s p r e t u s ) c r e a t e d havoc on the p r a i r i e farms but disappeared.  I t was  probably  later  the g r e g a r i o u s phase of the  common and widespread M, mexicanus ( a t l a r i s ) which i s , with the clear-winged  grasshopper (Camnula p e l l u c i d a ) , a major  -3-  crop pest i n North America.  Many other s p e c i e s of A c r i d i d a e  i n d i f f e r e n t r e g i o n s o c c a s i o n a l l y i n c r e a s e t o plague propo r t i o n s , hut few of them compare i n economic importance w i t h those named above. I n the Ashnola Resources Management area i n South C e n t r a l B r i t i s h Columbia, c a t t l e , deer, and  California  b i g h o r n sheep have been accorded a t t e n t i o n as major u s e r s of the g r a s s l a n d ranges (Blood 1961, Demarchi 19&5* Harper  I969, S c h e f f l e r 1972).  However, v i r t u a l l y n o t h i n g i s known  about use by other g r a s s l a n d animals such as r o d e n t s , lagomorphs, b i r d s , and phytophagous  insects.  The prime  o b j e c t i v e of t h i s p r e l i m i n a r y study was t o o b t a i n a q u a n t i t a t i v e or s e m i - q u a n t i t a t i v e assessment of the use o f range forage by i n s e c t s .  -4-  2.  DESCRIPTION OF STUDY AREA  Detailed description of the study area, some of i t s plant communities, and range history have been given by Scheffler (1972), Blood (1961), Demarchi (1965), and Harper (1969); therefore only an outline w i l l be given here. The whole area i s of great r e l i e f ; the semi-arid S i m i l kameen Valley l i e s at 1200 feet above sea l e v e l and the nearby mountains r i s e to 9000 feet above sea l e v e l .  The  t r a n s i t i o n to an Alpine climate, s o i l , and vegetation i s made at 6800 f e e t . Bordering the grasslands i s montane forest where Douglas fir  (Pseudosuga menziesii) and lodgepole pine (Pinus contorta).  and an undercover  species, pine grass (Calamagrostis rubescens)  are the dominants. steeply.  To the south-west the land f a l l s away  A number of small gulleys accept the runoff and  carry i t to Juniper and Ewart creeks.  Running south to north,  the l a t t e r creek i s r e l a t i v e l y inaccessible from the east side i n a l l but a few places, due to the roughness of the terrain.  A four-mile t r a i l along the west side of the Ewart  creek i s used f o r hiking access and sheep migrations during the spring and f a l l . To the north-east the h i l l s are covered i n serai forest, i n which lodgepole pine i s dominant.  The alplands, about  two miles from the intensive study area, are dotted with lakes and lush meadows.  On F l a t i r o n mountain there are four open  slopes: F l a t i r o n , Starvation, Juniper, and South slope.  -5-  A f t e r some p r e l i m i n a r y s t u d y , South s l o p e and J u n i p e r s l o p e were chosen f o r t h e i r a c c e s s i b i l i t y , convenience,  v a r i e t y of  r e a s o n a b l y homogenous g r a s s communities, and l a r g e numbers of i n s e c t s . South s l o p e i s a c r i t i c a l a r e a f o r the w i n t e r s u r v i v a l of b i g h o r n sheep (Ovis c a n a d e n s i s  californiana DouglasK  I n w i n t e r , sheep congregate on t h i s s o u t h - f a c i n g a r e a , where escape t e r r a i n i s n e a r b y and where wind and  greater  exposure t o s u n l i g h t reduce the snow c o v e r . J u n i p e r s l o p e d i f f e r s s u b s t a n t i a l l y from South s l o p e I The  s o i l o f most o f the a r e a o f J u n i p e r s l o p e i s O r t h i c  B l a c k S i l t ; on exposed r i d g e s , as on South s l o p e , i t i s Rego Dark Grey (Table 1) ( S o i l Survey 1968). swales occupy about two a c r e s . y  i s predominantly 1000  The South s l o p e v e g e t a t i o n  Agropyron spicatum,  and 6000 f e e t e l e v a t i o n .  mixed communities.  The  Several moist  a c l i m a x g r a s s between  J u n i p e r s l o p e i s composed o f  a s p e c t on South s l o p e i s  south-south-  e a s t , w h i l e t h a t o f J u n i p e r s l o p e i s south-west. are 28%  The  slopes  and 5% r e s p e c t i v e l y .  A narrow band o f t r e e s , and a creek, s e p a r a t e and J u n i p e r s l o p e s .  South  T h i s appears t o . a c t t o some degree as  a b a r r i e r , p r e v e n t i n g w a l k i n g i n s e c t s from moving between the two The for  open s l o p e s . c l i m a t e and v e g e t a t i o n of the A s h n o l a are  suitable  a wide a r r a y o f i n s e c t s , e s p e c i a l l y Camnula p e l l u c i d a  o f the o r d e r O r t h o p t e r a .  The warm summers and  green  s u c c u l e n t Poa stands are i d e a l f o r s e v e r a l o r d e r s .  -6-  3.  A l l equipment  MATERIALS AND METHODS  had t o be back-packed  or horse-packed  from  road end a t 2000 f e e t e l e v a t i o n t o the study s i t e s .  3.1  MEASUREMENT OF CLIMATIC AND EDAPHIC VARIABLES Two c l i m a t i c s t a t i o n s r e c o r d i n g b a s i c measurements  were maintained d u r i n g May, June, J u l y , and August o f 1969 and 1 9 7 0 .  The s t a t i o n s were e s s e n t i a l l y those e s t a b l i s h e d  by Harper  ( 1 9 6 9 ) two years p r i o r t o the i n i t i a t i o n of t h i s  study.  One was s i t u a t e d on J u n i p e r slope i n the Poa  p r a t e n s i s community (5225 the  f e e t a. s. 1 . )  and the other i n  Agropyron community on upper South slope ( 5 7 5 0 f e e t  a.s.l.).  Weather d a t a of d i r e c t use have been a b s t r a c t e d , the balance are  i n Table 2 . Measurements i n c l u d e wind speed, temperature,  evapor-  a t i o n , p r e c i p i t a t i o n , s o i l moisture, and r e l a t i v e h u m i d i t y . A Stevenson s c r e e n housed a hygrothermograph minimum thermometer.  and a maximum-  Preceding and throughout the g r a s s -  hopper l i f e - c y c l e the s o i l temperature a t the 5 em depth was r e c o r d e d . S o i l study was undertaken by S c h e f f l e r the  C. D. A.  ( 1 9 7 2 ) and by  and B.C. D. A. s o i l surveys  S c h e f f l e r a l s o i n c l u d e s g e o l o g i c a l and p h y s i o g r a p h i c a l descriptions.  -7-  3.2  SAMPLING FOR GRASSHOPPERS Grasshopper  3.2.1  counts were made throughout the summer by:  Sweep Net Four standard sweeps o f a n e t 12 i n c h e s i n diameter,  every t e n days on a Poa or S t i p a community gave a f a i r l y r e l i a b l e census over one square meter. 3.2.2  Thrown Traps A square meter frame was thrown about 15 f e e t  unsuspecting grasshoppers.  onto  The top of the permascreen  cage  had a s l e e v e i n i t so the grasshoppers could be e x t r a c t e d and  counted.  3.2.3  Dropping Cage A square meter frame was suspended  between p o l e s and  l e f t f o r 3 0 minutes f o r the grasshoppers below t o resume normal a c t i v i t y .  The frame was then dropped by a t r i p wire  onto the u n s u s p e c t i n g i n s e c t s .  Care was taken n o t t o use  t h i s method a t mid-day when the shadow of the frame  fell  d i r e c t l y below i t . 3.2.4  Convergence  on a Spot by Two People (Dempster 1 9 5 4 )  Premarked square meter areas were s l o w l y converged upon by two people from d i f f e r e n t d i r e c t i o n s , as the grasshoppers hopped, walked, 3.3  A count was made  or f l e w out o f the square.  SAMPLING, OTHER INSECTS A q u a l i t a t i v e sample o f the g r a s s l a n d i n s e c t s was  obtained by p l a c i n g p a i r e d t r a p s i n each of s i x p l a n t communities.  They were c o l l e c t e d weekly.  The t r a p s were  j a r s f i l l e d with water and ethylene g l y c o l , and b u r i e d w i t h  -8-  the r i m f l u s h w i t h ground l e v e l .  Unsuspecting  insects  f a l l i n g or a l i g h t i n g i n the s o l u t i o n were trapped, drowned, and  preserved.  3.4  SAMPLING, SOIL INVERTEBRATES S o i l i n v e r t e b r a t e s were sampled monthly by d i g g i n g t o  a t h r e e i n c h depth and then u s i n g a B e r l e s e f u n n e l (Kuhnelt 1961) 3.5 3.5.1  t o s c r e e n out the animals. SAMPLING, VEGETATION Community A n a l y s i s A p o i n t frame was  used to determine  frequency and b a s a l frequency.  the p l a n t  cover  Four hundred t o 800 random  p o i n t s i n each p l a n t community gave two measures of the f l o r a l composition.  As the p i n descended through the veget-  a t i o n the cover s p e c i e s was  recorded.  The p l a n t s p e c i e s  touched by the end of the p i n was noted as a b a s a l h i t . B a s a l h i t s are a measure of composition, while cover h i t s g i v e an estimate of the "biomass"of 3.5»2  I n s e c t Use 3.5,2.1  each s p e c i e s .  of P l a n t Communities  Grazed  Blade.  To estimate i n s e c t g r a z i n g damage the p l a n t m a t e r i a l which was and examined.  touched by the b a s a l h i t was  The numbers of i n t a c t and i n j u r e d  were recorded, and the amount removed from each blade was  e s t i m a t e d . To determine  i n s e c t s the blade was transversely i n half.  pulled  up  blades injured  the amount removed by  d i v i d e d on the m i d r i b and then d i v i d e d To c a l c u l a t e an o v e r a l l percentage  g r a s s removed the percentage  of i n j u r e d blades was  of  multiplied  -9-  by the average percent removed from them.  The  term " i n j u r e d "  r e f e r s t o the f a c t t h a t a grass blade has been grazed insects.  In many cases the extent  be a rough estimate, and  of g r a z i n g could  Wind  only  s i n c e i n s e c t s o f t e n ate a c r o s s a blade,  the s i z e of the uneaten t e r m i n a l p o r t i o n was 3.5.2.2  by  unknown.  Tunnel.  In an e f f o r t to determine whether grasshoppers s e l e c t p a r t i c u l a r p l a n t s , f o u r groups of 30 grasshoppers ( c o l l e c t e d on J u n i p e r slope and a l l the same age a wind t u n n e l .  and  c a r r i e d to the l a b o r a t o r y ) ,  s t a r v e d f o r 48 hours, were placed i n  F i v e d i f f e r e n t s p e c i e s of grass  (Poa p r a t e n s i s ;  Agropyron spicatum, K o e l e r i a c r i s t a t a , S t i p a columbiana, Calamagrostis  rubescens) were i n s e r t e d i n a p i l e ,  time, upwind, and 3.5.2.3  the response  Exclosure  one  at a  recorded.  Cages.  