THE EFFECT OF TWICE-OVER ROTATIONAL CATTLE

GRAZING ON THE GROUND BEETLES (COLEOPTERA: CARABIDAE)

AND SPIDERS (ARANEAE) ON THE YELLOW QUILL

MIXED GRASS PRAIRIE PRESERVE

by

Anita Stjernberg

A Thesis submitted to the Faculty of Graduate Studies of

The University of Manitoba

in partial fulfilment of the requirements of the degree of

MASTER OF SCIENCE

Department of Entomology

University of Manitoba

Winnipeg, Manitoba

Copyright © 2011 by Anita Stjernberg

ACKNOWLEDGEMENTS

I would like to thank my original thesis advisor, Dr. Rob Roughley, for providing guidance and sharing his valuable experience in taxonomy and fieldwork. I would also like to thank my new thesis advisor, Dr. Neil Holliday, for his patience and help with all my statistics and revisions, as well as Dr. John Markham and Dr. Pat MacKay, for their feedback. I would like to thank Gene Fortney and the Nature Conservancy of Canada for providing me with the location to do my study, as well as financial support for the installation and maintenance of the necessary infrastructure, and Gordon Bedhomme for providing and managing the cattle each year. Thank you also to Greencover Canada for providing a research grant to fund my project, as well as a partial stipend. Thank you to

Al Rogosin for help with plant identifications, David Wade for helping me with some spider identifications, and Yves Bousquet, Fritz Hieke, Daniel Duran, and Todd Lawton for helping with some carabid identifications.

A large number of people have helped me over the years and I really appreciate all their hard work. A big thank you goes to Dave Holder for all the invaluable services that he provides in the department and in the field. My traps were dug in and emptied weekly by various combinations of Michael Alperyn, Andrea Patenaude, Paul Kozak,

Chérie Dugal, Katrina Froese, Stacey Miller, Leanne Peixoto, Jen Murray, Heather

Collins, Kate Bergen, and Scott McMahon. Thank you to Erika Anderson and Jessie

Stjernberg for helping me in the field and in the lab on their vacations to Winnipeg.

I would also like to thank my family and friends who have supported and encouraged me throughout the course of this experience, and Scott McMahon in particular for being a wonderful partner in my life.

i ABSTRACT

Mixed grass prairie once covered a part of the Great Plains of North America, but it is now an endangered community, consisting of small, scattered fragments. The Yellow

Quill Mixed Grass Prairie Preserve is a remnant that is located in southwestern Manitoba and owned by The Nature Conservancy of Canada. In 2005 and 2006, this study was conducted to investigate the effect that the currently-practiced twice-over rotational cattle grazing regime is having on the invertebrate fauna, using carabid beetles and spiders as biological indicators. These groups were sampled weekly from May-October using pitfall traps and sweep nets. The primary experiment in this study compared grazed and ungrazed treatments on three paddocks. Cattle were moved through the paddocks beginning with a short graze in the late spring and ending with a long graze in the fall. A secondary experiment investigated whether it was the spring graze, fall graze, or the combination of the two that had the greatest impact on the carabids and spiders.

Effects on invertebrate fauna were examined in three periods each season: before grazing had begun, after the spring graze, and after the fall graze. A total of 81 species of carabids and 156 species of spiders were recorded, including potentially new provincial records (two carabid species and 20 spider species). The most frequently caught carabid was Calosoma calidum in both years, and the most frequently caught spider species were

Pardosa distincta, followed by Alopecosa aculeata. Seventy two species of plants were recorded in the study areas.

In the primary experiment, the soil was found to be significantly more compacted in the grazed treatments in both sampling years. Overall, the ungrazed treatments had significantly more plant species than the grazed treatments. Grazing did not significantly affect the cover of forbs, litter or bare ground but grass cover was lower in the grazed

ii treatments, as was the cover of shrubs in 2005. The cover of leafy spurge (Euphorbia esula) was not affected but the cover of ground juniper (Juniperus horizontalis) was greater in the ungrazed area in 2005 and in the grazed area in 2006.

The total catch and number of carabid species tended to be higher in the grazed treatment before grazing had begun but higher in the ungrazed treatment after the spring and fall grazes. Calosoma calidum followed the same pattern. There were no clear trends in the Berger Parker index of dominance before grazing, but it tended to be higher in the grazed treatments after the spring and fall grazes. The log series alpha index of diversity tended to be higher in the grazed treatment but trends were weak and inconclusive.

Principal Components Analysis indicated that while C. calidum was more commonly associated with the grazed treatment, most other species of carabids were variable in their responses to the grazing treatment.

The total catch of spider species tended to be higher in the ungrazed treatment before grazing had begun and after both spring and fall grazes. Pardosa distincta dominated the catches and was responsible for this pattern. Alopecosa aculeata followed this pattern too, though with insufficient numbers after the fall graze to provide any trends. There were no clear patterns in the number of spider species caught in any paddock in either sampling year. There were no clear trends in the Berger Parker index of dominance before grazing or after the fall graze, but the index tended to be higher in the ungrazed treatment after the spring graze. The Log Series Alpha index of diversity tended to be higher in the grazed treatment before grazing and after the spring graze but there were no patterns after the fall graze. Principal Components Analysis indicated that the high numbers of P. distincta obscured the treatment associations of most other species.

iii The results from the secondary experiment were inconclusive. It is recommended that rotational grazing be continued on the property, as it does not appear to be destructive to the invertebrate fauna. Periodic monitoring of ecosystem health using spiders is also recommended. Carabids are not considered to be suitable for this purpose.

iv TABLE OF CONTENTS

ACKNOWLEDGEMENTS ...... i

ABSTRACT ...... ii

LIST OF TABLES ...... vii

LIST OF FIGURES ...... xii

LIST OF APPENDICES ...... xvii

INTRODUCTION...... 1

LITERATURE REVIEW ...... 3 Mixed Grass Prairie ...... 3 Grazing As A Disturbance ...... 4 Management Challenges ...... 8 Effects of Grazing on Carabid Beetles...... 10 Effects of Grazing on Spiders ...... 11 Carabid Beetles as Bioindicators ...... 14 Spiders as Bioindicators ...... 17 Sampling Methods for Carabid Beetles and Spiders ...... 18 Diversity Measures ...... 24 Log Series Alpha Index ...... 25 Berger-Parker Index ...... 26 Summary ...... 26

MATERIALS AND METHODS ...... 28 Study Area ...... 28 Experimental Design ...... 29 Primary Experiment ...... 29 Secondary Experiment ...... 30 Sampling Methods ...... 31 Soil Compaction ...... 31 Vegetation Sampling ...... 32 Invertebrate Sampling ...... 33 Statistical Methods ...... 36 Diversity Indices ...... 37 Univariate Analysis ...... 37 Primary Experiment ...... 38 Secondary Experiment ...... 39 Multivariate Analysis ...... 39 Vegetation Quadrat Analysis ...... 40

v RESULTS ...... 41 Floral and Faunal Representation ...... 41 Vegetation ...... 41 Carabid beetles ...... 41 Spiders...... 42 Primary Experiment ...... 43 Soil Compaction ...... 43 Vegetation ...... 44 Carabid Beetles ...... 46 Summary Community Measures...... 46 Community Composition ...... 47 Spiders...... 50 Summary Community Measures...... 50 Community Composition ...... 52 Secondary Experiment ...... 56 Soil Compaction ...... 56 Vegetation ...... 56 Carabid Beetles ...... 58 Summary Community Measures...... 58 Community Composition ...... 58 Spiders...... 60 Summary Community Measures...... 60 Community Composition ...... 61

DISCUSSION ...... 196 Experimental Design ...... 196 Primary Experiment ...... 197 Soil Compaction ...... 197 Vegetation ...... 198 Invertebrates ...... 203 Carabids ...... 204 Spiders...... 208 Secondary Experiment ...... 211 Soil Compaction ...... 212 Vegetation ...... 212 Invertebrates ...... 213 Carabids ...... 213 Spiders...... 214 Conclusions ...... 215

LITERATURE CITED ...... 220

APPENDICES ...... 232

vi LIST OF TABLES

Table 1. Dates that cattle were present on each section of the Yellow Quill Mixed Grass Prairie Preserve during 2005 and 2006...... 64

Table 2. Sampling dates for 2005. Asterisk indicates that specimens collected that day were identified to species...... 65

Table 3. Sampling dates for 2006. Asterisk indicates that specimens collected that day were identified to species...... 66

Table 4. Vegetation species recorded during pin sampling on the Yellow Quill Mixed Grass Prairie Preserve in 2005 and 2006...... 67

Table 5. Species of carabid beetles collected in pitfall traps on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005 and 2006...... 70

Table 6. Weekly catches of the 25 most frequently-caught carabid species collected from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005. October 6 was not sampled due to snowfall. The value in bold indicates the peak catch for that species. Totals are derived from data from 300 pitfall traps for May 12 – 26, and 225 pitfall traps for June 2 – October 27 ...... 72

Table 7. Weekly catches of the 25 most frequently-caught carabid species collected from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2006. The value in bold indicates the peak catch for that species. Totals are derived from data from 225 pitfall traps...... 74

Table 8. Spider species collected by pitfall traps and sweep nets on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005 and 2006...... 76

Table 9. Potential new provincial records for Araneae, caught on the Yellow Quill Mixed Grass Prairie Preserve in 2005 and 2006...... 81

Table 10. Weekly catches by sex of the 25 most frequently-caught spider species collected in pitfall traps and sweep net samples from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005. Spiders were identified every second week (intervening days were omitted from the table). The value in bold indicates the peak catch for that species...... 82

vii Table 11. Weekly catch by sex of the 25 most frequently-caught spider species collected in pitfall traps and sweet net samples from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2006. Spiders were identified every second week (intervening days were omitted from the table). The value in bold indicates the peak catch for that species...... 84

Table 12. The effect of the grazing treatment on the soil compaction (measured in kiloPascals, kPa) of the 3 paddocks in the primary experiment. Measurements were taken at 10 locations in the grazed treatment and 4 locations in the ungrazed treatment. Only the top 15 cm of soil were used in the analyses, and each analysis had error degrees of freedom = 72. .... 86

Table 13. The relationship between the grazing treatment and the number of plant species in each paddock and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8. Data analyzed were blocks of five frames of the five-pin sampler...... 87

Table 14. The relationship between the grazing treatment and the percent cover of the most common plant species in each period and sampling year in the primary experiment. Each analysis had error degrees of freedom = 24. Data analyzed were blocks of five frames of the five-pin sampler...... 88

Table 15. The relationship between the grazing treatment and the distribution of living and non-living ground cover types among seven cover classes in the primary experiment in 2005 and 2006. GRA indicates the grazed treatment and UNG indicates the ungrazed treatment. Data are based on 75 1-m2 quadrats in each treatment. Leafy spurge is a subset of the forb data...... 89

Table 16. The relationship between the grazing treatment and the total catch of carabid beetles for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 91

Table 17. The relationship between the grazing treatment and the catch of Calosoma calidum in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 92

Table 18. The relationship between the grazing treatment and the number of species of carabid beetles for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 93

Table 19. The relationship between the grazing treatment and the Berger Parker index for carabid beetles in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps...... 94

viii Table 20. The relationship between the grazing treatment and the Log Series Alpha index for carabid beetles in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps...... 95

Table 21. The relationship between the grazing treatment and the total catch of spiders for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 96

Table 22. The relationship between the grazing treatment and the catch of Pardosa distincta for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 97

Table 23. The relationship between the grazing treatment and the catch of Alopecosa aculeata for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 98

Table 24. The relationship between the grazing treatment and the number of species of spiders for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8...... 99

Table 25. The relationship between the grazing treatment and the Berger Parker index for spiders in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and was based on blocks of five traps...... 100

Table 26. The relationship between the grazing treatment and the Log Series Alpha index for spiders in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and was based on blocks of five traps...... 101

Table 27. The relationship between the grazing treatment and the soil compaction (measured in kiloPascals, kPa) of the three treatments in the secondary experiment. Measurements were taken at five locations in each treatment. Only the top 15 cm of soil were used in the analysis, which had error degrees of freedom = 72...... 102

Table 28. The relationship between the grazing treatment and the number of plant species in each treatment and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12. Data analyzed were blocks of five frames of the five-pin sampler...... 103

Table 29. The relationship between the grazing treatment and the percent cover of the most common plant species in each treatment and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12. Data analyzed were blocks of five frames of the five-pin sampler...... 104

ix Table 30. The relationship between the grazing treatment and the distribution of living and non-living ground cover types among seven cover classes in the secondary experiment in 2005 and 2006. SP indicates the Spring treatment, FA indicates the Fall treatment, and SF indicates the Spring & Fall treatment. Data are frequencies of each cover class for each cover type based on 25 1-m2 quadrats in each treatment. Leafy spurge is a subset of the forb data...... 105

Table 31. The relationship between the grazing treatment and the total catch of carabid beetles for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 107

Table 32. The relationship between the grazing treatment and the catch of Calosoma calidum for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 108

Table 33. The relationship between the grazing treatment and the number of species of carabid beetles for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 109

Table 34. The relationship between the grazing treatment and the Berger-Parker index for carabid beetles in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 (except for Period 3 in 2006 which has df = 2,6) and is based on blocks of five traps...... 110

Table 35. The relationship between the grazing treatment and the Log Series Alpha index for carabid beetles in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps...... 111

Table 36. The relationship between the grazing treatment and the total catch of spiders for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 112

Table 37. The relationship between the grazing treatment and the catch of Pardosa distincta for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 113

Table 38. The relationship between the grazing treatment and the catch of Alopecosa aculeata for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 114

Table 39. The relationship between the grazing treatment and the number of species of spiders for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12...... 115

x Table 40. The relationship between the grazing treatment and the Berger Parker index for spiders in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 and was based on blocks of five traps...... 116

Table 41. The relationship between the grazing treatment and the Log Series Alpha index for spiders in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 and was based on blocks of five traps...... 117

xi LIST OF FIGURES

Figure 1. Location of the Yellow Quill Mixed Grass Prairie Preserve (YQMGPP) within the province of Manitoba...... 118

Figure 2. Layout of paddocks 27, 28, 29, and 34 on the Yellow Quill Mixed Grass Prairie Preserve, and the locations of the pitfall trap groups in the grazed areas...... 120

Figure 3. The layout of the pitfall traps on Paddock 34...... 122

Figure 4. Pin Sampler apparatus showing 5 pins ...... 124

Figure 5. Vegetation sample locations in 2005 and 2006 in the ungrazed and grazed areas of paddocks 27, 28, and 29, using a pin sampler...... 126

Figure 6. Vegetation sample locations in 2005 and 2006 on Paddock 34, using a pin sampler. These were also the locations of the 1 m2 quadrats in 2006...... 130

Figure 7. The rebar cage in place over a pitfall trap...... 132

Figure 8. The layout of pitfall traps in the grazing exclosures...... 134

Figure 9. Sampling dates included in each of the three time periods in 2005 for which samples were identified.  = Period 1 is prior to grazing,  = Period 2 is between the spring and fall grazes, and  = Period 3 is after the fall graze when the cattle have been removed. Samples were not identified for the first three sampling days because not all the pitfall traps were in place...... 136

Figure 10. Sampling dates included in each of the three time periods in 2006 for which samples were identified.  = Period 1 is prior to grazing,  = Period 2 is between the spring and fall grazes, and  = Period 3 is after the fall graze when the cattle have been removed...... 138

Figure 11. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 27, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm...... 140

Figure 12. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 28, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm...... 142

Figure 13. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 29, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm...... 144

xii Figure 14. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 in 2005 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 146

Figure 15. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 148

Figure 16. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 150

Figure 17. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 152

Figure 18. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 154

Figure 19. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2006 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 156

Figure 20. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 22 of 53 species caught in this period are shown on the graph...... 158

Figure 21. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 23 of 48 species caught in this period are shown on the graph...... 160

xiii Figure 22. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 19 of 52 species caught in this period are shown on the graph...... 162

Figure 23. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 21 of 54 species caught in this period are shown on the graph...... 164

Figure 24. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 20 of 34 species caught in this period are shown on the graph...... 166

Figure 25. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 23 of 41 species caught in this period are shown on the graph...... 168

Figure 26. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 18 of 50 species caught in this period are shown on the graph...... 170

Figure 27. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 20 of 34 species caught in this period are shown on the graph...... 172

Figure 28. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2006 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 18 of 28 species caught in this period are shown on the graph...... 174

xiv Figure 29. Line graph showing the soil compaction in the three treatments in paddock 34, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm. The Spring treatment only received a single graze in the spring, the Fall treatment only received a single graze in the fall, and the Spring/Fall treatment received both a spring and a fall graze...... 176

Figure 30. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 178

Figure 31. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 180

Figure 32. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 182

Figure 33. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 184

Figure 34. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 186

Figure 35. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 188

xv Figure 36. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 190

Figure 37. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 192

Figure 38. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 3 (after both grazes had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba...... 194

xvi LIST OF APPENDICES

Appendix 1. Total catch of spiders collected in pitfall traps in each paddock and treatment of the primary experiment on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba in 2005...... 232

Appendix 2. Total catch of spiders collected in pitfall traps in each paddock and treatment ...... 236

Appendix 3. Total catch of spiders collected in pitfall traps and by sweep netting .... 240

Appendix 4. Total catch of spiders collected in pitfall traps and by sweep netting .... 243

xvii INTRODUCTION

The mixed grass prairie is a historically important community that once covered an estimated 69 million hectares of land down the center of North America (Bragg and

Steuter 1996). It is a nutrient-rich ecosystem that is highly vulnerable to conversion to agriculture, and the remnants are fragmented and degraded. Estimates of the exact percentage of the original area that remains in Manitoba range from less than 1%

(Samson and Knopf 1994) to less than 18% (Sveinson et al. 2001). Manitoba

Conservation (2010) did a Mixed Grass Prairie Inventory Project from 1992 to 2001 in which remnants of prairie across the province were graded from “A” to “D”. A grade of

“C” or above indicated a good quality site that has the potential to improve over time, while a rating of “D” indicated a poor quality site that will require extensive management to improve. Of the 35,620 hectares surveyed, 14,957 hectares received a grade of “C” or above. According to the inventory, the main threats to this prairie type are cultivation, trembling aspen encroachment, exotic species invasion, and inappropriate grazing management.

The Yellow Quill Mixed Grass Prairie Preserve (hereafter referred to as the

Yellow Quill Prairie) is an approximately 842 hectare remnant in Manitoba (Sveinson et al. 2001) located approximately 20 km southeast of Brandon and 2 km north of the junction of the Souris and Assiniboine Rivers. It is primarily owned and maintained by the Nature Conservancy of Canada (NCC), and contains sections of “C”-grade prairie

(Manitoba Conservation 2010).

Historically, the mixed grass prairie evolved under grazing pressure from the millions of bison that once roamed the Great Plains of North America. Now that these

1 vast herds no longer exist, the maintenance of the remnants of this ecosystem depends on management regimes that mimic this disturbance. The NCC routinely employs herds of cattle as a substitute for bison and for 20 years, a season-long grazing regime was applied to the Yellow Quill Prairie. An idle year during which no grazing occurred separated this regime from a twice-over rotational grazing regime that began four years prior to my study. The twice-over rotational grazing system involves a stimulatory graze in the spring, lasting approximately 15 days, followed by a fall graze, lasting approximately 30 days. Duration and stocking density are at the discretion of the cattle producers.

To determine the impact that the grazing regime is having on the property‟s invertebrate fauna, a study was set up between the University of Manitoba and the NCC.

It was decided that ground beetles (Carabidae) and spiders (Araneae) would be the most appropriate bioindicators to use. In my study, a primary experiment was established to compare grazed and ungrazed areas. A secondary experiment was established to investigate whether the spring graze, the fall graze, or a combination of the two grazing episodes have the greatest impact on the invertebrate fauna. Vegetation and soil compaction were also examined to determine their correlation with the fauna.

The objectives of this study were to: (1) determine the effect of a twice-over rotational grazing regime on the ground beetle (Coleoptera: Carabidae) fauna, (2) determine the effect of a twice-over rotational grazing regime on the spider (Araneae) fauna, and (3) determine whether it is the spring or the fall graze, or a combination, that has the greatest impact.

2 LITERATURE REVIEW Mixed Grass Prairie

There is no universally accepted classification system for the different types of prairies that are found around the world. A review of literature on the subject reveals that most sources agree on certain aspects regarding the nature of the mixed grass prairie.

Mixed grass prairie is a climax grassland community that falls almost entirely within the area known as the Great Plains in North America (Weaver and Albertson 1956). It is composed of a mixture of mid-height grasses and short grasses and the whole community is unified by a set of major dominant species that vary in importance regionally as well as on a gradient from north to south (Weaver and Clements 1938). The climate is typically semi-arid with large seasonal and diurnal temperature fluctuations and a tendency for prolonged periods of drought and heavy precipitation (Weaver and Albertson 1956;

McHugh 1972). Annual precipitation tends to be heavier in the east and lighter in the west due to the rain shadow cast by the Rocky Mountains (McHugh 1972) and the growing season is relatively short (Wallis 1982).

There are three types of mixed grass prairie, based on plant communities. The northern mixed grass prairie historically covered 38 million hectares in the United States

(Nebraska, North Dakota, South Dakota), and Canada (Manitoba, Saskatchewan, Alberta)

(Weaver and Clements 1938; Bragg and Steuter 1996). The Sandhills prairie, located on stabilized sand dunes, covered 5 million hectares in Nebraska and 2 million hectares in

Kansas. The southern mixed grass prairie covered 24 million hectares from Kansas to

Texas (Bragg and Steuter 1996). In Canada, the mixed grass prairie tends to have a thinner cover of vegetation and smaller plants than on the Central Great Plains in the

United States (Weaver and Albertson 1956).

3 Grasslands tend to have a high level of belowground growth in the form of roots and rhizomes, and their decomposition as the plants die creates a nutrient-rich soil that is excellent for agriculture, making grasslands highly vulnerable to conversion to crops

(Risser 1988). Cultivation and increasing urbanization in particular have left the remnant pieces of native prairie in scattered fragments (Weaver and Clements 1938). Many of these fragments are areas that have been deemed unsuitable for cultivation due to climate, soil, or topography (Weaver and Albertson 1956).

Grazing As A Disturbance

Prior to the arrival of horse culture, herds of an estimated 28-30 million bison roamed the Great Plains (Flores 1991) providing the grazing pressure that shaped the evolution of the mixed grass prairie. Grasses are extremely tolerant of grazing due to extensive root systems and the location of their meristematic tissue, which lies close to the ground and remains unaffected if the leaves are removed (McHugh 1972). With the coming of the settlers came a drastic reduction in the bison population and their subsequent replacement with domestic cattle. Cattle and bison have different grazing strategies. Cattle tend to lightly graze a particular area often and for a long period of time, compared to bison that graze heavily but less frequently and for shorter periods of time

(Lauenroth and Milchunas 1992; Lauenroth et al. 1994). The increased densities and reduced mobility of cattle compared to wild bison (McNaughton 1993), creates the potential for range overgrazing. Approximately 12 hectares of land are required to support one cow from April to October, and an additional six hectares are needed if winter grazing occurs (Weaver and Albertson 1956).

4 The potential impacts that grazing has on the fauna of native grasslands depends on such factors as grazing intensity, frequency, duration, the time of year that it occurs

(Lauenroth et al. 1994), as well as the structure of the plant, the parts that are removed, the age of the plant, and its history (Hadley 1993). These impacts can be positive, negative, or neutral, and can be mitigated by other forces such as the climate and the structure, composition, and history of the region (Lauenroth et al. 1994). Herbivory by large mammals doesn‟t necessarily decrease the species richness of invertebrates, birds, and small mammals, but shifts the composition towards species that prefer open areas, reducing the occurrence of those species requiring dense cover (Duncan and Jarman

1993). A study by Zahn et al. (2007) found that cattle-grazed plots have higher numbers of arthropod species than ungrazed plots, most likely as a result of the mosaic of intensively grazed areas mixed with bare ground and patches of short vegetation. The grazed plots are characterized by carabid species that prefer both moist and sunny environments.

Many forms of grassland management remove the aerial and reproductive parts of the plants, decreasing the numbers of animals that depend on those parts in particular for food and for the completion of their lifecycles (Morris 1971; Duffey et al. 1974). Short, understory species respond positively to grazing, as their normal competition for space and sunlight are removed (Belsky 1992). The removal of native forb species by grazers changes the soil on the prairie, as their penetrating roots enrich the deep soil and make it more porous (Weaver and Albertson 1956). Trampling by a large number of grazers causes soil compaction, which decreases aeration and water penetration (Duffey et al.

1974).

5 Lenoir and Lennartsson (2010) compared the effect of continuous grazing and late-onset grazing (beginning at the end of July) on grassland arthropods, and found that the timing of grazing has no significant effect on the number of individuals of spiders.

However, significant differences were noticed amongst functional groups. More small web-builders (less than 3 mm in size) were caught in the continuous grazing treatment both before and after the start of late-onset grazing. Tall clumps of vegetation in the late- onset grazing treatment provide anchoring structures for web-builders. It was suggested that the prevalence of web-builders in the continuous grazing treatment is a result of the frequent destruction of webs by cattle, forcing the spiders to move locations and allowing them to be caught in the pitfall traps. However, small-bodied spiders and carabid beetles could benefit from the higher microhabitat temperatures that are found in shorter vegetation, such as that found in the continuous grazing treatment in the early summer.

There was no significant difference in their numbers between the two treatments after the late-onset grazing had begun. Spiders employing a sit-and-wait strategy as well as running spiders with body sizes greater than 10 mm were seven times as common in the late-onset grazing treatment, both before and after late grazing had begun.

Carabid beetles with bodies larger than 8 mm were also more prevalent in the late-onset grazing treatment. This suggests that the advantages of having a larger food supply potentially outweigh the disadvantages of denser vegetation and a deeper litter layer that could impede movement and make hunting more challenging for visual predators.

Uetz (1979) found that the species richness of spiders and of their prey is positively correlated with the depth of the available cover of litter. The Gnaphosidae,

6 Clubionidae, and Thomisidae, all litter-dwelling families, increase in dominance with the addition of litter, whereas a reduction in litter leads to an increase in dominance of the

Lycosidae. However, the relative influence of other environmental factors changes over the course of the seasons. Prey abundance is very important early in the season, as it results in species underutilizing the range of available prey and allows for the coexistence of a greater number of species in one area. In mid-season, the key factor influencing the species richness is litter complexity (interstitial space/volume). Increased complexity leads to an increase in the number and diversity of available microhabitats, as well as the number of refuges for the newly emerged immature spiders that forage in the litter and experience inter- and intra-specific competition and predation. According to Uetz (1979), late in the season, temperature variation is the most important factor, as individuals tend to expend a large amount of energy on moving to suitable microclimates. Deeper litter which helps insulate microhabitats from wide temperature fluctuations allows for certain species, particularly those that have not completed their reproductive cycles, to survive later in the season. A study by Pétillon et al. (2007) determined that sheep grazing decreases the species richness of spiders by creating a homogenous cover of vegetation with a limited availability of refuges for cursorial and diurnal wandering spiders. Carabid beetles are not significantly affected by this form of disturbance.

The deposition of dung and urine adds nutrients to an ecosystem, as well as providing an additional habitat, food source, and a new set of dependent insect species

(Morris 1971; Duffey et al. 1974). Cattle avoid dung and urine patches initially, but the new growth that is stimulated eventually draws them back (Hobbs et al. 1991). Plants can be killed by the toxic effect of large quantities of dung or urine being deposited on them

7 (Spedding 1971). Lenoir and Lennartsson (2010) observed that trap catches of small spiders, carabids, and ants increased when grazers were on their study area, but could not isolate the effect of dung from the effects of low vegetation and increased microhabitat temperatures.

Management Challenges

It is important to understand the effects that human disturbances have on ecosystems so that their impact can be mitigated and the ecosystems can be managed to conserve native species (Hayes and Holl 2003). The destruction of native vegetation and the introduction of exotic species are two of the most common forms of human disturbance on the prairies (Munroe 1956). The conversion of native grassland into cultivated land is a disturbance that is greater in intensity and scale than any other in the developmental history of the prairies (Lauenroth et al. 1994), and the speed with which it occurs precludes any attempt by wildlife to adapt and persist.

The ecological carrying capacity of grasslands can never be in perfect balance with the economic carrying capacity, delivering a profitable flow of animal products.

There is no one stocking rate that will optimize both of these (Hadley 1993). If the stocking rate that initially maximizes profitability is used year after year, the carrying capacity of the land can be greatly reduced, and may require years of careful management to restore it back to its former capacity (Weaver and Clements 1938). There is no guarantee that once the disturbing force is removed, the land will return to its former state

(Hadley 1993) or to its former carrying capacity.

8 The removal of the native grasses can lead to increased wind erosion of the rich topsoil (Samson and Knopf 1994), and outbreaks of species such as grasshoppers and white grubs, that can promote invasion of weeds and shrubs, and further soil erosion, leading to long-term degradation of the prairie (Watts et al. 1993). This in turn can affect agricultural land that is downstream in the drainage basin (Riveros 1993).

Grassland management studies are most often done in developed countries that have sufficient resources available for the conservation of wildlife (Morris 1971). It is often the “charismatic” species such as butterflies, birds, or the larger vertebrates that are chosen for conservation (Hadley 1993; Bell et al. 2001), not only because they are attractive, but also because they are easy to observe, collect, and identify (Duffey et al.

1974; Bell et al. 2001). However, the conditions that favour them might not be suitable for other native plants and animals. In addition, there is such a diversity of grasslands worldwide, each with different climatic, physical, and economic conditions, as well as cultural history (Hadley 1993) that a management solution that works in one area may not be applicable in another.

In addition to needing to do more grassland management studies in developing countries, changes need to be made in the way the studies are conducted. Baseline data are needed on all abiotic and biotic components in an ecosystem (Finnamore 1992) so that the effects of the chosen management regime can be monitored and adjusted to promote sustainability (Samson and Knopf 1994). The most flexible management system would incorporate rotational grazing with variable stocking rates and season of application (Duffey et al. 1974). Unfortunately, not even the most researched and carefully implemented management system is as effective at preserving all aspects and

9 inhabitants of the prairie grassland ecosystem that arose through the millions of years of evolution and co-evolution (McNaughton 1993).

Effects of Grazing on Carabid Beetles

Several studies have examined the effects of disturbances such as fire, pasture improvement, and other agricultural practices on carabid populations, but few have directly assessed the impact that grazing has on the carabid fauna of grasslands.

Dennis et al. (1997) compared two livestock treatments (sheep, and sheep with cattle) at two different grazing intensities with control pastures (ungrazed for one to two years) in Scotland, and found that 27 of the 32 species of carabids and staphylinids that were caught did not respond significantly to the grazing treatments. However, certain species correlated with particular combinations of grazers and grazing intensities, possibly as a result of variations in the removal of vegetation by the grazers, the amount of trampling, and the levels of dung deposition. They concluded that different combinations of livestock and grazing intensities, rotated over time, could yield direct benefits to the diversity of Coleoptera in this type of grassland.

Petit and Usher (1998) found that in a Scottish agricultural landscape, woody hedgerows bordering meadows harbour both woodland carabid beetle species and species that are normally found in open grassland habitat. However, those hedgerows that are heavily grazed support an assemblage of carabids that is similar to that found on grasslands. When these areas are fenced off to exclude grazing animals (such as along roads and tracks), the assemblage tends to be composed of forest species. The condition of the substrate and the spatial isolation of the woody areas are major factors in the

10 distribution of carabids. Hedgerows that would normally serve as dispersal and recolonization corridors between wooded areas for many forest species are no longer good habitats or refuges for species that are sensitive to environmental disturbances if they are heavily grazed. Maintaining ungrazed woodland elements is therefore necessary for the stability of the biodiversity of the whole agricultural landscape.

Effects of Grazing on Spiders

Luff and Rushton (1989) found that, similar to the carabid beetles, spider numbers and diversity are highest on unmanaged pastures. Application of the insecticide chlorpyrifos does not have the same reducing effect on the spider populations as it does on the carabid beetles, so appears to play a lesser role in determining the species composition of the sites than other improvement and management techniques.

Spiders do not have strong associations with particular plants (Bell et al. 2001).

However, spiders use the three-dimensional structure of plants to anchor their webs and to sense vibrations in their environment that could signal the capture of a prey item

(Rypstra et al. 1999). Any reduction in the complexity of their environment (including litter depth) due to grazing has repercussions for the resident spider community, as well as for their prey (Bell et al. 2001; Dennis et al. 2001). For example, a reduction in the number of flowering plants translates to a reduction in pollinators, and consequently a potential food shortage for spiders that depend on the presence of these insects. The state of the plants is also important. Living plants tend to retain more spiders than do dead ones. In addition, adults and juveniles may have differences in their preferred microhabitats, and the same is true for their prey (Bell et al. 2001). Different spider

11 guilds differ in their preferences for vegetation structure. Robinson (1981) found that jumping spiders (family Salticidae) prefer open structures where they can visually detect prey, whereas certain web-builders prefer dense habitat. Neither pursuers nor ambushers, hunting strategies employed by crab spiders (family Thomisidae) and running crab spiders (family Philodromidae), show any preference between open and dense architecture. Spiders benefit from the deposition of dung as this encourages taller vegetation around dung patches, providing moisture, humidity, over-wintering habitat and ballooning sites for juvenile spiders (Turnbull 1966; Bell et al. 2001).

There is also horizontal as well as vertical stratification amongst spiders. An

Australian study by Churchill and Ludwig (2004) used distance from water as a surrogate for grazing intensity, and found that araneid (orb-weaving) spiders and theridiid (cob- web) spiders increase in abundance in areas with more perennial grass cover away from water, representing areas of reduced grazing. Zorid spiders are found on bare soils close to water, and lycosid (wolf) spiders occur in areas with an intermediate level of bare ground; spiders in these two families do not use webs to capture their prey. Prodidomids, araneids, and small oonopids increase in abundance with a deeper litter layer. Other families are positively associated with shrub and tree cover. Changes in assemblages were therefore a result of changing hunting surfaces and structures for web attachment.

The families Theridiidae and Lycosidae are abundant on grazed sites but the Gnaphosidae are not as abundant as in undisturbed sites. If the litter becomes compacted due to trampling, spiders have fewer spaces in which to build webs and hunt (Bell et al. 2001).

Soil compaction limits burrowing spiders (Churchill and Ludwig 2004). In addition to

12 walking, running, and jumping, grazing animals will also sit, lie, scratch, and paw the ground, which causes additional damage (Spedding 1971).

Dennis et al. (2001) tested the effect that stocking mixed livestock at different rates has on the vegetation structure of an upland grassland, and the subsequent effect of that on the epigeal spiders, harvestmen and pseudoscorpions. The treatments were no livestock, sheep only, and a mixture of sheep and cattle. Epigeic spiders occur in higher numbers in the ungrazed treatments and the less intensively grazed treatments that have taller vegetation and more plant litter. This is most likely related to the different hunting methods, locomotion, and temperature requirements of the spider species, as well as increased abundance of particular prey species that are affected by plant architecture and litter levels. Sheep trample the litter layer less than cattle, leaving more open spaces for spiders to seek refuge. Spider captures were consistently larger in the sheep-grazed than the mixed livestock treatment. Sheep tend to avoid large tussocks of grass compared to the cattle, thus providing refuges, a mosaic of vegetation sward heights, and leaving webs intact. Turnbull (1966) collected more spiders from samples that included large clumps of tall grass than from samples that did not.

Gibson et al. (1992) examined the effect of five different sheep grazing treatments

(ungrazed, short-period spring grazing, short-period fall grazing, continuous fall grazing, and spring and fall grazing) on the spiders of limestone grassland in England. They found that species richness and density decrease with increased grazing intensity. The short- period spring grazed, short-period fall grazed, and continuous fall grazed treatments do not differ significantly in the number of spiders and species. These treatments do, however, have higher numbers than the treatment that got both spring and fall grazes.

13 Sheet-web building species are less abundant in the continuous fall-grazed pasture, but more abundant in the pastures receiving spring and fall grazes. Web-spinning species of all types are highly abundant on ungrazed pastures. Spring and fall grazing on land that was once arable results in a low richness of web-spinners, whereas the same treatment applied to old grassland produces quite a rich fauna of web-spinners; the remnant tussocks provide the right substrates for web anchorage and protect the webs from destruction by the grazing sheep. Web-spinners tend to prefer tall plants, with the exception of most grasses, the flowering heads of which do not provide very rigid anchors for their webs. All spider taxa tend to avoid low-lying plants, those with narrow leaves, those that lack rigid structures, and those where rigid structures are short-lived.

The fauna of the grazed treatments is an impoverished version of the fauna found on the ungrazed control treatment, with the exception of the treatment that received both the spring and fall grazes. It has its own distinctive assemblage of spiders, consisting mainly of Linyphiidae which can invade an area through ballooning, even as adults, and thermophilic species that prefer the microclimate of the short grazed vegetation.

Carabid Beetles as Bioindicators

The best bioindicator species are ones that are always collected when a particular habitat is sampled, and that are preferably not collected in other habitats (Dufrêne et al.

1990). Carabids are a popular choice as bioindicators as they are widely distributed in terrestrial habitats and are easily influenced by changes in environmental conditions and resource availability (Maelfait and Desender 1990; Butovsky 1994; Loreau 1994). The family has approximately 40,000 described species, most of which are predators, and

14 range widely in size (Loreau 1994). They are easily caught using passive methods like pitfall traps (Thiele 1977; Maelfait and Desender 1990; Butovsky 1994). To make the most of their usefulness as bioindicator species, standardized survey techniques are required that are understandable by not only specialized biologists, but also by non- academic people such as planners and policy makers (Eyre et al. 1996).

The taxonomy of carabid beetles is relatively stable (Maelfait and Desender 1990) and they are easy to identify (Thiele 1977). However, more work needs to be done on understanding their biology, regional diversity, distribution patterns, and ecological correlations, particularly in the southern hemisphere, as well as on making specialist literature more available to a wider range of researchers (New 1998).

Tiger beetles (now reclassified as a subfamily of Carabidae) are potentially useful as bioindicator species in tropical forests as they are found in a wide range of habitat types overall, but show specialization at the species level (Rodriguez et al. 1998). The ecological requirements of the larval stage for each species also need to be studied in the future (Rodriguez et al. 1998) as they tend to be more abundant than adults, and due to their reduced mobility, they are physiologically adapted to specific microhabitats and are not able to tolerate wide fluctuations in the habitat conditions (Knisley 1987).

Carabid beetles can be useful in monitoring detrimental changes in the environment linked to industrialization. A study in Ontario by Freitag et al. (1973) examines populations of 20 species of Carabidae and one species of Silphidae at different distances from a kraft paper mill. As the distance to the mill decreases, there is a drastic reduction in the number of individuals caught. The exact reason is not known, but this decrease in numbers parallels an increase in Na2SO4 precipitation.

15 A German study by Maurer (1974) compares populations of carabid beetles at 2 m and 30 m from a road with a volume of 5000-8000 vehicles per day and a road with a volume of only 200 vehicles per day, and finds that the lead content (from traffic exhaust gases) in the bodies of Pterostichus cupreus L. caught near the roads is higher by a factor of 7-8 compared to the level in the bodies of beetles caught far from the roads, in nearby fields. In Carabus auratus L. individuals, the factor is 4-7. Next to the relatively busy road, only half as many carabid individuals are caught 2 m from the road edge, compared to 30 m away, while next to the quieter road, there is no difference between the two sites.

Butovsky (1994) tests the influence of a road with 25,000-50,000 vehicles per day near Moscow on carabid populations and finds that there are significantly fewer carabids in his test sites, located 15-40 m from the road edge, compared to his control sites, located 200-240 m from the road edge in three agroecosystems (oat with clover, strawberry, and winter wheat). He suggests that it could be due to a reduction in the amount of available prey, especially for zoophagous species, which are less frequently caught at these sites compared to what he calls “myxophagous” species, a term that literally means slime-feeding but is probably intended to imply a fungivorous habit.

Another possible contributing factor is an accumulation of heavy metals in the food chain from exhaust pollution. The biomass of the carabids from his tests sites is found to be significantly lower than that of the carabids from the control sites. As a result of his study, he concludes that using the catch of carabid beetles at the family level, the ratio of zoophagous to “myxophagous” species in catches, and the average biomass of carabids per trap are good biological indicators of the influence of roadways on the surrounding ecosystem.

16 It is, however, difficult to determine which environmental factors are the critical ones that determine carabid distribution in nature. Attempts to isolate such factors in the laboratory are unnatural, and may produce results that directly contradict what is observed in the field (Thiele 1977), many factors are mutually dependent and impossible to isolate in such a way as to mimic natural conditions.

Spiders as Bioindicators

As predators, spiders have the potential to have an impact on a wide variety of primary and secondary consumers, and the amount of prey that they ingest, which is proportional to the amount available, can be used as an indication of the “biological quality of the habitat” (Marc et al. 1999). Food intake has been correlated with body length or body weight at the intermoult phase, metabolic rate, the production of excreta, and the reproductive rate (Marc et al. 1999).

Habitat structure greatly affects spiders and can be used to monitor changes in the fauna associated with anthropogenic changes to the vegetation. Inferences can then be made about spider predators and prey based on the particular species that make up an assemblage. The most disturbed agroecosystems are cereal fields and these tend to contain the spiders with the greatest dispersal abilities. Vegetable fields are less disturbed, followed by orchards which are more stable and contain spiders with the lowest dispersal abilities (Marc et al. 1999).

Spiders are not directly associated with particular plant species, but rather an apparent preference for a plant species is the result of a combination of factors such as cover, food, moisture, temperature, and soil (Allred 1975). Baseline data are therefore

17 needed before spiders can be used to their full potential as biological indicators. Churchill

(1997) lists metal pollution, fire, grazing, pasture improvement, clear-cutting, mowing, and plowing as environmental disturbances to which spider faunas respond.

Clausen (1986) found that as spiders are predaceous, they have the potential to accumulate heavy metals in their bodies and could be used as ecological indicators.

Levels of lead in specimens of species of Araneus indicate atmospheric levels from up to two years prior to sampling, compared to the four or more years for lichen, another popular indicator. The other advantage of spiders is that measurements can be made on individuals and comparisons can be made between different age groups, qualities that lichen does not share.

Spiders may be used as indicators of human disturbance in meadow ecosystems.

Pristavko and Zhukovets (1988) did a study on the Berezinsky Nature Reserve in Belarus and found that population numbers are markedly higher in protected areas compared to areas with agricultural disturbance. They also concluded that the most effective spiders for monitoring are surface-dwellers, numbers of which change proportionally with the degree of anthropogenic disturbance.

Sampling Methods for Carabid Beetles and Spiders

Carabidae and Araneae are often sampled together in ecological studies and both groups can be used as biological indicators of the effects of environmental disturbance

(Uetz and Unzicker 1976). Ground beetles and wolf spiders can be considered to be a trophic guild since they are generalist predators, similar in size, live in the same habitat and stratum, and hunt on the ground surface (Lang et al. 1999). The families that make up

18 the majority of the cursorial spider guild include Lycosidae, Clubionidae, Gnaphosidae,

Hahniidae, Ctenidae, and some Agelenidae and Pisauridae (Uetz and Unzicker 1976).

Since spiders are abundant and exhibit such a range of behaviours, many sampling techniques are available. These include pitfall traps, sweep net sampling, quadrat collection, web visualization, beating bushes, branch clipping and beating, bark trapping, sticky trapping, suction trapping, airplane trapping, window trapping, chemical knockdown, restricted canopy fogging, visual searching and hand collection, and for those species inhabiting the leaf litter, Berlese or Tullgren funnels (Churchill 1997; Marc et al. 1999). Larger ground-living spiders are often caught primarily in pitfall traps.

However, members of the Salticidae are rarely caught this way (Merrett and Snazell

1983). Pitfall traps sample continuously but catches are influenced by the activity levels of the organisms (Uetz and Unzicker 1976; Standen 2000), therefore the relative densities of particular organisms cannot be determined with this method, and since they sample from an unknown area, the absolute density cannot be calculated either (Standen 2000).

Grazed areas have a lower resistance against movement because vegetation is less dense, so catches can increase in these areas, while species that live primarily in the grass canopy and do not regularly travel across the ground surface are often few in number or absent from pitfall traps (Zulka et al. 1997; Green 1999). Greenslade (1964) tested three types of pitfall traps and found that carabids moving on the surface of litter have different capture rates from those that move both on top of and within the litter layer. In the spring, pitfall traps that are sunk into the ground with vegetation up to the edge of the trap are more efficient than a jar whose mouth is level with the top surface of the vegetation, suggesting that there is carabid movement within the layer of vegetation. However, in the

19 summer, the reverse is true, suggesting that the compact layer of vegetation and litter allows for more movement on its surface, and less within, or between it and the soil below. Pitfall traps that are sunk into the ground, but are surrounded by an area cleared of all vegetation (to eliminate variation in the immediate area and reduce debris) consistently catch the most carabids, but not significantly more than a pitfall trap without the cleared area.

Avoidance behaviours displayed by carabid beetles upon encountering pitfall traps include hanging down into the trap by their hind legs before retreating, or skirting around the edge of the trap without lowering into it (Halsall and Wratten 1988) but no relationship is found between the capture rate of the species and the type of avoidance behaviour displayed.

Pitfall traps should be used conjunction with other sampling methods as no one method will effectively sample fauna from all microhabitats in an environment (Standen

2000). Traps should be placed in a way that accounts for the patchiness of the environment in question, the size of the area being sampled, the size of the trap and of the target organisms, and the potential to deplete their populations (Uetz and Unzicker 1976).

Quadrat sampling only captures those animals that are passing through a small, finite space at a particular point in time, and the presence of the researchers can cause some organisms to flee the area (Uetz and Unzicker 1976). This method is most effective with slow moving or non-motile species, or web-building spiders (Fichter 1941; Uetz and

Unzicker 1976). A study by Uetz and Unzicker (1976) comparing pitfall traps and quadrat sampling found that quadrats add very few additional species beyond those caught in pitfall traps. In addition, a greater number of species were absent from the

20 quadrats and present in the pitfall traps than vice versa. It was concluded that pitfall traps give a more accurate estimate of the total number of species present in a community and can be used, with caution, in studies of species diversity. However, they should not be used to compare the numbers of one species in two different habitats unless they are accompanied by mark and recapture studies and quadrat sampling (Greenslade 1964). If two vegetation types of different densities are sampled with pitfalls, and a carabid species is predominantly caught in the vegetation type that provides the most resistance to carabid movement, then it can be concluded that the pitfalls are successfully mirroring the species‟ true numbers (Greenslade 1964), rather than reflecting the ease of mobility in the less dense vegetation type.

Canopy fogging can underestimate the diversity and abundance of web-building species of spiders since they can remain attached to their webs even after death. Branch beating also underestimates these species (Green 1999). Topping and Sunderland (1992) compared pitfall trapping with D-vac suction samplers in 0.5 m2 rings and found that the pitfall traps caught more individuals and species than the suction samples. In addition,

95% of the pitfall catches were adult organisms, compared to only 33% in the suction samples. Males outnumbered the females in the pitfall traps in most cases, whereas the sexes were distributed in a nearly one to one ratio in the suction samples, with females tending to outnumber the males. Hand-collecting is another method for collecting spiders but Merrett and Snazell (1983) found that while more species are collected this way, there were fewer individuals collected. There is a tendency for collectors to preferentially choose a species that they have not yet collected if several individuals are seen together.

21 In addition, it is laborious, time-consuming, and is heavily dependent on each individual collector and their fatigue levels.

Life histories, especially mating behaviours, should be investigated before any conclusions about species abundance are drawn from collected organisms. Male spiders, for example, sometimes display a sexual cursorial activity (Muma and Muma 1949), which leads to an increased number being caught in pitfall traps. Male and female spiders may have differing abilities to escape pitfall traps (Topping and Sunderland 1992). Other behaviours such as mate-searching, post-copulatory dispersal of females, searching for oviposition sites, hunting, and vegetation structure surrounding the traps can also influence the catch numbers (Topping and Sunderland 1992), as well as fluctuations in prey availability (Niemelä et al. 1992).

Catches cycle temporally throughout a day as well, peaking in the late evening, and decreasing in the morning hours (Muma and Muma 1949) due to the nocturnal habits of many species (Lövei and Sunderland 1996; Green 1999). Some carabid beetle species can exhibit nocturnal and diurnal behaviour within a single population, depending on the environment (Thiele 1977). Greenslade (1963) found that both nocturnal and diurnal species were active at dusk, whereas all species ceased or reduced activity at dawn, when temperature was the lowest. The study also supported findings that suggest that woodland and forest species tend to be nocturnal, whereas grassland species tend to be diurnal, trends that most likely are linked to the differing temperatures and humidities of the two environments. Diurnal carabid beetles can be under-represented in pitfall catches

(Greenslade 1964), possibly because they are able to see, and therefore avoid, the traps.

However, Halsall and Wratten (1988) found that diurnal and nocturnal species did not

22 differ in their capture rate and concluded that vision was not a major factor in trap avoidance. It has been suggested that perhaps smaller pitfall traps show a greater relative efficiency at collecting organisms because they are not detected as being different from general environmental heterogeneity (Work et al. 2002).

Merrett and Snazell (1983) found seasonal variations too. In their study, May,

June and October were the months during which most species were collected. Activity, and consequently catch numbers, often peak in the spring or in the fall, corresponding with the reproductive period (Lövei and Sunderland 1996). Thiele (1977) identified five different groupings of carabid beetles. The first group consists of species that reproduce in the spring, have larvae in the summer, and hibernate in the winter as adults. The second group reproduces in the summer and fall, have larvae in the winter, and do not hibernate. The third group resembles the second, except that the adults that emerge in the spring undergo an aestivation period in the summer before reproduction occurs. The fourth group has flexible reproductive cycles. Reproduction events and larval development can occur in different seasons, even within a single population. The fifth group is those species that require more than one year to complete their life cycles.

Halsall and Wratten (1988) tested beetles caught in the spring/summer period

(i.e., mixture of new generation and overwintered adults) and beetles caught in the fall/winter period (i.e., mostly new generation adults), and found that capture rate did not differ between the two groups.

Catches of single specimens of a species can result from a low density of that species, or sampling methods that are inefficient for collection of the species. More than

23 one collecting method should be used, as species that are less common or harder to catch may be those that are the most affected by disturbance (Standen 2000).

Diversity Measures

Diversity measures are a common way for researchers to quantify the diversity of a site or a sample with a single number that can then be compared with those from other sites or samples. According to Magurran (1988), there are three main groups of diversity indices. The first group contains the species richness indices that indicate the total number of species in a particular sampling unit. The second group contains the species abundance models that describe the distribution of species abundances. The third and final group contains the indices based on the proportional abundances of species, and produces a single number that quantifies both species richness and evenness. Species richness (the number of species) and evenness (the similarity of the abundances of different species) are the two factors that most indices take into account, although different indices will give different weights to the two factors (Magurran 1988).

Species richness is the simplest, and most widely used, way to represent diversity, provided that the study has a definite area and time period and all the species can be counted and identified (Magurran 1988; Spellerberg 1991). However, most biological studies are done on a larger scale and not every individual in a community can be caught, so sampling is a necessary approach. In addition, species richness models do not account for differences in the proportional abundances of different species (Spellerberg 1991).

Species abundance models were developed when it was observed that in different communities, species range from being very common to being rare, even in cases where

24 conditions are relatively uniform and representative of the habitat being sampled (Fisher et al. 1943; Magurran 1988). There are four main rank/abundance models. In the geometric series, a few species are common and the rest are relatively rare. In the log normal distribution and the logarithmic series, species of medium abundance are common. Lastly, in MacArthur‟s broken stick model, species are distributed as uniformly as is biologically realistic (Magurran 1988). The resource pool (the “stick”) is partitioned at random, and the lengths of the resulting segments (or niches) are proportional to the abundances of the species occupying each niche (MacArthur 1957). However, this model is quite sensitive to sample size as it is dependent on a single parameter, the number of species (MacArthur 1957; Magurran 1988).

Diversity indices that are based on the proportional abundance of species are a simpler, non-parametric alternative to species abundance models. No assumptions are made about the underlying distribution of species abundances. Examples of this type are the Shannon-Weiner index of diversity, the Simpson index, and the Berger-Parker index

(Magurran 1988). In my research I used the Log Series Alpha Index and the Berger

Parker Index so I will review these indices.

Log Series Alpha Index

The log series α index (Fisher et al. 1943) is a species abundance model that combines species richness and the total number of individuals in a study. It has the best ability to discriminate between sites or samples that are similar to one another, an important consideration if it is to be applied to environmental and conservation studies. It is also fairly unaffected by rare or common species, and is completely independent of

25 sample size when there are more than 1000 individuals. Its only real disadvantage is that in cases where the species richness and the number of individuals are constant between sites or samples, but there are differences in the evenness, the log series α index cannot distinguish this (Magurran 1988).

Berger-Parker Index

In order to compensate for the inability of the log series α index to distinguish differences in dominance or evenness, combining it with a measure of either of these can be informative. A good index to use is the Berger-Parker index (Berger and Parker 1970).

The Berger-Parker Index is independent of the number of species but can be affected by changes in the abundance of the most common species and works best with a large sample size, especially in cases where the individuals being sampled are aggregated in one area and may not reflect the true species abundance (Magurran 1988).

Summary

With so little mixed grass prairie remaining in good condition, it is critical that the flora and fauna of this endangered ecosystem are studied so that informed management decisions can be made and remnants can be preserved. The Yellow Quill Mixed Grass

Prairie Preserve is surrounded by agricultural and military-owned land and has been grazed by cattle for several decades, so it is in danger of further degradation if its management is not carefully monitored. Grazing studies are done on so many different types of pasture, with varied histories and environmental factors, and trying to choose the right one for a particular area like the Yellow Quill Prairie can be overwhelming for a land manager. It is important that the goal of the regime is clearly understood, whether it

26 is ultimately increased animal production and profit, or sustained biological diversity that is desired.

The manner in which cattle graze is different from the grazing pressure of the bison that shaped the evolution of the mixed grass prairie. In addition, the reduced mobility of a herd of cattle that is confined to a pasture increases the potential for range overgrazing. A rotational grazing system, rather than continuous grazing, helps to alleviate overgrazing, but the timing of the graze, the types of grazers, and the intensity that is applied are also important factors. Knowing whether it is the spring graze or the fall graze, or both, that has the greatest impact on the flora and fauna can help managers determine when and where to move their herds in order to minimally impact the ecosystem. Also, knowing which taxonomic groups are the most appropriate biological indicators can help refine monitoring programs in the future so that a more targeted and effective survey can be performed to assess the continuing health of the prairie.

27 MATERIALS AND METHODS

Study Area

The study took place on the Yellow Quill Mixed Grass Prairie Preserve, located approximately 20 km southeast of Brandon and 2 km north of the junction of the Souris and Assiniboine Rivers (Fig. 1). It is bordered on the north and east by the Canadian

Forces Base at Shilo, on the south by the Assiniboine Wildlife Corridor, and on the west by cultivated potato fields. This approximately 842-hectare site (Sveinson et al. 2001) is primarily owned and maintained by the Nature Conservancy of Canada (NCC). Paddock

29 and the northern half of Paddock 34 are Crown Land. Paddocks 27, 28, 29, and 34 were used in this study.

The Yellow Quill Prairie is located on Miniota sands, which are well-drained and vary from sand to loamy sand in texture. Also in the area are Stockton loamy sands, which include large areas of extremely well-drained sand dunes (Ehrlich et al. 1957). The vegetation consists mainly of mature aspen parkland forest and open prairie. Trembling aspen (Populus tremuloides Michx.) stands and mixed stands of trembling aspen and bur oak (Quercus macrocarpa Michx.) are the most frequent woodlands in the area. There is also some white spruce (Picea glauca Moench), balsam poplar (Populus balsamifera L.), and American elm (Ulmus americana L.). Areas of the prairie are designated as shrub prairie due to high levels (over 50%) of ground juniper (Juniperus horizontalis Moench) and western snowberry (Symphoricarpos occidentalis Hook). Leafy spurge (Euphorbia esula L.) is a highly invasive introduced species that is particularly abundant in the grazing exclosure in Paddock 28. In total 144 species of plants have been identified on

28 the Yellow Quill Mixed Grass Prairie Preserve. For a complete inventory and maps, see

Sveinson et al. (2001).

Current management of the property includes a twice-over rotational grazing regime, beginning in early June and ending in late October. This involves a short, so- called stimulatory graze on each paddock in the spring, lasting approximately 15 days

(the “spring” graze), when growing conditions are ideal for quick recovery of lost plant tissue (Weaver 1954), followed by a longer graze on each paddock, lasting approximately

30 days (the “fall” graze).

Experimental Design

Primary Experiment

The objective of the primary experiment was to determine, compared with a situation with no grazing, the effect a twice-over rotational cattle-grazing regime has on the invertebrates of the mixed-grass prairie, using the number of individuals and the diversity of species of carabid beetles and spiders as biological indicators.

Recommendations would be provided to the Nature Conservancy of Canada regarding the suitability of the grazing regime for preserving this endangered ecosystem.

The Yellow Quill Prairie (Figs. 1, 2) is located in Range 16, Township 8, and the three main paddocks are numbered according to their respective land sections. Paddock

27 is located on the southern half of section 27 and the southwestern corner of section 26, and is 2.4 km by 0.8 km. Paddocks 28 and 29 are both 1.6 km x 1.6 km and extend over the entire section (Fig. 2). Within each paddock was a 1 ha grazing exclosure that was fenced with barbed wire to keep out grazing animals, primarily cattle. These exclosures

29 had not been grazed since their establishment in 2000. The latitude and longitude of the centre of each of these exclosures is as follows: paddock 27: 49°40‟51.4” N 99°33‟15.4”

W, paddock 28: 49°41‟27.7” N 99°34‟38.7” W, and paddock 29: 49°40‟55.4”N

99°36‟40.8” W. Season-long (typically June to October) grazing was done on the property for approximately 20 years, followed by one year (2000) during which the range was left idle. There were four years of twice-over rotational grazing before the start of this study.

The study was conducted in 2005 and 2006 and the herd of cattle present for both years consisted of 75 cow/calf pairs and 3 bulls. The single herd was moved from one paddock to another over the season. The dates of grazing for each paddock (Table 1) were determined by the cattle producers based on the amount of available vegetation.

Secondary Experiment

The objective of the secondary experiment was to determine whether it is the spring graze, the fall graze, or a combination of both grazes that has the greatest effect on the number of individuals and the diversity of species of carabid beetles and spiders that are found on the mixed-grass prairie.

Paddock 34 is located on the western half of section 34 (Fig. 2) and measures 0.8 km by 1.6 km. This paddock had season-long cattle grazing until the end of the 1999 growing season. From then until the start of this study, no cattle grazing occurred in the paddock. In 2005, the first year of the study, the paddock was grazed by nine cow/calf pairs. In 2006, this was increased to eleven cow/calf pairs and one bull. The cows used in

2006 were smaller than those in 2005 and the cattle producer felt that the grazing pressure

30 would be similar in the two years. Paddock 34 had three treatment areas, each 0.8 km x

0.1 km (Fig. 3). One area only received a spring graze and remained ungrazed for the rest of the summer. Another area only received a fall graze. The third area received both a spring graze and a fall graze. The latitude and longitude of the centre of each treatment was as follows: spring graze only: 49°42‟05.8” N 99°34‟00.9”W, fall graze only:

49°42‟11.6” N 99°33‟58.6” W, and both spring and fall grazes: 49°42‟09.1” N

99°34‟00.6” W. Each area was divided from the others with electric fences. The cattle producer moved the cattle based on an assessment of the vegetation in the paddock. The north and south ends of Paddock 34 were used for summer grazing when the cattle were not on the treatment areas.

Sampling Methods

Soil Compaction

Soil compaction was measured to determine whether grazing causes an increase in compaction. Soil compaction was measured in October 2006 using a Field Scout® SC

900 Soil Compaction Meter from Spectrum Technologies. Measurements were initially taken in pounds per square inch (psi) at every inch until the probe could penetrate no further. These measurements were then converted to kiloPascals (kPa) at each interval of

2.5 cm (1 inch ≈ 2.5 cm, 1 psi ≈ 6.89 kPa).