S i t e s f o r experimental  determination  of e f f e c t s of  grasshoppers on g r a s s y i e l d were chosen f o r homogeneity of v e g e t a t i o n and use by deer and l a t t e r had  f o r high i n s e c t populations,  as w e l l as f o r  sheep at some time of the y e a r .  Both the  emigrated f o r the summer a t the time of the  experiment, so t h a t v i r t u a l l y a l l g r a z i n g d u r i n g the iment was  exper-  by i n s e c t s ; the cages were l o c a t e d w e l l away  from rodent  burrows and  runways.  In 1969 the cages were placed on two  communities:  South slope f l a t s dominated by S t i p a columbiana Agropyron spicatum, and  and  on a J u n i p e r slope community domin-  ated by S t i p a columbiana and  Poa spp.  (denoted J u n i p e r  slope  -10-  Poa-Stipa).  I n 1970 t h e cages were moved from t h e f l a t s t o  a Poa community on J u n i p e r s l o p e where t h e g r a s s h o p p e r p o p u l a t i o n was t h e h i g h e s t o f e i t h e r s l o p e . The  e x c l o s u r e cages were made o f permascreen on an  i r o n frame.  They were c y l i n d r i c a l w i t h a d i a m e t e r  meter so t h a t t h e y o n l y touched t h e square meter  o f 1.41 experimental  p l o t s a t t h e f o u r c o r n e r s ; t h i s e l i m i n a t e d an " e d g e - e f f e c t " o f t h e cages. by u s i n g t h r e e  Any "greenhouse" e f f e c t c o u l d be d e t e r m i n e d treatments.  On each community t h r e e t r e a t m e n t s were used w i t h 8 r e p l i c a t e s each (South s l o p e F l a t s and J u n i p e r s l o p e Poa ended up w i t h o n l y 7 r e p l i c a t e s due t o l o s s o f a cage d u r i n g a s p r i n g storm).  I n o r d e r t o measure t h e e f f e c t on g r a s s  growth o f t h e a l t e r e d m i c r o - e n v i r o n m e n t w i t h i n t h e cage, one c o n t r o l cage was r a i s e d 12 t o 20 cm t o a l l o w i n v e r t e b r a t e s t o move i n and o u t . The e x p e r i m e n t a l cage was lowered t o exclude i n v e r t e b r a t e s . p l o t w i t h o u t a cage.  Nearby t h e r e was another c o n t r o l  The f i r s t s i t e o f each r e p l i c a t e was  p l a c e d randomly, and s i m i l a r s p o t s w i t h s i m i l a r d e n s i t y and type o f v e g e t a t i o n p i c k e d f o r t h e o t h e r two s i t e s . assignment o f t r e a t m e n t s The  The  t o t h e t h r e e p l o t s was a l s o random.  cages were p l a c e d on t h e range i n t h e l a s t week o f  May b e f o r e t h e g r a s s h o p p e r eggs hatched,  and removed f o r  c l i p p i n g on 20 September 1969 and 4 October 1970. A l l p l a n t s were c l i p p e d t o ground l e v e l and o v e n - d r i e d b e f o r e  weighing;  g r a s s e s , f o r b s , and shrubs were weighed s e p a r a t e l y . 3.5.2.4  Insect Grazing Observations.  Observations of  g r a z i n g by i n s e c t s o t h e r t h a n O r t h o p t e r a were n o t made.  -11-  4.  4.1  OBSERVATIONS AND RESULTS  ENVIRONMENT C l i m a t i c d a t a f o r the Ashnola are shown i n Table 2 . c l i m a t e i s D f c ( K r a j i n a 1 9 5 9 , a f t e r Koppen) w i t h the  The  summers r e c e i v i n g about 4 - 8 inches of r a i n , while the w i n t e r s have about 3 6 inches o f snow. 9.01  Harper ( 1 9 6 9 ) r e c o r d s  and 1 2 . 3 7 inches o f p r e c i p i t a t i o n f o r 1967 and I 9 6 8 ,  respectively.  The summer o f 1970 (May 1 t o September 3 0 )  only 1 . 2 5 i n c h e s .  had  The  summer temperatures  above 100 degrees  are q u i t e high, o f t e n going  i n the shade.  (The Stevenson  screen,  however, gave low r e a d i n g s compared t o a thermometer on the shady s i d e of the cabin.) screen r a r e l y reached  I n I 9 6 9 the temperature  70 degrees  i n the  F, while i n 1970 "the  mercury" f r e q u e n t l y climbed above t h a t . The r e l a t i v e humidity i n summer, as would be expected in  a sub-humid c l i m a t e i n a mountain l e e , was v e r y low,  u s u a l l y below 15% a t mid-day. d e a l of t h e summer and f a l l  A l i g h t breeze blows a good  (averages 4 . 2 m i l e s p e r h o u r ) .  The y e a r l y e v a p o r a t i o n was h i g h e s t from 22 J u l y t o 2 1 August (1100  mis). S o i l moisture d i r e c t l y a f f e c t s p l a n t growth as w e l l as  l o c a l grasshopper (Fig.  1)  movements and l i f e  cycle.  Hatching of eggs  occurred on a l l p l a n t communities when s o i l  was 85 t o 90% and s o i l temperature  60 degrees.  moisture  Shotwell  ( 1 9 4 1 ) has shown i n the l a b o r a t o r y t h a t eggs w i l l n o t hatch  -12-  i f allowed t o g e t t o o d r y . the  I n the f i e l d ,  i n the middle o f  summer, i t was observed t h a t a r a i n shower brought on a  f r e s h h a t c h i n g , a c l e a r s i g n t h a t eggs stop h a t c h i n g as moisture d i m i n i s h e s . On the r i d g e the hopper p o p u l a t i o n s b u i l t up t o about 50 per square meter by 11 June, then s t a r t e d t o decrease as the  On k June on the r i d g e the  s o i l moisture decreased.  s o i l moisture was 9 0 % ; by 10 June i t was down t o 50%, w h i l e on the Poa s i t e i t was s t i l l moved i n t o the l o c a l i z e d  a t 9 0 % . The grasshoppers then  Poa swales where they were  uncount-  able due t o the d e n s i t y of the cover; they were probably i n excess o f 80 per square meter. On t h e l a r g e Poa areas, about 1 0 0 0 f e e t from the r i d g e , the  grasshoppers d i d not s t a r t h a t c h i n g u n t i l 20 June  (moisture 85 t o 9 0 % , temperature the  60 d e g r e e s ) .  By 17 J u l y  r i d g e grasshoppers s t a b i l i z e d a t about 7 per square meter.  The grasshoppers i n the Poa stand of two acres averaged 50 per square meter on 1 August. about 3 August.  about  C o p u l a t i o n was i n i t i a t e d  O v i p o s i t i n g was f i r s t seen on 7 August; a  n o t i c e a b l e decrease i n numbers was then e v i d e n t . Hatching s t a r t e d on 2 t o 6 June, both years, on the ridges  (Fig. 2 ) .  S i n c e the range has a southern exposure, a  r e l a t i v e l y l a r g e p a r t o f the s o l a r r a d i a t i o n i s absorbed and h e l d by the e a r t h .  The daytime temperatures  o f the  r i d g e averaged 9 degrees F warmer than on the swales. a mid-day temperature  of 60 degrees F the temperature  With o f the  bare d r y r i d g e s o i l a t a depth of 3 cms would go as h i g h as  -13-  78 d e g r e e s the  F; a t t h e same t i m e u n d e r m o i s t s o i l  t e m p e r a t u r e was  appearance of  63 d e g r e e s F.  o f Poa  Observations of  spp.  first  o f nymphs i n a b u n d a n c e i n a l l a r e a s and a s t u d y  the weather  r e c o r d s show t h a t g e n e r a l h a t c h i n g o f  Melano-  p l u s s p p . and C a m n u l a s p p . e g g s t a k e s p l a c e d u r i n g t h e warm p e r i o d  o f f r o m 3 t o 5 d a y s , h a v i n g a maximum a i r temp-  e r a t u r e a b o v e 65 d e g r e e s degrees.  first  A i r and  shown i n F i g u r e  soil  60  and a s o i l t e m p e r a t u r e a b o v e  t e m p e r a t u r e s on J u n i p e r s l o p e a r e  3.  W i t h i n t h e f i r s t two weeks o f J u l y t h e v e g e t a t i o n throughout F l a t i r o n mountain, goes i n t o dormancy.  except i n the moists swales,  T h i s i s important from a  nutritive  p o i n t of view, f o r the p r o t e i n content of g r a s s can four to five times.  For example,  Agropyron  s p r i n g has a p r o t e i n c o n t e n t o f about s e r e s p r o t e i n d r o p s t o 3 t o k% The  15%;  inerme  drop i n the  when t h e  ( M a c l e a n and  Tisdale  plant i960).  Alpine v e g e t a t i o n stays green throughout the short  summer, b u t t h e t e m p e r a t u r e i s t o o l o w f o r a l l b u t a  few  g r a s s h o p p e r s p e c i e s and  temp-  i n d i v i d u a l grasshoppers.  e r a t u r e f r e q u e n t l y f a l l s below lethal  k.2  50 d e g r e e s  The  F, w h i c h i s  i f i t happens d u r i n g h a t c h i n g .  SAMPLING, • GRASSHOPPERS By t h e u s e o f a d r o p p i n g f r a m e  and  "convergence  on  a  s p o t " , e s t i m a t e s w e r e made o f t h e number o f g r a s s h o p p e r s per square meter. p o p u l a t i o n was 1  August  1970.  102 The  The  f i g u r e s are c o n s e r v a t i v e .  The h i g h e s t  p e r s q u a r e m e t e r on a Poa c o m m u n i t y summer a v e r a g e  on t h i s a r e a was  50  on per  -14-  square meter.  The lowest numbers were on Agropyron  where only one grasshopper per 20 square meters was  spicatum found.  A few a d u l t Cratypedus n e g l e c t u s were seen i n a l l l o c a t i o n s d u r i n g the v/inter.  On warm days they c o u l d be found on  g r a s s y patches between snow d r i f t s .  Grasshopper  phenology i s  shown i n Table 3 • Weighing  of 60 a d u l t d r i e d grasshoppers, of mixed s p e c i e s ,  gave an average weight of 72 mg  per grasshopper.  Thus a  maximum estimate of mass o f grasshoppers on a Poa community was  about 7 . 5  gms  per square meter.  On the g r a s s l a n d s the common Orthoptera of the A c r i d a e f a m i l y were Camnula p e l l u c i d a , Melanoplus s a n g u i n i p e s , and B r u n e r i a brunnea; spp.  of the T e t t i g o n i i d a e f a m i l y , Gyphoderris  Camnula p e l l u c i d a was  a t l e a s t 20 times more p l e n t i f u l  than any other s p e c i e s . The sweep n e t was thick vegetation.  I f too sparse, such as on r i d g e s  to Artemesia f r i g i d a , s o i l surface.  u n s u c c e s s f u l i n v e r y sparse or v e r y  i t was  f o r comparison  I t was  prevented from  a s a t i s f a c t o r y method  of p o p u l a t i o n s on one area on s u c c e s s i v e d a t e s .  The dropping frame was and was  i m p o s s i b l e t o c o l l e c t from the  I f too dense the net was  p a s s i n g c l o s e t o the ground.  established  the best sampling method used,  s a t i s f a c t o r y i n a l l areas f o r both nymphs and  Convergence  on a spot by two people was  used  adults.  successfully  f o r immature grasshoppers up to a d e n s i t y of about 4-0 per square meter. count.  