In the primary experiment, measurements were taken at two arbitrarily chosen locations around each group of five pitfall traps in the grazed areas, and four locations in each grazing exclosure. In the secondary experiment, measurements were taken at five arbitrarily chosen locations in each treatment, for a total of 15 locations. Measurements

31 were not taken within 1-2 m of the pitfall trap locations as these areas were more heavily trampled than the rest of the paddock.

Vegetation Sampling

A pin sampler (Barbour et al. 1987) was used to estimate the percentage of cover of each plant species, and the amount of bare ground and litter. Only five pins were used out of the available 10 pins on the wooden frame (Fig. 4), as recommended by Diana

Bizecki-Robson, the Curator of Botany at the Manitoba Museum. All plants that touched a pin were identified to species and recorded. Multiple parts of the same plant or the same species that touched a pin were only counted once. In the primary experiment, samples were taken in a uniform pattern, at regular intervals on transects between the lines of pitfall traps in the grazing exclosures (Fig. 5a) and roughly 8 m away from each trap in the grazed areas (Fig. 5b). In the secondary experiment, samples were taken as illustrated in Fig. 6. Sampling was done in every paddock in August of 2005 and again in July of

2006.

The percentage cover of grasses, forbs, shrubs, bare ground, litter, leafy spurge, and ground juniper were visually estimated using 1 m x 1 m quadrats. Leafy spurge was included in the forb category but also recorded separately. While ground juniper is a shrub, it was recorded separately from the ot9her species of shrubs. Cover was classified into seven classes based on a slightly modified version of the Braun-Blanquet system

(Barbour et al. 1987). Each class is a range of cover percentages, the mean of which is used to calculate the absolute cover of that vegetation type. Class 0 indicates that a species was not present in a quadrat. The remaining class definitions were: 1: < 1%

32 cover; 2: 1-5 %; 3: 5-25 %; 4: 25-50%; 5: 50-75 %; 6: 75-100% cover. Sampling was done in August of 2005 and July of 2006, in all four paddocks. In 2005, the quadrats were placed directly over each pitfall trap, but due to intensive trampling by cattle, these areas were mostly bare ground and therefore not representative of the whole paddock. In 2006, the quadrats were placed in the same locations as the pin sampler.

Invertebrate Sampling

Pitfall traps were the primary sampling devices used in this study to collect both spiders and ground beetles. Each trap consisted of two clear plastic containers, each 12 cm deep, with a top diameter of 11 cm, and a volume of 750 mL. One container was sunk in the ground, and then the second was placed inside it so that the top of the inner container was as flush as possible with the ground surface. Each trap was half filled with preservative liquid. In 2005, this consisted of saline water with a few drops of dish detergent to act as a surfactant. In 2006, the preservative was food-grade propylene glycol.

A cover was placed over the top of each trap to keep out rain and debris. The cover consisted of a plywood square (15 cm x 15 cm), with holes drilled in each corner for supporting pieces of dowel, 1.6 cm in diameter. The dowel was sharpened with a

® Veritas mini tenon cutter to fit into the drilled holes. Dowel was used instead of nails to protect the cattle from injury. The trap number was written on each cover and the location of the trap was marked with a bamboo stake with flagging tape on it. The covers were hammered down so that they were a few centimeters above the ground surface. In 2006, due to extensive cattle damage the year before, two pieces of 1.6 cm rebar were bent into

33 a U shape and placed over each trap to form a cage (Fig. 7) to deter cattle from destroying the traps. In both years traps that were destroyed by cattle were dug in and set again each week.

In each grazing exclosure in the primary experiment, 25 pitfall traps were laid out in a five by five square grid, with approximately 16.7 m in between lines of traps and between the edge of the grid and the perimeter fence (Fig. 8). In the grazed area, five groups of five traps were laid out in areas that appeared representative of the vegetation and terrain within the paddock (Fig. 2). The location of each group was the same in both years, with the exception of groups B and E in Paddock 27, which had to be relocated because their original locations were burned in 2006. In the secondary experiment, twenty five pitfall traps were laid out in each treatment area in open spaces between aspen stands (Fig. 3). Traps were 16.7 m apart from each other and from the fences.

Traps were emptied every week and the contents were poured through a sieve with 1 mm mesh in the field and put into small plastic containers in 70% ethanol. These were taken to the University of Manitoba for sorting and identification. Sampling began in 2005 on May 12 and continued until October 27. In 2006, sampling began on May 3 and continued until October 26.

The grass canopy was sampled each week using a 45.7cm (18”) triangular-shaped sweep net from Rose Entomology (www.roseentomology.com). In the primary experiment, three 100 m transects were walked from one fence to the opposite fence of each grazing exclosure, with approximately one sweep made per meter. Three transects of the same length were walked in straight lines but in random directions in the grazed

34 areas of each paddock. In the secondary experiment, six 100 m transects of grass canopy were swept each week.

The net contents from each transect were emptied into a separate labeled Ziploc bag and a small piece of paper towel soaked in ethyl acetate was inserted to kill the insects. Bags were transported in a cooler to the Department of Entomology at the

University of Manitoba where they were frozen until the contents could be sorted.

Samples were sorted in the laboratory. Carabid beetles were cleaned using tri- sodium phosphate in an ultrasonic cleaner, and pinned immediately. Spiders were placed in glass shell vials (Fisher Scientific, Fisherbrand®, 7.5 mL) in 70% ethanol for later identification. All by-catch was discarded. Carabid beetles were identified using Lindroth

(1961-1969). All Amara species were verified by Dr. Fritz Heike in Germany.

Cicindelids were verified by Daniel Duran from Vanderbilt University in Nashville,

Tennessee, and by Todd Lawton. Spiders were identified using Aitchison-Benell and

Dondale (1990), Chamberlin and Gertsch (1958), Chamberlin and Ivie (1940, 1941),

Dondale and Redner (1978, 1982, 1990), Dondale et al. (2003), Leech (1972), Levi

(1954, 1957a, 1957b, 1981), Levi and Levi (1962), Maddison and Proszynski (2007),

Millidge (1981a, 1981b, 1983), Opell and Beatty (1976), Paquin and Dupérré (2003),

Platnick and Dondale (1992), and Ubick et al. (2005). Voucher specimens of all carabid and spider species will be deposited at the J.B. Wallis Museum of Entomology at the

University of Manitoba, Winnipeg, Canada.

Only mature spiders were kept and identified to species. Carabid beetles from every sampling week were identified but due to the large volume of samples, only spiders

35 from every second sampling week were identified to species. Sampling dates for which carabid beetles and spiders were identified are in Tables 2 (2005) and 3 (2006).

Statistical Methods

The three paddocks used in this study are not considered to be replicates because the cattle were grazing each one at different times of the year because of the nature of a twice-over rotational grazing regime and the need to feed the cattle on pasture throughout the summer. Also, the paddocks cannot be compared between years as the grazing began on Paddock 28 in 2005 and in Paddock 29 in 2006, a decision made by the cattle producers based on available forage. As a result, each paddock and each year were analyzed separately.

When the cattle were grazing on the paddocks, they interfered with the pitfall traps; this data loss prevented analysis of trap catches during grazing periods. Therefore analyses were restricted to three time periods when cattle were not grazing: Period 1 was the time before the cattle were introduced onto the paddock, Period 2 was the time between the end of the spring graze and the beginning of the fall graze, and Period 3 was the time after the end of the fall graze until the end of the sampling for the season (Figs.

9, 10). Depending on when the cattle were put on the range in the spring and removed in the fall, not every paddock had all three periods in each year. The first three weeks of sampling in 2005 were not used in the analyses due to changes that were made to the experimental design.

36 Diversity Indices

The diversity indices used in the analysis of both the carabid beetle and the spider data were the Berger-Parker dominance index (Berger and Parker 1970) and the Log

Series Alpha index (Fisher et al. 1943). The Berger-Parker index (d) was chosen due to its low sensitivity to sample size, and was calculated using the following equation:

d = Nmax / N where Nmax is the number of individuals in the most abundant species and N is the total number of individuals caught.

The Log Series Alpha index was chosen due to its good discriminant abilities as well as its low sensitivity to sample size. It was calculated using the following equation

(Magurran 1988):

α = [N * (1-x)] / x where N is the total number of individuals and x is estimated by iterating the following equation:

S / N = [(1-x)/x][-ln (1-x)] where S is the total number of species and N is the total number of individuals.

Univariate Analysis

The univariate analysis of the data was done using SYSTAT 11 (Systat 2004).

Analysis of variance (ANOVA) was done using an alpha level of 0.05. In this thesis, where this alpha level was not met but there seemed to be large differences between treatment means, I refer to these as trends. Traps were consolidated into blocks of five traps within each sampling period to reduce the number of zeroes in the data. Data were

37 tested as to whether they met the assumptions of analysis of variance by plotting the residuals and visual assessment of heteroscedasticity and normality. If necessary, data were transformed by taking the square root or the log of the data.

Primary Experiment

An ANOVA was done to determine the effects of the grazing, soil depth, and their interaction on the mean soil compaction in each treatment and paddock.

For the pin sampler data, the percent cover of each species was calculated using the following formula:

% Cover of species A = 100 X (number of pins of species A) / (total number of pins)

An ANOVA was done on cover data for four species (Andropogon gerardii,

Juniperus horizontalis, Euphorbia esula and Stipa sp.) as well as litter and bare ground to determine the effect of the grazing treatment, the paddock, and the interaction between the two.

The carabid beetle and spider data, summed into blocks of five traps for each sampling period were subjected to ANOVA to assess the effect of grazed and ungrazed treatments on the total catch of individuals and the number of species per block in each period, paddock and sampling year. The most common carabid beetle species, Calosoma calidum, and the two most common spider species, Pardosa distincta and Alopecosa aculeata were also examined in the same way.

An ANOVA was done on the Berger-Parker Index and the Log Series Alpha

Index for carabid beetles and spiders, as well as the most common species, in each period, paddock, and sampling year to determine the effect of the grazing treatment.

38 Secondary Experiment

Soil compaction and vegetation data were analyzed using the same methods as in the primary experiment, with the exception that the paddock was not a factor.

The carabid beetle and spider data were summed into blocks of five traps within each sampling period and ANOVAs were used to assess the effect of the Spring, Fall, and

Spring/Fall treatments on the total catch of individuals and the number of species per block in each period and sampling year. Data for the most common carabid beetle and two most common spider species were analyzed in the same way.

The Berger-Parker Index and the Log Series Alpha Index were analyzed using the same methods as in the primary experiment, with the exception that the paddock was not a factor.

Multivariate Analysis

The multivariate analysis of the data was done using CANOCO, version 4.51 (ter

Braak and Smilauer 2002). A preliminary Detrended Correspondence Analysis (DCA) by segments showed that gradient lengths were less than four, so a linear model was chosen for further analysis. Principal Components Analysis (PCA) was performed on each vegetation, carabid beetle and spider data set, using log-transformed data. Environmental data („Grazed‟ and „Ungrazed‟ in the primary experiment; „Spring‟, „Fall‟, and

„Spring/Fall‟ in the secondary experiment) were used as supplementary variables in indirect gradient analysis which focused on inter-sample distances. CanoDraw 4.5 was used to create the biplots of the resulting ordinations. Where the diagram was too congested to interpret, species with influence were omitted.

39 Vegetation Quadrat Analysis

The quadrat data were recorded as the number of occurrences of each type of ground cover (Andropogon gerardii, Juniperus horizontalis, Euphorbia esula, Stipa sp., litter, bare ground) in each of the seven cover classes. These frequencies were used to construct contingency tables, which were analyzed with a log linear model using the grazing treatment, the cover class, and the ground cover as model terms, as well as the interactions between all three terms. A delta of 0.5 was added to each frequency so that zeroes did not affect the degrees of freedom in the model.

40 RESULTS

Floral and Faunal Representation

Vegetation

Over the course of the two study years, 72 species of plants were identified on the

Yellow Quill Mixed Grass Prairie Preserve (Table 4). These included 54 species of forbs,

12 species of grass, and 5 species of shrub.

Carabid beetles

In 2005, 4,177 carabid beetles were caught in pitfall traps, and in 2006 the number was 4,681. No carabid beetles were caught using sweep nets. The carabids represented 81 species in 13 tribes (see Table 5 for species and authorities). The tribe Carabini made up

48.0% of the carabids caught in this study. The next most common tribes were the

Platynini (19.2%) and the Lebiini (6.5%). Two of the species of carabids caught are new provincial records for Manitoba: Amara aenea and A. familiaris. While all beetles collected were identified to the species level, not all beetles were used in the analyses for the two studies.

In 2005, most common species peaked in abundance around June 23 (Table 6). In

2006, the peak was a little earlier, around May 31 and June 8 (Table 7). The most frequently caught species overall was Calosoma calidum, accounting for 57.7% of the catch in 2005 and 32.2% of the catch in 2006. The greatest numbers of C. calidum were caught on June 23, 2005 and on May 31, 2006. The next most frequently caught species in 2005 was Pasimachus elongatus, accounting for 4.5% of the catch. The greatest number was caught on June 23, 2005. In 2006, the next most frequently caught species

41 was Agonum cupreum, accounting for 30.5% of the catch. The greatest number was caught on June 8, 2006. Some carabid species were not caught during the three sampling periods analyzed, these species were: Agonum piceolum, Amara lunicollis, Bembidion obscurellum obscurellum, Chlaenius pennsylvanicus pennsylvanicus, Cicindela scutellaris lecontei, Euryderus grossus, Harpalus plenalis, Harpalus lewisii, Lebia moesta, Platynus decentis, Trichocellus mannerheimi. These species were not common species and do not appear in any subsequent tables.

Spiders

In 2005, 16,664 adult spiders were identified to species, and in 2006 the number was 8,316. These include spiders caught in both pitfall traps and sweep nets (Table 8,

Appendices 1-4). Only the results of the pitfall traps will be discussed, as there were not enough data from the sweep netting to do a formal analysis. Juvenile spiders were not kept or identified. These spiders represented 156 species in 17 families (see Table 8 for species and authorities). The family Lycosidae made up 73.85% of the spiders identified in this study. The next most frequently caught family was Thomisidae, which made up

6.49% of the identified spiders. Twenty species were caught that are potential new provincial records for Manitoba, pending verification by experts (Table 9).

In 2005, catches of most species peaked around June 9 and June 23 (Table 10). In

2006, catches of many species peaked earlier, around May 24 and June 8 (Table 11).

Males and females tended to peak in catch at about the same dates, although the ratio of males to females varied by species. The most frequently caught species in this study was

Pardosa distincta, accounting for 59.45% of the total number of spiders caught overall.

42 The greatest numbers of both sexes of Pardosa distincta were caught on June 23, 2005 and on July 6, 2006. The next most frequent species was Alopecosa aculeata at 9.38%.

This species peaked earlier than P. distincta in both years, on June 9, 2005 and on May

24, 2006. Schizocosa mccooki differed from most species in that the peak catch of males was 5-6 weeks earlier in both years than the peak catch of females. The following spider species were trapped during the sampling season but not during the sampling periods that were included in the analyses: Misumenops asperatus, Xysticus fervidus, Tibellus oblongus, Araniella displicata, Dictyna volucripes, Bathyphantes canadensis, Erigone dentigera, Kaestneria pullata, Soucron arenarium, Metepeira palustris, Argiope trifasciata, Cercidia prominens, Larinoides sclopetarius, Cyclosa conica, Gonatium crassipalpum, Mimetus epeirodes, Theridion murarium, Theridion differens. These species were not common species and do not appear in any subsequent tables.

Primary Experiment

Soil Compaction

Only the first 15 cm of soil compaction measurements were compared since measurements to that depth were common to all sites. In all three paddocks, the soil was significantly more compacted in the grazed treatment than in the ungrazed treatment

(Figs. 11-13) but depth, and the interaction between the treatment and the depth were not significant in any paddock (Table12). Paddock 28 had the highest mean compaction measurements in both the grazed and ungrazed treatments, while paddock 27 had the lowest measurements.

43 Vegetation

The 25 pin sampler frames in each treatment were divided into five groups of five frames, and the number of occurrences of each species on the pins within those groups was summed for the analyses.

Over all paddocks, the ungrazed treatment had a significantly higher number of plant species than the grazed treatment (2005: F=11.3, df=1,28, p=0.002; 2006: F=21.8, df=1,28, p<0.001). When individual paddocks were examined, in both study years, the mean number of species was significantly higher in the ungrazed treatments in paddock

27 and paddock 29 but not in paddock 28 (Table 13).

The percent cover of Andropogon gerardii (Big Bluestem), Euphorbia esula

(Leafy Spurge), Juniperus horizontalis (Ground Juniper), Stipa sp. (needle grass), litter, and bare ground, as measured using the pin sampler was examined further (Table 14).

Andropogon gerardii (Big Bluestem) and Stipa sp. (genus made up of feather grass, needle grass, and spear grass) are tall grasses characteristic of the prairies, while

Juniperus horizontalis (Ground Juniper) is a characteristic shrub, and Euphorbia esula

(Leafy Spurge) is an invasive species on the Yellow Quill Prairie. Andropogon gerardii was only present in the ungrazed treatment in paddock 28 in both years but the difference between treatments was not significant. The cover of Euphorbia esula varied significantly by paddock and by treatment. In both of the study years, it was present in the highest amounts in the ungrazed treatment of paddock 28. Juniperus horizontalis was present in all paddocks in both years, most commonly in paddock 29, but the difference between treatments was not significant. Stipa sp. was more common in 2005 than in

2006, and the differences between paddocks and treatments were significant in both

44 years. It had a greater mean percent cover in the ungrazed treatment of each paddock.

Litter was significantly higher in the ungrazed treatment of all paddocks in 2005 and in the grazed treatments of all paddocks in 2006. Overall, the difference in bare ground between treatments was not significant.

The way in which the treatment affects the distribution of seven ground cover types among seven cover classes was examined using a log linear model, and was found to be significant in both sampling years (2005: LRχ2=102.41, df=36, p<0.001; 2006:

LRχ2=82.53, df=36, p<0.001). However, in 2005, the quadrats were placed directly over each pitfall trap, but curious cattle destroyed the traps and most vegetation in the immediate area around each trap, leaving mostly bare ground. Therefore they did not accurately reflect the paddock as a whole and should be caution should be used in interpreting these results. In 2006, the quadrats were moved away to a distance of approximately 8 m from the row of traps.

Seven types of ground cover (grasses, forbs, shrubs, bare ground, litter, leafy spurge, and ground juniper) were examined more closely using two-way contingency tables (Tables 15a and 15b). Grazing did not significantly affect the cover of forbs, litter or bare ground, but the cover of grasses was lower in the grazed areas in both sampling years, as was the cover of shrubs in 2005. It did not significantly affect the cover of leafy spurge, a subset of the forb data, in either year, but the cover of ground juniper was greater in the ungrazed area in 2005 and the grazed area in 2006. The decrease in bare ground in 2006 may have been due to the change in the sampling position of the quadrats.

45 Carabid Beetles

Summary Community Measures

Results of the effect of the grazing treatment on the total catch for each period and sampling year are given in Table 16. In Period 1, there was a consistent trend for higher mean catch in the grazed treatment in all paddocks in 2005, as well as in paddock 27 in

2006. In Periods 2 and 3, there were consistently more individuals caught in the ungrazed treatments and this trend was significant in three instances.

The most frequently caught beetle was Calosoma calidum. Results of the effect of the grazing treatment on the total catch of this species in each period and sampling year are given in Table 17. In Period 1, C. calidum tended to be caught in higher numbers in the grazed treatment in all three paddocks in 2005. In 2006, the same pattern was only marked and significant in paddock 27. In Period 2, there tended to be a higher total catch in the ungrazed treatment of paddocks 27 and 29 in both sampling years. There were insufficient C. calidum caught in Period 3 in both years to provide any trends.

Results of the effect of the grazing treatment on the number of species for each period and sampling year are given in Table 18. In Period 1, the mean number of species tended to be higher in the grazed treatment in all paddocks in both sampling years but the trend was significant only in paddock 27 in 2005. In Period 2, there was a trend for a higher mean number of species to be caught in the ungrazed treatment. In Period 3, the trend was for a higher mean number of species in the ungrazed treatment, but the trend was significant only in paddock 27 in 2005.

Results of the effect of the grazing treatment on the Berger-Parker Dominance

Index for each period and sampling year are given in Table 19. There was no clear trend

46 in the index in Period 1 in either sampling year. In Period 2 there was a trend for the index to be higher in then grazed treatment, but this trend was significant only in paddock

27 in 2006. In Period 3, there was also a trend for the index to be higher in the grazed treatment.

The results of the effect of the grazing treatment on the Log Series Alpha Index for each period and sampling year are given in Table 20. In Period 1, the index tended to be higher in the grazed treatment but it was significant only in paddock 27 in 2005. There was a slight trend for the index to be higher in the grazed treatment in Period 2 but there were no clear and consistent patterns in Period 3.

Community Composition

A Principal Components Analysis was performed on each year/paddock/period combination. There was no clear separation between samples from the grazed and the ungrazed treatments in any analysis: in all cases the envelope for a grazing regime includes sites from the other regime. Representative diagrams are included from each period and paddock to illustrate some trends amongst the many species of carabid beetles.

In Figs. 14 and 17-19, the first axis distinguishes the grazed treatment from the ungrazed treatment, while the second axis represents the variation amongst the different samples within each treatment. However, in Figs. 15 and 16, it is the second axis that is most associated with the grazing regime. Only select species will be discussed.

Period 1 in 2005 is represented by paddock 29 in Fig. 14. The first axis, which explains 34.4 % of the total variation, shows partial separation between the two treatments. The vector for the most frequently caught carabid beetle, Calosoma calidum,

47 tended to point towards the grazed treatment in all three paddocks in 2005. The vector for another large beetle, Cicindela longilabris, also pointed towards the grazed treatment in all three paddocks. However, Pasimachus elongatus did not exhibit any strong preference for a particular treatment. The second axis, which explains 15.0 % of the total variation, is driven by a high number of this species in one of the samples from the grazed treatment. The smallest carabid beetle caught in this study, Syntomus americanus, did not exhibit a strong preference for one treatment or the other in any paddock during this period. Period 1 in 2006 is represented by paddock 27 in Fig. 15. The second axis, which explains 18.3% of the total variation, is responsible for the greater degree of separation between the two treatments than in the previous year. Vectors for Calosoma calidum and

Cicindela longilabris tend to point towards the grazed treatment in this diagram, while that for Syntomus americanus points towards the ungrazed treatment. However, these species showed inconsistent preferences in the other two paddocks.

Period 2 in 2005 is represented by paddock 27 in Fig. 16. The first axis, which explains 24.6 % of the total variation, shows that the two treatments barely overlapped in this ordination. However, this was not the case in the other ordinations. During this period, Calosoma calidum was not consistently associated with either treatment. The vector for Pasimachus elongatus pointed towards the grazed treatment in paddocks 27 and 28 and towards the ungrazed treatment in paddock 29. Cicindela longilabris only appeared in paddock 28 in this period and did not prefer either treatment; however C. nebraskana was associated with the grazed treatment in both paddocks 27 and 28 but was not caught in paddock 29. Carabus taedatus was associated with the ungrazed treatment in all three paddocks, and while C. serratus only appeared in paddock 28, it too was more

48 frequently caught in the ungrazed treatment. Period 2 in 2006 is represented by paddock

28 in Fig. 17. The first axis, which explains 29.6 % of the total variation, does not show a clear distinction between the grazed and the ungrazed treatments. In this ordination,

Calosoma calidum and Pasimachus elongatus were strongly associated with the ungrazed treatment, but neither species exhibited a preference in paddocks 27 and 29 in 2006.

Cicindela longilabris appeared to prefer the grazed treatment in the two paddocks where it was caught. Agonum cupreum was consistently associated with the ungrazed treatment in all three paddocks. Syntomus americanus was only caught in paddock 29 in each year, and was not associated strongly with either treatment. The spread along the second axis, which explains 17.6 % of the total variation, is driven in particular by higher numbers of

Amara obesa in several of the traps in the grazed area.

Relatively few individuals were caught in the traps during Period 3 in either sampling year. This period in 2005 is represented by paddock 28 in Fig. 18. The spread along the first axis, which explains 30.6 % of the total variation, is caused by two traps in the ungrazed treatment that caught eight and 13 individuals respectively. While it appears that species are strongly associated with the ungrazed treatment, it is in fact an illusion as even the presence of a single individual of a species can change the ordinations in this period. The spread of the second axis, which explains 20.3 % of the total variation, is caused by three traps in the ungrazed treatment that caught up to 13 individuals and were different enough from the other traps to cause the wider spread. Period 3 in 2006 is represented by paddock 29 in Fig. 19. The first axis, which explains 50.5 % of the total variation, does not show a clear separation between the grazed and ungrazed treatments.

The spread along this axis is driven by only a few individuals of Agonum cupreum. The

49 second axis explains 16.2 % of the total variation but that too is only driven by five individuals of Pterosticus femoralis from two traps in the ungrazed area.

Spiders

Summary Community Measures

Results from the effect of grazing on the total catch of spiders can be found in

Table 21. In Period 1, the mean number of spiders caught was highest in the ungrazed treatment in all paddocks in both sampling years, but it was significant only in paddocks

28 and 29 in 2006. In Period 2, the mean number caught was significantly higher in the ungrazed treatment in all paddocks in 2005, and in paddocks 27 and 28 in 2006. There was no significant effect of the grazing treatment in paddock 29 in 2006. In Period 3, the mean number caught was significantly higher in the ungrazed treatment of paddocks 27 and 28 in 2005. In 2006, the mean number caught was highest in the ungrazed treatment of paddock 28; there were no significant effects of the grazing treatment in the other paddocks.

The most frequently caught species of spider was Pardosa distincta and its dominance of catches had greatest influence on the patterns seen in total spider catches in

Table 21. Results of the effect of grazing on the total catch of this species in each period and sampling year are given in Table 22. In Period 1 there was no clear pattern. Paddock

28 in 2006 had significantly greater mean catch of this species in the ungrazed treatment.

In Period 2, there was a greater mean catch in the ungrazed treatment in all paddocks in both sampling years, and the difference between treatments was significant in all but paddock 29 in 2006. In Period 3 there was no clear pattern. In 2005, a significantly

50 greater mean catch was found in the ungrazed treatment of paddocks 27 and 28, and in

2006, a significantly greater mean catch was found in the ungrazed treatment of paddock

29.

The second most frequently caught species of spider was Alopecosa aculeata.

Results of the effect of grazing on the total catch of this species in each period and sampling year are given in Table 23. In Periods 1 and 2 there was a tendency for a higher number of individuals to be caught in the ungrazed treatment, and this pattern was significant in Paddock 29 in both sampling years. There were insufficient numbers caught in Period 3 to provide any trends.

Results of the effect of grazing on the number of species for each period and sampling year are given in Table 24. There were no clear patterns in any of the three paddocks in either sampling year.

Results of the effect of grazing on the Berger-Parker Dominance Index for each period and sampling year are given in Table 25. There were no clear patterns in Period 1 and the difference between treatments was significant only in paddocks 27 and 29 in

2006. In Period 2, the index was higher in the ungrazed treatment in all paddocks in both sampling years, and the difference between treatments was significant in all paddocks and years with the exception of paddock 29 in 2005. In this period, Pardosa distincta is the dominant spider species in the ungrazed treatments in all paddocks and sampling years, and it is this species that is responsible for the pattern in the Berger Parker index. In

Period 3, the index was significantly higher in the ungrazed treatment in paddocks 27 and

28 in 2005. There were no samples in Period 3 in paddock 29 that year. The index tended

51 to be higher in the grazed treatment in all three paddocks in 2006 but the difference between treatments was only significant in paddock 28.

The results of the effect of the grazing treatment on the Log Series Alpha Index for each period and sampling year are given in Table 26. In Period 1, the index tended to be higher in the grazed treatment but the difference was only significant in paddock 29 in

2006. There were no samples from paddock 28 Period 1 in 2005. In Period 2, the index tended to be higher in the grazed treatment in all three paddocks in both sampling years; this trend was significant in four of the six paddock-year combinations. In Period 3, there were no significant differences or consistent patterns.

Community Composition

A Principal Components Analysis was performed on each year/paddock/period combination. Representative diagrams were included from each period and paddock. The first axis in Figs. 22-27 distinguishes the grazed treatment from the ungrazed treatment, while the second axis represents the variation amongst the different samples within each treatment. However, in Figs. 20-21 and 28-29, it is the second axis that is most associated with the grazing regime. Only select species will be discussed.

Period 1 in 2005 is represented by paddock 27 in Fig. 20. The first axis, which explains 17.6% of the total variation, does not show any distinct separation between the two treatments. The spread in the ungrazed treatment is mainly the result of the presence of single individuals of various species. The vector for Coloncus siou is extended on the right hand side of the ordination due to a maximum of five individuals being caught in a single trap in the grazed treatment and four individuals in each of two traps in the

52 ungrazed treatment. However, this species did not show a preference for either treatment in this period. The second axis, which explains 14.7% of the total variation, does not show any separation between the two treatments either. The vector for Euryopsis gertschi points strongly towards the ungrazed treatment, but the strength of the vector is misleading as the highest number of this species caught in any pitfall was only five individuals. In this ordination, Pardosa distincta, the most frequently caught spider species in the study, was associated with the ungrazed treatment, whereas Alopecosa aculeata, the next most frequently caught species, was associated with the grazed treatment. The only other species with comparatively high numbers of individuals was

Xysticus ampullatus, which was associated with the ungrazed treatment. Period 1 in 2006 is represented by paddock 27 in Fig. 21. The first axis, which explains 19.9% of the total variation, shows only a slight separation between the two treatments. Pardosa distincta and Schizocosa mccooki were the leading causes of the spread in the grazed treatment at the right hand side of the diagram, as the highest catches for each species were in single traps in this treatment (19 and 12 individuals respectively). The second axis, which explains 17.2% of the total variation shows partial separation between the two treatments, driven by Xysticus ampullatus and X. luctans, which both vector towards the ungrazed treatment, and X. montanensis and Habronattus altanus which both vector towards the grazed treatment.

Period 2 in 2005 is represented by paddock 27 in Fig. 22 and paddock 28 in Fig.

23. Both paddocks show complete separation between the grazed and ungrazed treatments along the first axis, which explains 66.0% of the total variation in paddock 27 and 38.6% of the total variation in paddock 28. The cause of this separation is the large

53 difference in the numbers of Pardosa distincta between the two treatments. In paddock

27 during period 2, there were 1,016 individuals caught in the ungrazed treatment, whereas only 36 individuals were caught in the grazed treatment. In paddock 28 in this same period, there were 1,818 individuals caught in the ungrazed treatment and 277 individuals caught in the grazed treatment. The distribution of the other species is hidden on the ordination by such large numbers of this one species. However, most species were only represented by comparatively few individuals, so do not exhibit any definitive preference for either treatment. The second axis explains only 4.5% of the variation in paddock 27 and 10% of the variation in paddock 28. Schizocoza mccooki and Zelotes lasulanus were caught in greater numbers in the grazed treatment, whereas other species such as Alopecosa aculeata, Coloncus siou, Thanatus rubicellus, Micaria laticeps,

Euryopis pepini, and Xysticus pellax were caught in greater numbers in the ungrazed treatment in both paddocks. Period 2 in 2006 is represented by paddock 27 in Fig. 24 and paddock 28 in Fig. 25. While the first axis explains 48.1% of the total variation in paddock 27 and 29.6% of the variation in paddock 28, the separation between the two treatments along this axis is not complete in any paddock in the second sampling year.

There were a lot fewer individuals caught this year compared to the first year of sampling, and patterns in the treatment preference for many species were not as consistent. Once again, Pardosa distincta was strongly associated with the ungrazed treatment in both paddocks, and was a leading cause of the spread in ordination diagrams.

Schizocoza mccooki was present in both treatments but was more strongly associated with the grazed treatment. Castianeira descripta was also associated with the grazed treatment in both paddocks. The second axis explained 13.1% of the total variation in paddock 27

54 and 11.1% in paddock 28. In paddock 27, Xysticus pellax appeared not to exhibit a strong preference for either treatment, but it was in fact more common in the ungrazed treatment. In paddock 28, the vector for this species clearly pointed towards the ungrazed treatment.

Period 3 in 2005 is represented by paddock 27 in Fig. 26 and paddock 28 in Fig

27. There were very few individuals caught in this period, especially in paddock 27. The first axis explains 50.1% of the total variation in paddock 27 and 41.3% in paddock 28.

Pardosa distincta was caught exclusively in the ungrazed treatment in paddock 27, and it is the distribution of these 36 individuals among the traps that drives the horizontal spread in this treatment. This species was present in both treatments in paddock 28 but it was more than four times as common in the ungrazed treatment as in the grazed treatment. The second axis explains 12.2% of the total variation in paddock 27 and 13.5% in paddock 28. All other species in paddock 27 had four or fewer individuals so the distribution of traps in the ordination diagram is a result of the presence of single individuals, as well as the varying combinations of the species, rather than a demonstration of treatment preference. Pardosa distincta abundance also influenced the spread of the traps in paddock 28 but Castianeira longipalpa and Xysticus gulosus were also present in high enough numbers to influence the spread towards the ungrazed treatment. Period 3 in 2006 is represented by paddock 29 in Fig. 28. The spread along the first axis, which explains 42.3% of the total variation, is primarily due to Pardosa distincta, which is associated with the ungrazed treatment and Xysticus gulosus, which is associated with the grazed treatment. The second axis, which explains 14.2% of the total variation, is not related to high numbers of any particular species. The only other species

55 to exceed two individuals is Castianeira longipalpa, which has a slight association with the ungrazed treatment. Agelenopsis potteri appears to have a large vector, but is represented by a single individual caught in both treatments.

Secondary Experiment

The electric fences that were erected between the three treatments in the secondary experiment were only working intermittently, and this allowed the cattle to move between treatments on occasion. The results from this experiment should therefore be interpreted with this in mind.

Soil Compaction

Only the first 15 cm of soil compaction measurements were compared. The soil was most compacted in the Spring/Fall treatment and least compacted in the Fall treatment (Fig. 29), but the differences between the treatments were not significant.

Depth played a significant role in the soil compaction (Table 27). The soil became more compacted as depth increased.

Vegetation

In 2005, the pin sampler technique found 30 plant species in the Spring treatment,

25 species in the Fall treatment, and 24 species in the Spring/Fall treatment. In 2006, there were 25 species in the Spring treatment, 26 species in the Fall treatment, and 23 species in the Spring/Fall treatment. There were no significant differences between the mean number of species found in each treatment in either sampling year (Table 28).

56 The percent cover of Andropogon gerardii, Euphorbia esula, Juniperus horizontalis, Stipa sp., litter, and bare ground, as measured using the pin sampler was examined further (Table 29). Andropogon gerardii was only present in the Spring & Fall treatment in 2005. Euphorbia esula was highest in the Fall treatment in 2005 and the

Spring graze in 2006, but levels were low across all treatments in both years. Juniperus horizontalis was present at slightly higher levels in the Spring/Fall treatment in both sampling years, but levels were also high in the other two treatments and were not significantly different from one another. In 2005, Stipa sp. was highest in the Spring/Fall treatment and lowest in the Spring treatment, but the treatments did not differ significantly from one another. However, in 2006, Stipa sp. was present in significantly different levels in the three treatments: the mean percent cover was highest in the Fall treatment, and much lower in the Spring and Spring/Fall treatments. The mean percent cover of litter was similar in all three treatments in 2005, but was significantly lower in the Fall treatment in 2006 compared to the other two treatments. Bare ground was only seen in the Spring treatment in 2005 and was not seen at all in 2006.

The way in which the treatment affects the distribution of ground cover types among the cover classes was examined using a log linear model, and was found not to be significant in either sampling year (2005: LRχ2=47.23, df=72, p=0.990; 2006:

LRχ2=52.78, df=72, p=0.957). As in the primary experiment, the location of the quadrats directly over the pitfall traps in 2005 resulted in data that is not representative of the paddock as a whole and should be interpreted with caution.

The seven types of ground cover (grasses, forbs, shrubs, bare ground, litter, leafy spurge, and ground juniper) were examined more closely using two-way contingency

57 tables (Tables 30a and 30b). Grazing did not significantly affect the distribution of the cover classes for any of the types of ground cover in either sampling year. The decrease in bare ground in 2006 may have been due to the change in the sampling position of the quadrats.

Carabid Beetles

Summary Community Measures

The same time periods as the primary experiment (Figs. 9 and 10) were used in the analysis of the data from Paddock 34. All data are from pitfall traps because no carabids were caught in sweep nets. There were no significant effects of the grazing treatments in paddock 34 on the total catch of carabid beetles (Table 31), the catch of the most frequently caught species, Calosoma calidum (Table 32), the number of species caught (Table 33), the Berger Parker index of dominance (Table 34) or the log series alpha index of diversity (Table 35).

Community Composition

A Principal Components Analysis was performed on each year/period combination. Only select species will be discussed.

Period 1 in 2005 is represented in Fig. 30. The first axis, which explains 50.4% of the total variation, does not show any separation between the three treatments. Period 1 in

2006 is represented in Fig. 31 and the first axis, which explains 35.0% of the total variation, does not show any separation between the three treatments. Calosoma frigidum vectored towards the Fall treatment, but the association is misleading as there were 118

58 individuals of this species caught in one single trap. This species contributes to the spread along the second axis, which explains 21.2% of the total variation.

Period 2 in 2005 is represented in Fig. 32. Once again, the first axis, which explains 63.8% of the total variation, does not show any separation between the three treatments. The spread is mainly driven by the numbers of Calosoma calidum, which were highest in the Spring/Fall treatment in this period. The second axis explains 16.3% of the total variation and the main species driving the spread at the top of the diagram are

Carabus serratus, which was only caught in the Fall treatment, and C. taedatus, which was most frequently caught in the Fall treatment. Pasimachus elongatus and Syntomus americanus are not major species in this paddock during this period. Period 2 in 2006 is represented in Fig. 33. Very few individuals were caught during this period. The first axis, which explains 37.9% of the total variation, does not show any separation between the three treatments. Carabus taedatus appears to be associated with the Fall treatment, but the apparent strength of the vector is misleading as only fourteen individuals were caught during this period. The second axis explains 20.6% of the total variation.

Pasimachus elongatus appears to be influencing this axis but there were only ten individuals caught during this period. No vectors for other species were strongly associated with any particular treatment in this period.

Relatively few individuals were caught in the traps during Period 3 in either sampling year. As a result, all ordinations for Period 3 responded greatly to catches of one or two individuals in single traps, and cannot be considered indicative of community structure. Consequently, no ordination diagrams are presented.

59 Spiders

Summary Community Measures

The same time periods as the primary experiment (Figs. 9 and 10) were used in the analysis of the data from Paddock 34. All data are from pitfall traps because insufficient numbers of spiders were caught in sweep nets.

Results of the effect of the grazing treatments on the total catch for each period and sampling year are given in Table 36. In Period 1 in 2006, the differences between the three treatments were significant. The lowest catch was in the Spring/Fall treatment, which had received the most grazing episodes. In Period 2, the mean number of spiders was significantly higher in the Spring/Fall treatment in 2005. In Period 3 there was no pattern in the mean number of spiders caught in any treatment in either year. In 2005, the highest number was caught in the Spring treatment and the lowest was caught in the Fall treatment. In 2006, very few individuals were caught, most likely as a result of the single sampling day in this period.

The most frequently caught species of spider in this experiment was Pardosa distincta. Results of the effect of the grazing treatments on the total catch of this species in each period and sampling year are given in Table 37. The differences between treatments were not significant in any period or sampling year. Due to the dominance of this species, the patterns observed between treatments are the same as with the total catch of spiders.

The second most frequently caught species in this experiment was Alopecosa aculeata. Results of the effect of the grazing treatments on the total catch of this species in each period and sampling year are given in Table 38. Catches of A. aculeata were

60 greatest in Period 1 in both years. The differences between treatments were not significant in any period or sampling year.

Results of the effect of the grazing treatments on the number of species for each period and sampling year are given in Table 39. In Period 1, there were no clear patterns between the three treatments in either sampling year. In Period 2, there was a tendency for the mean number of species to be highest in the Spring/Fall treatment and lowest in the Spring treatment in both years but the differences were not significant. In Period 3, there were no clear patterns between the three treatments in either sampling year.

Results of the effect of the grazing treatments on the Berger-Parker Dominance

Index for each period and sampling year are given in Table 40. The differences between the treatments were not significant in any period or sampling year.

Results of the effect of the grazing treatment on the Log Series Alpha Index for each period and sampling year are given in Table 41. There were no significant differences among grazing treatments in either sampling year.

Community Composition

A Principal Components Analysis was performed on each year/period combination. Only select species will be discussed.

Period 1 in 2005 is represented in Fig. 34, and there is no separation between the three treatments. The first axis explains 15.7% of the total and the second axis explains

10.8% of the total variation. The absence of any separation between the three treatments is appropriate as no differences in grazing regime had yet been experienced at the time of sampling in Period 1 of 2005. Period 1 in 2006 is represented in Fig. 35, and once again

61 there is no separation between the three treatments. The first axis explains 21.5% of the total variation. Alopecosa aculeata was most frequently caught in the Spring treatment this year. The second axis explains 12.9% of the total variation. As in 2005, Pardosa distincta was most frequently caught in the Spring treatment, though the traps do not group together clearly. It is the combination of the two most frequently caught species that drives the spread of the entire ordination diagram.

Period 2 in 2005 is represented in Fig. 36, and there was no separation between the three treatments. The spread along the first axis, which explains 52.4% of the total variation, is driven on the left hand side of the diagram by the high numbers of Pardosa distincta, which peaked in abundance in the Spring/Fall treatment during this period. The placement of traps along this axis on the right hand side of the diagram is caused by four traps (one in the Spring treatment, one in the Spring/Fall treatment, and two in the Fall treatment) that did not catch any individuals during this period. The second axis explains only 6.7% of the total variation. While the vectors for Alopecosa aculeata and Thanatus coloradensis appear to be important based on their length, they represent extremely low numbers of individuals. Period 2 in 2006 is represented in Fig. 37. Certain vectors appear to be quite strong but the number of individuals caught in this period was relatively low, therefore the associations with particular treatments are exaggerated. The first axis explains 56.5% of the total variation and the spread is driven by the numbers of Pardosa distincta, which is the most frequently caught species in this period. The second axis explains 12.0% of the total variation. The trap in the top right hand corner of the diagram has the highest catch of Castianeira longipalpa and Pardosa distincta of any trap in this

62 period. Both species were most frequently caught in the Fall treatment, as was Hogna frondicola, and all three contributed to the spread along the second axis.

Period 3 in 2005 is represented in Fig. 38. The first axis, which explains 27.9% of the total variation, and the second axis, which explains 22.3% of the total variation, are both strongly influenced by the distribution of Cicurina arcuata, which was strongly associated with the Spring treatment, and by Pardosa distincta, which was both the most frequently caught species and approximately equal in the numbers caught in all three treatments. In Period 3 in 2006 only 17 individuals were caught in total so no meaningful ordination could be performed.

63

Table 1. Dates that cattle were present on each section of the Yellow Quill Mixed Grass Prairie Preserve during 2005 and 2006.

Year Site Spring Graze Fall Graze 2005 Paddock 27 June 11- June 25 September 20 – October 31 Paddock 28 June 1 – June 11 July 15 – August 18 Paddock 29 June 25 – July 15 August 18 – September 20

Paddock 34 June 25 – July 14 August 16 – September 15

2006 Paddock 27 June 30 – July 15 September 21 – October 15 Paddock 28 June 15 – June 30 August 30 – September 21 Paddock 29 June 1 – June 15 July 15 – August 30

Paddock 34 June 30 – July 15 September 15 – October 15

64

Table 2. Sampling dates for 2005. Asterisk indicates that specimens collected that day were identified to species.

Carabids Spiders Sampling Date - 2005 Identified Identified May 12 * * May 19 * May 26 * * June 2 * June 9 * * June 16 * June 23 * * June 30 * July 7 * * July 14 * July 21 * * July 28 * August 4 * * August 11 * August 18 * * August 25 * September 1 * * September 8 * September 15 * * September 22 * September 29 * * October 6 Snowed – no sampling took place† October 13 * * October 20 * October 27 * * † – samples were left in the traps and collected the following week

65

Table 3. Sampling dates for 2006. Asterisk indicates that specimens collected that day were identified to species.

Carabids Spiders Sampling Date - 2006 Identified Identified May 3 * May 10 * * May 17 * May 24 * * May 31 * June 8 * * June 15 * June 22 * * June 29 * July 6 * * July 13 * July 20 * * July 27 * August 3 * * August 10 * August 17 * * August 24 * August 31 * * September 7 * September 14 * * September 21 * September 28 * * October 5 * October 12 * * October 19 * October 26 * *

66 Table 4. Vegetation species recorded during pin sampling on the Yellow Quill Mixed Grass Prairie Preserve in 2005 and 2006. Family Species

Asteraceae Achillea millefolium L. Agoseris glauca (Pursh) Raf. Artemisia campestris L. Artemisia frigida Willd. Artemisia ludoviciana Nutt. Aster ericoides L. Aster ptarmicoides (Nees) Torr. & A. Gray Aster simplex Willd. Aster sp. Chrysopsis villosa (Pursh) Nutt. Erigeron asper Nutt. Erigeron caespitosus Nutt. Erigeron sp. Gaillardia aristata Pursh Helianthus laetiflorus Pers. Solidago nemoralis Ait. Solidago sp. Tragopogon dubius Scop.

Boraginaceae Lithospermum canescens (Michx.) Lehm. Onosmodium hispidisimum Mack. Onosmodium molle Michx.

Brassicaceae Arabis holboellii var. collinsii (Fern.) Rollins

Campanulaceae Campanula rotundifolia L.

Caprifoliaceae Symphoricarpos occidentalis Hook.

Caryophyllaceae Cerastium arvense L.

Cupressaceae Juniperus horizontalis Moench

Cyperaceae Carex sp.

Equisetaceae Equisetum hyemale L.

Ericaceae Arctostaphylos uva-ursi (L.) Spreng.

Euphorbiaceae Euphorbia esula L.

67 Table 4 continued.

Family Species

Fabaceae Astragalus crassicarpus Nutt. Astragalus sp. Lathyrus ochroleucus Hook. Lathyrus sp. Oxytropis splendens Douglas Psoralea esculenta Pursh

Iridaceae Sisyrinchium montanum Greene

Lamiaceae Monarda fistulosa L.

Leguminosae Petalostemum candidum (Willd.) Michx. Petalostemum purpureum (Vent.) Rydb.

Liliaceae Allium textile A. Nelson & J.F. Macbr.

Linaceae Linum lewisii Pursh

Onagraceae Oenothera nuttallii Sweet Oenothera serrulata Nutt.

Poaceae Agropyron sp. Agropyron trachycaulum (Link) Malte ex H.F. Lewis Andropogon gerardii Vitman Andropogon scoparius Michx. Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths Festuca sp. Koeleria cristata (Ledeb.) Schult Koeleria macrantha (Ledeb.) Schult. Koeleria sp. Panicum sp. Poa sp. Stipa sp.

Ranunculaceae Anemone canadensis L. Anemone cylindrica A. Gray Anemone patens L.

68

Table 4 continued.

Family Species

Rosaceae Geum triflorum Pursh Potentilla arguta (Pursh) Rydb. Potentilla pensylvanica L. Potentilla sp. Prunus pumila L. Rosa arkansana Porter

Rubiaceae Galium boreale L.

Salicaceae Populus tremuloides Michx.

Santalaceae Comandra umbellata (L.) Nutt.

Saxifragaceae Heuchera richardsonii R. Br.

Solanaceae Physalis virginiana Mill.

Violaceae Viola pedatifida G. Don

69 Table 5. Species of carabid beetles collected in pitfall traps on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005 and 2006. Tribe Species Number Caught Bembidiini Bembidion muscicola Hayward 1 Bembidion mutatum Gemminger & Harold 18 Bembidion nitidum Kirby 102 Bembidion obscurellum obscurellum (Motschulsky) 1 Bembidion quadrimaculatum LeConte 11 Bembidion rapidum (LeConte) 2 Carabini Calosoma calidum (Fabricius) 3820 Calosoma frigidum Kirby 241 Calosoma lepidum LeConte 9 Carabus serratus Say 40 Carabus taedatus agassii LeConte 144 Chlaeniini Chlaenius pennsylvanicus pennsylvanicus Say 3 Chlaenius purpuricollis Randall 240 Chlaenius sericeus sericeus (Forster) 2 Chlaenius tomentosus tomentosus (Say) 96 Cicindelini Cicindela longilabris longilabris Say 47 Cicindela nebraskana Casey 98 Cicindela punctulata punctulata Olivier 28 Cicindela scutellaris lecontei Haldeman 1 Harpalini Anisodactylus merula (Germar) 6 Anisodactylus rusticus (Say) 4 Euryderus grossus (Say) 3 Harpalus erythropus Dejean 1 Harpalus fuscipalpis Sturm 1 Harpalus herbivagus Say 11 Harpalus lewisii LeConte 1 Harpalus megacephalus LeConte 6 Harpalus nigritarsus C.R. Sahlberg 15 Harpalus opacipennis (Haldeman) 37 Harpalus pensylvanicus (DeGeer) 9 Harpalus plenalis Casey 4 Harpalus somnulentus Dejean 8 Harpalus spadiceus Dejean 2 Harpalus ventralis LeConte 13 Stenolophus conjunctus (Say) 30 Trichocellus mannerheimi C.R. Sahlberg 1 Lebiini Calleida purpurea (Say) 1 Calleida viridis amoena (LeConte) 73 Cymindis borealis LeConte 123 Cymindis cribicollis Dejean 6

70 Table 5 continued. Tribe Species Number Caught Lebiini cont‟d Cymindis pilosus Say 4 Cymindis planipennis LeConte 27 Lebia moesta LeConte 1 Syntomus americanus (Dejean) 340 Licinini Diplocheila obtusa (LeConte) 5 Loricerini Loricera pilicornis pilicornis (Fabricius) 3 Notiophilini Notiophilus aquaticus (Linne) 2 Platynini Agonum cupreum Dejean 1,577 Agonum cupripenne (Say) 12 Agonum errans (Say) 1 Agonum gratiosum (Mannerheim) 1 Agonum obsoletum Say 3 Agonum piceolum (LeConte) 3 Agonum placidum (Say) 79 Agonum propinquum (Gemminger & Harold) 1 Agonum retractum LeConte 3 Agonum trigeminum Lindroth 6 Platynus decentis (Say) 1 Synuchus impunctatus (Say) 15 Pterostichini Poecilus corvus (LeConte) 1 Poecilus lucublandus lucublandus (Say) 381 Pterostichus femoralis (Kirby) 92 Pterostichus melanarius (Illiger) 15 Pterostichus mutus (Say) 2 Pterostichus novus Straneo 3 Pterostichus pensylvanicus LeConte 1 Scaritini Pasimachus elongatus LeConte 473 Zabrini Amara aenea (DeGeer) 3 Amara coelebs Hayward 41 Amara convexa LeConte 54 Amara ellipsis (Casey) 56 Amara familiaris (Duftschmid) 2 Amara farcta LeConte 85 Amara latior (Kirby) 1 Amara littoralis Mannerheim 26 Amara lunicollis Schiodte 1 Amara obesa (Say) 179 Amara pallipes Kirby 1 Amara quenseli (Schönherr) 15 Amara sinuosa (Casey) 1 Amara tenax Casey 82 Grand Total 8,858

71

Table 6. Weekly catches of the 25 most frequently-caught carabid species collected from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005. October 6 was not sampled due to snowfall. The value in bold indicates the peak catch for that species. Totals are derived from data from 300 pitfall traps for May 12 – 26, and 225 pitfall traps for June 2 – October 27

72

Sampling Date

Oct 6 Oct

Aug 4 Aug

July 7 July

Sept 1 Sept 8 Sept

June 2 June 9 June 13 Oct 20 Oct 27 Oct

Aug 11 Aug 18 Aug 25 Aug

July 14 July 21 July 28 July

Sept 15 Sept 22 Sept 29 Sept

May 12 May 19 May 26 May

June 23 June 30 June Species 16 June Totals Calosoma calidum 26 70 97 42 155 58 215 98 86 22 164 87 77 1 0 4 1 0 0 64 199 - 21 132 86 1705 Pasimachus elongatus 4 3 3 1 11 1 21 2 1 1 16 12 2 0 0 9 9 0 0 17 17 - 2 12 3 147 Chlaenius purpuricollis 0 0 0 0 0 0 0 5 4 1 7 2 0 0 0 2 1 0 0 0 0 - 7 24 55 108 Agonum cupreum 3 11 5 3 12 0 4 0 2 0 3 2 0 0 2 3 1 8 4 4 3 - 1 8 8 87 Syntomus americanus 2 6 6 1 18 1 6 1 0 0 3 1 0 0 0 0 0 4 3 7 8 - 1 12 5 85 Amara ellipsis 0 0 0 0 2 0 46 0 0 0 5 17 3 0 1 0 0 1 0 1 0 - 0 1 0 77 Cicindela nebraskana 0 1 0 0 0 0 62 0 0 0 7 3 0 0 0 0 0 0 0 0 0 - 0 1 0 74 Poecilus lucublandus lucublandus 3 4 4 2 3 2 7 2 1 4 3 1 0 0 0 4 0 0 0 7 4 - 2 8 7 68 Cymindis borealis 0 0 0 0 0 0 0 0 0 1 0 0 1 1 13 5 4 14 6 10 0 - 3 0 0 58 Carabus taedatus agassii 0 0 3 5 10 4 0 4 5 1 0 0 0 0 0 1 0 0 0 2 3 - 2 1 11 52 Cicindela longilabris longilabris 0 0 0 0 0 0 33 0 0 0 1 1 0 0 0 0 0 0 0 1 0 - 0 0 1 37 Pterostichus femoralis 0 0 0 1 0 0 1 0 0 0 0 0 0 0 2 0 2 11 10 1 0 - 4 0 0 32 Amara obesa 0 0 0 2 0 3 0 0 1 0 3 1 2 4 3 2 0 0 0 1 0 - 3 0 4 29 Amara coelebs 0 0 0 0 1 0 21 0 0 0 0 0 0 0 0 0 0 2 0 0 0 - 0 2 0 26 Chlaenius tomentosus tomentosus 0 0 3 1 0 0 3 0 1 0 6 1 4 0 1 0 0 0 0 0 2 - 0 0 1 23 Amara tenax 4 2 0 2 7 0 1 0 0 0 0 0 0 0 1 0 0 0 0 3 1 - 0 1 0 22 Agonum placidum 1 1 0 0 0 0 4 0 0 0 5 1 0 0 0 0 1 0 0 3 0 - 1 4 1 22 Amara convexa 0 1 0 0 0 0 17 0 0 0 0 0 0 0 0 0 0 0 0 1 0 - 1 1 1 22 Cymindis planipennis 0 0 0 0 0 0 0 0 0 0 0 0 8 3 0 0 0 0 0 4 0 - 0 0 0 15 Bembidion nitidum 0 0 0 0 0 0 0 0 0 0 7 3 1 0 1 0 0 0 0 0 0 - 0 1 1 14 Amara littoralis 0 0 1 0 1 0 2 3 1 0 0 0 0 0 0 0 0 0 0 2 0 - 0 2 1 13 Calleida viridis amoena 0 0 0 1 0 0 2 0 0 0 7 0 1 0 0 0 0 0 0 0 0 - 0 1 0 12 Cicindela punctulata punctulata 0 0 0 0 0 0 0 0 0 0 0 3 7 2 0 0 0 0 0 0 0 - 0 0 0 12 Amara quenseli 0 0 0 0 0 0 0 0 0 0 1 0 2 1 2 0 0 0 0 2 0 - 0 0 1 9 Carabus serratus 0 0 1 0 2 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 2 - 0 1 2 9

73

Table 7. Weekly catches of the 25 most frequently-caught carabid species collected from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2006. The value in bold indicates the peak catch for that species. Totals are derived from data from 225 pitfall traps.