Above t h i s number they were too d i f f i c u l t  to  -15-  4.3  SAMPLING, OTHER INSECTS The  herbivorous  Orthoptera,  orders t h a t r e c u r e d i n the samples were  C o l e o p t e r a , Hemiptera, Homoptera, and  Lepidoptera.  Many D i p t e r a and Hymenoptera were a l s o caught but p l a n t - e a t i n g f a m i l i e s were uncommon (Table 4 ) .  Only Orthoptera,  and Homoptera occurred i n l a r g e numbers.  Hemiptera,  Scarabidae  p t e r a ) and Aphidae (Homoptera) numbers were found  (Coleo-  to  fluct-  uate throughout the summer, v a r y i n g from n e g l i g a b l e to v e r y numerous.  The  e f f e c t on t h e i r food s p e c i e s d u r i n g t h e i r  p e r i o d s of h i g h numbers may of s p e c i e s present The  have been j u s t as g r e a t as t h a t  i n moderate numbers throughout the summer.  l a r g e s t number of i n s e c t s was  ens i s g r a s s l a n d .  The  i n the P. p r a t -  to note t h a t i n the two  (Table 2 ) .  It i s interesting  climax communities,  Agropyron spicatum,  Pseudosllga-  the i n s e c t numbers  remained r e l a t i v e l y low and the s p e c i e s composition q u i t e uniform 4.4  Poa  u n t i l much l a t e r i n the summer  than i n most other communities  and  found  permanent w i l t i n g p o i n t i n the  communities i s not reached  Calamagrostis  few  remained  throughout the summer ( F i g . 4 ) ,  SAMPLING, SOIL INVERTEBRATES Few  s o i l i n v e r t e b r a t e s were found  than C o l e o p t e r a and Arachnida  s h e l t e r i n g under r o c k s .  t y p i c a l c a t c h from J u n i p e r slope was Homoptera 28%,  C o l e o p t e r a 3%,  on South s l o p e ,  Heteroptera  D i p t e r a 2%,  other A  47%,  and Arachnida  20%.  4.5  SAMPLING, VEGETATION  4.5.1  Community A n a l y s i s The r e s u l t s are shown i n Tables 5 and 6.  4.5.2  I n s e c t Use of P l a n t Commionities ( F i g . 4) 4.5.2.1  Grazed Blade  (Table  7).  Poa p r a t e n s i s , P. secunda, and K o e l e r i a c r i s t a t a were the p l a n t s most o f t e n eaten by grasshoppers and  8).  (Tables 7  Damage was t o the grass blades, r a r e l y t o the stem.'  Bernays and Chapman (1970) a l s o made t h i s o b s e r v a t i o n , t h a t "only the grass blades were of g e n e r a l importance t o the grasshopper as f o o d " . were observed  When a l l grass had cured  grasshoppers  e a t i n g Wooly M u l l e i n (Verbascum t h a p s i s ) and  Arternesia t r i d e n t a t a . Agropyron spicatum.  There was v e r y l i t t l e g r a z i n g on Although  there were many other p l a n t s  i  present i n each area, only those l i s t e d  i n Table 7 showed  more than a t r a c e of damage. On the J u n i p e r slope A. f r i g i d a community, P. secunda was the only important  grasshopper food s p e c i e s .  Of 69 P.  secunda blades examined, 45% showed s i g n s of i n j u r y ; f u r t h e r examination  showed t h a t about 42% m a t e r i a l was removed from  the i n j u r e d b l a d e s . blades  Thus the o v e r a l l removal from the t o t a l  (both i n j u r e d and u n i n j u r e d ) was about  19%.  On the J u n i p e r slope Poa community, P. p r a t e n s i s comprised 74% or the v e g e t a t i o n (Table 5 h  of 700 grass  blades of a l l s p e c i e s examined 523 were P. p r a t e n s i s .  Of  the Poa blades 77% were i n j u r e d , with an average of 43% f o l i a g e removed. was about 33%.  The o v e r a l l percent removed f o r P. p r a t e n s i s  -17-  On the J u n i p e r s l o p e P o a - S t i p a community, t h e two main g r a s s e s were P. p r a t e n s i s (51%)  and S. columbiana  (18%).  Of 263 P. p r a t e n s i s b l a d e s examined 32% were i n j u r e d , the average amount removed from t h e i n j u r e d b l a d e s was 55%» g i v i n g a t o t a l r e m o v a l o f about 18%. ant g r a s s , S. columbiana,  The second most abund-  had 17% o f 138 b l a d e s i n j u r e d , 24%  r e m o v a l from the i n j u r e d b l a d e s ; removal t o t a l was about 4%. U s i n g weighted  means f o r t h e t o t a l s ,  on t h e J u n i p e r s l o p e  A* f r i g i d a community o f 75 b l a d e s o f a l l g r a s s s p e c i e s examined 44% were i n j u r e d , w i t h an average o f 43% f o l i a g e removed from each b l a d e .  One might say, then, t h a t about 19% o f t h e  a v a i l a b l e g r a s s on the A. f r i g i d a community was removed bygrasshoppers  and o t h e r g r a z i n g i n s e c t s .  On t h e J u n i p e r s l o p e Poa community 700 b l a d e s o f a l l s p e c i e s were examined.  Of these 80% were i n j u r e d , and 35%  o f the a v a i l a b l e g r a s s was consumed by i n s e c t s .  On t h e Poa-  S t i p a community 135 b l a d e s out o f a t o t a l o f 472 o f a l l s p e c i e s were i n j u r e d , and 14% o f t h e t o t a l g r a s s was removed. Of t h e g r a s s e s i n the A s h n o l a , K. c r i s t a t a and P. p r a t e n s i s were consumed f i r s t ,  and P. secunda and S. columbiana  t h i r d and f o u r t h c h o i c e s (Table 8 ) .  were  K. c r i s t a t a , a f t e r b e i n g  averaged over a l l t h e a r e a s , showed 46% o f 99 l e a v e s t o be removed by i n s e c t s ; P. p r a t e n s i s had 28% o f 786 l e a v e s removed; and S. columbiana grazing  insects.  had 13% o f 203 l e a v e s removed by  -18-  4.5.2.2  Wind Tunnel.  The wind tunnel experiments were c a r e f u l l y and conducted.  designed  However there was no s i g n i f i c a n t difference  i n response by the grasshoppers to any of the f i v e grasses; i n fact t h e i r use of any of the f i v e species was minimal. 4.5.2.3  Exclosure Cages.  On 14 May 1970 the standing dead phytomass on the Juniper slope Poa-Stipa community averaged 9.1 gms per square meter, while that of f a l l e n phytomass plus that standing averaged 52.2 gms per square meter (Table 9).  By f a l l the  previous year's carryover had almost disappeared  and what  remained was not separated from the exclosure cage clippings. The vegetation from the cages was not collected u n t i l late September when copulation, egg-laying, and feeding of grasshoppers was completed. The exclosure cages worked very well when the grasshoppers were fewer than 28 per square meter, but when t h e i r numbers were very high on hot days they crawled on top of the cages and ate large holes i n the screening, through which they entered the cage.  This happened on the Poa  community during August 1970; accordingly during t h i s time the cages ,were sprayed with i n s e c t i c i d e to k i l l the few grasshoppers which had gained entry. The results from the exclosure cages are shown i n Table 10.  Although i n a l l four areas the mean grass yields were  higher i n the exclosure (lowered) cage, and lower and approximately  equal i n the two control plots (no cage and  -19-  raised  c a g e ) , none of the  significant.  The  t - t e s t g i v e n i n the  s a m p l e means; a t e s t was means o f p a i r e d result.  The  little  were  statistically-  t a b l e used  non-paired  a l s o done u s i n g d i f f e r e n c e s  s a m p l e s , and  t h i s a l s o gave  u n c a g e d c o n t r o l p l o t and  means were v e r y c l o s e , had  differences  indicating that  e f f e c t on g r a s s  yield.  the the  between  ainon-significant  raised  cage  plot  cages themselves  -20-  5.  5.1  BACKGROUND In  was  DISCUSSION  t h e A s h n o l a t h e predominant p l a n t on t h e open range  Agropyron s p i c a t u m .  S i n c e t h e l a t e 1800's l i v e s t o c k ,  h o r s e s , c a t t l e , and sheep, have grazed t h e p l a t e a u x , b a s i n s , and moderate s l o p e s o f t h e a r e a .  Where t h e g r a s s e s a r e  a c c e s s i b l e t o cows c e r t a i n s p e c i e s have d i m i n i s h e d o r d i s appeared.  Less d e s i r a b l e " i n c r e a s e r s " have become more  abundant, e.g. S t i p a columbiana, S. r i c h a r d s o n i , Bromus tectorum,  A n t e n n a r i a r o s e a , Taraxacum o f f i c i n a l e , Lupinus spp.,  A s t r a g a l u s sp., Poa p r a t e n s i s , P. secunda.  Of t h e s e t h e  two most common a r e S. columbiana and P. p r a t e n s i s .  It is  i n t e r e s t i n g t o n o t e t h a t t h e l a t t e r i s p o s s i b l y an i n t r o duced p l a n t from Europe, but so c o m p l e t e l y has i t r e p l a c e d the i n d i g e n o u s A. spicatum  t h a t i t w i l l p r o b a b l y be a l o n g  time b e f o r e A. spicatum r e t u r n s .  On J u n i p e r s l o p e P. p r a t e n s i s  i s i n d i s c l i m a x , and appears t o have reached  a state of  e q u i l i b r i u m w i t h t h e c l i m a t e , s o i l , and b i o t a .  Oosting  (1948) d e f i n e s d i s c l i m a x : "When d i s t u r b a n c e i s such t h a t t r u e c l i m a x becomes m o d i f i e d o r l a r g e l y r e p l a c e d by new s p e c i e s , t h e r e s u l t i s an apparent c l i m a x , c a l l e d d i s c l i m a x . " There a r e few s t u d i e s anywhere o f i n s e c t s on c l i m a x g r a s s l a n d s o f t h e n a t u r e found i n t h e Ashnola a t between 4000 and 6000 f e e t . for  a comparative  u n d i s t u r b e d biome.  The A s h n o l a o f f e r s a unique o p p o r t u n i t y  s t u d y f o r t h e r e i s both d i s t u r b e d and I n s e c t s , u n l i k e cows and h o r s e s , do n o t  -21-  a p p e a r t o c a u s e d r a s t i c i m m e d i a t e c h a n g e s on t h e f l o r a l composition. to  this  Presumably t h e c l i m a x South slope has evolved  s t a t e and r e m a i n e d s t a b l e e v e r  t h e bad g r a s s h o p p e r r e p o r t s the worst  outbreaks  s i n c e , even  o f 1921-23,  i n B. C.'s h i s t o r y  through  according to  ( B r i n k , p e r s . comm.).  From my o b s e r v a t i o n s , and o t h e r s , i t a p p e a r s t h a t i f t h e g r a s s l a n d s a r e i n good c o n d i t i o n t h e y c a n w i t h s t a n d  insect  T r e h e r n e and B u c k e l l ( 1 9 2 4 ) s a y "...where t h e  activity.  