74

Sampling Day

Oct 5

Aug 3

July 6

Sept Sept 7

May 3

June 8 Oct 12 Oct 19 Oct 26

Aug 10 Aug 17 Aug 24 Aug 31

July 13 July 20 July 27

Sept Sept 14 Sept 21 Sept 28

May 10 May 17 May 24 May 31

June 22 June 29 Species June 15 Totals Calosoma calidum 6 20 81 370 264 218 105 61 39 8 13 20 8 14 7 2 0 0 1 0 0 0 0 0 0 0 1237 Agonum cupreum 26 32 21 29 169 216 143 196 214 15 8 14 11 3 5 1 1 0 0 4 3 9 40 0 6 8 1174 Calosoma frigidum 0 0 0 81 142 8 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 234 Poecilus lucublandus lucublandus 9 19 28 26 37 17 9 28 32 3 3 5 0 1 1 0 0 0 0 3 0 0 0 0 0 0 221 Pasimachus elongatus 0 3 4 10 11 45 16 27 14 1 7 5 5 3 12 2 6 6 1 11 2 1 1 0 0 0 193 Syntomus americanus 66 24 18 3 6 0 0 0 9 1 0 1 0 0 3 0 1 0 0 0 0 0 3 0 1 0 136 Amara obesa 1 0 0 0 0 1 1 0 0 3 0 7 8 7 20 23 17 9 4 3 4 3 1 0 2 1 115 Bembidion nitidum 1 2 3 1 5 3 8 19 20 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 63 Cymindis borealis 0 0 0 0 0 0 0 0 0 0 0 0 1 3 15 11 8 5 0 0 0 0 0 0 0 0 43 Chlaenius tomentosus tomentosus 0 0 0 4 11 6 4 9 3 0 1 1 0 0 0 2 0 0 0 0 0 0 0 0 0 0 41 Calleida viridis amoena 0 3 0 2 3 0 2 1 4 7 3 3 0 2 5 1 0 0 0 3 0 0 0 0 0 0 39 Chlaenius purpuricollis 1 9 2 0 3 1 2 0 1 4 0 2 5 1 2 2 0 0 0 0 0 0 0 0 0 0 35 Carabus taedatus agassii 0 1 1 5 3 1 0 0 0 0 0 2 0 1 3 0 3 4 3 3 0 1 0 0 0 0 31 Pterostichus femoralis 3 1 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 8 15 29 Amara tenax 10 2 3 9 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 27 Agonum placidum 0 1 1 5 11 2 2 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 Amara familiaris 4 4 1 2 2 5 1 0 3 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 23 Stenolophus conjunctus 12 2 2 0 4 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 21 Harpalus opacipennis 0 1 3 2 3 0 0 0 4 2 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 16 Amara convexa 1 0 1 0 4 2 2 0 0 0 3 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 14 Carabus serratus 0 0 0 1 4 1 1 0 2 1 2 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 13 Cicindela punctulata punctulata 0 0 0 0 0 0 0 0 0 0 3 0 1 1 3 0 2 1 0 0 0 0 0 0 0 0 11 Bembidion mutatum 1 0 2 0 1 0 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 Amara littoralis 2 0 0 1 1 0 2 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 Cymindis planipennis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 1 1 0 1 0 0 0 0 2 8

75 Table 8. Spider species collected by pitfall traps and sweep nets on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005 and 2006. Number Caught In Pitfall Sweep Family Species Traps Nets Agelenidae Agelenopsis actuosa (Gertsch & Ivie) 20 0 Agelenopsis potteri (Blackwall) 6 0 Agelenopsis utahana (Chamberlin & Ivie) 17 0 Araneidae Araneus pratensis (Emerton) 1 10 Araneus saevus (L. Koch) 1 0 Araneus trifolium (Hentz) 6 0 Araniella displicata (Hentz) 0 6 Argiope trifasciata (Forsskål) 0 20 Cercidia prominens (Westring) 0 2 Cyclosa conica (Pallas) 0 1 Hypsosinga rubens (Hentz) 9 1 Larinia borealis Banks 3 1 Larinoides sclopetarius (Clerck) 0 1 Metepeira palustris Chamberlin & Ivie 0 1 Neoscona arabesca (Walckenaer) 1 12 Clubionidae Clubiona kiowa Gertsch 101 1 Clubiona moesta Bank 1 0 Clubiona obesa Hentz 2 0 Corinnidae Castianeira descripta (Hentz) 67 0 Castianeira longipalpa (Hentz) 183 0 Phrurotimpus borealis (Emerton) 6 0 Phrurotimpus certus Gertsch 16 0 Scotinella pugnata (Emerton) 6 0 Dictynidae Cicurina arcuata Keyserling 135 0 Cicurina robusta Simon 2 0 Dictyna terrestris Emerton 11 0 Dictyna volucripes Keyserling 1 33 Gnaphosidae Callilepsis pluto Banks 9 0 Drassodes neglectus (Keyserling) 192 0 Gnaphosa muscorum (L. Koch) 61 0 Gnaphosa parvula Banks 11 0 Haplodrassus bicornis (Emerton) 13 0 Haplodrassus hiemalis (Emerton) 8 0 Haplodrassus signifer (C.L. Koch) 165 0 Micaria gertschi Barrows & Ivie 1 0 Micaria laticeps Emerton 231 0 Micaria longipes Emerton 2 0 Micaria pulicaria (Sundevall) 1 0

76 Table 8 continued.

Number Caught In Pitfall Sweep Family Species Traps Nets Gnaphosidae cont‟d Nodocion mateonus Chamberlin 1 0 Sergiolus capulatus (Walckenaer) 6 0 Zelotes exiguoides Platnick & Shadab 15 0 Zelotes fratris Chamberlin 15 0 Zelotes hentzi Barrows 131 0 Zelotes lasalanus Chamberlin 372 0 Zelotes puritanus Chamberlin 2 0 Hahniidae Hahnia cinerea Emerton 175 0 Neoantistea agilis (Keyserling) 4 0 Linyphiidae Agyneta allosubtilis Loksa 5 0 Bathyphantes canadensis (Emerton) 1 1 Centromerus sylvaticus (Blackwall) 6 0 Ceraticelus crassiceps Chamberlin & Ivie 11 0 Ceraticelus laetus (O.P.-Cambridge) 24 0 Ceraticelus minutus (Emerton) 1 0 Ceratinella brunnea Emerton 18 0 Ceratinella sp. 3 0 Ceratinops crenatus (Emerton) 11 0 Ceratinops latus (Emerton) 26 0 Ceratinopsis interpres (O.P.-Cambridge) 1 0 Ceratinopsis nigriceps Emerton 3 0 Coloncus siou (Chamberlin) 373 0 Eperigone tridentata Emerton 2 0 Eperigone trilobata Emerton 19 0 Erigone aletris Crosby & Bishop 38 3 Erigone atra Blackwall 13 4 Erigone dentigera O.P.-Cambridge 1 0 Erigone psychrophila Thorell 2 0 Gonatium crassipalpum Bryant 1 0 Grammonota capitata Emerton 144 0 Halorates plumosus Paquin & Dupérré 6 1 Islandiana longisetosa (Emerton ) 19 0 Kaestneria pullata (O.P.-Cambridge) 1 0 Lepthyphantes alpinus (Emerton) 298 0 Maso sundevallii (Westring) 10 0 Microlinyphia mandibulata (Emerton) 2 1 Pocadicnemis americana Millidge 94 3 Scotinotylus alpinus (Banks) 2 0 Scotinotylus pallidus (Emerton) 25 0

77 Table 8 continued.

Number Caught In Pitfall Sweep Family Species Traps Nets Linyphiidae cont‟d Soucron arenarium (Emerton) 0 1 Tenneseelum formicum (Emerton) 5 0 Walckenaeria castanea (Emerton) 3 1 Walckenaeria communis (Emerton) 50 0 Walckenaeria digitata (Emerton) 7 0 Walckenaeria directa (O.P.-Cambridge) 2 0 Walckenaeria pallida (Emerton) 3 0 Walckenaeria spiralis (Emerton) 10 0 Liocranidae Agroeca ornata Banks 1 0 Agroeca pratensis Emerton 30 0 Lycosidae Alopecosa aculeata (Clerck) 2344 0 Arctosa rubicunda (Keyserling) 152 0 Geolycosa missouriensis (Banks) 1 0 Hogna frondicola (Emerton) 252 0 Pardosa distincta (Blackwall) 14849 3 Pardosa fuscula (Thorell) 3 0 Pardosa mackenziana (Keyserling) 3 0 Pardosa moesta Banks 223 0 Pardosa ontariensis Gertsch 1 0 Pirata canadensis Dondale & Redner 1 0 Pirata minutus Emerton 2 0 Schizocosa mccooki Montgomery 582 0 Schizocosa minnesotensis (Gertsch) 2 0 Trochosa terricola Thorell 33 0 Mimetidae Ero canionis Chamberlin & Ivie 1 0 Mimetus epeiroides Emerton 1 0 Philodromidae Philodromus histrio (Latreille) 4 2 Thanatus coloradensis Keyserling 214 0 Thanatus formicinus (Clerck) 112 0 Thanatus rubicellus Mello-Laitao 190 0 Thanatus striatus C.L. Koch 4 1 Tibellus duttoni (Hentz) 1 0 Tibellus oblongus (Walckenaer) 1 5 Salticidae Eris militaris (Hentz) 1 2 Euophrys monadnock Emerton 5 0 Evarcha hoyi (Peckham & Peckham) 22 4 Habronattus altanus (Gertsch) 76 1 Habronattus americanus (Keyserling) 6 0 Habronattus borealis (Banks) 76 1

78 Table 8 continued.

Number Caught In Pitfall Sweep Family Species Traps Nets Salticidae cont‟d Habronattus cognatus 30 0 (Peckham & Peckham) Habronattus decorus (Blackwall) 2 0 Maevia inclemens (Walckenaer) 1 0 Pellenes wrighti Lowrie & Gertsch 1 0 Phiddipus borealis Banks 27 0 Phiddipus johnsoni 260 0 (Peckham & Peckham) Phiddipus purpuratus Keyserling 38 1 Phiddipus whitmani Peckham & Peckham 9 0 Tutelina similis (Banks) 6 1 Tetragnathidae Tetragnatha laboriosa Hentz 5 92 Theridiidae Chrysso pelyx (Levi) 5 0 Enoplognatha marmorata (Hentz) 8 0 Euryopis gertschi Levi 122 0 Euryopis pepini Levi 139 0 Steatoda americana (Emerton) 10 0 Theridion differens Emerton 0 2 Theridion murarium Emerton 0 0 Theridion prataeum L. Koch 19 0 Thomisidae Misumena vatia (Clerck) 0 4 Misumenops asperatus (Hentz) 0 11 Misumenops celer (Hentz) 3 30 Ozyptila sincera canadensis 12 1 Dondale & Redner Xysticus ampullatus 529 1 Turnbull, Dondale & Redner Xysticus auctificus Keyserling 10 1 Xysticus canadensis Gerstch 2 0 Xysticus cunctator Thorell 18 0 Xysticus elegans Keyserling 5 0 Xysticus emertoni Keyserling 10 0 Xysticus ferox (Hentz) 34 0 Xysticus fervidus Gerstch 0 1 Xysticus gulosus Keyserling 285 1 Xysticus luctans (C.L. Koch) 389 0 Xysticus luctuosus (Blackwall) 1 0 Xysticus montanensis Keyserling 67 0 Xysticus nigromaculatus Keyserling 9 0

79

Table 8 continued.

Number Caught In Pitfall Sweep Family Species Traps Nets Thomisidae cont‟d Xysticus pellax O.P.-Cambridge 158 1 Xysticus triangulosus Emerton 2 0 Xysticus triguttatus Keyserling 21 15 Xysticus winnipegensis 1 0 Turnbull, Dondale, & Redner Titanocidae Titanoeca silvicola Chamberlin & Ivie 14 0 Grand Totals 24,695 285

80

Table 9. Potential new provincial records for Araneae caught on the Yellow Quill Mixed Grass Prairie Preserve in 2005 and 2006.

Number of Family Species Individuals Caught 2005 2006 Araneidae Araneus pratensis (Emerton) 0 11 Araneidae Metepeira palustris Chamberlin & Ivie 0 1 Dictynidae Dictyna terrestris Emerton 10 1 Gnaphosidae Micaria laticeps Emerton 170 61 Gnaphosidae Micaria longipes Emerton 0 2 Gnaphosidae Nodocion mateonus Chamberlin 0 1 Gnaphosidae Sergiolus capulatus (Walckenaer) 4 2 Gnaphosidae Zelotes hentzi Barrows 78 53 Linyphiidae Ceratinops latus (Emerton) 25 1 Linyphiidae Ceratinopsis interpres (O.P.-Cambridge) 0 1 Linyphiidae Ceratinopsis nigriceps Emerton 2 1 Linyphiidae Erigone aletris Crosby & Bishop 39 2 Linyphiidae Halorates plumosus Paquin & Dupérré 5 2 Linyphiidae Maso sundevallii (Westring) 9 1 Salticidae Pellenes wrighti Lowrie & Gertsch 1 0 Theridiidae Theridion prataeum L. Koch 15 4 Thomisidae Misumenops celer (Hentz) 6 27 Thomisidae Xysticus auctificus Keyserling 2 9 Thomisidae Xysticus cunctator Thorell 18 0 Thomisidae Xysticus pellax O.P.-Cambridge 63 96

81

Table 10. Weekly catches by sex of the 25 most frequently-caught spider species collected in pitfall traps and sweep net samples from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2005. Spiders were identified every second week (intervening days were omitted from the table). The value in bold indicates the peak catch for that species.

Sampling Date

Sub- Species Sex Totals

ept 15 totals

Aug 4

July 7

Sept Sept 1

June 9 Oct 13 Oct 27

Aug 18

July 21

S Sept 29

May 12 May 26 June 23

Pardosa distincta M 0 0 75 2701 1318 247 6 0 0 0 1 48 0 4396 7311 F 0 0 21 1213 228 364 780 0 87 96 94 23 9 2915 Alopecosa aculeata M 31 267 272 139 2 1 0 0 0 0 0 0 0 712 902 F 41 42 43 12 6 30 7 1 4 4 0 0 0 190 Xysticus ampullatus M 0 32 85 139 3 1 0 0 0 0 0 0 0 260 282 F 2 3 0 9 0 2 5 1 0 0 0 0 0 22 Coloncus siou M 0 0 132 114 1 0 0 0 0 0 0 0 0 247 276 F 0 0 11 10 7 1 0 0 0 0 0 0 0 29 Schizocosa mccooki M 0 0 2 60 21 8 2 0 0 0 0 3 0 96 136 F 0 0 0 10 2 1 15 1 3 2 4 2 0 40 Micaria laticeps M 0 3 16 44 8 3 1 0 0 0 0 0 0 75 135 F 0 2 4 34 9 7 3 0 1 0 0 0 0 60 Pardosa moesta M 0 9 24 56 4 1 0 0 0 0 0 0 0 94 112 F 0 1 2 0 4 3 7 0 1 0 0 0 0 18 Euryopis pepini M 0 0 12 78 1 1 0 0 0 0 0 0 0 92 102 F 0 0 0 7 1 0 2 0 0 0 0 0 0 10 Zelotes lasalanus M 1 15 20 29 3 3 0 0 0 0 0 0 0 71 101 F 0 6 8 8 1 5 1 0 0 0 0 1 0 30 Xysticus luctans M 11 27 30 9 0 0 0 0 0 0 0 0 0 77 100 F 3 12 5 1 0 0 1 1 0 0 0 0 0 23 Lepthyphantes alpinus M 28 2 6 4 3 4 2 0 0 0 0 3 1 53 89 F 12 4 12 7 1 0 0 0 0 0 0 0 0 36 Grammonota capitata M 1 4 28 19 0 1 0 0 0 0 0 0 0 53 88 F 0 1 15 12 5 2 0 0 0 0 0 0 0 35 Cicurina arcuata M 0 0 0 0 0 0 0 0 0 0 1 17 32 50 81 F 0 0 0 0 0 0 0 0 0 0 0 6 25 31 Castianeira longipalpa M 0 0 0 0 0 0 2 4 8 4 5 2 0 25 71 F 0 0 0 0 0 0 0 1 5 9 12 17 2 46 Drassodes neglectus M 1 9 16 16 2 3 1 0 0 0 0 0 0 48 69 F 0 1 2 14 0 2 1 0 0 0 1 0 0 21 Thanatus coloradensis M 1 0 2 37 6 9 1 0 0 0 0 0 0 56 68 F 1 1 0 1 0 1 6 2 0 0 0 0 0 12 Thanatus rubicellus M 1 0 5 33 11 10 0 0 0 0 0 0 0 60 63 F 0 0 0 2 1 0 0 0 0 0 0 0 0 3 Arctosa rubicunda M 0 4 37 13 0 0 0 0 0 0 0 0 0 54 62 F 0 0 1 1 0 5 1 0 0 0 0 0 0 8

82

Table 10 continued.

Sampling Date

Sub- Species Sex Totals

totals

Aug 4

July 7

Sept Sept 1

June 9 Oct 13 Oct 27

Aug 18

July 21

Sept Sept 15 Sept 29

May 12 May 26 June 23 Hogna frondicola M 12 12 2 0 1 0 0 0 6 5 2 0 0 40 61 F 3 1 1 1 0 3 2 2 3 4 1 0 0 21 Pocadicnemis americana M 0 3 24 8 0 0 0 0 0 0 0 0 0 35 50 F 1 1 3 3 0 0 0 0 0 0 0 0 7 15 Zelotes hentzi M 0 11 6 2 0 2 1 0 3 0 0 0 0 25 46 F 2 3 6 6 2 2 0 0 0 0 0 0 0 21 Euryopis gertschi M 0 1 36 3 0 0 0 0 0 0 0 0 0 40 45 F 0 0 3 0 0 2 0 0 0 0 0 0 0 5 Haplodrassus signifer M 5 3 12 3 0 0 0 0 0 0 0 0 0 23 43 F 1 1 12 6 0 0 0 0 0 0 0 0 0 20 Clubiona kiowa M 1 0 5 4 1 2 2 0 0 0 0 0 0 15 42 F 1 3 11 6 2 4 0 0 0 0 0 0 0 27 Xysticus gulosus M 0 0 0 0 0 0 0 3 2 12 12 10 0 39 40 F 0 0 0 0 0 0 0 1 0 0 0 0 0 1

83

Table 11. Weekly catch by sex of the 25 most frequently-caught spider species collected in pitfall traps and sweet net samples from all four paddocks on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba, in 2006. Spiders were identified every second week (intervening days were omitted from the table). The value in bold indicates the peak catch for that species.

Sampling Date

Sub- Species Sex Totals

totals

Aug 3

July 6

Oct 12 Oct 26

Aug 17 Aug 31

July 20

Sept Sept 14 Sept 28

June8

May 10 May 24 June 22

Pardosa distincta M 0 1 160 414 475 57 1 0 0 0 0 0 0 1108 2713 F 0 0 26 116 467 298 405 147 71 54 13 7 1 1605 Alopecosa aculeata M 52 428 144 30 0 0 0 0 0 0 0 0 0 654 869 F 50 127 10 6 17 3 0 0 0 1 1 0 0 215 Schizocosa mccooki M 9 0 42 71 36 19 1 0 0 0 0 0 0 178 311 F 0 0 9 17 16 25 31 19 10 4 1 1 0 133 Phiddipus johnsoni M 5 36 32 6 3 1 0 0 0 0 0 0 0 83 177 F 2 14 74 2 0 1 1 0 0 0 0 0 0 94 Zelotes lasalanus M 1 56 42 2 4 1 0 0 1 0 0 0 0 107 171 F 0 11 18 10 5 9 9 2 0 0 0 0 0 64 Xysticus gulosus M 0 0 0 0 0 0 0 0 54 65 4 1 0 124 139 F 0 0 0 1 0 1 0 0 3 9 1 0 0 15 Xysticus luctans M 40 63 5 0 0 0 0 0 0 0 0 0 0 108 130 F 6 9 4 0 2 0 1 0 0 0 0 0 0 22 Xysticus ampullatus M 0 36 44 17 0 0 0 0 0 0 0 0 0 97 122 F 1 7 6 5 2 3 1 0 0 0 0 0 0 25 Hogna frondicola M 31 9 3 0 0 0 0 5 8 6 0 0 0 62 94 F 3 3 0 1 7 1 3 8 3 3 0 0 0 32 Thanatus rubicellus M 0 0 33 26 13 0 1 0 0 0 0 0 0 73 79 F 0 0 4 0 0 2 0 0 0 0 0 0 0 6 Thanatus coloradensis M 1 2 14 42 7 1 0 0 0 0 1 0 0 68 77 F 0 1 2 1 1 2 1 0 1 0 0 0 0 9 Haplodrassus signifer M 19 22 9 2 0 0 0 0 0 0 0 0 0 52 71 F 0 9 8 1 0 1 0 0 0 0 0 0 0 19 Xysticus pellax M 0 0 0 0 0 0 1 33 29 0 0 0 0 63 71 F 0 0 0 0 0 0 0 6 1 1 0 0 0 8 Arctosa rubicunda M 1 6 39 11 0 0 0 0 1 0 0 0 0 58 70 F 0 1 3 0 0 7 1 0 0 0 0 0 0 12 Drassodes neglectus M 6 19 8 11 6 1 0 0 0 0 0 0 0 51 67 F 0 2 3 6 2 0 0 1 0 0 1 0 1 16 Lepthyphantes alpinus M 33 2 0 0 0 0 0 0 0 0 0 0 1 36 53 F 14 1 2 0 0 0 0 0 0 0 0 0 0 17 Pardosa moesta M 0 7 13 8 2 0 0 0 0 0 0 0 0 30 49 F 0 0 4 4 7 4 0 0 0 0 0 0 0 19 Castianeira longipalpa M 0 0 0 0 0 0 2 4 5 1 0 0 0 12 45 F 0 0 0 0 0 0 0 1 4 20 7 1 0 33 Zelotes hentzi M 11 1 2 0 1 2 7 3 1 0 0 0 0 28 43 F 1 6 6 0 2 0 0 0 0 0 0 0 0 15

84

Table 11 continued.

Sampling Date

Sub- Species Sex Totals

totals

Aug 3

July 6

Oct 12 Oct 26

Aug 17 Aug 31

July 20

Sept Sept 14 Sept 28

June8

May 10 May 24 June 22 Micaria laticeps M 1 4 6 8 0 0 0 0 0 0 0 0 0 19 38 F 0 1 6 3 8 1 0 0 0 0 0 0 0 19 Grammonota capitata M 0 1 13 5 0 0 0 0 0 0 0 0 0 19 34 F 2 1 10 2 0 0 0 0 0 0 0 0 0 15 Castianeira descripta M 0 0 0 0 2 6 4 0 0 2 0 0 0 14 33 F 0 0 0 0 0 2 5 6 4 2 0 0 0 19 Habronattus altanus M 0 1 3 0 1 1 0 1 3 3 0 0 0 13 33 F 0 7 3 1 3 1 0 1 3 1 0 0 0 20 Habronattus borealis M 0 0 1 1 2 1 2 1 0 1 0 0 0 9 32 F 2 6 2 3 2 3 1 0 3 1 0 0 0 23 Euryopis gertschi M 0 12 11 5 0 0 0 0 0 0 0 0 0 28 31 F 0 1 2 0 0 0 0 0 0 0 0 0 0 3

85

Table 12. The effect of the grazing treatment on the soil compaction (measured in kiloPascals, kPa) of the 3 paddocks in the primary experiment. Measurements were taken at 10 locations in the grazed treatment and 4 locations in the ungrazed treatment. Only the top 15 cm of soil were used in the analyses, and each analysis had error degrees of freedom = 72.

Mean compaction (kPa) Depth Treatment Depth*Treatment

(± SEM) in the top 15 cm of soil (df =5) (df = 1) (df = 5) Paddock Grazed Ungrazed F-ratio P-value F-ratio P-value F-ratio P-value

27 1427 ± 37 1234 ± 42 2.3 0.054 9.3 0.003 0.1 0.988

28 1885 ± 56 1639 ± 110 1.6 0.160 4.7 0.034 0.7 0.627

29 1760 ± 46 1481 ± 45 1.5 0.204 12.7 0.001 0.1 0.989

86

Table 13. The relationship between the grazing treatment and the number of plant species in each paddock and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8. Data analyzed were blocks of five frames of the five-pin sampler.

Mean number of species Paddock 27 Paddock 28 Paddock 29 Year Grazed Ungrazed F- P- Grazed Ungrazed F- P- Grazed Ungrazed F- P- ratio value ratio value ratio value 2005 13.2±1.1 19.6±0.7 24.1 0.001 8.8±0.4 9.2±1.3 <0.1 0.859a 10.0±0.5 18.6±1.2 43.7 <0.001b 2006 10.0±0.8 17.6±1.4 23.1 0.001a 11.2±0.9 13.0±0.5 3.1 0.116 13.2±0.5 19.6±1.5 16.3 0.004 a – square root transformation b – log transformation

87

Table 14. The relationship between the grazing treatment and the percent cover of the most common plant species in each period and sampling year in the primary experiment. Each analysis had error degrees of freedom = 24. Data analyzed were blocks of five frames of the five-pin sampler.

Mean % cover Treatment Paddock Treatment*Paddock Paddock 27 Paddock 28 Paddock 29 (df = 1) (df = 2) (df = 2) Ungraze Species Year Grazed Ungrazed Grazed Grazed Ungrazed F-ratio P-value F-ratio P-value F-ratio P-value d Andropogon 2005 0.0±0.0 0.0±0.0 0.0±0.0 0.4±0.4 0.0±0.0 0.0±0.0 1.0 0.327 1.0 0.383 1.0 0.384 gerardii 2006 0.0±0.0 0.0±0.0 0.0±0.0 1.4±1.0 0.0±0.0 0.0±0.0 2.0 0.166 2.0 0.152 2.0 0.152

Euphorbia 2005 2.4±0.7 0.0±0.0 1.0±0.8 15.2±1.8 0.0±0.0 0.8±0.5 35.0 <0.001 47.4 <0.001 51.3 <0.001 esula 2006 2.0±2.0 0.0±0.0 0.8±0.6 14.8±0.7 0.0±0.0 1.0±1.0 29.2 <0.001 34.5 <0.001 37.5 <0.001

Juniperus 2005 2.0±2.0 0.2±0.2 8.6±3.3 5.2±1.7 8.8±3.4 15.0±1.4 <0.1 0.860 11.2 <0.001 2.5 0.101 horizontalis 2006 1.8±1.2 0.0±0.0 10.2±3.1 3.2±1.7 15.0±3.6 15.4±2.4 2.2 0.285 18.9 <0.001 1.3 0.285

2005 6.8±2.1 18.0±2.1 6.8±0.7 8.0±3.6 13.8±2.6 16.4±1.3 7.3 0.012 6.0 0.008 2.9 0.076 Stipa sp. 2006 0.0±0.0 11.6±2.4 1.6±0.7 7.0±1.4 3.6±1.2 20.0±1.2 98.0 <0.001 16.6 <0.001 8.0 <0.002

2005 8.2±1.3 18.4±0.7 7.0±2.8 19.0±2.8 5.8±0.8 16.4±1.2 53.5 <0.001 0.9 0.440 0.1 0.876 Litter 2006 11.4±2.1 1.2±0.7 14.2±1.7 0.4±0.2 8.2±2.2 0.0±0.0 82.0 <0.001 2.5 0.100 1.9 0.170

Bare 2005 2.6±0.5 4.0±0.8 3.4±1.8 1.4±0.9 2.0±0.5 0.0±0.0 1.3 0.273 3.0 0.069 2.1 0.139 Ground 2006 0.4±0.2 0.0±0.0 0.4±0.2 0.4±0.2 0.2±0.2 0.0±0.0 1.6 0.213 1.3 0.298 0.5 0.587

88

Table 15a. The relationship between the grazing treatment and the distribution of living ground cover types among seven cover classes in the primary experiment in 2005 and 2006. GRA indicates the grazed treatment and UNG indicates the ungrazed treatment. Data are based on 75 1-m2 quadrats in each treatment. Leafy spurge is a subset of the forb data.

Number of quadrats in each class Grasses Forbs Shrubs Leafy Spurge Ground Juniper 2005 2006 2005 2006 2005 2006 2005 2006 2005 2006 Cover Class GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG GRA UNG Absent 1 1 2 1 5 1 1 2 49 29 62 48 60 46 66 49 55 51 40 49 <1 % 13 0 3 0 29 9 10 5 7 5 6 6 6 6 2 0 5 0 2 0 1-5 % 17 8 29 7 21 33 40 20 5 12 7 11 7 11 5 7 2 1 0 1 5-25 % 24 26 26 23 18 26 21 38 3 9 0 7 2 8 2 17 2 4 4 0 25-50% 19 25 8 23 2 5 2 9 4 0 0 3 0 3 0 2 4 0 1 1 50-75 % 1 11 6 16 0 1 1 1 2 2 0 0 0 1 0 0 2 2 6 2 75-100 % 0 4 1 5 0 0 0 0 5 18 0 0 0 0 0 0 5 17 22 22 Weighted 15.9 31.9 16.5 35.5 5.6 9.9 7.7 13.8 10.3 25.0 0.3 3.4 0.7 4.4 0.6 4.7 10.0 22.3 32.0 27.9 Mean % LRχ2 37.533 34.321 4.808 4.818 24.975 3.115 3.851 6.458 20.563 12.709 df 6 6 6 6 6 6 6 6 6 6 p <0.001 <0.001 0.569 0.567 <0.001 0.794 0.697 0.374 0.002 0.048

89

Table 15b. The relationship between the grazing treatment and the distribution of non- living ground cover types among seven cover classes in the primary experiment in 2005 and 2006. GRA indicates the grazed treatment and UNG indicates the ungrazed treatment. Data are frequencies of each cover class for each cover type based on 75 1-m2 quadrats in each treatment.

Number of quadrats in each class Litter Bare Ground 2005 2006 2005 2006 Cover Class GRA UNG GRA UNG GRA UNG GRA UNG Absent 1 0 2 0 13 35 40 71 <1 % 0 0 2 0 0 4 9 1 1-5 % 3 4 5 5 23 29 9 3 5-25 % 9 15 11 8 19 4 13 0 25-50% 28 21 10 18 16 1 4 0 50-75 % 29 23 24 29 4 2 0 0 75-100 % 5 12 21 15 0 0 0 0 Weighted 45.9 46.8 51.9 52.5 16.1 4.2 5.0 0.1 Mean % LRχ2 0.693 9.816 10.021 7.623 df 6 6 6 6 p 0.995 0.133 0.124 0.267

90

Table 16. The relationship between the grazing treatment and the total catch of carabid beetles for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc 2005 61.0±12.1 11.6±1.1 42.3 <0.001b 2 8.6±1.9 4.8±1.0 2.8 0.135a 1 49.8±5.2 26.2±2.0 23.1 0.001b 4 1 2006 100.6±7.8 65.6±5.5 14.6 0.005a 9 29.0±8.0 35.2±4.8 0.4 0.523 7 20.0±3.9 29.4±3.0 3.6 0.093 5

2005 35.2±8.2 42.4±3.4 0.9 0.361a 8 20.0±5.2 30.4±2.7 3.2 0.114 5 19.4±3.7 28.2±3.4 3.1 0.118 10 2 2006 13.4±2.2 24.8±6.9 1.9 0.202b 10 17.4±3.2 22.2±4.6 0.7 0.415 9 8.0±2.3 21.4±3.1 13.7 0.006a 4

2005 3.6±0.6 5.4±0.2 7.7 0.024 5 8.0±2.3 15.6±2.7 4.6 0.065 10 - - - - - 3 2006 1.0±0.3 1.2±0.4 0.2 0.694 2 1.8±0.4 2.8±0.8 0.9 0.362a 5 3.6±1.9 12.8±2.5 10.6 0.012a 8 a – square root transformation b – log transformation c – number of weeks of sampling in the period

91

Table 17. The relationship between the grazing treatment and the catch of Calosoma calidum in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc 2005 23.6±3.6 7.8±1.3 20.4 0.002b 2 4.4±1.8 1.0±0.3 2.5 0.154a 1 36.4±6.2 18.8±1.4 10.6 0.011b 4 1 2006 39.0±3.3 24.8±3.0 10.1 0.013 9 18.0±6.0 17.8±1.9 <0.1 0.975 7 9.2±2.3 15.6±2.8 3.2 0.114 5

2005 18.8±5.2 29.0±2.7 3.1 0.119 8 13.2±5.5 11.4±1.7 0.1 0.764 5 12.2±2.9 21.0±3.3 4.0 0.081 10 2 2006 1.2±0.5 3.0±0.1 3.9 0.084a 10 0.2±0.2 0.0±0.0 8.2 0.021a 9 2.4±1.0 4.2±1.0 1.5 0.249 4

2005 0.0±0.0 0.0±0.0 - - 5 0.2±0.2 0.0±0.0 1.0 0.347 10 - - - - - 3 2006 0.0±0.0 0.0±0.0 - - 2 0.0±0.0 0.0±0.0 - - 5 0.0±0.0 0.2±0.2 1.0 0.347 8 a – square root transformation b – log transformation c - number of weeks of sampling in the period

92

Table 18. The relationship between the grazing treatment and the number of species of carabid beetles for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc 2005 8.6±0.9 3.0±0.3 44.4 <0.001b 2 3.4±0.7 2.6±0.5 1.0 0.357a 1 8.2±2.2 4.6±0.7 1.8 0.211b 4 1 2006 11.4±0.6 9.6±1.1 2.1 0.182 9 7.8±0.7 7.8±1.1 <0.1 1.000 7 7.0±1.3 6.4±0.5 0.1 0.784a 5

2005 9.0±1.5 8.0±0.3 0.4 0.528 8 6.2±1.2 8.8±0.9 3.1 0.116 5 3.8±0.7 5.2±0.8 1.8 0.215 10 2 2006 6.8±1.1 9.6±1.2 3.0 0.121 10 6.6±1.3 7.8±0.9 0.6 0.461 9 4.4±1.3 4.4±0.2 <0.1 1.000 4

2005 2.4±0.2 3.8±0.2 19.6 0.002 5 4.0±0.4 6.8±1.3 3.9 0.082b 10 - - - - - 3 2006 1.0±0.3 1.2±0.4 0.2 0.694 2 1.6±0.2 1.6±0.2 <0.1 1.000 5 2.4±0.7 4.6±0.7 4.7 0.061 8 a – square root transformation b – log transformation c- number of weeks of sampling in the period

93

Table 19. The relationship between the grazing treatment and the Berger Parker index for carabid beetles in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps.

Mean index per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value 2005 0.443±0.077 0.664±0.078 4.1 0.078 0.583±0.091 0.642±0.126 0.1 0.712 0.731±0.094 0.727±0.054 <0.1 0.974 1 2006 0.498±0.058 0.438±0.035 0.7 0.416b 0.575±0.075 0.520±0.035 0.4 0.526 0.480±0.072 0.523±0.057 0.2 0.653

2005 0.518±0.077 0.682±0.023 4.2 0.074 0.603±0.114 0.480±0.050 1.0 0.354 0.693±0.106 0.735±0.053 0.1 0.730 2 2006 0.386±0.031 0.291±0.017 7.4 0.026a 0.540±0.115 0.306±0.023 4.3 0.072b 0.536±0.078 0.516±0.046 <0.1 0.830

2005 0.540±0.058 0.440±0.058 1.5 0.258 0.484±0.060 0.381±0.082 1.0 0.341 - - - - 3 2006 0.700±0.200 0.600±0.187 0.1 0.724 0.733±0.113 0.843±0.067 0.7 0.428 0.658±0.142 0.603±0.070 <0.1 0.925b a – square root transformation b – log transformation

94

Table 20. The relationship between the grazing treatment and the Log Series Alpha index for carabid beetles in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps.

Mean index per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value 2005 1.683±0.110 1.165±0.104 11.7 0.009a 1.619±0.264 1.756±0.346 0.1 0.802a 0.365±0.188 0.187±0.078 0.8 0.407b 1 2006 0.520±0.045 0.480±0.062 0.3 0.618b 0.617±0.082 0.484±0.083 1.3 0.286b 4.135±0.855 2.623±0.384 2.6 0.145

2005 0.599±0.127 0.467±0.022 1.0 0.337b 0.556±0.225 0.611±0.045 0.1 0.816b 0.145±0.123 0.257±0.110 0.5 0.512b 2 2006 2.429±0.343 2.744±0.208 0.6 0.455a 0.575±0.214 0.682±0.050 0.2 0.641b 0.537±0.185 0.240±0.041 2.5 0.154b

2005 0.546±0.344 2.595±0.301 20.1 0.002a 0.691±0.147 0.642±0.142 0.1 0.815b - - - - 3 2006 - - - - 0.324±0.324 0.799±0.336 1.0 0.339a 0.110±0.110 0.413±0.070 5.4 0.048b a – square root transformation b – log transformation

95

Table 21. The relationship between the grazing treatment and the total catch of spiders for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc

2005 24.0±4.9 33.2±3.1 2.5 0.153 1 - - - - - 127.6±17.3 135.0±7.1 0.2 0.702 2 1 2006 60.0±14.1 67.2±9.5 0.2 0.683 4 33.2±4.6 63.0±6.1 14.5 0.005a 3 25.0±6.2 66.2±7.1 17.1 0.003a 2

2005 12.7±4.9 167.4±36.7 12.1 0.008b 4 19.0±6.0 223.0±10.4 288.2 <0.001 2 22.0±6.2 58.4±3.6 25.8 0.001 5 2 2006 50.6±11.1 94.6±11.2 7.8 0.024 5 81.4±9.3 162.2±10.4 33.4 <0.001 5 93.0±10.1 93.8±4.5 <0.1 0.934 2

2005 4.4±1.3 9.2±0.9 8.9 0.021b 3 12.6±1.0 40.0±4.9 56.1 <0.001b 5 - - - - - 3 2006 0.6±0.2 0.2±0.2 1.6 0.242 1 1.6±0.2 2.4±0.7 5.7 0.048b 3 8.4±1.0 11.0±1.7 1.8 0.222 4 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

96

Table 22. The relationship between the grazing treatment and the catch of Pardosa distincta for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc

2005 1.6 ± 0.7 3.6 ± 0.5 4.9 0.058 1 - - - - - 68.0 ± 19.9 63.2 ± 5.8 <0.1 0.972a 2 1 2006 17.8 ± 8.9 10.0 ± 3.3 0.5 0.513b 4 1.0 ± 0.3 14.6 ± 3.0 38.6 <0.001b 3 0.0 ± 0.0 0.0 ± 0.0 - - 2

2005 3.7 ± 2.3 145.9 ± 37.7 5.5 0.050b 4 7.2 ± 3.5 203.2 ± 10.5 312.9 <0.001 2 11.0 ± 5.8 42.0 ± 3.3 21.6 0.002 5 2 2006 13.0 ± 7.5 74.0 ±10.9 22.9 0.001a 5 53.4 ± 8.2 139.8 ± 10.6 35.9 <0.001a 5 63.8 ±10.1 72.0 ± 3.8 0.8 0.398 2

2005 0.0 ± 0.0 7.2 ± 1.2 33.7 <0.001 3 5.8 ± 0.9 25.2 ± 3.9 41.8 <0.001b 5 - - - - - 3 2006 0.0 ±0.0 0.0 ±0.0 - - 1 0.8 ± 0.4 0.0 ± 0.0 4.6 0.065 3 2.0 ± 0.7 5.4 ± 1.0 7.4 0.026 4 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

97

Table 23. The relationship between the grazing treatment and the catch of Alopecosa aculeata for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc

2005 2.0 ±0.8 1.4 ± 0.4 0.1 0.727a 1 - - - - - 7.6 ± 3.5 29.8 ±3.6 19.5 0.002 2 1 2006 4.4 ±1.5 7.4 ± 2.0 1.4 0.263 4 4.4 ± 1.3 14.2 ± 1.2 30.0 <0.001 3 11.6 ± 5.5 52.4 ± 7.8 14.7 0.005a 2

2005 0.0 ± 0.0 0.2 ± 0.2 1.0 0.347 4 0.0 ± 0.0 0.2 ± 0.2 1.0 0.347 2 1.0 ± 0.6 5.6 ± 1.9 10.0 0.013b 5 2 2006 0.0 ± 0.0 0.0 ± 0.0 - - 5 0.2 ± 0.2 0.4 ± 0.4 0.2 0.667 5 2.2 ± 1.0 5.8 ± 1.2 5.4 0.048 2

2005 0.0 ±0.0 0.0 ± 0.0 - - 3 0.2 ± 0.2 0.0 ± 0.0 1.0 0.347 5 - - - - - 3 2006 0.0 ± 0.0 0.0 ± 0.0 - - 1 0.0 ± 0.0 0.0 ± 0.0 - - 3 0.0 ± 0.0 0.4 ± 0.4 1.0 0.347 4 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

98

Table 24. The relationship between the grazing treatment and the number of species of spiders for each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8.

Mean catch per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc Grazed Ungrazed F-ratio P-value Nc

2005 19.4 ± 3.9 26.6 ± 2.2 0.6 0.468 1 - - - - - 19.0 ± 1.5 19.6 ± 1.3 0.1 0.815 2 1 2006 16.4 ± 1.9 18.8 ± 1.4 1.1 0.332 4 15.8 ± 1.8 16.4 ± 2.1 <0.1 0.871b 3 10.6 ± 1.2 10.2 ± 1.1 0.1 0.814 2

2005 8.8 ± 1.4 15.0 ± 1.3 4.9 0.057 4 8.8 ± 1.4 15.0 ± 1.3 5.1 0.055 2 7.8 ± 1.2 10.8 ± 1.2 3.3 0.105a 5 2 2006 10.4 ± 1.4 12.0 ± 0.7 1.1 0.328 5 12.4 ± 0.8 11.0 ± 0.6 1.8 0.220a 5 15.0 ± 1.1 10.5 ± 1.0 8.9 0.017 2

2005 3.8 ± 1.3 2.6 ± 0.7 2.7 0.146b 3 4.8 ± 0.4 8.4 ± 1.0 11.8 0.009 5 - - - - - 3 2006 0.6 ± 0.2 0.2 ± 0.2 1.6 0.242 1 1.2 ± 0.2 2.0 ± 0.5 1.9 0.207 3 0.6 ± 0.2 0.2 ± 0.2 1.6 0.242 4 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

99

Table 25. The relationship between the grazing treatment and the Berger Parker index for spiders in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and was based on blocks of five traps.

Mean index per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value 2005 0.231±0.055 0.204±0.029 0.9 0.359 - - - - 0.496±0.086 0.465±0.026 0.1 0.743 1 2006 0.376±0.041 0.195±0.008 27.1 0.001 0.198±0.027 0.293±0.048 3.4 0.102 0.393±0.104 0.774±0.049 10.9 0.011

2005 0.289±0.033 0.842±0.069 48.7 <0.001 0.331±0.050 0.910±0.011 80.7 <0.001 0.476±0.103 0.720±0.042 4.8 0.059 2 2006 0.429±0.066 0.771±0.025 23.5 0.001 0.642±0.044 0.859±0.012 22.8 0.001 0.680±0.034 0.782±0.015 7.4 0.026

2005 0.292±0.072 0.785±0.116 130.6 <0.001 0.450±0.039 0.624±0.036 10.8 0.011 - - - - 3 2006 0.600±0.245 0.200±0.200 1.6 0.242 0.900±0.100 0.400±0.100 12.5 0.008 0.605±0.105 0.486±0.048 0.7 0.436

100

Table 26. The relationship between the grazing treatment and the Log Series Alpha index for spiders in each period and sampling year in the primary experiment. Each analysis had degrees of freedom = 1,8 and was based on blocks of five traps.

Mean index per five traps per sampling period Paddock 27 Paddock 28 Paddock 29 Period Year Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value Grazed Ungrazed F-ratio P-value 2005 15.348 ± 3.116 10.181 ± 1.216 2.4 0.161 - - - - 6.609 ± 1.035 6.329 ± 0.514 0.1 0.815 1 2006 7.919 ± 0.716 8.953 ± 0.536 1.3 0.281 12.513 ± 2.052 7.290 ± 1.174 4.7 0.062b 12.696 ± 5.499 3.542 ± 0.560 6.5 0.035b

2005 10.245 ± 1.390 4.438 ± 0.646 17.2 0.004 8.313 ± 1.371 3.661 ± 0.398 14.3 0.007b 5.819 ± 0.973 4.007 ± 0.658 2.4 0.162 2 2006 4.445 ± 0.708 3.720 ± 0.301 0.9 0.373 4.353 ± 0.669 2.687 ± 0.207 7.0 0.029b 5.157 ± 0.547 3.206 ± 0.356 9.9 0.014

2005 14.187 ± 12.595 1.581 ± 0.779 3.0 0.143b 3.110 ± 0.573 3.429 ± 0.635 0.1 0.719 - - - - 3 2006 0.000 ± 0.000 0.000 ± 0.000 - - 0.000 ± 0.000 0.000 ± 0.000 - - 1.071± 0.273 0.910 ± 0.389 0.1 0.744b a – square root transformation b – log transformation c – number of samples

101

Table 27. The relationship between the grazing treatment and the soil compaction (measured in kiloPascals, kPa) of the three treatments in the secondary experiment. Measurements were taken at five locations in each treatment. Only the top 15 cm of soil were used in the analysis, which had error degrees of freedom = 72.

Mean compaction (kPa) (± SEM) Depth Treatment Depth*Treatment

in the top 15 cm of soil (df = 5) (df = 2) (df = 10) Spring Graze Fall Graze Spring and F-ratio P-value F-ratio P-value F-ratio P-value Only Only Fall Grazes

1215 ± 45 1199 ± 42 1273 ± 42 9.9 <0.001 1.3 0.292 1.0 0.413

102

Table 28. The relationship between the grazing treatment and the number of plant species in each treatment and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12. Data analyzed were blocks of five frames of the five-pin sampler.

Mean number of species Spring Graze Fall Graze Spring and Year F-ratio P-value Only Only Fall Grazes 2005 14.4±2.0 13.0±1.1 11.0±0.5 1.6 0.236 2006 12.0±0.9 12.8±0.9 10.4±0.7 2.2 0.149

103

Table 29. The relationship between the grazing treatment and the percent cover of the most common plant species in each treatment and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12. Data analyzed were blocks of five frames of the five-pin sampler.

Mean % cover Spring Graze Fall Graze Spring and Year F-ratio P-value Only Only Fall Grazes Andropogon 2005 0.0±0.0 0.0±0.0 0.8±0.8 1.000 0.397 gerardii 2006 0.0±0.0 0.0±0.0 0.0±0.0 - -

Euphorbia 2005 0.6±0.6 1.2±1.2 0.6±0.6 0.167 0.848 esula 2006 2.0±2.0 0.4±0.2 0.0±0.0 0.828 0.461

Juniperus 2005 10.4±2.5 13.0±4.0 14.2±1.2 0.402 0.678 horizontalis 2006 10.6±2.8 10.4±2.5 11.8±2.7 0.081 0.923

2005 8.2±1.2 9.0±2.1 11.2±1.0 1.037 0.384 Stipa sp. 2006 6.2±1.9 13.8±2.6 1.2±0.2 11.816 0.001

2005 13.0±1.8 11.8±1.2 10.2±1.7 0.781 0.480 Litter 2006 13.8±2.8 5.8±1.9 14.0±1.5 4.869 0.028

Bare 2005 1.2±1.0 0.0±0.0 0.0±0.0 1.532 0.256 Ground 2006 0.0±0.0 0.0±0.0 0.0±0.0 - -

104

Table 30a. The relationship between the grazing treatment and the distribution of living ground cover types among seven cover classes in the secondary experiment in 2005 and 2006. SP indicates the Spring treatment, FA indicates the Fall treatment, and SF indicates the Spring & Fall treatment. Data are frequencies of each cover class for each cover type based on 25 1-m2 quadrats in each treatment. Leafy spurge is a subset of the forb data.

Number of quadrats in each class Grasses Forbs Shrubs Leafy Spurge Ground Juniper 2005 2006 2005 2006 2005 2006 2005 2006 2005 2006 Cover Class SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF SP FA SF Absent 0 1 0 0 0 1 0 0 0 0 1 2 4 2 2 6 8 6 25 22 25 22 22 23 6 5 2 6 8 6 <1 % 1 1 3 1 0 3 3 9 4 2 1 5 2 1 0 1 0 0 0 1 0 0 2 1 1 0 0 1 0 0 1-5 % 7 7 6 9 6 11 12 9 12 16 12 14 3 0 1 1 0 0 0 1 0 2 0 1 2 0 1 1 0 0 5-25 % 9 9 12 11 10 7 5 5 8 7 7 3 4 1 4 1 3 4 0 1 0 1 1 0 4 0 5 1 3 4 25-50% 5 5 4 2 8 1 4 1 1 0 4 1 2 5 3 2 2 1 0 0 0 0 0 0 2 4 3 2 2 1 50-75 % 3 2 0 1 1 2 1 1 0 0 0 0 3 3 6 3 2 2 0 0 0 0 0 0 3 2 5 4 2 2 75-100 % 0 0 0 1 0 0 0 0 0 0 0 0 7 13 9 11 10 12 0 0 0 0 0 0 7 14 9 10 10 12 Weighted 21.3 18.8 14.0 16.7 21.2 12.1 13.0 8.3 7.8 6.2 11.7 5.1 37.8 61.1 53.5 49.7 44.8 50.9 0.0 0.7 0.0 0.8 0.6 0.1 37.7 60.0 51.6 48.7 44.8 50.9 Mean % LRχ2 2.702 19.094 0.000 2.111 15.101 7.665 1.021 0.677 19.213 8.396 df 12 12 12 12 12 12 12 12 12 12 P 0.997 0.086 1.000 0.999 0.236 0.812 1.000 1.000 0.084 0.753

105

Table 30b. The relationship between the grazing treatment and the distribution of non- living ground cover types among seven cover classes in the secondary experiment in 2005 and 2006. SP indicates the Spring treatment, FA indicates the Fall treatment, and SF indicates the Spring & Fall treatment. Data are frequencies of each cover class for each cover type based on 25 1-m2 quadrats in each treatment.

Number of quadrats in each class Litter Bare Ground 2005 2006 2005 2006 Cover Class SP FA SF SP FA SF SP FA SF SP FA SF Absent 0 0 0 0 0 0 13 14 14 24 25 25 <1 % 1 0 0 1 1 0 3 2 4 0 0 0 1-5 % 2 3 0 1 1 1 8 7 7 1 0 0 5-25 % 1 8 7 6 3 7 1 1 0 0 0 0 25-50% 7 7 7 2 5 5 0 1 0 0 0 0 50-75 % 8 5 10 5 6 2 0 0 0 0 0 0 75-100 % 6 2 1 10 9 10 0 0 0 0 0 0 Weighted 54.4 35.2 43.2 54.2 55.9 51.8 1.6 3.0 0.9 0.1 0.0 0.0 Mean % LRχ2 0.000 1.812 1.162 0.336 df 12 12 12 12 P 1.000 1.000 1.000 1.000

106

Table 31. The relationship between the grazing treatment and the total catch of carabid beetles for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean catch per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Nc Only Only Fall Grazes 2005 50.8±3.7 61.0±9.1 44.6±8.2 1.3 0.318 4 1 2006 132.6±34.8 96.0±22.3 117.4±18.0 0.5 0.599a 9 2005 32.6±5.8 25.4±2.8 25.8±3.1 0.8 0.474b 5 2 2006 5.4±2.7 2.6±0.9 3.0±0.5 0.3 0.751a 9 2005 3.2±0.7 6.4±2.0 2.4±0.7 2.9 0.096b 6 3 2006 0.6±0.2 1.0±0.4 0.8±0.4 0.3 0.746 2 a – square root transformation b – log transformation c – number of weeks of sampling in the period

107

Table 32. The relationship between the grazing treatment and the catch of Calosoma calidum for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean catch per five traps per sampling period Spring Graze Fall Graze Spring and Fall Period Year F-ratio P-value Nc Only Only Grazes 2005 43.4 ± 5.1 30.0 ± 6.2 34.6 ± 2.5 2.0 0.179 4 1 2006 33.6 ± 6.5 28.8 ± 7.2 40.4 ± 10.9 0.5 0.631 9 2005 19.2 ± 2.3 19.2 ± 3.0 22.6 ± 2.5 0.6 0.584 5 2 2006 0.6 ± 0.4 1.0 ± 0.3 1.6 ± 0.8 0.8 0.461 9 2005 0.2 ± 0.2 0.0 ± 0.0 0.2 ± 0.2 0.5 0.619 6 3 2006 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 - - 2 a – square root transformation b – log transformation c – number of weeks of sampling in the period

108

Table 33. The relationship between the grazing treatment and the number of species of carabid beetles for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean # species per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Nc Only Only Fall Grazes 2005 7.4±0.9 7.4±0.9 8.2±0.6 0.3 1 0.460 4 2006 9.4±0.9 8.6±0.8 8.6±0.5 0.4 0.691 9 2005 5.0±1.0 4.0±0.9 5.6±1.5 0.5 2 0.642 5 2006 2.0±0.7 2.2±0.9 2.6±0.5 0.2 0.832 9 2005 4.0±0.9 2.0±0.4 2.8±0.6 2.0 a 3 0.177 6 2006 1.0±0.4 0.6±0.2 0.8±0.4 0.3 0.746 2 a – square root transformation b – log transformation c – number of weeks of sampling in the period

109

Table 34. The relationship between the grazing treatment and the Berger-Parker index for carabid beetles in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 (except for Period 3 in 2006 which has df = 2,6) and is based on blocks of five traps.

Mean index per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Only Only Fall Grazes 2005 0.729±0.048 0.655±0.057 0.684±0.034 0.6 0.552 1 2006 0.477±0.038 0.589±0.064 0.549±0.034 1.4 0.282 2005 0.762±0.066 0.756±0.083 0.732±0.073 <0.1 0.956 2 2006 0.642±0.131 0.641±0.154 0.550±0.133 0.2 0.861 2005 0.475±0.080 0.687±0.135 0.480±0.138 1.0 0.397 3 2006 0.667±0.167 1.000±0.000 0.833±0.167 1.5 0.296

110

Table 35. The relationship between the grazing treatment and the Log Series Alpha index for carabid beetles in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 1,8 and is based on blocks of five traps.

Mean index per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Only Only Fall Grazes 2005 2.315±0.395 2.695±0.406 2.798±0.265 0.5 0.620 1 2006 2.679±0.229 2.635±1.997 4.037±1.415 3.2 0.078 2005 2.083±0.618 1.371±0.341 2.133±0.703 0.5 0.592 2 2006 5.786±1.930 2.635±1.997 4.037±1.415 0.7 0.543 2005 0.475±0.080 0.687±0.135 0.480±0.138 0.5 0.660 3 2006 - - - - -

111

Table 36. The relationship between the grazing treatment and the total catch of spiders for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean catch per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Nc Only Only Fall Grazes 2005 230.2 ± 34.7 254.6 ± 24.2 274.6 ± 22.1 0.7 0.539 2 1 2006 109.4 ± 15.4 78.0 ± 7.0 55.4 ± 3.5 9.5 0.003b 4 2005 43.0 ± 11.2 68.2 ± 9.6 82.6 ± 7.1 4.5 0.035 3 2 2006 7.6 ± 1.7 18.2 ± 8.3 11.0 ± 3.0 0.1 0.895b 5 2005 25.0 ± 2.2 13.0 ± 3.7 17.6 ± 3.1 4.0 0.047 3 3 2006 0.8 ± 0.4 1.0 ± 0.4 1.6 ± 0.4 1.0 0.383 1 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

112

Table 37. The relationship between the grazing treatment and the catch of Pardosa distincta for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean catch per five traps per sampling period Spring Graze Spring and Fall Period Year Fall Graze Only F-ratio P-value Nc Only Grazes 2005 124.0 ± 30.2 132.0 ± 17.7 158.0 ± 31.5 0.4 0.662 2 1 2006 23.2 ± 5.3 16.8 ± 2.0 10.2 ± 2.6 3.3 0.074 4 2005 37.0 ± 11.2 61.2 ± 8.6 72.4 ± 7.8 3.8 0.053 3 2 2006 5.0 ± 0.9 11.2 ± 4.6 7.0 ± 2.6 1.0 0.382 5 2005 6.4 ± 1.1 7.6 ± 2.2 6.6 ± 0.7 0.1 0.919a 3 3 2006 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 - - 1 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

113

Table 38. The relationship between the grazing treatment and the catch of Alopecosa aculeata for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean catch per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Nc Only Only Fall Grazes 2005 38.8 ± 8.3 41.4 ± 8.6 44.0 ± 8.4 0.1 0.910 2 1 2006 33.0 ± 8.8 21.6 ± 3.9 15.6 ± 2.2 2.4 0.133 4 2005 0.4 ± 0.2 1.4 ± 0.5 0.8 ± 0.4 1.3 0.307a 2 3 2006 0.0 ± 0.0 0.2 ± 0.2 0.0 ± 0.0 1.0 0.397 5 2005 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 - - 3 3 2006 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 - - 1 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

114

Table 39. The relationship between the grazing treatment and the number of species of spiders for each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12.

Mean # species per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Nc Only Only Fall Grazes 2005 26.2 ± 1.7 28.8 ± 1.8 24.2 ± 1.8 1.7 0.219 2 1 2006 21.4 ± 2.1 18.6 ± 2.1 16.0 ± 1.6 1.9 0.190 4 2005 6.4 ± 0.2 7.0 ± 0.7 8.4 ± 1.6 1.0 0.392 3 2 2006 3.2 ± 0.7 3.8 ± 1.7 4.0 ± 0.5 0.4 0.666c 5 2005 8.4 ± 1.2 4.4 ± 0.5 6.8 ± 1.2 3.8 0.051 3 3 2006 0.6 ± 0.2 0.8 ± 0.4 1.2 ± 0.2 1.2 0.344 1 a – square root transformation b – log transformation c – number of weeks of sampling represented in the analysis

115

Table 40. The relationship between the grazing treatment and the Berger Parker index for spiders in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 and was based on blocks of five traps.

Mean index per five traps per sampling period Spring Graze Fall Graze Spring and Period Year F-ratio P-value Only Only Fall Grazes 2005 0.519 ± 0.065 0.514 ± 0.045 0.555 ± 0.072 0.1 1 0.901 2006 0.321 ± 0.018 0.279 ± 0.039 0.310 ± 0.037 0.5 0.592 2005 0.832 ± 0.030 0.898 ± 0.007 0.873 ± 0.029 1.8 2 0.204 2006 0.673 ± 0.069 0.558 ± 0.155 0.592 ± 0.076 1.1 0.366 2005 0.389 ± 0.041 0.580 ± 0.056 0.413 ± 0.048 2.9 3 0.097 2006 0.600 ± 0.245 0.500 ± 0.224 0.933 ± 0.067 1.4 0.296

116

Table 41. The relationship between the grazing treatment and the Log Series Alpha index for spiders in each period and sampling year in the secondary experiment. Each analysis had degrees of freedom = 2,12 and was based on blocks of five traps.

Mean index per five traps per sampling period Spring Graze Fall Graze Spring and Fall Period Year F-ratio P-value Only Only Grazes 2005 7.852 ± 0.713 8.443 ± 0.620 6.585 ± 0.842 1.7 0.226 1 2006 8.237 ± 1.147 7.927 ± 1.095 7.922 ± 1.521 < 0.1 0.980 2005 2.273 ± 0.250 1.977 ± 0.202 2.492 ± 0.608 0.4 0.665 2 2006 2.655 ± 0.882 2.068 ± 0.810 2.841 ± 0.477 0.3 0.763 2005 4.673 ± 1.023 2.872 ± 0.498 4.246 ± 0.841 1.3 0.301 3 2006 0.796 ± 0.000 0.796 ± 0.000 1.709 ± 0.913 0.3 0.816

117 Figure 1. Location of the Yellow Quill Mixed Grass Prairie Preserve (YQMGPP) within the province of Manitoba.

118

119 Figure 2. Layout of paddocks 27, 28, 29, and 34 on the Yellow Quill Mixed Grass Prairie Preserve, and the locations of the pitfall trap groups in the grazed areas.

12 0

121 Figure 3. The layout of the pitfall traps on Paddock 34.

122 123 Figure 4. Pin Sampler apparatus showing 5 pins.

124 125 Figure 5a. Vegetation sample locations in 2005 and 2006 in the ungrazed areas of Paddocks 27, 28, and 29, using a pin sampler.

126

127 Figure 5b. Vegetation sample locations in 2005 and 2006 in the grazed areas of Paddocks 27, 28, and 29, using a pin sampler. This pattern was repeated for each group of 5 pitfall traps.

128

129 Figure 6. Vegetation sample locations in 2005 and 2006 on Paddock 34, using a pin sampler. These were also the locations of the 1 m2 quadrats in 2006.

130 131 Figure 7. The rebar cage in place over a pitfall trap.

132 133 Figure 8. The layout of pitfall traps in the grazing exclosures.

134 135 Figure 9. Sampling dates included in each of the three time periods in 2005 for which samples were used in the analysis.  = Period 1 is prior to grazing,  = Period 2 is between the spring and fall grazes, and  = Period 3 is after the fall graze when the cattle have been removed. Samples were not identified for the first three sampling days because not all the pitfall traps were in place.

136

Paddock Sampling Date 27 28 29 34 May 12 SAMPLES May 19 SAMPLES NOT USED IN ANALYSES NOT USED IN ANALYSES May 26 June 2   June 9 SPRING GRAZE   June 16 SPRING June 23 GRAZE June 30  SPRING SPRING July 7 GRAZE GRAZE July 14 July 21 July 28  Aug 4 FALL GRAZE  Aug 11 Aug 18  Aug 25

Sept 1 FALL Sept 8 FALL GRAZE GRAZE Sept 15 Sept 22  Sept 29 Oct 6  Oct 13  FALL GRAZE Oct 20

Oct 27

137 Figure 10. Sampling dates included in each of the three time periods in 2006 for which samples were used in the analysis.  = Period 1 is prior to grazing,  = Period 2 is between the spring and fall grazes, and  = Period 3 is after the fall graze when the cattle have been removed.

138

Paddock Sampling Date 27 28 29 34 May 3 May 10 May 17  May 24  May 31  

June 8 SPRING GRAZE June 15

June 22 SPRING June 29 GRAZE  July 6 SPRING SPRING July 13 GRAZE GRAZE July 20 July 27 Aug 3  Aug 10 FALL GRAZE Aug 17   Aug 24 Aug 31 Sept 7 FALL Sept 14 GRAZE Sept 21

Sept 28 FALL Oct 5 FALL GRAZE  GRAZE Oct 12  Oct 19   Oct 26

139 Figure 11. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 27, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm.

140 141 Figure 12. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 28, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm.

142

143 Figure 13. Line graph showing the soil compaction in the grazed and ungrazed treatments in paddock 29, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm.