numbers o f s t o c k t o t h e a r e a a v a i l a b l e f o r r a n g i n g i s i n j u d i c i o u s p r o p o r t i o n o r where r o t a t i o n s o f g r a z i n g g r o u n d s are p r a c t i s e d , grasshoppers  do n o t ,  o r even cannot,  perman-  ently injure the range-grasses. " In  the Nicola Valley,  about 80 m i l e s t o t h e n o r t h o f  t h e s t u d y a r e a i n B r i t i s h C o l u m b i a , most o f t h e c l i m a x b u n c h g r a s s " b e l l y h i g h t o a cow" h a s d i s a p p e a r e d . no r e c o r d o f g r a s s h o p p e r of c a t t l e ,  There i s  numbers b e f o r e t h e i n t r o d u c t i o n  b u t f o r t h e p a s t 50 y e a r s  f i r s t ) has a p p a r e n t l y been n e c e s s a r y  spraying t o prevent  (baiting outbreaks.  W i t h o u t c o n t r o l many r a n g e s were s t r i p p e d o f t h e i r forage.  I n the Ashnola,  valuable  on t h e o t h e r hand, t h e g r a s s l a n d s  have a l w a y s been i n r e l a t i v e l y good c o n d i t i o n . n e v e r been any g r a s s h o p p e r  control.  There has  -22-  5.2  EFFECTS OF TEMPERATURE AND S O I L MOISTURE ON INSECTS AND GRASS (1930) i n Montana found t h a t about  Parker soil  temperature  would was  occur.  75 d e g r e e s  f o r t h r e e d a y s was n e c e s s a r y b e f o r e h a t c h i n g  I n t h e A s h n o l a 60 d e g r e e s  F. s o i l  necessary before hatching occurred.  temperature  This difference  b e t w e e n o u r f i n d i n g s c o u l d be r e a l o r a p p a r e n t . difference the  F.  An a p p a r e n t  c o u l d be c a u s e d b y a d i f f e r e n c e i n e x p o s u r e o f  e g g pod s i t e s ;  u n f o r t u n a t e l y he d o e s n ' t s t a t e  aspect, or slope of h i s study area, a l l of which  altitude, could  i n f l u e n c e t h e s o i l t e m p e r a t u r e , w h i c h a p p e a r s t o be more important than a i r temperature. difference  c o u l d be r e a l ,  On t h e o t h e r h a n d , t h e  due t o s e l e c t i o n f o r nymphs w h i c h  hatch a t c o o l e r temperatures, s i n c e temperatures as h i g h as Parker's o b l i g a t e temperatures are infrequent a t high e l e v a t i o n s . In the  1969 and 1970 t h e t h r e e warm d a y s p r e c e d i n g h a t c h w e r e f i r s t warm d a y s  since the winter.  S u c h warm p e r i o d s  g e n e r a l l y do n o t o c c u r i n t h e A s h n o l a u n t i l t h e l a s t t w o weeks o f May o r t h e f i r s t week o f J u n e . Hatching started xeric Juniper ridges ( T a b l e 3). swept,  2 J u n e 19&9 a n d 6 J u n e 1970 on t h e (theArtemesia f r i g i d a  The r i d g e h a s a s o u t h w e s t  community)  exposure,  i s wind-  and has s p a r s e v e g e t a t i o n compared w i t h t h e s w a l e s ;  thus i t q u i c k l y reaches t h e "required" s o i l temperature of 60 d e g r e e s  f o rhatching.  W i t h i n two weeks many o f t h e f i r s t  and  i n s t a r s walked  a s f a r a s 300 f e e t t o t h e h y d r i c  second  Poa s w a l e s .  I n t h e swales t h e p o p u l a t i o n probably stayed  above 8 0 p e r square  meter.  -23-  n e x t o b s e r v e d 22 J u n e  H a t c h i n g was  P o a - S t i p a community.  Immature h o p p e r s  1970  on t h e m e s i c  soon c r a w l e d t o  n e a r b y p a t c h e s o f Poa s p p . where t h e p o p u l a t i o n was  greater  t h a n 20 p e r s q u a r e m e t e r , w h i l e t h e n e a r b y S t i p a c o n t a i n e d about  8 per square  meter.  H a t c h i n g o c c u r r e d n e x t on a m e s i c Poa c o m m u n i t y 20 J u n e .  About  two a c r e s o f P. p r a t e n s i s p r o v i d e d f o o d and  c o v e r f o r up t o 100 side of t h i s  grasshoppers per square meter.  s t a n d was  forest,  c o l u m b i a n a ; t h e numbers d r o p p e d square meter  100  about  On  one  and on t h e o t h e r ,  Stipa  s h a r p l y t o about  7 per  f e e t on e i t h e r s i d e o f t h e  Poa.  S o i l m o i s t u r e i s r e l a t e d t o p l a n t s u c c u l e n c e and j u i c y p l a n t s a r e c h o s e n by nymphs and a d u l t s .  This fact  partially  a c c o u n t s f o r t h e numbers o f g r a s s h o p p e r s a t  different  elevations.  c a . 1500  On t h e l o w e r g r a s s l a n d s ( e l e v a t i o n s  f e e t ) t h e r e a r e few g r a s s h o p p e r s .  The  plants dry  e a r l i e r and l o s e t h e i r s u c c u l e n c e .  The  t h e y o c c u r , home i n on g r e e n p l a n t s  ( P o a s p p . ) and  abundant  where m o i s t u r e i s a v a i l a b l e .  g r a s s h o p p e r s , when are  P e r h a p s t h i s i s why  t h e y a r e s o p l e n t i f u l a t 4 0 0 0 t o 6000 f e e t .  Above  this  e l e v a t i o n t h e s e a s o n i s p r o b a b l y t o o s h o r t f o r many g r a s s hoppers  (and o t h e r g e n e r a l l y - a d a p t e d i n s e c t s ) t o  complete t h e i r l i f e  cycle.  successfully  A h i g h m o r t a l i t y has been  ob-  s e r v e d i f n e w l y - h a t c h e d nymphs o f C. p e l l u c i d a a r e s u b j e c t e d t o t e m p e r a t u r e s b e l o w 50 d e g r e e s F. is  often cold  A t 7000 f e e t t h e  f o r l o n g p e r i o d s e v e n i n summer, w h i c h  a c c o u n t f o r t h e r e d u c t i o n o f numbers w i t h a l t i t u d e .  weather may Only  -24-  G.  p e l l u c i d a was  found i n the A l p i n e r e g i o n s .  (19^1) b e l i e v e s t h i s s p e c i e s t o be  adapted t o a  growing season.  A t a l l e l e v a t i o n s C.  species to reach  maturity.  5.3  J u n i p e r s l o p e t h e r e was  o n l y a few  orders  Lepidoptera,  contained  Orthoptera,  l a t t e r three  l a r g e numbers.  p e l l u c i d a was  the  first  an a b u n d a n c e o f i n s e c t s ,  phytophagous i n s e c t s ;  H e m i p t e r a , and  P o p u l a t i o n counts  by  but  Coleoptera,  Homoptera.  o r d e r s were r e p r e s e n t e d  o f damage t o v e g e t a t i o n by  Only  insects i n  were made, b u t t h e  amount  i n s e c t s c a n n o t be r e l a t e d  solely  t o i n s e c t n u m b e r s : c l i m a t i c c o n d i t i o n s and and  short  INSECT SAMPLING On  the  Shotwell  the  c o n d i t i o n o f t h e v e g e t a t i o n must a l s o be  composition  taken  into  account. All time;  p i t t r a p s were l a i d  thus the  t e n d e n c y was those  probably  not  most a b u n d a n t i n s e c t i n t h e  spp.  same p r o p o r t i o n . samples, except  I t s p r e s e n c e was  (Putnam 1962).  (1924) i t i s by  probably  According  The  a n t i - f r e e z e , and  By  f a r the  f o r ants,  was  related to that  t o T r e h e r n e and  of  Buckell  f a r t h e most common s p e c i e s o f g r a s s h o p p e r  f o u n d on c a t t l e r a n g e s o f B. C. open g r a s s y  same  Those t h a t f l e w from p l a c e t o p l a c e were  sampled i n the  pellucida.  at the  to c o l l e c t a higher p r o p o r t i o n of  i n s e c t s a t t r a c t e d to the sweet-smelling  probably  Poa  collected  s a m p l e s a r e c o m p a r a b l e as t o c a t c h .  crawling insects.  C.  o u t and  areas  and  i s nearly ubiquitous  a t a l l a l t i t u d e s and  latitudes in  south  on  -25-  c e n t r a l B. C. Throughout the Agropyron spicatum  site  only a few species  o f i n s e c t s and o t h e r i n v e r t e b r a t e s were n o t i c e d .  The most  common were dung b e e t l e s , f l i e s ,  spiders  a l s o w e r e common.  and b u t t e r f l i e s ;  Occasionally a cricket  (family Tetligon-  i d a e ) was f o u n d c l o s e t o t h e f o r e s t b o r d e r . crawled  about t h e base o f g r a s s t u s s o c k s .  Insects  Sweeps d i d n o t  r e v e a l many i n v e r t e b r a t e s o n t h e g r a s s b l a d e s I n s e c t numbers a n d f a m i l y c o m p o s i t i o n l o w and c o n s t a n t  t h r o u g h o u t t h e summer, a f i n d i n g t h a t i s  (1964)  abundant grasshopper,  " i sinvariably associated with" and e l s e w h e r e , i t  o f f e r i n g many n u t r i e n t s , t h e p l a n t s a r e s u c c u l e n t  j u i c y , w h i l e A. s p i c a t u m  cell walls.  i s " d r y " and c o n t a i n s  Because i t i s t a l l  the  c e l l w a l l becomes t h i c k e n e d  has  l i t t l e weight t o support  thickened  a n d h a s t o b e a r more (Bell  1971).  weight  P. p r a t e n s i s  and has t h i n c e l l w a l l s , making  i d e a l f o r y o u n g nymphs w h i c h seem t o r e l y  blades.  on t h e t e n d e r  Nymphs o f most s p e c i e s may s i m p l y be u n a b l e t o g e t  enough t o e a t i n a n A. s p i c a t u m in  t h e most  b e e n f o u n d i n t h e A l p i n e where t h e r e i s n o P o a ) .  Besides  it  ofstability i n  c l a i m s t h a t C. p e l l u c i d a ,  P. p r a t e n s i s ( a l t h o u g h , i n t h e A s h n o l a  and  relatively  communities.  Anderson  has  o r stems.  remained  consistent with the e c o l o g i c a l p r i n c i p l e climax  mainly  Montana observed  community,  Aulocara e l l i o t t i  s m i t h i i a n d A. c r i s t a t u m .  Anderson  (1964)  i n patches o f Agropyron  5.4  COMMUNITY ANALYSIS  V e g e t a t i o n appears t o p l a y an i m p o r t a n t r o l e i n d e t e r m i n i n g g r a s s h o p p e r d i s t r i b u t i o n and numbers beyond t h a t of p r o v i d i n g s p e c i f i c h o s t - p l a n t s . entomologists 1934)  F o r example, R u s s i a n  ( B e i - B i e n k o 1 9 3 0 , Netedor 1 9 3 1 , R u b t z o r 1 9 3 2 ,  n o t o n l y found d i r e c t c o r r e l a t i o n s between t h e abundance  o f c e r t a i n g r a s s h o p p e r s p e c i e s and t h e taxonomic c o n s t i t u t i o n of g r a s s l a n d s , b u t a l s o w i t h t h e amount o f p l a n t c o v e r . I n E n g l a n d , C l a r k ( 1 9 4 8 ) found t h a t t h e d e n s i t y and t h e height of the vegetation are important  features f o r grass-  hoppers . An attempt i s made here t o c o r r e l a t e g r a s s h o p p e r numbers w i t h predominant g r a s s s p e c i e s and/or cover d e n s i t y . Table 8 shows t h e f o u r m o s t - u t i l i z e d g r a s s e s t o be K o e l e r i a c r i s t a t a , Poa p r a t e n s i s , P. secunda, and S t i p a columbiana . The  l o w e s t g r a s s h o p p e r p o p u l a t i o n was found on upper South The p l a n t s p e c i e s c o m p o s i t i o n here (Table 5) was  slope.  57% Agropyron s p i c a t u m , able t o grasshoppers,  24% A r t e m e s i a  f r i g i d a , both  unpalat-  and o n l y 17% K, c r i s t a t a and 4% Poa spp.  I n a d d i t i o n t h e cover was v e r y s p a r s e ; o n l y 32% o f t h e a r e a was  covered w i t h v e g e t a t i o n (Table 6 ) . The  covered spp.,  Artemesia f r i g i d a ridges are a l s o very sparsely (24%), but the grass species composition  (25% Poa  6% K o e l e r i a and S t i p a ) appeared t o be f a v o r a b l e f o r  f e e d i n g by young nymphs, and indeed t h e nymph p o p u l a t i o n was  v e r y h i g h f o r a s h o r t time a f t e r h a t c h i n g o c c u r r e d on t h e  -27-  ridge.  However, t h e n e w l y - h a t c h e d  nymphs q u i c k l y moved t o  t h e more s u c c u l e n t and d e n s e l y - c o v e r e d n e a r b y  Poa s w a l e s .  The two a r e a s m o s t d e n s e l y p o p u l a t e d b y g r a s s h o p p e r s J u n i p e r P o a and P o a - S t i p a c o m m u n i t i e s .  Their cover  r e l a t i v e l y d e n s e , b e i n g 62 and 4 8 % , r e s p e c t i v e l y .  were  was On t h e  Poa c o m m u n i t y , 76% o f t h e v e g e t a t i o n c o n s i s t e d o f P o a s p p . and  a ' f u r t h e r 1 4 % o f t h e o t h e r two m o s t - u t i l i z e d s p e c i e s ,  K o e l e r i a and S t i p a  (Table 5 ) .  On t h e P o a - S t i p a c o m m u n i t y ,  t h e p l a n t c o m p o s i t i o n was 57% P o a s p p . , and a f u r t h e r  21%  K o e l e r i a and S t i p a . I t w o u l d seem, t h e n , t h a t g r a s s h o p p e r  populations are  h i g h e r on a r e a s w i t h a h i g h f r e q u e n c y o f P o a s p p . , and o t h e r p a l a t a b l e g r a s s e s , and w i t h a r e l a t i v e l y of  cover.  large  amount  However, a s i m p l e c o r r e l a t i o n does n o t n e c e s s a r i l y  i m p l y a cause  and e f f e c t r e l a t i o n s h i p ,  probable t h a t the apparent  importance  and i t w o u l d  seem  o f c o v e r i s due t o i t s  relationship to species-composition.  5.5  EFFECTS OF GRASSHOPPERS ON GRASS Y I E L D The e x c l o s u r e c a g e r e s u l t s  In  ( T a b l e 10)  view of the f a c t t h a t the grazed-blade  a large  (19  was e x p e c t e d  t o 35%)  consumption  were  unexpected.  analysis  o f g r a s s by g r a s s h o p p e r s , i t  that the grass y i e l d  i n grazed  (control)  t r e a t m e n t s w o u l d be much l o w e r 'than i n t h e u n g r a z e d closure) treatment. areas d i f f e r e d  indicated  (ex-  A l t h o u g h t h e mean g r a s s y i e l d s on a l l  i n the expected d i r e c t i o n s ,  were n o t s t a t i s t i c a l l y  significant.  the d i f f e r e n c e s  (This discussion  assumes  -28-  that this n o t due  c o n f i r m a t i o n of the n u l l hypothesis i s r e a l ,  t o some u n i f o r m b i a s o r t o c h a n c e . )  two r e s u l t s ,  one  and  Combining these  c o n c l u s i o n t h a t c a n be r e a c h e d i s t h a t a l -  t h o u g h g r a s s h o p p e r s e a t a l o t o f g r a s s , f o r some r e a s o n t h e y do n o t s i g n i f i c a n t l y a f f e c t i t s a n n u a l y i e l d . b e t w e e n - r e p l i c a t e v a r i a b i l i t y was  Alternatively,  s o g r e a t as t o make  i s t i c s u n r e l i a b l e w i t h such a s m a l l  stat-  sample.  A n d e r s o n (1961) a l s o made an a t t e m p t t o d e t e r m i n e g r a s s h o p p e r damage by s p r a y i n g a l a r g e a r e a o f M o n t a n a rangeland with i n s e c t i c i d e , grass y i e l d s was  and t h e n s u b s e q u e n t l y  on t h e s p r a y e d and' u n s p r a y e d  areas.  s u r p r i s e d a t h i s r e s u l t s w h i c h showed an  increase i n grass y i e l d  on u n s p r a y e d  " i n s p i t e of the presence  a r e a s o f K.  increased i n y i e l d d u r i n g the season. b e t w e e n t h e two  areas.  of these species  b o t h t h e s p r a y e d and u n s p r a y e d  The  comparing He,  too,  apparent He  found  that  of grasshoppers cristata  had  difference  p o r t i o n s o f t h e a r e a , h o w e v e r , was  not  s i g n i f i c a n t . . . A number o f u n e x p l a i n a b l e d i s c r e p a n c i e s i n t h e d a t a , e.g.,  western wheatgrass  (Agropyron  appear  smithii)...,  S a n d b e r g b l u e g r a s s ( P o a s e c u n d a ) , . . . and n e e d l e and t h r e a d ( S t i p a comata),..decreased second  i n weight between t h e f i r s t  c l i p p i n g s i n t h e s p r a y e d a r e a s and  i n the unsprayed  and  increased i n weight  a r e a s where g r a s s h o p p e r s were f e e d i n g .  From  this result  one m i g h t c o n c l u d e t h a t t h e p r e s e n c e o f g r a s s -  h o p p e r s was  r e s p o n s i b l e f o r an i n c r e a s e i n p r o d u c t i o n o f t h e s e  grasses."  He  a t t r i b u t e s t h i s r e s u l t t o a l a c k of homogeneity  o f t h e v e g e t a t i o n i n t h e a r e a t h a t he s t u d i e d ,  and  concluded  -29-  that  "random s a m p l e s . . . d i d  not  g i v e a r e l i a b l e measure  t h e l o s s e s c a u s e d by g r a s s h o p p e r s . " h o w e v e r , an a t t e m p t was  I n the  present  made when s e l e c t i n g t h e  of  study,  treatment  p l o t s t o o b t a i n t h r e e a r e a s as homogeneous as p o s s i b l e , t h a t h i s e x p l a n a t i o n may Anderson d i s c u s s e s s p a r s i f o l i a i s one p a c k a r d i i , M.  not  a p p l y t o my  results.  another unusual f i n d i n g :  of the  p r e f e r r e d food  b i l i t u r a t u s , M.  "Vicia  p l a n t s of  b i ' v i t t a t u s . . .and  Melanoplus  M.  confusus...  a l l o f w h i c h were p r e s e n t  on t h e u n s p r a y e d p o r t i o n o f  study  l o s s i n w e i g h t o f V.  was  area.  not  However, t h e  significant  t h e r e was present  no  on t h e two  significant. one  on t h i s p o r t i o n b u t was  grasshopper feeding.  The  a r e a s a t the' end  Normally,  sparsifolia  significant  s e a s o n was  o f t h e p l a n t s and  of p l a n t p a r t s . areas i s not  The  easily  grasshoppers  present,  c o n s e q u e n t b r e a k a g e and  d i f f e r e n c e recorded explained.  between the  sprayed  competed f o r l i g h t .  V i c i a i n t h e u n s p r a y e d a r e a may extent  by  a r e a and  i n c r e a s e d growth of t h i s  Thus, t h e  feeding  l o s s of v e g e t a t i o n .  on on  species." saying,  "Little  f o u n d b e t w e e n numbers o f g r a s s h o p p e r s p e r the  the  h a v e b e e n masked t o some  A n d e r s o n s u m m a r i z e s h i s w o r k by a t i o n was  loss  stimulated  s p a r s i f o l i a by r e m o v a l o f v e g e t a t i o n w h i c h area  of  two  I t i s a p o s s i b i l i t y that  f e e d i n g by g r a s s h o p p e r s on t h e u n s p r a y e d a r e a g r o w t h o f V.  where  also  might expect l o s s e s of V i c i a d u r i n g a season because  the drying-up  the  the  d i f f e r e n c e i n amounts  of the  e v e n w i t h no  so  T h i s may  be  correlunit  accounted  by t h e d i f f e r e n c e i n f e e d i n g h a b i t s o f t h e v a r i o u s  for  species  -30-  c o m p r i s i n g any p a r t i c u l a r g r a s s h o p p e r p o p u l a t i o n . " c o u l d a l s o be a c c o u n t e d f o r by t h e f a c t t h a t  This  grasshopper  f e e d i n g i s d i r e c t l y a f f e c t e d by t e m p e r a t u r e ; A n d e r s o n  reports  t h a t a n a d u l t g r a s s h o p p e r e a t s n e a r l y 2|- t i m e s as much f o o d a t 100 d e g r e e s as a t 80 d e g r e e s Another p o s s i b i l i t y f o r l o s s e s due  F.  i s t h a t t h e v e g e t a t i o n compensates  t o i n s e c t s and  i s a c t u a l l y s t i m u l a t e d by  c e r t a i n amount o f i n s e c t g r a z i n g .  I f t h e g r a s s stems a r e  b r o k e n by l i v e s t o c k t r a m p l i n g , g r a s s h o p p e r s c o n g r e g a t e these areas.  a  on  S i n c e g r a s s h o p p e r s c o n g r e g a t e on t h e s e t r a m p l e d  a r e a s , t h e s l i g h t e s t damage by l i v e s t o c k i s g r e a t l y m a g n i f i e d by t h e g r a s s h o p p e r p o p u l a t i o n .  I n the absence of  the grasshopper grazing i s d i s t r i b u t e d  livestock,  o v e r a l a r g e number  o f h e a l t h y , i n t a c t p l a n t s , and u n l e s s t h e p o p u l a t i o n r e a c h e s an e x t r a o r d i n a r i l y h i g h l e v e l no damage i s done t o t h e This l e v e l ,  range.  h o w e v e r , c a n n o t be p r e d i c t e d a t t h e p r e s e n t  t i m e s i n c e i n g e s t i o n r a t e s d e p e n d u p o n so many d i f f e r e n t factors. It  i s a l s o p o s s i b l e t h a t an e r r o r i n t e c h n i q u e a f f e c t e d  the r e s u l t s . delicate  C l i p p i n g t h e c u r e d p l a n t s i s an e x t r e m e l y  job, e s p e c i a l l y i f a wind i s b l o w i n g .  When t h e  c l i p p e r s t o u c h t h e stem t h e d r y b l a d e s f a l l  t o the ground,  and  T h i s might  one t h e n o b t a i n s more s t e m t h a n b l a d e .  account f o r t h e - u n e x b e c t e d l y s m a l l d i f f e r e n c e between and  experimental plot yields,  eat the blades.  control  since grasshoppers mostly  -31-  5.6  GRAZING MAMMALS As h a s b e e n m e n t i o n e d cows a n d h o r s e s  range s i n c e t h e 1800's.  have g r a z e d t h e  I n I969 a n d 1970 t h e g r a z i n g l e a s e s  were c a n c e l l e d t o l e t t h e r a n g e r e c u p e r a t e . years  a r e m a r k a b l e d i f f e r e n c e was s e e n .  I n those two  Forthe f i r s t  i n y e a r s many o f t h e g r a s s e s were a b l e t o s e t s e e d . o f t h e u s u a l 4 i n c h h i g h g r a s s , i n some a r e a s  time  Instead  i t g r e w 2\ f e e t  high. I n t h e summer o f 1970 s e v e n cows e s c a p e d o n t o slope f o r s i x days, d u r i n g which time damage.  They a t e a n d t r a m p l e d  i n t h e Poa swales. wasn't t r a m p l e d . and  they d i d a l o t o f  a large p o r t i o n of the grass  T h e i r f e c e s seemed t o c o v e r much t h a t They d e s t r o y e d  the shallow d r i n k i n g pool,  eroded t h e steep s i d e s o f t h e creek.  