144

145 Figure 14. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 in 2005 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_pla = Agonum placidum, Ama_coe = Amara coelebs, Ama_con = Amara convexa, Ama_far = Amara farcta, Ama_ell = Amara ellipsis, Ama_ten = Amara tenax, Ani_mer = Anisodactylus merula, Ani_rus = Anisodactylus rusticus, Bem_nit = Bembidion nitidum, Cal_vir = Calleida viridis amoena, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Car_tae = Carabus taedatus agassii, Chl_pur = Chlaenius purpuricollis purpuricollis, Chl_tom = Chlaenius tomentosus tomentosus, Cic_lon = Cicindela longilabris longilabris, Cic_neb = Cicindela nebraskana nebraskana, Cic_nvs = Cicindela nebraskana var. spissitarsis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Syn_ame = Syntomus americanus

146

147 Figure 15. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_cue = Agonum cupripenne, Ago_pla = Agonum placidum, Ago_tri = Agonum trigeminum, Ama_coe = Amara coelebs, Ama_con = Amara convexa, Ama_fam = Amara familiaris, Ama_lit = Amara littoralis, Ama_obe = Amara obesa, Ama_ten = Amara tenax, Bem_mut = Bembidion mutatum, Bem_nit = Bembidion nitidum, Bem_qua = Bembidion quadrimaculatum, Cal_vir = Calleida viridis amoena, Cal_cal = Calosoma calidum, Car_ser = Carabus serratus, Car_tae = Carabus taedatus agassii, Chl_pur = Chlaenius purpuricollis purpuricollis, Chl_tom = Chlaenius tomentosus tomentosus, Cic_lon = Cicindela longilabris longilabris, Cic_neb = Cicindela nebraskana nebraskana, Har_opa = Harpalus opacipennis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_fem = Pterostichus femoralis, Ste_con = Stenolophus conjunctus, Syn_ame = Syntomus americanus

148

149 Figure 16. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_obs = Agonum obsoletum, Ago_pla = Agonum placidum, Ama_aen = Amara aenea, Ama_ell = Amara ellipsis, Ama_lit = Amara littoralis, Ama_que = Amara quenseli, Bem_mus = Bembidion muscicola, Bem_nit = Bembidion nitidum, Bem_qua = Bembidion quadrimaculatum, Bem_rap = Bembidion rapidum, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Car_tae = Carabus taedatus agassii, Chl_pur = Chlaenius purpuricollis purpuricollis, Cic_neb = Cicindela nebraskana nebraskana, Dip_obt = Diplocheila obtusa, Har_opa = Harpalus opacipennis, Har_pen = Harpalus pensylvanicus, Har_spa = Harpalus spadiceus, Har_ven = Harpalus ventralis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_mel = Pterostichus melanarius, Ste_con = Stenolophus conjunctus

150

151 Figure 17. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_tri = Agonum trigeminum, Ama_con = Amara convexa, Ama_lun = Amara lunicollis, Ama_obe = Amara obesa, Bem_mut = Bembidion mutatum, Cal_vir = Calleida viridis amoena, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Car_ser = Carabus serratus, Car_tae = Carabus taedatus agassii, Chl_pur = Chlaenius purpuricollis purpuricollis, Chl_tom = Chlaenius tomentosus tomentosus, Cic_lon = Cicindela longilabris longilabris, Cic_neb = Cicindela nebraskana nebraskana, Cic_nvs = Cicindela nebraskana var. spissitarsis, Cic_pun = Cicindela punctulata punctulata, Cym_bor = Cymindis borealis, Cym_cri = Cymindis cribicollis, Cym_pla = Cymindis planipennis, Har_ery, Harpalus erythropus, Har_opa = Harpalus opacipennis, Har_pen = Harpalus pensylvanicus, Har_som = Harpalus somnulentus, Har_ven = Harpalus ventralis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_mel = Pterostichus melanarius, Pte_pen = Pterostichus pensylvanicus, Ste_con = Stenolophus conjunctus Tri_man = Trichocellus mannerheimi

152 153 Figure 18. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_cue = Agonum cupripenne, Ago_pla = Agonum placidum, Ama_coe = Amara coelebs, Ama_obe = Amara obesa, Ama_que = Amara quenseli, Chl_pur = Chlaenius purpuricollis purpuricollis, Cic_pun = Cicindela punctulata punctulata, Cym_bor = Cymindis borealis, Cym_pla = Cymindis planipennis, Har_her, Harpalus herbivagus, Har_opa = Harpalus opacipennis, Har_pen = Harpalus pensylvanicus, Har_spa = Harpalus spadiceus, Har_ven = Harpalus ventralis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_fem = Pterostichus femoralis, Syn_ame = Syntomus americanus

154 155 Figure 19. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2006 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_tri = Agonum trigeminum, Ama_lat = Amara latior, Ama_lun = Amara lunicollis, Ama_obe = Amara obesa, Bem_mut = Bembidion mutatum, Cal_vir = Calleida viridis amoena, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Car_tae = Carabus taedatus agassii, Cic_nvs = Cicindela nebraskana var. spissitarsis, Cym_pil = Cymindis pilosus, Cym_pla = Cymindis planipennis, Har_ery, Harpalus erythropus, Har_som = Harpalus somnulentus, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_fem = Pterostichus femoralis, Syn_ame = Syntomus americanus, Tri_man = Trichocellus mannerheimi

156 157 Figure 20. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 22 of 53 species caught in this period are shown on the graph.

Species codes: Alo_acu = Alopecosa aculeata, Arc_rub = Arctosa rubicunda, Chr_pel = Chrysso pelyx, Col_sio = Coloncus siou, Dra_neg = Drassodes neglectus, Eri_atr = Erigone atra, Eur_ger = Euryopis gertschi, Eur_pep = Euryopis pepini, Gna_mus = Gnaphosa muscorum, Gra_cap = Grammonota capitata, Hab_bor = Habronattus borealis, Hal_plu = Halorates plumosus, Hap_bic = Haplodrassus bicornis, Lep_alp = Lepthyphantes alpinus, Mas_sun = Maso sundevallii, Mic_lat = Micaria laticeps, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Phr_bor = Phrurotimpus borealis, Sch_mcc = Schizocosa mccooki, Ten_for = Tenneseelum formicum, Tha_col = Thanatus coloradensis, Tha_rub = Thanatus rubicellus, Xys_lucta = Xysticus luctans, Xys_pel = Xysticus pellax

158 159 Figure 21. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 23 of 48 species caught in this period are shown on the graph.

Species codes: Alo_acu = Alopecosa aculeata, Arc_rub = Arctosa rubicunda, Clu_kio = Clubiona kiowa, Eur_ger = Euryopis gertschi, Eur_pep = Euryopis pepini, Eva_hoy = Evarcha hoyi, Hab_alt = Habronattus altanus, Hab_bor = Habronattus borealis, Hab_cog = Habronattus cognatus, Hah_cin = Hahnia cinerea, , Hap_sig = Haplodrassus signifer, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Phi_joh = Phiddipus johnsoni, Poc_ame = Pocadicnemis americana, Sch_mcc = Schizocosa mccooki, Sco_pal = Scotinotylus pallidus, Tha_for = Thanatus formicinus, Tha_rub = Thanatus rubicellus, Xys_amp = Xysticus ampullatus, Xys_lucta = Xysticus luctans, Xys_mon = Xysticus montanensis, Zel_exi = Zelotes exiguoides

160

161 Figure 22. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 19 of 52 species caught in this period are shown on the graph.

Species codes: Age_uta = Agelenopsis utahana, Cer_lat = Ceratinops latus, Col_sio = Coloncus siou, Dra_neg = Drassodes neglectus, Eno_mar = Enoplognatha marmorata, Eri_ale = Erigone aletris, Eri_atr = Erigone atra, Eur_ger = Euryopis gertschi, Eur_pep = Euryopis pepini, Gra_cap = Grammonota capitata, Hab_bor = Habronattus borealis, Hab_cog = Habronattus cognatus, Mic_lat = Micaria laticeps, Par_dis = Pardosa distincta, Sch_mcc = Schizocosa mccooki, Ten_for = Tenneseelum formicum, Tha_col = Thanatus coloradensis, Tha_rub = Thanatus rubicellus, Xys_gul = Xysticus gulosus, Xys_lucta = Xysticus luctans, Xys_pel = Xysticus pellax, Zel_fra = Zelotes fratris, Zel_hen = Zelotes hentzi, Zel_las = Zelotes lasalanus

162 163 Figure 23. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 21 of 54 species caught in this period are shown on the graph.

Species codes: Alo_acu = Alopecosa aculeata, Cer_bru = Ceratinella brunnea, Cer_lat = Ceratinops latus, Clu_kio = Clubiona kiowa, Col_sio = Coloncus siou, Epe_tril = Eperigone trilobata, Eur_pep = Euryopis pepini, Gra_cap = Grammonota capitata, Hab_cog = Habronattus cognatus, Lep_alp = Lepthyphantes alpinus, Mic_lat = Micaria laticeps, Neo_ara = Neoscona arabesca, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Pel_wri = Pellenes wrighti, Phi_joh = Phiddipus johnsoni, Phr_bor = Phrurotimpus borealis, Poc_ame = Pocadicnemis americana, Sch_mcc = Schizocosa mccooki, Tha_rub = Thanatus rubicellus, Tha_str = Thanatus striatus, Xys_eme = Xysticus emertoni, Xys_fox = Xysticus ferox, Xys_pel = Xysticus pellax

164

165 Figure 24. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 20 of 34 species caught in this period are shown on the graph.

Species codes: Age_uta = Agelenopsis utahana, Arc_rub = Arctosa rubicunda, Cas_des = Castianeira descripta, Cas_lon = Castianeira longipalpa, Eur_pep = Euryopis pepini, Hab_alt = Habronattus altanus, Hab_bor = Habronattus borealis, Hab_cog = Habronattus cognatus, Hog_fro = Hogna frondicola, Mic_lon = Micaria longipes, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Sch_mcc = Schizocosa mccooki, Tha_rub = Thanatus rubicellus, The_pra = Theridion prataeum, Tut_sim = Tutelina similes, Xys_gul = Xysticus gulosus, Xys_mon = Xysticus montanensis, Xys_pel = Xysticus pellax, Zel_las = Zelotes lasalanus

166 167 Figure 25. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 2 (in between the spring and fall grazes) in 2006 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 23 of 41 species caught in this period are shown on the graph.

Species codes: Age_act = Agelenopsis actuosa. Age_uta = Agelenopsis utahana, Cas_des = Castianeira descripta, Cas_lon = Castianeira longipalpa, Col_sio = Coloncus siou, Eur_pep = Euryopis pepini, Hab_ame = Habronattus americanus, Hab_bor = Habronattus borealis, Hap_sig = Haplodrassus signifer, Nod_mat = Nodocion mateonus, Par_dis = Pardosa distincta, Par_mac = Pardosa mackenziana, Par_moe = Pardosa moesta, Phi_pur = Phiddipus purpuratus, Phr_cer = Phrurotimpus certus, Sch_mcc = Schizocosa mccooki, Tha_rub = Thanatus rubicellus, Xys_auc = Xysticus auctificus, Xys_gul = Xysticus gulosus, Xys_nig = Xysticus nigromaculatus, Xys_pel = Xysticus pellax, Zel_hen = Zelotes hentzi, Zel_las = Zelotes lasalanus

168 169 Figure 26. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 27 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 18 of 50 species caught in this period are shown on the graph.

Species codes: Age_uta = Agelenopsis utahana, Agr_pra = Agroeca pratensis, Cal_plu = Callilepsis pluto, Cas_lon = Castianeira longipalpa, Cen_syl = Centromerus sylvaticus, Cer_lat = Ceratinops latus, Cic_arc = Cicurina arcuata, Epe_trid = Eperigone tridentate, Eri_ale = Erigone aletris, Ero_can = Ero canionis, Geo_mis = Geolycosa missouriensis, Gon_cra = Gonatium crassipalpum, Gra_cap = Grammonota capitata, Hab_alt = Habronattus altanus, Hab_dec = Habronattus decorus, Hah_cin = Hahnia cinerea, Lar_bor = Larinia borealis, Lep_alp = Lepthyphantes alpinus, Mis_cel = Misumenops celer, Par_dis = Pardosa distincta, Par_mac = Pardosa mackenziana, Sch_mcc = Schizocosa mccooki, Sco_alp = Scotinotylus alpinus, Sco_pug = Scotinella pugnata, Ten_for = Tenneseelum formicum, Wal_com = Walckenaeria communis, Xys_gul = Xysticus gulosus, Xys_mon = Xysticus montanensis, Xys_tria = Xysticus triangulosus,

170

171 Figure 27. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2005 from paddock 28 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 20 of 34 species caught in this period are shown on the graph.

Species codes: Age_act = Agelenopsis actuosa, Ara_tri = Araneus trifolium, Cas_lon = Castianeira longipalpa, Cer_lat = Ceratinops latus, Cic_arc = Cicurina arcuata, Eri_ale = Erigone aletris, Hab_alt = Habronattus altanus, Hab_bor = Habronattus borealis, Hab_cog = Habronattus cognatus, Hog_fro = Hogna frondicola, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Sch_mcc = Schizocosa mccooki, Tha_for = Thanatus formicinus, Tut_sim = Tutelina similes, Wal_com = Walckenaeria communis, Xys_gul = Xysticus gulosus, Xys_mon = Xysticus montanensis, Xys_pel = Xysticus pellax, Zel_hen = Zelotes hentzi

172

173 Figure 28. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from ungrazed treatment,  from grazed treatment) in Period 3 (after the fall graze) in 2006 from paddock 29 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba. The top 18 of 28 species caught in this period are shown on the graph.

Species codes: Age_pot = Agelenopsis potteri, Agr_pra = Agroeca pratensis, Alo_acu = Alopecosa aculeata, Cal_plu = Callilepsis pluto, Cas_des = Castianeira descripta, Cas_lon = Castianeira longipalpa, Cen_syl = Centromerus sylvaticus, Cic_arc = Cicurina arcuata, Clu_kio = Clubiona kiowa, Dra_neg = Drassodes neglectus, Eur_pep = Euryopis pepini, Geo_mis = Geolycosa missouriensis, Gna_mus = Gnaphosa muscorum, Gon_cra = Gonatium crassipalpum, Gra_cap = Grammonota capitata, Hab_alt = Habronattus altanus, Hab_bor = Habronattus borealis, Hab_dec = Habronattus decorus, Hah_cin = Hahnia cinerea, Hog_fro = Hogna frondicola, Lep_alp = Lepthyphantes alpinus, Mis_cel = Misumenops celer, Par_dis = Pardosa distincta, Sch_mcc = Schizocosa mccooki, Sco_pug = Scotinella pugnata, Xys_fox = Xysticus ferox, Xys_gul = Xysticus gulosus, Xys_tria = Xysticus triangulosus

174 175 Figure 29. Line graph showing the soil compaction in the three treatments in paddock 34, measured in kilopascals (kPa) at 2.5 cm intervals, to a depth of 15 cm. The Spring treatment only received a single graze in the spring, the Fall treatment only received a single graze in the fall, and the Spring/Fall treatment received both a spring and a fall graze.

176 177 Figure 30. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_cue = Agonum cupripenne, Ama_coe = Amara coelebs, Ama_con = Amara convexa, Ama_ell = Amara ellipsis, Ama_lit = Amara littoralis, Ama_ten = Amara tenax, Cal_cal = Calosoma calidum, Cal_fri = Calosoma frigidum, Chl_tom = Chlaenius tomentosus tomentosus, Cic_lon = Cicindela longilabris longilabris, Cic_neb = Cicindela nebraskana nebraskana, Cic_nvs = Cicindela nebraskana var. spissitarsis, Cic_scu = Cicindela scutellaris lecontei, Har_nig = Harpalus nigritarsus, Pas_elo = Pasimachus elongatus, Poe_cov = Poecilus corvus, Poe_luc = Poecilus lucublandus lucublandus, Ste_con = Stenolophus conjunctus, Syn_ame = Syntomus americanus

178

179 Figure 31. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cue = Agonum cupripenne, Ago_cum = Agonum cupreum, Ago_err = Agonum errans, Ago_pic = Agonum piceolum, Ago_pla = Agonum placidum, Ago_ret = Agonum retractum, Ama_lun = Amara lunicollis, Ama_ten = Amara tenax, Bem_qua = Bembidion quadrimaculatum, Cal_fri = Calosoma frigidum, Car_tae = Carabus taedatus agassii, Chl_pen = Chlaenius pennsylvanicus pennsylvanicus, Chl_tom = Chlaenius tomentosus tomentosus, Cic_lon = Cicindela longilabris longilabris, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Ste_con = Stenolophus conjunctus, Syn_ame = Syntomus americanus

180

181 Figure 32. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_tri = Agonum trigeminum, Ama_lun = Amara lunicollis, Ama_obe = Amara obesa, Bem_mut = Bembidion mutatum, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Cal_vir = Calleida viridis amoena, Car_tae = Carabus taedatus, Car_ser = Carabus serratus, Chl_tom = Chlaenius tomentosus tomentosus, Cic_nvs = Cicindela nebraskana var. spissitarsis, Har_ery = Harpalus erythropus, Har_som = Harpalus somnulentus, Har_ven = Harpalus ventralis, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Syn_ame = Syntomus americanus, Syn_imp = Synuchus impunctatus, Tri_man = Trichocellus mannerheimi

182 183 Figure 33. Principal Components Analysis ordination diagram of carabid species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Ago_cum = Agonum cupreum, Ago_tri = Agonum trigeminum, Ama_con = Amara convexa, Ama_lun = Amara lunicollis, Ama_obe = Amara obesa, Bem_mut = Bembidion mutatum, Cal_cal = Calosoma calidum, Cal_lep = Calosoma lepidum, Car_ser = Carabus serratus, Car_tae = Carabus taedatus agassii, Chl_pur = Chlaenius purpuricollis, Cic_nvs = Cicindela nebraskana var. spissitarsis, Har_ery = Harpalus erythropus, Har_som = Harpalus somnulentus, Pas_elo = Pasimachus elongatus, Poe_luc = Poecilus lucublandus lucublandus, Pte_mel = Pterostichus melanarius, Tri_man = Trichocellus mannerheimi

184 185 Figure 34. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Alo_acu = Alopecosa aculeata, Arc_rub = Arctosa rubicunda, Cer_cra = Ceraticelus crassiceps, Col_sio = Coloncus siou, Eur_pep = Euryopis pepini, Gra_cap = Grammonota capitata, Hap_sig = Haplodrassus signifer, Lep_alp = Lepthyphantes alpinus, Mic_lat = Micaria laticeps, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Poc_ame = Pocadicnemis americana, Ser_cap = Sergiolus capulatus, Tha_for = Thanatus formicinus, Tro_ter = Trochosa terricola, Xys_amp = Xysticus ampullatus, Xys_lucta = Xysticus luctans, Zel_exi = Zelotes exiguoides, Zel_las = Zelotes lasalanus

186 187 Figure 35. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 1 (before any grazing had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Alo_acu = Alopecosa aculeata, Arc_rub = Arctosa rubicunda, Cer_nig = Ceratinopsis nigriceps, Clu_obe = Clubiona obesa, Dra_neg = Drassodes neglectus, Eur_ger = Euryopis gertschi, Gra_cap = Grammonota capitata, Hap_sig = Haplodrassus signifer, Hog_fro = Hogna frondicola, Lep_alp = Lepthyphantes alpinus, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Phi_his = Philodromus histrio, Phi_joh = Phiddipus johnsoni, Sch_mcc = Schizocosa mccooki, Tha_col = Thanatus coloradensis, Tha_rub = Thanatus rubicellus, Wal_dig = Walckenaeria digitata, Xys_amp = Xysticus ampullatus, Xys_lucta = Xysticus luctans, Xys_tria = Xysticus triangulosus

188

189 Figure 36. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Alo_acu = Alopecosa aculeata, Arc_rub = Arctosa rubicunda, Cas_des = Castianeira descripta, Cer_cre = Ceratinops crenatus, Dra_neg = Drassodes neglectus, Epe_tri = Eperigone trilobata, Hab_bor = Habronattus borealis, Mic_lat = Micaria laticeps, Par_dis = Pardosa distincta, Par_moe = Pardosa moesta, Phi_joh = Phiddipus johnsoni, Phi_whi = Phiddipus whitmani, Phr_cer = Phrurotimpus certus, Pir_min = Pirata minutus, Sch_mcc = Schizocosa mccooki, Tha_col = Thanatus coloradensis, Tha_rub = Thanatus rubicellus, Xys_amp = Xysticus ampullatus, Xys_pel = Xysticus pellax, Zel_las = Zelotes lasalanus

190 191 Figure 37. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 2 (after the spring graze had occurred) in 2006 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Age_act = Agelenopsis actuosa, Alo_acu = Alopecosa aculeata, Cas_des = Castianeira descripta, Cas_lon = Castianeira longipalpa, Gna_mus = Gnaphosa muscorum, Hab_bor = Habronattus borealis, Hog_fro = Hogna frondicola, Par_dis = Pardosa distincta, Par_ont = Pardosa ontariensis, Phi_joh = Phiddipus johnsoni, Sch_mcc = Schizocoza mccooki, Tha_col = Thanatus coloradensis, Xys_lucta = Xysticus luctans, Xys_pel = Xysticus pellax, Zel_las = Zelotes lasalanus

192

193 Figure 38. Principal Components Analysis ordination diagram of spider species and pitfall traps ( from Spring treatment, from Spring/Fall treatment, and  from Fall treatment) in Period 3 (after both grazes had occurred) in 2005 from paddock 34 of the Yellow Quill Mixed Grass Prairie Preserve, Manitoba.

Species codes: Age_pot = Agelenopsis potteri, Ara_sae = Araneus saevus, Ara_tri = Araneus trifolium, Cas_lon = Castianeira longipalpa, Cen_syl = Centromerus sylvaticus, Cic_arc = Cicurina arcuata, Cic_rob = Cicurina robusta, Eri_ale = Erigone aletris, Eri_atr = Erigone atra, Hah_cin = Hahnia cinerea, Hog_fro =Hogna frondicola, Lep_alp = Lepthyphantes alpinus, Par_dis = Pardosa distincta, Sch_mcc = Schizocosa mccooki, Tro_ter = Trochosa terricola, Xys_eme = Xysticus emertoni, Xys_gul = Xysticus gulosus, Wal_com = Walckenaeria communis

194 195 DISCUSSION

Experimental Design

The design of both the experiments in this study was not ideal as a result of the nature of the rotational grazing system being studied. The three paddocks in the primary experiment were pseudo-replicates because the cattle started at different times on each paddock and on different paddocks in each sampling year, at the discretion of the cattle producer and The Nature Conservancy of Canada. Therefore, the grazing treatment was not applied when environmental and temporal conditions were the same and the three paddocks cannot be compared directly. In the secondary experiment, there was no replication as no other paddock was available to use. Again, the timing of the grazing was not the same in either sampling year. A consequence of these issues is that I cannot be sure when I find a significant treatment effect of whether this arose because of a peculiarity in an individual paddock rather than as a genuine effect of the grazing treatment. In the primary experiment, if I observe the same pattern and significance in each paddock then I am fairly confident that this is a response to grazing rather than to local conditions.

Another issue that arose in this study was the destruction of the pitfall traps by the cattle whenever they grazed on a paddock. I was obliged to analyze data only from periods when there were no cattle. The timeline of the study was divided into three periods for data analysis. However, these periods could not be the same length or at the same time and this must be borne in mind when interpreting the results of the analyses.

196 Primary Experiment

The objective of the primary experiment was to determine the impact that the current twice-over rotational grazing regime has on the abundance and diversity of the carabid beetle and spider assemblages on the Yellow Quill Prairie. Environmental components such as soil compaction and the cover of various types of vegetation were used to supplement the invertebrate data to provide a more complete understanding of the impact of this particular disturbance.

Soil Compaction

In this study, the soil in the grazed treatment was significantly more compacted than in the ungrazed treatment in all three paddocks. Lodge (1954) did a study on the mixed grass prairie in Saskatchewan and concluded that grazing leads to soil compaction and a decrease in the ability of soil to retain water. Fleischner (1994) did a review of numerous grazing studies and reached the same conclusion, adding that desertification is of particular concern in arid and semi-arid grasslands. However, Laycock and Conrad

(1967) found that there is no difference between the bulk density of soil in grazed and ungrazed treatments, but that the location of the treated area has a significant effect.

The hoof pressure of a grazing cow can be nearly 200 kPa (Willatt and Pullar

1984), and a walking animal can have two or three hooves on the ground at one time, so there is the potential for large amounts of pressure to be applied to a pasture where a herd is grazing, such as in this experiment. An increase in the bulk density of soil in a pasture results in the reduction of the total pore space as well as a reduction in large individual pores (Willatt and Pullar 1984; Holt et al. 1996). This reduces soil aeration and water penetration, and can be a severely limiting factor for plant root growth (Duffey et al.

197 1974; Willatt and Pullar 1984), particularly for those species with root systems are shallow, near the soil surface (da Silva et al. 2003). Under light grazing pressure, a grassland can retain its natural assemblage of species. However, when large grazers such as cattle are confined to a fixed area, grazing and trampling are intensified to the point where plants may not recover sufficiently (Weaver 1954). Compaction of soil can also impact invertebrates that use the top layer of the soil for burrowing such as termites (Holt et al. 1996) and spiders that make permanent refuges, like trap-door spiders, (Abensperg-

Traun et al. 1996), as their tunnels would be constantly destroyed by the weight of the grazing herd. Pasimachus elongatus is an example of a species of carabid with a life cycle that would be greatly affected by increased soil compaction. Cress and Lawson

(1971) reported that fourth instar P. elongatus larvae overwinter at soil depths of greater than 76 cm, and prepupae are found at depths of approximately 10 cm. If soil is greatly compacted, this species may not be able to reach the depth that would provide ideal conditions for each stage of its life cycle. Tiger beetles (Cicindela) dig shallow burrows to provide protection from the weather or as a refuge at night, and deep burrows from 15 cm to 122 cm (depending on the species and soil type) for overwintering (Wallis 1961).

Vegetation

The vegetation on the Yellow Quill Prairie was described in detail by Bird (1927) as an area that was transitioning from a prairie climax to a deciduous forest. Overall, my study recorded 72 species of plants on the Yellow Quill Prairie, far less than an inventory done in 2001 by Sveinson et al. that recorded 144 species. Their study used ortho-photos, infra-red photos, and true-colour aerial photos, as well as ground verification using

198 quadrats, to do a complete inventory of the entire property. It included trees and life forms such as lichen, rushes, and lycophytes, which this study did not include.

In my study, a higher number of plant species was recorded in the ungrazed treatments in both years in all three paddocks of the primary experiment. However, the differences were only significant in paddocks 27 and 29. Paddock 28 had lower numbers overall than the other two paddocks, and the treatments were very similar to one another.

A review of the effects of livestock grazing on plant communities by Fleischner (1994) suggests that many studies have concluded that grazing reduces the cover and density of grasses, forbs, and palatable shrubs, as well as overall plant species richness, whereas a cessation of grazing leads to an increase in the cover of all these groups.

Patenaude (2007) examined the bee fauna and associated vegetation on the

Yellow Quill Prairie and found that there was a greater density of plants in bloom in the grazed treatments. Potential reasons for this observation include the removal, by the grazing herd, of competitive grass species and of detritus, which then allows more sunlight to penetrate to shorter plants. The removal of plant matter could also increase a plant‟s allocation of its resources to reproductive tissue. No differences were noted between the bee fauna of the grazed and ungrazed treatments, as the foraging range of most species would be sufficient to allow them to travel easily across the distances between treatments (Patenaude 2007).

There was significantly less grass cover in the grazed treatment in both sampling years, however overall forb cover did not differ between the treatments. Shrubs were lower in the grazed treatment in both years but this was only significant in 2005. Big bluestem (Andropogon gerardii), a characteristic species of the North American

199 grasslands and once one of the most important dominant plants (Weaver 1954) was found only in the ungrazed treatment in paddock 28, and with a low percent cover, in contrast with Bird (1927) who listed it (under the synonym A. furcatus) as one of the main grasses in the area of the Yellow Quill Prairie. Vinton and Hartnett (1992) found that grazing and cutting increased the relative growth rate of A. gerardii tillers, which is highest early in the season and declines thereafter, but they reduce the total aboveground tiller size throughout the whole season. In the following year, tillers that have been grazed have significantly lower relative growth rates the following year and reduced biomass compared to ungrazed tillers. Despite an increased production of tillers in the following year, these tillers have a greater mortality rate than ungrazed tillers (Vinton and Hartnett

1992). Years of continuous grazing on the Yellow Quill Prairie may have had a cumulative effect on the remaining A. gerardii plants, leading to the much lower levels in

2005 and 2006 compared to previous studies. The most common grass, Stipa sp., had a significantly greater mean percent cover in the ungrazed treatments in both years. Dusek

(1975) found that 67% of the diet of cattle in the summer was composed of grass species, increasing to 85% in the fall, whereas forbs and shrubs only accounted for 26% and 7% of the diet respectively. Plumb and Dodd (1993) found that forbs and shrubs accounted for 15% and nearly 10% of the diet of cattle respectively in the early summer, but declined in late summer. Therefore, given that cattle prefer to graze on grasses (Weaver

1954) as opposed to the woody shrubs, it is not surprising that grasses are more common when protected from grazing. Biondini and Manske (1996) found that on plots with sandy soil, an ungrazed treatment has a higher relative cover of cool-season grasses (including

Stipa sp.) compared to both rotational and season-long grazing treatments.

200 Leafy spurge (Euphorbia esula) is an invasive and noxious weed that requires monitoring and control so that it doesn‟t overwhelm native prairie and ranchland

(Bangsund and Leistritz 1991). The plant‟s latex can cause skin irritation, weakness, diarrhea, and death in cattle that eat it (Lym and Kirby 1987). Cattle tend to avoid areas with even low density infestations in the summer, though they are most inclined to graze on the more heavily infested areas in the fall after the plants have started to senesce and the latex begins to disappear (Lym and Kirby 1987). This hardy weed has resulted in losses of millions of dollars worth of income to ranchers and landowners due to reduced carrying capacity on rangelands on the northern Great Plains (Bangsund and Leistritz

1991). Recorded as a subset of the forb data on the Yellow Quill Prairie, it was not very abundant in either year in any paddock with the exception of the ungrazed treatment in paddock 28. These results are consistent with the results of the inventory by Sveinson et al. (2001). The Nature Conservancy of Canada performed a controlled burn on paddock

27 at the beginning of 2006 as part of their ongoing control program for this species.

Ground juniper (Juniperus horizontalis) is a low-growing shrub that prevents the growth of other plant species and the accumulation of litter by forming a tight round mat over the ground (Sveinson et al. 2001). Bird (1927) recorded it as a dominant plant in the area, growing in the forest and along the forest border. It was present in all paddocks and treatments in both years. The mean percent cover was greater overall in the ungrazed treatments in 2005 and in the grazed treatments in 2006, most likely as a result of the change in sampling protocol between the two years. According to Dusek (1975), cattle do not graze on juniper species at all, though it forms a component of the diet of mule deer during the colder months of the year.

201 Litter, composed of dead plant material, is an important component of a grassland ecosystem. Hart et al. (1988) found that litter levels increased in all grazing treatments during the five years of their study, particularly in the treatment receiving continuous light grazing. However, according to Dennis et al. (1997) and O‟Neill et al. (2003), grazing decreases the amount of litter available on a range, as plants are consumed rather than die at the end of the season, and trampling by large animals like cattle increases the rate at which the litter layer is broken down, potentially physically crushing the arthropods that live within it. Litter was present in my study in moderate to high quantities in both sampling years based on the estimate of mean percent cover provided by the quadrats. However, the differences between treatments were not significant. As sampling was done in the late summer, these estimates included a lot of plant material that was naturally senescing in the fall. Using the pin sampler method, dead plants that were classed as litter were only recorded in low amounts. Litter levels were significantly greater in the ungrazed treatments in 2005 and in the grazed treatments in 2006 when it was measured using the pin sampler. The cause of this shift is not known but reflects the contradictory results in the literature.