study  apparatus  Juniper  The damage t o my  was c o n s i d e r a b l e ? t h e y a t e t h e l e a d s  from t h e ground f o r t h e s o i l m o i s t u r e , e x c l o s u r e cages, and d e s t r o y e d  knocked over  most o f t h e i n s e c t  coming 7 o f 16  collecting  jars. A n d e r s o n (1961) r e p o r t s t h a t " c h a n g e s i n g r a s s h o p p e r distribution  and a c t i v i t i e s r e s u l t  from d i s t u r b a n c e s t o an  area, p a r t i c u l a r l y that o f trampling vegetation i n l o c a l i z e d spots."  On J u n i p e r s l o p e g r a s s h o p p e r s  d i d seem t o c o n g r e g a t e  on a r e a s t h a t h a d b e e n s p r i n g - c l i p p e d , t r a m p l e d , by  cattle  or horses.  o r grazed  I n a d d i t i o n , p o p u l a t i o n d e n s i t y appeared  t o be i n v e r s e l y r e l a t e d t o P o a h e i g h t , a n o b s e r v a t i o n a l s o r e p o r t e d by Anderson  (1964).  -32-  While grasshoppers' related A.  18%,  s p i c a t u m t o t h e p r o t e i n - r i c h l e a f o f Poa, c o u n t r e v e a l e d t h a t A.  i s almost  t h e s w a l e s and  s p i c a t u m made  c e r t a i n t h a t sheep choose t h e  habitat  W i n t e r snows c o l l e c t  p r o t e c t e d a r e a s ; t h e r i d g e s and  migrate to higher elevations.  Poa  communities,  have an o p p o r t u n i t y t o u t i l i z e  b u t t h e y make l i t t l e  expanse of p r i m i t i v e bunchgrass  use  the  o f them. "the  large  slope, interspersed  I t seems t h a t t h e s e b r o k e n  slopes are e s s e n t i a l .  with  My  b l u f f s and  steep  o b s e r v a t i o n s i n d i c a t e t h a t ewes  l a m b s r e q u i r e e i t h e r a w i d e open s l o p e , o r a l o o k - o u t  s i t e w i t h nearby  s t e e p escape  terrain.  J u n i p e r slope there are s m a l l patches  Near the bottom  a steep c l i f f .  escarpments.  of  o f P. p r a t e n s i s w h i c h  s h e e p g r a z e e x t e n s i v e l y , and w i t h i n a few h u n d r e d f e e t is  half  b l u f f s . . . p r o v i d e s an e x c e l l e n t c o m b i n a t i o n o f b i g h o r n  requirements."  and  sheep  I t i s the  S u g d e n (I96I) s a y s o f t h e A s h n o l a r a n g e ,  broken  sheep  Soon a f t e r l a m b i n g about  lambs l e a v e t h e w i n t e r r a n g e .  r e m a i n i n g sheep which  first  steep  As s o o n a s t h e snow r e c e d e s , most o f t h e  t h e ewes and  up  Koeleria with  s l o p e s a r e r e a s o n a b l y f r e e o f snow, and h e r e t h e forage.  (1967)  15%.  t h e n Poa s p p . w i t h  r a t h e r t h a n t h e g r a s s community. in  he  Blood's  o f t h e s h e e p ' s d i e t ; t h e n e x t h i g h e s t was  It  to  t o s u c c u l e n c e , the sheep p r e f e r the c o a r s e - s t r u c t u r e d  s p r i n g grazed-stem 4-7%  g r a s s s e l e c t i o n appears  there  F r i g h t e n e d sheep always dashed f o r t h e s e  Even i n l a t e  they r a r e l y ventured  summer when t h e l o w e r Poa  f a r from the c l i f f s ,  and  thus  sered  seldom  -33-  sampled  t h e g r e e n P o a f u r t h e r up t h e s l o p e .  do n o t n e e d t h i s k i n d  o f escape  t e r r a i n t h e y have  l u s h a r e a s p r e t t y much t o t h e m s e l v e s Thus t h e r e seems t o be l i t t l e  Since  insects certain  t h r o u g h o u t t h e summer.  c o m p e t i t i o n between sheep and  g r a s s h o p p e r s d u r i n g t h e summer, a n d s i n c e  grasshoppers  seem t o h a v e l i t t l e  i t would  e f f e c t on g r a s s y i e l d  that they are n o t a f f e c t i n g of  5.7  forage f o rthew i l d herbivores  the Ashnola.  WIND TUNNEL There  failure of  appear  are probably s e v e r a l reasons accounting f o r t h e  o f t h e wind t u n n e l experiment.  t h e journey from f i e l d  Perhaps  t h e trauma  t o l a b o r a t o r y , and t h e two-day  i n t e r v a l b e t w e e n c a p t u r e a n d t e s t i n g was t h e r e a s o n t h e grasshoppers f a i l e d Shotwell  t o respond.  (19^1) h a d o b s e r v e d nymphs a n d a d u l t s m i g r a t i n g  a g a i n s t t h e wind toward believes  fields  o f green g r a i n or corn.  He  " . . . t h a t t h e y f o l l o w up t h e stream o f m o i s t a i r  coming from t h e s e g r e e n f i e l d s . " may be c a u s e d perspiration.  He s a y s t h e same r e a c t i o n  by a pan o f wet b a i t o r a person wet w i t h Female m o s q u i t o e s  are attracted t o their  b l o o d s o u r c e b y a c o m b i n a t i o n o f warmth and m o i s t u r e f r o m t h e body o f t h e h o s t .  Grasshoppers  might  emitting  locate  food  by a s i m i l a r m e t h o d , a h y p o t h e s i s s u p p o r t e d b y t h e o b s e r v a t i o n t h a t they congregate experiment  on t h e m o i s t P o a s w a l e s .  w a t e r was s p r i n k l e d  In this  on t h e g r a s s b l a d e s t o k e e p  them f r o m d r y i n g o u t , w i t h t h e r e s u l t t h a t when t e s t i n g a l l  -34-  t h e g r a s s e s had  a b o u t t h e same m o i s t u r e  Although t h i s experiment response  density), to  showed no d i f f e r e n c e s i n  t o g r a s s e s , s e l e c t i o n o f h a b i t a t by p r e f e r e n c e f o r  c e r t a i n g r a s s s p e c i e s cannot elements  content.  of importance soil  the s o i l  i n c l u d e ground  out.  Other  cover  (both height  t y p e , s o i l m o i s t u r e , and  and  vegetation.  ance have been s u g g e s t e d importance.  be r u l e d  The  Of t h e s e b o t h c o v e r and  by t h i s s t u d y t o be  be  disturb-  of major  p a r t i c u l a r c h a r a c t e r i s t i c s o f an a r e a  subject f o r f u r t h e r experiment. critical  and  degree of d i s t u r b a n c e  a r e i m p o r t a n t i n h a b i t a t s e l e c t i o n w o u l d be an  a l t e r a t i o n o f one  possible  which  interesting  I t i s p o s s i b l e t h a t the  characteristic  s u f f i c i e n t to prevent congregations of  o f an a r e a would grasshoppers.  6.  1.  Grasshopper  SUMMARY  numbers r a n g e d  m e t e r on t h e c l i m a x A g r o p y r o n  f r o m l e s s t h a n one p e r s q u a r e s p i c a t u m c o m m u n i t y , t o more  t h a n 100 p e r s q u a r e m e t e r on t h e d i s c l i m a x P o a c o m m u n i t i e s . The most common s p e c i e s were C a m n u l a p e l l u c i d a ,  C. x a n t h i p p u s ,  and M e l a n o p l u s s a n g u i n i p e s . 2.  The l a r g e s t numbers o f i n s e c t s t h r o u g h o u t t h e summer  were found i n t h e d i s c l i m a x Poa c o m m u n i t i e s , i n these communities  t h e permanent w i l t i n g  r e a c h e d u n t i l much l a t e r  relatively  q u i t e uniform throughout 3.  because  p o i n t was n o t  i n t h e summer t h a n i n o t h e r  On t h e c l i m a x ( A g r o p y r o n s p i c a t u m ) numbers remained  perhaps  communities  communities.  the insect  l o w and t h e s p e c i e s c o m p o s i t i o n  t h e summer.  A p l a n t c o m m u n i t y a n a l y s i s showed t h a t t h e a r e a s  under  s t u d y were c h a r a c t e r i z e d by v a r i o u s c o m b i n a t i o n s o f f o u r prominent  grass s p e c i e s : Agropyron  Poa p r a t e n s i s , 4.  Poa - S t i p a .  respectively,  and P o a ) showed t h a t 19%,  (Artemesia 14%,  a n d 35%,  o f g r a s s b l a d e s was r e m o v e d b y g r a z i n g i n s e c t s .  The g r a s s s p e c i e s most u t i l i z e d b y g r a s s h o p p e r s  Koeleria cristata (21%),  cristata,  columbiana.  A grazed blade a n a l y s i s o f t h r e e communities  frigida,  5.  and S t i p a  spicatum, K o e l e r i a  (46%  damage), Poa p r a t e n s i s  and S t i p a c o l u m b i a n a  g r a z i n g on A g r o p y r o n  (13%).  spicatum.  There  were  ( 2 8 % ) , P.  secunda  was v i r t u a l l y no  -36-  6.  Grasshoppers  were l e a s t numerous on t h e c l i m a x  Agropyron  s p i c a t u m c o m m u n i t y w h e r e o n l y 21% o f t h e t o t a l g r a s s was o f t h e f o u r p r e f e r r e d s p e c i e s , and where o n l y 32% o f t h e g r o u n d was c o v e r e d b y v e g e t a t i o n . were found  H i g h e s t numbers o f g r a s s h o p p e r s  on a d i s c l i m a x P o a c o m m u n i t y , w h e r e 90% o f t h e  g r a s s was o f a p r e f e r r e d s p e c i e s , and where t h e g r o u n d 62% c o v e r e d . gregate 7.  W i t h i n these communities,  on a r e a s t h a t had b e e n g r a z e d  The e x c l o s u r e c a g e e x p e r i m e n t  h o p p e r s consume a f a i r l y ently  have l i t t l e  o r t r a m p l e d by  t o conlivestock.  showed t h a t w h i l e g r a s s -  l a r g e amount o f g r a s s , t h e y  o r no e f f e c t  of g r a s s as d e t e r m i n e d  they tended  was  on t h e t o t a l  b y an e n d - o f - s e a s o n  appar-  standing yield c l i p of vegetation.  - 3 7 -  LITERATURE CITED A n d e r s o n , N. L. and J . C. W r i g h t 1 9 52 . Grasshopper i n v e s t i g a t i o n s on M o n t a n a r a n g e l a n d s . M o n t a n a A g r . E x p t . S t a . T e c h . B u l l . 486. 46 pp. A n d e r s o n , L. I 9 6 I . Seasonal losses i n rangeland vegetation due t o g r a s s h o p p e r s . J . Econ. Entomol. 54: 369-378. A n d e r s o n , L. 1964. Some r e l a t i o n s h i p s b e t w e e n g r a s s h o p p e r s and v e g e t a t i o n . Ann. E n t o m o l . S o c . Amer.  57:  736-742.  B a r n e s , 0 . L. 1948. P r o g r e s s r e p o r t on some r a n g e grass research at Archer F i e l d S t a t i o n . Agr. S t a . S t a . , U n i v . Wyoming, L a r a m i e .  and Exp.  B e i - B i e n k o . , G. Y. 1 9 3 0 . The z o n a l and e c o l o g i c a l d i s t r i b u t i o n o f A c r i d i d a e i n t h e West S i b e r i a n and Zaisan Plains. ( I n R u s s i a n w i t h E n g l i s h summary). B u l l . P l a n t P r o t . , L e n i n g r a d . 1: 5 1 - 9 0 . Bell,  R. H. V. 1971. A g r a z i n g ecoysystem Serengeti. S c i . Amer. 2 2 5 : 86-93.  i n the  B e r n a y s , E. A. and R. F. Chapman 1 9 7 0 . Food s e l e c t i o n by C h o r t h i p p u s p a r a l l e l u s ( Z e t t e r s t e d t ) ( O r t h o p t e r a ? A c r i d i d a e ) i n the f i e l d . J . Anim. E c o l . 39: 3 8 3 - 3 9 4 . B l o c k e r , H. D. 1969. The i m p a c t o f i n s e c t s as h e r b i v o r e s i n g r a s s l a n d ecosystems. 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The A f r i c a n migratory locust (Locusta migratoria migratorioides R. & F.) i n N i g e r i a . A n t i - l o c u s t B u l l . 22: 18-30. D e M a r c h i , R. A. 19^5. An e c o l o g i c a l s t u d y o f t h e A s h n o l a b i g h o r n w i n t e r r a n g e s . M.Sc. T h e s i s , U n i v e r s i t y of B. C. D e m p s t e r , J . P. 1954-58. The p o p u l a t i o n d y n a m i c s o f t h e Moroccan l o c u s t ( D o c i o s t a u r u s maroccanus Thunberg) i n C y p r u s . A n t i - l o c u s t B u l l . 27: 18-30. H a r p e r , F. E. I 9 6 9 . E f f e c t s of c e r t a i n c l i m a t i c f a c t o r s on t h e p r o d u c t i v i t y and a v a i l a b i l i t y o f f o r a g e s on t h e A s h n o l a b i g h o r n w i n t e r r a n g e s . M.Sc. Thesis, U n i v e r s i t y o f B. C. H a r p e r , R. W. 1952. Grasshoppers i n C a l i f o r n i a . C a l i f . Dep. A g r . 4 1 : 105-112. H i t c h c o c k , A. S. 1950. United States. U.  Manual of the g r a s s e s of S. Dep. A g r . M i s c . P u b l .  Bull. the 200.  H i t c h c o c k , C. L., A. C r o n q u i s t , M. Ownbey, and J . W. Thompson. 1955, 1959, 1961, 1964, 1969. Vascular p l a n t s o f t h e P a c i f i c n o r t h w e s t . U n i v . o f Wash. P u b l . i n B i o l o g y . 5 v o l u m e s . U n i v . o f Wash. P r e s s (Seattle). K r a j i n a , V. S. 1959. B i o - c l i m a t i c zones. o f B. C. B o t o n y s e r i e s , No. 1. K u h n e l t , W. I 9 6 I . 397 PP.  S o i l biology.  F a b e r and  University Faber,  London.  McLean, A. and E. W. T i s d a l e . i960. Chemical compositions of n a t i v e forage p l a n t s i n B r i t i s h Columbia i n r e l ation to grazing practices. Can. J . P l a n t S c i . 40:  405-423.  M a n l y , B. F. J . and M. J . P a r r . 1968. A new method o f e s t i m a t i n g p o p u l a t i o n s i z e , s u r v i v o r s h i p , and b i r t h r a t e from c a p t u r e - r e c a p t u r e d a t a . T r a n s . Soc. B r i t . E n t . 18: 8 1 - 8 9 . N a t i o n a l S o i l Survey. I968. Report of the N i n t h meeting of the N a t i o n a l S o i l Survey committee of Canada. Can. E x p . Farm, Can. D e p t . A g r . ( O t t a w a ) .  -39-  N e f e d o v , N. I . 1931. On t h e d e g r e e o f i n f e s t a t i o n o f s o i l s o f T r o i t z k S t e p p e F o r e s t R e s e r v e w i t h eggpods o f A r c y p t e r a m i c r o p t e r a F.W. ( I n R u s s i a n w i t h E n g l i s h summary.) B u l l . I n s t . R e c h . , B i o l . Perm 8:  1-17.  P a r k e r , J . R. 1930. Some e f f e c t s o f t e m p e r a t u r e and m o i s t u r e upon M e l a n o p l u s m e x i c a n u s s a u s s u r e and Camnula p e l l u c i d a Scudder ( O r t h o p t e r a ) . Univ. o f M o n t a n a A g r i c . E x p e r . S t a . , Bozeman, M o n t a n a B u l l . No. 223. 132 p p . P f a d t , R. E . 194-9. Range g r a s s h o p p e r s a s a n e c o n o m i c f a c t o r i n the p r o d u c t i o n of l i v e s t o c k . A g r i c . Exp. S t a . U n i v . Wyoming, L a r a m i e . Putnam, L..G. 1962. The damage p o t e n t i a l o f some g r a s s hoppers ( O r t h o p t e r a ; A c r i d i d a e ) of the n a t i v e g r a s s lands of B r i t i s h Columbia. C a n . J . P l a n t S c i . 42:  496-601.  R u b t z o v , I . A. 1932. On t h e amount o f f o o d consumed b y l o c u s t s . ( I n R u s s i a n w i t h E n g l i s h summary) Plant P r o t . , L e n i n g r a d . 1932 (2): 31-40. R u b t z o v , I . A. 1934. F e r t i l i t y i n Siberian grasshoppers.  339-348.  and c l i m a t i c a d a p t a t i o n s B u l l . E n t o m o l . R e s . 25:  S c h e f f l e r , E . G. 19?2. A n a p p r a i s a l o f u n g u l a t e h a b i t a t s i n t h e A s h n o l a R e s o u r c e Management U n i t . M.Sc, T h e s i s , U n i v e r s i t y o f B. C. S h o t w e l l , R. L . 1941. L i f e h i s t o r i e s and h a b i t s o f some g r a s s h o p p e r s o f economic i m p o r t a n c e on t h e g r e a t plains. U. S. Dep. A g r . T e c h . B u l l . 774. 47 p p . S m i t h , C. C. 1940. The e f f e c t o f o v e r g r a z i n g and e r o s i o n yupon t h e b i o t a o f t h e m i x e d - g r a s s p r a i r i e o f O k l a h o m a . E c o l o g y 21: 381-397. S p e n c e r , G. J . 1956. The n a t u r a l c o n t r o l c o m p l e x a f f e c t i n g grasshoppers i n the dry b e l t of B r i t i s h Columbia. P r o c . T e n t h I n t . C o n g r e s s o f E n t . 4: 497-502. S u g d e n , L . G. I96I. The C a l i f o r n i a b i g h o r n i n B r i t i s h Columbia w i t h p a r t i c u l a r r e f e r e n c e t o the Churn C r e e k h e r d . B. C. D e p t . o f R e c . and Con. Pub. ( V i c t o r i a ) .  -40-  T a y l o r , W. P., C. T. V o r h i e s , and P. B. L i s t e r . 1935. The r e l a t i o n o f j a c k r a b b i t s t o g r a z i n g i n s o u t h e r n Arizona. J . F o r e s t r y 3 3 : 4-90-498. T r e h e r n e , R. C. and E . R. B u c k e l l . 1 9 2 4 . Grasshoppers of B r i t i s h Columbia. D e p t . o f A g r i c . B u l l . No. 3 9 .  -41-  TABLE 1.  E l e v a t i o n , a s p e c t , s l o p e , and s o i l c l a s s e s of each study a r e a . I n f o r m a t i o n i s from t h e N a t i o n a l S o i l S u r v e y Committee o f C a n a d a ( 1 9 6 8 ) , H a r p e r ( 1 9 6 9 ) , and f r o m t h e present study.  SITE  ELEVATION  ASPECT  SLOPE  28  S O I L CLASS  SOUTH SLOPE: Mesic Ridge (A. s p i c a t u m )  5750'  SSE  JUNIPER SLOPE: M e s i c Met S t a t i o n (P. p r a t e n s i s )  5525'  SW  5  Orthic Silt  Black  H y d r i c Swale (P. p r a t e n s i s )  5600'  SE  2  Orthic Silt  Black  Mesic "Poa-Stipa" (P. p r a t e n s i s , S. c o l u m b i a n a )  5400'  SW  12  Orthic Silt  Black  Mesic Ridge (Artemesia f r i g i d a )  56OO'  SW  23  Rego D a r k  Rego D a r k  Grey  Grey  TABLE 2 A. DATE  May 19  ANEMOMETER (Miles)  C l i m a t i c d a t a f o r J u n i p e r Slope 1969.  EVAPORATION (mis)  -  424,318  PRECIPITATION (inches)  S O I L MOISTURE (percent) 10* 20 30 50  -  -  TEMPERATURE (F.) Max. Min. 69.5  22.0  J u n e 18  6,938  (1) 275 ( 2 ) 275  (1) n i l (2) n i l  (1) 43 ( 2 ) 28 ( 3 ) 41 ( 4 ) 44  61 36 60 70  78 70 72 80  95 80 85 86  _  _  J u l y 22  895,043  (1) •750 ( 2 ) 715  (1) 0 . 2 0 (2) 0 . 2 1  ( 1 ) 28 ( 2 ) pw** ( 3 ) pw ( 4 ) 18  21 pw pw pw  55 31 20 70  75  48  pw pw 21  A u g u s t 24  152,715  (1) 1100 ( 2 ) 1100  S e p t . 28  399,350  (1) (2)  750 775  _  (1) (2) (3) (4)  pw pw pw pw  at at at at  a a a a  l l l l  l l l l  depths depths depths depths  80  _  (1) (2) (3) (4)  pw pw pw pw  at at at at  a a a a  l l l l  l l l l  depths depths depths depths  52  36  * D e p t h i n cms b e l o w s o i l s u r f a c e . ** B e l o w p e r m a n e n t w i l t i n g p o i n t .  TABLE 2 B. DATE  ANEMOMETER (miles)  C l i m a t i c Data f o r South Slope 1969.  EVAPORATION (mis)  S O I L MOISTURE (percent)  PRECIPITATION (inches)  10*  20, 3 0 , 5 0  TEMPERATURE (F.) Max. M i n .  May 20 729  (1) 306 (2) -  (1) n i l (2) n i l  22  333,084  (1) 750  (1) 0 . 2 5  July  (2)  -  76  30  pw  74  35  pw a t a l l s t a t i o n s and a l l depths.  J u n e 19  (2) 0 . 2 5  A u g u s t 24  622,873  (1) 1026 ( 2 ) 947  (1) 0 . 3 3 (2) 0 . 3 9  pw  80  36  S e p t . 28  958,670  (1) 446 ( 2 ) 475  (1) 0 . 7 0  ( 1 ) 44 pw ( 2 ) 38 pw pw a t a l l (3) d e p t h s ata l l (4) dpw epths  70  30  (2) 0 . 6 9  * D e p t h i n cms b e l o w s o i l ** B e l o w permanent w i l t i n g  surface. point.  -44-  TABLE 3 .  STAGE  Grasshopper phenology, Juniper  RIDGE POA SWALE (A. f r i g i d a )  HATCH  June 6  F I R S T INSTAR  J u n e 11  J u n e 22  IMMATURE  July 1  July  July  IMMATURE PLUS ADULTS J u l y 10 ADULTS  J u l y 17  slope,  MET STATION (Poa)  1970.  POA-STIPA COMMUNITY  J u n e 20  J u n e 22  J u n e 2k t o J u l y 1?  J u n e 23  10  June 2 6  July  10  16  July  10  July  19  J u l y 28  August 1  August 1  August 3  COPULATION OVIPOSITION  August 5  August 7  August 7  August 8  DECREASE I N NUMBERS  J u l y 20  A u g u s t 20  A u g u s t 15  August  15  -45-  TABLE 4.  ORDER Orthoptera  Common phytophagous i n s e c t s o f the Ashnola.  FAMILY. GENUS. AND SPECIES Acrididae:  Camnula p e l l u c i d a Camnula xanthippus Melanoplus s a n g u m i p e s  Tettigoniidae:  Cyphoderris sp.  Coleoptera  Chrysomelidae, B l a t e r i d a e , Carabidae, Scarabidae, Tenebrionidae, C u r c u l i o n i d a e .  Diptera  Cecidomyiidae,  Hemiptera and Homoptera  C i c a d e l l i d a e , Miridae,  Hymenoptera  Formicidae,  Lepidoptera  Nymphalidae, H e s p e r i i d a e , P i e r i d a e  Tipulidae, Bibionidae. Cercopidae.  Megachididae.  -46-  TABLE 5 .  Vegetation: basal h i tanalysis. Total number o f h i t s made i n e a c h c o m m u n i t y i s i n p a r e n t h e s e s b e s i d e c o m m u n i t y name. The f i g u r e s i n p a r e n t h e s e s b e s i d e t h e number o f v e g e t a t i o n h i t s i n d i c a t e the percentage of t o t a l v e g e t a t i o n h i t s ; the f i g u r e s i n parentheses beside the n o n - l i v i n g m a t e r i a l indicate the percentage o f t o t a l h i t s o f b o t h l i v i n g and n o n - l i v i n g m a t e r i a l . Dominant s p e c i e s are s t a r r e d .  SPECIES  JUNIPER SLOPE Poa Poa-Stipa (HOO) (800)  SOUTH SLOPE Upper Plats (400) (400)  (9)  14  (8)  Koeleria cristata  5  (17)  11  Poa s e c u n d a  1  (4)  9 (6) 130 (74)* 78 ( 5 D * 1 (1) 33 ( 2 6 ) * 11 (6) 27 (18)*  0 0  P. p r a t e n s i s Stipa columbiana Agropyron spicatum  17  Artemesia frigida  7  (57) *  (9)  18  (14)* 2 0  (370)  2  4 (2)  12  (24)  5 (3)  Ridge  (3)  19  (25)* 0 0  4 (3)  1  (1)  0  8 (5)  7 (9)  0  0  0  (1)  Eriogonium heracleoides  0  2  Achillea', millefolium  0  2 (2)  2  (1)  4 (3)  0  0  2  (1)  0 0 0  (7)  A n t e n n a r i a spp . 2  (2)  0 0  0 2 (2)  9 (5) 0  10 (7) 1 (1) 0  Taraxacum officinale  0  0  0  2 (l)  0  Aster spp.  0  0  0  1 (l)  0  Verbascum thapsus  0  0  0  1 (l)  0  T r i f o l i u m spp.  0  0 0  0  0  0  3 (2) 0  0  0  P o t e n t i l l a spp . Lupinus spp.  Arabis spp.  1  (4)  Lewisia rediviva  0  0  Oxytropis  0 0  0  Bryophytes TOTAL VEGETATION 30 (8) NON-LIVING MATTER  47 128  36? (92)  1  (1) 0 (37)* (32) 173 (22)  (68)  (78)  0 1  (1)  0 0 152  (81)  0  (19)  46 77  (6o)* (21)  (79)  -47-  TABLE 6 , Vegetations cover h i t a n a l y s i s . T o t a l number o f h i t s made i n e a c h c o m m u n i t y i s i n p a r e n t h e s e s b e s i d e c o m m u n i t y name. The f i g u r e s i n p a r e n t h e s e s r e p r e s e n t t h e percentage o f t o t a l h i t s which touched v e g e t a t i o n . Comparison o f t h i s t a b l e w i t h T a b l e 5 shows t h a t g e n e r a l i m p r e s s i o n s o f which s p e c i e s a r e abundant a r e u n r e l i a b l e e s t i m a t e s o f a c t u a l p l a n t n u m b e r s , s i n c e a s i n g l e p l a n t o f a b u s h y s p e c i e s may p r o v i d e more c o v e r t h a n s e v e r a l p l a n t s o f a s p a r s e l y f o l i a g e d species. SPECIES  SOUTH SLOPE Upper Flats  (400)  (800)  (400)  Koeleria cristata  13  Poa  secunda  1  P.  pratensis  0  1  Stipa columbiana  0  74  do) (1)  JUNIPER SLOPE Poa-Stipa Ridge (800) (370)  Poa  9  (2)  19  (10). 27  (5)  15  (8)  11  (2)  18  ( 3 8 ) * 27  (5)  78  (20)*  6  (7)  ( 2 5 ) * 22  (4)  11  (3)  4  (5)  26  (7)  46  Agropyron spicatum  87  (70)*  48  Artemesia frigida  20  (16)  6  (1)  (3)  278  2  (1)  (2)  14  (7)  0  24  (6)  Achillea millefolium  (2)  14  (7)  0  39  (10)  A n t e n n a r i a s p p ,.  0  0  4  P o t e n t i i l a spp  0  0  105  Lupinus spp  0  Taraxicum officinale  0  0  A s t e r spp  0  0  4  Verbascum t h a p s u s 0  (2)  (1)  1  (1)  0  0  0  A r a b i s spp 0 Lewisia rediviva 0  0 0  0 0  Oxytropis  0  0  Allium  0  0  T r i f o l i u m spp  cernuum  Unidentified  2  No c o v e r h i t : Cover h i t s :  270 125  (1) (68) (32)  10  202 195  (2)  8 (51) (49)  301 499  (2) (38) (62)  (2) 0  (6)  0 0  11  0  (3)  7  (2)  0  3  (1) 0  0  1  0  0  2  0  (1)  (52)* 0  (1)  ( 2 1 ) * 21  0  0  2  0 3  (10)  22 ( 2 5 ) * (5) ( 5 6 ) * 122 ( 3 2 ) * 0  Eriogonium heracleoides 2 2  9  0  (1)  3  (1)  4  (1)  4  (1)  418 382  (52) (48)  0 1  (1) 0 0  1  (1) 0  281 89  (76) (24)  -48-  TABLE 7 , I n s e c t g r a z i n g o f g r a s s e s on J u n i p e r slope, 1 9 7 0 . The t o t a l number o f blades and the number o f these t h a t are i n jured are s t r a i g h t counts. The "percentage removed" from i n j u r e d blades i s an e s t i m a t e . The " t o t a l percentage removed" i s c a l c u l a t e d from the number of i n j u r e d blades and the estimated "percentage removed". The t o t a l percent damage ( t o a l l s p e c i e s ) i n each a r e a i s a weighted mean of the " t o t a l percentage r e moved" from each s p e c i e s , and i s u n d e r l i n e d . ARTEMESIA FRIGIDA RIDGE COMMUNITY Grass s p e c i e s  No. blades  Koeleria cristata  -  Poa  secunda  Poa p r a t e n s i s Stipa columbiana Agropyron spicatum  No. i n j u r e d  % Removed from i n j u r e d blades  69  31 (45%)  42%  19%  -  -  -  -  6  2 (33%)  50%  17%  33 (44%)  43%  19%  A l l species (weighted t o t a l ) 75  Total % removed  POA COMMUNITY Koeleria cristata  75  71 (95%)  54%  51%  Poa  28  23 (82%)  48%  39%  Poa p r a t e n s i s  523  405 (77%)  43%  33%  Stipa columbiana  65  51 (78%)  40%  31%  Agropyron spicatum  9  7 (78%)  85%  66%  All  700  557 (80%)  45%  3^  secunda  species  POA - STIPA COMMUNITY Koeleria cristata  24  13 (54%)  53%  29%  Poa  35  8 (23%)  48%  11%  Poa p r a t e n s i s  263  83 (32%)  55%  18%  Stipa columbiana:  138  24 (17%)  24%  4%  Agropyron spicatum  12  7 (58%)  53%  31%  All  472  135 (29%)  49%  14%  secunda  species  -49-  TABLE 8 . G r a s s e s g r a z e d b y i n s e c t s : C o n s o l i d a t e d E s t i m a t e s . The w e i g h t e d d a t a f r o m t h e t h r e e c o m m u n i t i e s shown i n T a b l e 7 i s summed t o g i v e a n e s t i m a t e o f g r a s s e s p r e f e r r e d b y grasshoppers.  GRASS S P E C I E S  MEAN % INJURED  TOTAL % REMOVED  Koeleria cristata (N~^~99l  85%  46%  Poa p r a t e n s i s (N = ? 8 6 )  62%  28%  Poa s e c u n d a (N = 132)  47%  21%  S t i p a columbiana (N = 2 0 3 )  37%  13%  (weighted)  -50-  TABLE 9.  C a r r y o v e r on t h e J u n i p e r s l o p e c o m m u n i t y , 14 May 1970.  Poa-Stipa  MEAN WEIGHT OF CARRYOVER (Gms/square m e t e r ) Standing  (8 r e p l i c a t e s )  Fallen plus standing (8 r e p l i c a t e s ) * Standard  error  9.15  + 1.7 *  52.2  + 18.7  -51-  TABLE 10.  E x c l o s u r e cage r e s u l t s : Mean g r a s s y i e l d s from three communities i n 1969 a n d 1970. None o f t h e d i f f e r ences a r e s i g n i f i c a n t . Statistics a r e shown i n A p p e n d i x 2.  COMMUNITY  CONTROL grams  RAISED CAGE LOWERED CAGE p e r square meter  SOUTH SLOPE: 6l + 7 . 6 *  78 + 7.6  95 + 7.6  57 + 14.9  59 + 14.9  81 + 14.9  Poa - S t i p a TT970)  46+12.6  54+12.6  76+12.6  Poa TT970)  140 + 21.5  144 + 21.5  171 + 21.5  S t i p a - Agropyron  TT?69) JUNIPER SLOPE: Poa - S t i p a  (1969)  * Standard error  -52-  FIGURE 1. . Soil moisture at depth of 30 cms on "two communities on Juniper slope, 1970.  0 MESIC POA: MET STATION  -53-  FIGURE 2. Grasshopper numbers i n relation to grass phenology on Juniper slope ridge community. Cover composition: 52% Artemesia frigida, 25% Poa'secunda, 10% Koeleria cristata.  COVER  COMPOSITION. A. FRIGIDA 5 2 % POA SECUNDA 25 % KOELERIA SPP 1 0 %  15  22  29  JUNE KOELERIA BLOOMING  POA BLOOMING  SEEDS DISSEMINATING  6 JULY KOELERIA CURED  13  20 f POA\ CURED  I  -54-  FIGURE 3.  •Air and s o i l temperatures, Juniper slope 1970.  SOIL  TEMPERATURES  AT  3 CMS  O  A R T E M E S I A FRIGIDA RIDGE  •  M E T STATION  -55-  FIGURE.LL.  Changes i n abudnance of insects on seven communities, 1970. South slope Agropyron spicatum and Juniper slope Calamagrostis are climax ccsmunities. Juniper slope Poa communities are dominated by Poa pratensis and P_^ secunda, and the Ridge community by Artemesia frigida and P. secunda.  • oracnnt O HOMOmM A ouam** 6  POA COMMUNITY  •  JUNIPER NET. STATION  CALAMAMOSTI8  POA  JUMPER SLOPE  4  5  6  A R T E M E S I A FRIGIDA JUNIPER  (WALE  SOUTH  JUMPER SLOPE  7  8  9  10  RIDGE  SLOPE  AOMPYMM SPICATUM SOUTH SLOPE  -J  i  T  POA  SWALE NORTH  JUNIPER SLOPE  TIME IN WEEKS BEGINNING'JUNE 1  -56-  APPENDIX I S c i e n t i f i c and common names, and date o f f l o w e r i n g f o r p l a n t s mentioned. P r i n c i p a l r e f e r e n c e s : H i t c h c o c k ( 1 9 5 0 ) , Hitchcock et a l ( 1 9 5 5 , 1 9 5 9 , 1 9 6 1 , 1 9 6 4 , 1 9 6 9 ) . Where nomenclatural c o n f l i c t s arose the l a t t e r was taken as the a u t h o r i t y . SCIENTIFIC NAME  COMMON NAME  FIRST DATE OF FLOWERING  1970.at 5000' GRASSES: Agropyron spicatum Pursh S c n b n & Smith  Bluebunch wheatgrass  June 25  Bromus tectorum L.  Downy Chess  June 29  Calamagrostis rubescens Buckl.  Pine grass  F e s t u c a i d a h o e n s i s Elmer  Bluebunch fescue  June 29  Koeleria cristata  June g r a s s  June 11  Poa ampla Merr,  Big bluegrass  June 3  Poa p r a t e n s i s (L)  Kentucky b l u e g r a s s  June 9  Poa secunda ( P r e s l . )  Sandberg b l u e g r a s s  June 4  S t i p a columbiana Macoon  Columbia needlegrass  J u l y 10  Stipa richardsoni  Richardson needlegrass  June 25  Sedge  June 4  Yarrow  June 26  (L) Pers.  Link.  SEDGES: Carex spp. FORBS : A c h i l l e a m i l l e f o l i u m L. v a r , l a n u l o s a Nutt.  A g o s e r i s g l a u c a (Pursh) R a f .F a l s e d a n d e l i o n  June 9  A l l i u m cernuum  Nodding onion  J u l y 15  Anemone spp  Anemone  June 22  A n t e n n a r i a spp. L.  Pussytoes  June 9  A q u i l e g i a formosa  Columbine  Arabis  Rockcress  May 24  A r e n a r i a formosa F i s c h .  Sandwort  June 4  Aster campestris L.  Aster  holhiellii  -57-  APPENDIX I Astragalus  miser  Continued J u n e 22  Milk vetch  Calochortus macrocarpus Dougl.  Mariposa  Castilleja miniata  Indian paintbrush  C i r s i u m spp. L  Canada t h i s t l e  Collinsia  parviflora  Dougl.  lily  Blue-eyed  Mary  J u n e 25  Delphinium spp.  Delphinium  June 7  Dodecatheon sp  Peacock  May 23  Draba sp.  Whillow "grass"  June 7  Epilobium  angustifolium  E r i g e r o n spp.  Fireweed June 9  Fleabane  Eriogonum h e r a c l e o i d e s N u t t . Eriogonum 11  Fragaria glauca  Wild strawberry  June  Fritillaria  Yellowbell  May  Geranium v i s c o s i s s i m u m F i s c h . & Mey  S t i c k y geranium  J u n e 22  Gilia  Gilia  June 3 June 7  pudica  sp  Lappula  floribunda  False forget-me-not  Lewisia  rediviva  Bitterroot  Lupinus s e r i c e u s  Pursh  Perennial  lupine J u n e 26  O x y t r o p i s c a m p e s t r i s ( L ) D.C .Loco-weed Pentstemon procerus Phacelia  Dougl.  Slender blue tongue  beard-  J u n e 22 J u n e 29  Phacelia  linearis  24  s p p L.  Blue Jacob's  Potentilla  gracilis Daryl  Cinquefoil  J u n e 26  Ranunculus glaberrimas  Buttercup  May  Saxifraga sp.  Saxifrage  June  Sedum s p p .  Stonecrop  Taraxacum Tellima  officinale  parviflora  Verbascum  thapsus  V i o l a sp Zigadenus  Weber  June  24 21  Dandelion  May 23  F r i n g e cup  May 23  Common m u l l e i n Violet  venenosus  ladder  11  Polemonium  D e a t h camas  . May 23 June  11  -58-  APPENDIX I SHRUBS AND  Continued  TREES:  Arctostaphylus u v a - u r s i (L) Spreng  Bearberry  Artemesia  frigida  Pasture  Juniperus  commonis  P i c e a engelmanni  Willd.  June 9  sage  Ground j u n i p e r  Parry  Engelmann  spruce  P i n u s c o n t o r t a Loudon var. l a t i f o l i a Engelm.  Lodgepole  pine  Populus  Trembling  aspen  tremuloides  Michx.  Pseudotsuga m e n z i e s i i (Mirb. ) Franco v a r . g l a u c a Douglas f i r R i b e s s p p . L. Currant Rosa woodsii L i n d l . Wild rose Shepherdia canadensis (L) Canada b u f f a l o b e r r y Nutt.  APPENDIX I I A n a l y s i s o f v a r i a n c e o f e x c l o s u r e cage r e s u l t s . SOUTH SLOPE: S t i p a - Agropyron (1969) Source Total Treatment Residual  df 20 2 18  Mean Square 563 2006 403  t (18 d f )  t (21 d f )  23 2 21  Mean Square 1760 1410 1793  (1970) df  Mean Square  t  1.7  JUNIPER SLOPE: Poa - S t i p a  Source Total Treatment Residual Poa - S t i p a Source Total Treatment Residual Poa  (1969)  df  23 2 21  1.1 (21 d f )  1449  3284 1279  1.4  (1970)  Source Total Treatment Residual  df  Mean Square  20 2  3092 1564 3261  18  t (18 d f ) 0.9  

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