Many arthropods use litter as a refuge from predators and the many different microhabitats afford protection from desiccation, freezing, or overheating (Lenoir and

Lennartsson 2010), as well as overwintering habitat (Uetz 1979). A deeper litter layer has been shown to increase the species richness of the spider families Gnaphosidae,

Clubionidae, and Thomisidae, and of their prey, while a reduction in the litter layer leads to an increase in the dominance of the Lycosidae family (Uetz 1979). Gnaphosid and

202 Clubionid spiders build silk retreats in the litter, in rolled up leaves, folded grass, or under objects. They spend the daylight hours in these tubes and emerge at night to hunt

(Dondale and Redner 1982; Platnick and Dondale 1992). Carabid species that overwinter as larvae can be affected by trampling or a reduction in the depth and suitability of the litter layer (Lenoir and Lennartsson 2010). Litter also provides habitat for many other invertebrates that are prey species for carabids and spiders, so a reduction in litter means predator numbers are reduced as well (Dennis et al. 1997). The relative importance of litter to the grassland invertebrates changes throughout the course of the summer, so in order to have explored the link between the litter and the spiders and carabids that were trapped, relative percent cover should have been assessed at the beginning of each sampling season as well towards the middle and the end.

There were no clear trends in the amount of bare ground but it was clear that it was not present in significant amounts in any paddock or grazing treatment.

Invertebrates

Carabids and spiders are often sampled together and are known to be sensitive to environmental disturbances (Uetz and Unzicker 1976; Pristavko and Zhukovets 1988;

Maelfait and Desender 1990; Butovsky 1994; Loreau 1994). Wolf spiders (family

Lycosidae) in particular can be considered to be in the same trophic guild as carabids as they occupy the same habitats and both groups hunt for prey on the ground surface (Lang et al. 1999). Pristavko and Zhukovets (1988) concluded that cursorial spiders were the most effective group for monitoring disturbance. Therefore, both groups were examined to see if cattle grazing was affecting their numbers and species diversity. In this study,

203 their responses are potentially a direct result of the presence of the grazers, or an indirect result of changes to the environment brought about by actions of the grazers (Dennis et al. 1997).

Carabids

In 2005, there was a trend for the mean catch of carabid beetles to be greater in the grazed treatment at the beginning of the season in Period 1. This trend was not evident in 2006. However, after the spring and fall grazes had occurred in Periods 2 and

3, the mean catch was greater in the ungrazed treatment in all paddocks and in both sampling years. In 2005, Period 1 began in early June and was considerably shorter in duration compared to in 2006, when it began in early May. In 2005, Calosoma calidum was the numerically dominant species and it was associated with the grazed treatment. In

2006, other species such as Pasimachus elongatus, and Bembidion nitidum were present in relatively high numbers and strongly associated with the grazed treatment, whereas

Poecilus lucublandus lucublandus and Syntomus americanus were also present in relatively high numbers but were strongly associated with the ungrazed treatment.

Agonum cupreum was the second most frequently-caught species in 2006 but it was not strongly associated with either of the two treatments.

The most abundant species of carabid, Calosoma calidum was examined in greater detail. This species is a large-bodied carnivore that has previously been identified as being typical of open habitat with low levels of vegetation (Larochelle and Larivière

2003). Therefore, it is not surprising that there was a trend for the grazed areas to have a higher mean catch prior to grazing in both sampling years. There were no clear trends for this species in Period 2, and very few individuals were caught in Period 3. This species is

204 known to be active from April to December (Larochelle and Larivière 2003) and in this study, the peak catches were on June 23, 2005 and May 31, 2006. These dates were primarily a part of Period 1 in most paddocks, and are similar to the trapping dates for this species that were recorded by Epstein and Kulman (1990). Large beetles like C. calidum are able to move quickly and cover greater distances, and it is possible that this increases the chance of encountering a pitfall trap (Halsall and Wratten 1988). Calosoma calidum is known to consume prey such as lepidopterous caterpillars, chrysomelids, scarabeids and acridids (Larochelle and Larivière 2003). The latter two groups were frequently caught in my pitfall traps (personal observation). Chrysomelids have been found to be more abundant in areas of mixed grass prairie with lower grazing intensity

(Smith 1940). However, the grazed areas on the Yellow Quill Prairie contain patches of aspen forest, a potential source of lepidopterous caterpillars in the early spring.

According to Larochelle and Larivière (2003), despite being recorded as a poor climber, this species can be trapped on lower tree trunks. Studies of grasshopper populations have found both increases (Smith 1940; Hoernemann et al. 2001) and decreases (O‟Neill et al.

2003) in abundance with increasing grazing intensity on the mixed grass prairie (Smith

1940). However, individual species can respond differently from the assemblage as a whole, and local populations of a species may respond differently from the same species in a different location (O‟Neill et al. 2003).

There was a slight trend in Period 1 in both years for a greater number of carabid species to be caught in the grazed treatment. In Periods 2 and 3, there was a slight trend for the ungrazed treatment to have a greater number of species. However, in most cases, the differences between the treatments were not significant. The ungrazed treatment most

205 likely afforded a better selection of food for both omnivorous and carnivorous species, but the addition of cattle dung in the grazed areas from the previous year as well as during Periods 2 and 3 would attract a unique assemblage of species that could also serve as prey for predatory carabids (Cress and Lawson 1971; Dennis et al. 1997). Based on

Larochelle and Larivière (2003), 24 of the 51 carabid species caught in this study have been recorded as preying upon insects that feed or reproduce on dung. Among the 25 most frequently-caught species, Agonum cupreum, A. placidum, Amara littoralis,

Bembidion mutatum, B. nitidum, and Pterostichus femoralis all feed on various combinations of dipterous eggs, larvae, pupae, and adults. Calosoma calidum eats scarabeid larvae, Chlaenius tomentosus tomentosus eats scarabeids, dead carabids, and fungi, Poecilus lucublandus lucublandus eats dipterous larvae, pupae and adults, scarabeid larvae, other carabids, and fungi. The dung also provides a moist microhabitat and shaded refuges for species such as Pasimachus elongatus which has been observed living under a single dung pat for several weeks as larvae and as adults before moving on to the next available pat (Cress and Lawson 1971). In my study, the highest numbers of

P. elongatus were caught in the early spring and summer months, and predominantly in the grazed treatments. This corresponds approximately to the two-year lifecycle described by Cress and Lawson (1971) during which adults emerge in late April and lay eggs in the early summer. Larvae develop through several instars before overwintering as fourth instars. These larvae re-emerge in late April, develop into pupae towards the end of June, and the second generation of adults emerges in July. Harpalus opacipennis and

H. ventralis have also been recorded taking shelter under cow dung during the daylight hours (Larochelle and Larivière 2003). The extra input of fertilizer provided to plants by

206 dung pats may lead to better quality vegetation that attracts herbivorous species, such as members of the genus Amara (Dennis et al. 1997), some species of which feed on seeds

(Larochelle and Larivière 2003). However the Amara species caught in this study were divided between the two treatment areas, and the vegetation canopy, including potential grass seed heads, in the grazed areas was cropped quite low by the cattle.

While Calosoma calidum was numerically dominant in this study, the Berger-

Parker index of dominance indicated that its dominance was spread over both grazed and ungrazed treatments. This index did not provide much information overall. Species richness, measured using the Log Series Alpha index of diversity, tended to be greatest in the grazed treatments during Period 1, but this shifted to a slight trend in the other direction in Period 2, and no clear trends in Period 3. While diversity indices are frequently used in environmental impact studies, Dritschilo and Erwin (1982) found that they are not highly effective means of assessing the changes in carabid beetle communities. Their highly-controlled and replicated agricultural study, comparing organic and conventionally managed farms, tested a variety of diversity indices, including the Berger-Parker index of dominance and the Log Series Alpha index of diversity. They found that while Alpha is more sensitive than the other indices, no index provides as much information as the examination of simple abundance and species richness. In their study, Alpha failed to distinguish between two sites where abundance was seven times higher at one site and species richness was twice as high. Their conclusion is that while carabid beetles respond to changes to the environment, diversity indices do not, and the other data in impact studies is often sufficient to answer the questions that are posed.

207

Spiders

Spiders have great potential as biological indicators because they are generalist predators, and are influenced by changes in habitat structure, microclimates, and prey availability. The effects of disturbances that alter the vegetation in a particular habitat can be monitored using spiders (Marc et al. 1999). While they are not associated with particular plant species, factors such as cover, food, moisture, and temperature combine to form a spider‟s preferred habitat (Allred 1975; Bell et al. 2001).

The peak spider catches in the first year were around June 9 and June 23, whereas in the second year they were several weeks earlier, around May 24 and June 8. The patterns observed for the most abundant species, Pardosa distincta, fall within the normal observed frequencies of males and females (Dondale and Redner 1990; Moring and

Stewart 1994). During three weeks each year (2005: June 9, 23, July 7; 2006: June 8, 22,

July 6), the number of males caught was far greater than the number of females, indicating a probably sexual cursorial activity (Muma and Muma 1949). This pattern was also observed by Moring and Stewart (1994). Male activity decreased rapidly in late July and early August, whereas female activity extended into mid-October. This corresponds to their known biology, as females carrying egg sacs have been observed in late summer and early fall (Dondale and Redner 1990). The second most-frequently caught species,

Alopecosa aculeata, also displayed the same pattern of increased male activity early in the season, followed by a rapid decline and a prolonged period of female activity that lasted until late September. Females carrying egg sacs have been observed until mid-

208 October, whereas females transporting young on their backs have been observed in

August (Dondale and Redner 1990).

There were clear trends in nearly all the paddocks and in both sampling years for the total catch of spiders to be highest in the ungrazed treatments. Pardosa distincta is largely responsible for these trends. Wolf spiders (family Lycosidae) are generalist predators (Foelix 1982) that use their vision to hunt their prey, often using stalking and ambushing as hunting techniques (Ubick et al. 2005). While not demonstrating any clear patterns in Period 1, the mean total catch of this species in Period 2 was significantly higher in the ungrazed treatment in all but one paddock in both sampling years, and there was a trend for this pattern to occur in Period 3 as well. This agrees with findings by

Dennis et al. (2001), who found that surface-dwelling spiders are more prevalent in ungrazed treatments and the less intensively grazed treatments which have taller vegetation and more plant litter. However, Churchill and Ludwig (2004) found that wolf spiders are more common on grazed sites, areas that have intermediate levels of bare ground. My experiment did not find that there were significant levels of bare ground in either treatment. Finnamore et al. (2000) found no differences in numbers of wolf spiders between grazed and ungrazed sites within Grasslands National Park, in Saskatchewan.

Bultman and Uetz (1982) concluded that litter complexity had greater impact on web- building species rather than active hunters. Moring and Stewart (1994) found P. distincta individuals predominantly in a grass-willow habitat, but also in sand-cobble, rock-cobble, and grass-litter habitats. However, they did not find this species in a leaf-litter habitat.

The influence of so many factors on the spiders makes this situation rather complex.

However, it is clear that ungrazed sites provide a greater availability of prey choices and

209 a deeper litter layer with more microhabitats, which could serve as refuges from predators and from intense light and high temperatures during the summer (Moring and Stewart

1994), options that would be unavailable to them in the wide-open grazed treatments.

The second most frequently-caught spider was Alopecosa aculeata. This species was not caught in large numbers, if at all in some paddocks. However, when it was caught in larger numbers, there was a significant trend for there to be more individuals in the ungrazed treatment, mirroring Pardosa distincta. Moring and Stewart (1994) had similar results for this species. Their study caught A. aculeata in pitfall traps in all five of the habitats they examined (rock-cobble, sand-cobble, grass-willow, grass-litter, and litter from cottonwoods), but visual searches only revealed this species in the grass-litter and leaf-litter habitats.

There were no clear patterns for the number of spider species that were caught in either sampling year. In Periods 1 and 2 there were slight trends for the ungrazed area to have a higher number of species but there were no patterns in Period 3. The Berger-

Parker Index of Dominance was strongly influenced by the presence of Pardosa distincta. This index was not able to discern any instances where another species could begin to approach dominance, based on the sheer volume of individuals of this species that were caught relative to the other spiders. The Log Series Alpha index of diversity did not find any clear patterns in Periods 1 and 3 in either year. However, in Period 2, there was a clear trend for the species richness of the spider assemblage to be greater in the grazed area. Finnamore et al. (2000) used rarefaction curves and found this same pattern in the spider community in Grasslands National Park. Crested wheatgrass sites and grazed sites had significantly higher species diversity than ungrazed sites. The crested

210 wheatgrass sites had the highest diversity overall for spiders, and are considered to be in a state of flux, in some cases establishing an equilibrium that is different from those in the grazed and ungrazed sites, while in others, reverting back towards a former state that is represented by the grazed and ungrazed sites.

Bell et al. (2001) reviewed the implications of management decisions on grassland spider communities and noted that while grazing generally reduces the architectural diversity and litter depth, which in turns decreases spider diversity, even closely related species can have completely different architectural preferences for vegetation and the resulting microclimates. Arthropod groups need to be examined separately as each responds differently to the same grazing disturbance. Hoernemann et al. (2001) compared rotational grazing and season-long grazing on mixed grass prairie with a hayed field and an idle (control) field. Their study found that Diplopods and

Hymenoptera (primarily ants) were more abundant in the hayed and idle fields, plant bugs (Miridae) were most abundant in the hayed fields, and Elateridae (click beetles) were most abundant in the idle fields. Conversely, grasshopper populations were favoured by the grazed treatments, while carabid beetles were affected by neither the grazing nor the haying treatments. Such a variety of responses makes it challenging to choose the optimum grazing intensity that favours the richest fauna, and keeps pest outbreaks to a minimum.

Secondary Experiment

211 The objective of the secondary experiment was to determine whether it is the short, stimulatory spring graze, the longer fall graze, or a combination of the two grazes that has the greatest impact on the abundance and diversity of carabid beetles and spiders.

Soil Compaction

As in the primary experiment, soil compaction was measured once during each of the two sampling years. The soil was tested at various points in each of the three treatments and compared. The differences in soil compaction between the three treatments in paddock 34 were not significant. One hypothesis for the lack of differences between treatments is that this paddock had not been grazed in five and half years, so it is possible that any previous soil compaction caused by the grazing cattle had decreased over time.

Vegetation

Similar numbers of plant species were recorded in each of the three treatments

(Spring graze only, Fall graze only, both Spring and Fall grazes) in both years. Quadrat data did not show any clear trends in the cover of grasses in either year, whereas using the pin sampler, there was a significant difference in 2006 between treatments in the grass group Stipa sp. The greatest percent cover was found in the Fall treatment and the lowest in the Spring/Fall treatment that year. Big bluestem (Andropogon gerardii) was found only in the Spring/Fall treatment in 2005.

There were no clear trends in the cover of forbs in either year. As a subset of the forb data, both sampling methods reflected the same low levels of leafy spurge

(Euphorbia esula) across all treatments. It is possible that the infestation is in the early stages in this paddock, as it is separated from the three paddocks in the primary

212 experiment. These findings are consistent with the trends in percent cover for this species in this paddock that were recorded in the inventory by Sveinson et al. (2001).

There were no clear trends in the cover of shrubs in either year. Ground juniper

(Juniperus horizontalis) was found in similar amounts in all three treatments in both years. The pin sampler and the quadrat data reflect different patterns in percent cover between the treatments.

In 2005, the pin sampler and the quadrat methods recorded the same pattern of litter deposition between the three treatments, but the differences were not significant. In

2006, while the quadrat data did not show any differences between treatments, the pin sampler recorded a significant difference between the Spring and Spring/Fall treatments, which had similar mean percent covers, and the Fall treatment which had a lower percent cover. The two similar treatments had already received the spring graze that year, whereas the Fall treatment had not yet been grazed. As in the main experiment, sampling was done in the late summer, so many of the plants on the paddock were naturally senescing. The use of a pin sampler to measure the percentage of litter cover does not appear to be a reliable method based on the contradictory results for the same areas in this study.

Bare ground was only recorded at very low levels in 2005 and at even lower levels in 2006 using both the pin sampler and the quadrats. This corresponded to the relocation of the quadrat position away from the immediate area surrounding each pitfall trap.

Invertebrates

Carabids

213 Carabids were caught and treated in the same manner as in the primary experiment. No carabids were caught in the sweep nets in this experiment either. There were no patterns or significant differences between treatments in the mean catch of carabids, the mean number of species caught, the Berger-Parker index of dominance, or the Log Series Alpha index of diversity in either sampling year. There were no patterns in the distribution of Calosoma calidum either.

Spiders

Spiders were caught and treated in the same manner as in the primary experiment.

There were no clear patterns in the mean catch of spiders in either sampling year. There were, however, some significant differences between treatments. In Period 1 in 2006, the highest mean number of spiders was caught in the Spring treatment and the lowest in the

Spring/Fall treatment. The three main species that were responsible for this result were

Pardosa distincta, Alopecosa aculeata, and Xysticus ampullatus (family Thomisidae, the crab spiders). The latter is often collected along the borders of meadows or wooded areas

(Dondale and Redner 1978). In Period 2 in 2005, the highest mean number of spiders was caught in the Spring/Fall treatment and the lowest in the Spring treatment. Pardosa distincta was the principal species caught during this period. In Period 3 in 2005, the highest mean number of spiders was caught in the Spring treatment, and the lowest in the

Fall treatment. The two main species that were responsible for this result were P. distincta and Cicurina arcuata (family Dictynidae). The numbers of P. distincta and A. aculeata alone were not significantly different between treatments in either year.

There were no definite trends in the mean number of species caught in either sampling year. There was a slight pattern in Period 2 in both years for the highest number

214 of species to be caught in the Spring/Fall treatment and the lowest number to be caught in the Spring treatment, but this does not appear to be due to the grazing as both of these treatments had just received the spring graze.

There were no significant effects of the grazing treatments in paddock 34 on the

Berger Parker index of dominance or the Log Series Alpha index of diversity. Very few studies have been done to explore the effects of the timing of grazing on grassland invertebrates. Gibson et al. (1992) used sheep to examine the effects of five sheep grazing treatments on the spiders of limestone grassland in England, admittedly a different type of grassland from the Canadian mixed grass prairie. Species richness and density decrease as grazing intensity increases. Short-period spring grazing, short-period fall grazing, and continuous fall grazing have higher numbers of spiders than the treatment that received both a spring and fall graze. This treatment had the most impoverished spider fauna of all five treatments. Lenoir and Lennartsson (2010) compared continuous cattle grazing with late-onset grazing, and found that spider species richness was greatest in the late-onset grazing treatment prior to the start of the grazing in mid-July, but did not differ between treatments after it had begun.

Conclusions

Research on the effects of various grazing regimes and pasture improvement on vegetation and invertebrate groups has been done for many years and results are quite varied, making it difficult for range managers to know which is the best regime to choose.

215 One of the concerns with rotational grazing is the cost of setting up the dividing fences and the water supply, as well as the cost of managing the animals more frequently or managing multiple pastures. McIlvain and Savage (1951) and Fisher and Marion

(1951) studied rotational versus continuous grazing at both moderate and heavy stocking rates, and found that while the vegetation fares slightly better under the rotational regime, it is not enough to justify the associated expenses. Bryant et al. (1989) examined short- duration grazing (one to six days of grazing followed by 30-60 days of rest) which often involves a single herd but multiple pastures, and reached the same conclusion regarding the cost of the infrastructure.

Animal performance is also a key issue when it comes to choosing the best grazing regime. Biondini and Manske (1996) compared twice-over rotational cattle grazing with season-long grazing and discovered that rotational grazing might allow for a higher stocking rate on the pasture without impacting individual animal performance, and

Hart et al. (1988) found that in a comparison of continuous, rotational, and short-duration grazing on mixed grass prairie, cattle gains are not affected by the grazing regime.

However, short- duration grazing has also been found to decrease animal performance

(Bryant et al. 1989). Other studies have shown that animal gains are maximized under a continuous grazing regime at a moderate stocking density (Hubbard 1951; Rogler 1951;

McIlvain and Savage 1951).

The types of grazing animals make a difference in the pasture‟s response to the regime. Bison eat predominantly graminoid species, and are less productive but require less maintenance than cattle, which prefer more palatable forbs, and tend to use riparian and wooded areas more (Plumb and Dodd 1993; Steuter and Hidinger 1999). Low-

216 density cattle grazing has been shown to increase the number of carabids and spider species by creating a diverse array of habitats (Zahn et al. 2007). However, herds of sheep have been contrasted in several studies with mixed herds of sheep and cattle and carabids and staphylinids show little response to these livestock differences (Dennis et al.

1997; Pétillon et al. 2007). Spiders on the other hand are a lot more sensitive to the types of grazing animals. Sheep are smaller animals, so webs are destroyed less frequently, and trampling is not as much of an issue as it is with cattle. Epigeal arachnid species in particular decrease with increasing grazing intensity, and are more abundant in pastures with patches of tall vegetation that create a mosaic of habitat options and an increased level of litter (Dennis et al. 2001).

Based on the results of this experiment, carabid beetles had either already adapted to the disturbance of the rotational grazing regime prior to the beginning of the experiment, or the stocking density was too high to maintain the required mosaic of habitats to promote an increase in carabid diversity. In this study, carabids were not effective indicators of the health of the mixed grass prairie ecosystem. The spiders were a more useful group for this purpose, although the response of one species effectively prevented detection of any effect that the grazing might have had on the less common species. Without a properly replicated experiment it is impossible to distinguish between the role that the timing of the grazing played on the population cycles of these invertebrates compared to the impact that grazing has on their numbers. It appeared overall that the ungrazed treatments harboured a greater number of individuals whereas the species richness was greater in the grazed treatment. This agrees with the

Intermediate Disturbance Hypothesis which states that local species diversity is highest

217 when ecological disturbances are intermediate in frequency and intensity (Connell 1978).

If disturbances, or in this case, grazing, occurs too frequently, diversity will be reduced as the assemblage will consist of only those species who can reproduce and reach maturity quickly. If grazing is too infrequent (as in the ungrazed treatment), diversity will be reduced as well, as the assemblage will consist of the most efficient competitors and species that are the most tolerant of physical extremes.

The period immediately after the spring graze appears to be the time when the impact of grazing, if present, is reflected in the invertebrate community. If numerically dominant species such as Pardosa distincta are eliminated due to the grazing treatment, it shifts the composition of the assemblage towards species that thrive in open areas and do not require dense vegetation or a deep litter layer to survive (Duncan and Jarman 1993).

The secondary experiment was an attempt to tease out whether it is the spring graze, the fall graze, or a combination of the two that has the greatest impact on the carabids and spiders. However, I believe that the two years of this study were not a sufficient amount of time for any cumulative effects that the timing of each graze may produce to become apparent, and that any effects that did occur during this time were too subtle to be observed. This was compounded by the lack of replication, the small size of each treatment area, and the lack of consistent electricity in the fences between treatments. Based on the primary experiment, it is the spring graze that has the greatest impact on the invertebrate community. By the time the fall graze has occurred, the levels of many species have diminished naturally, as individuals of many species have entered their overwintering states, so there are many fewer individuals for the grazing treatment to affect. An example is Pasimachus elongatus which has a two year life cycle during

218 which it moults into the fourth instar larval stage by July and prepares to overwinter deep in the soil. Adults from the second generation are active until cooling temperatures force them into hibernation (Cress and Lawson 1971).

The established regime of twice-over rotational cattle grazing does not appear to have a significant impact on the carabid fauna of the Yellow Quill Mixed Grass Prairie

Preserve, whereas it reduced the total catch of spiders but tended to increase the species richness. This study was not able to complete the objective of determining whether it is the spring graze or the fall graze that has the most impact on the invertebrate fauna. No baseline studies were done while bison still roamed freely on the mixed grass prairie and before the arrival of European settlers suppressed the natural fires that help maintain the grasslands. Therefore it is impossible to know the exact composition of the original prairie. However, if the Nature Conservancy of Canada wishes to preserve the current state of the prairie remnants, it appears the current management regime is not destructive to the carabid and spider communities and tends to enhance species diversity.

219 LITERATURE CITED

Abensperg-Traun, M., Smith, G.T., Arnold, G.W. and Steven, D.E. 1996. The Effects of Habitat Fragmentation and Livestock-Grazing on Animal Communities in Remnants of Gimlet Eucalyptus salubris Woodland in the Western Australian Wheatbelt. I. Arthropods. Journal of Applied Ecology 33: 1281-1301.

Aitchison-Benell, C.W. and Dondale, C.D. 1990. A Checklist of Manitoba Spiders (Araneae) With Notes on Geographic Relationships. Le Naturaliste Canadien 117: 215-237.

Allred, D.M. 1975. Arachnids as Ecological Indicators. Great Basin Naturalist 35: 405- 406.

Bangsund, D.A. and Leistritz, F.L. 1991. Economic impacts of leafy spurge on grazing lands in the northern Great Plains. NDSU Agriculture Economic Report 275-S: 10 pps.

Barbour, M.G., Burk, J.H. and Pitts, W.D. 1987. Terrestrial Plant Ecology. The Benjamin/Cummings Publishing Company Inc., New York.

Bell, J.R., Wheater, C.P. and Cullen, W.R. 2001. The Implications of Grassland and Heathland Management for the Conservation of Spider Communities: A Review. Journal of Zoology (London) 255: 377-387.

Belsky, A.J. 1992. Effects of Grazing, Competition, Disturbance, and Fire on Species Composition and Diversity in Grassland Communities. Journal of Vegetation Science 3: 187-200.

Berger, W.H. and Parker, F.L. 1970. Diversity of Planktonic Foraminifera in Deep-Sea Sediments. Science 168: 1345-1347.

Biondini, M.E. and Manske, L. 1996. Grazing Frequency and Ecosystem Processes in a Northern Mixed Prairie, USA. Ecological Applications 6: 239-256.

Bird, R.D. 1927. A Preliminary Ecological Survey of the District Surrounding the Entomological Station at Treesbank, Manitoba. Ecology 8: 207-220.

Bragg, T.B. and Steuter, A.A. 1996. Prairie Ecology - The Mixed Prairie. In Prairie Conservation: Preserving North America's Most Endangered Ecosystem. Edited by F. B. Samson and F. L. Knopf. Island Press, Washington, D.C.

Bryant, F.C., Dahl, B.E., Pettit, R.D. and Britton, C.M. 1989. Does Short-Duration Grazing Work In Arid and Semiarid Regions? Journal of Soil and Water Conservation 44: 290-296.

220 Bultman, T.L. and Uetz, G.W. 1982. Abundance and Community Structure of Forest Floor Spiders Following Litter Manipulations. Oecologia 55: 34-41.

Butovsky, R.O. 1994. Carabids in Roadside Ecosystems: Perspectives of Bioindication. In Carabid Beetles: Ecology and Evolution. Edited by K. Desender. Kluwer Academic Publishers, Netherlands. pp. 241-246.

Chamberlin, R.V. and Gertsch, W.J. 1958. The Spider Family Dictynidae in America North of Mexico. Bulletin of the American Museum of Natural History 116.

Chamberlin, R.V. and Ivie, W. 1940. Agelenid Spiders of the Genus Cicurina. Bulletin of the University of Utah 30: 3-108.

Chamberlin, R.V. and Ivie, W. 1941. North American Agelinidae of the Genera Agelenopsis, Calilena, Ritalena, and Tortolena. Annals of the Entomological Society of America 34: 585-628.

Churchill, T.B. 1997. Spiders as Ecological Indicators: An Overview from Australia. Memoirs of the Museum of Victoria 56: 331-337.

Churchill, T.B. and Ludwig, J.A. 2004. Changes in Spider Assemblages along Grassland and Savanna Grazing Gradients in Northern Australia. Rangeland Journal 26: 3- 16.

Clausen, I.H.S. 1986. The Use of Spiders (Araneae) as Ecological Indicators. Bulletin of the British Arachnological Society 7: 83-86.

Connell, J.H. 1978. Diversity in Tropical Rain Forests and Coral Reefs. Science 199: 1302-1310.

Cress, D.C. and Lawson, F.A. 1971. Life History of Pasimachus elongatus. Journal of the Kansas Entomological Society 44: 304-313. da Silva, A.P., Imhoff, S. and Corsi, M. 2003. Evaluation of Soil Compaction in an Irrigated Short-Duration Grazing System. Soil and Tillage Research 70: 83-90.

Dennis, P., Young, M.R. and Bentley, C. 2001. The Effects of Varied Grazing Management on Epigeal Spiders, Harvestmen and Pseudoscorpions of Nardus stricta Grassland in Upland Scotland. Agriculture, Ecosystems and Environment 86: 39-57.

Dennis, P., Young, M.R., Howard, C.L. and Gordon, I.J. 1997. The Response of Epigeal Beetles (Col.: Carabidae, Staphylinidae) to Varied Grazing Regimes on Upland Nardus stricta Grasslands. Journal of Applied Ecology 34: 433-443.

221 Dondale, C.D. and Redner, J.H. 1978. The Crab Spiders of Canada and Alaska. Friesen Printers, Altona, Manitoba, Canada.

Dondale, C.D. and Redner, J.H. 1982. The Sac Spiders of Canada and Alaska. Araneae: Clubionidae and Anyphaenidae. Canadian Government Publishing Centre, Ottawa, Ontario, Canada.

Dondale, C.D. and Redner, J.H. 1990. The Wolf Spiders, Nurseryweb Spiders, and Lynx Spiders of Canada and Alaska. Araneae: Lycosidae, Pisauridae, and Oxyopidae. Canadian Government Publishing Centre, Ottawa, Ontario, Canada.

Dondale, C.D., Redner, J.H., Paquin, P. and Levi, H.W. 2003. The Orb-Weaving Spiders of Canada and Alaska. Araneae: Uloboridae, Tetragnathidae, Araneidae, Theridiosomatidae. National Research Press, Ottawa, Ontario, Canada.

Dritschilo, W. and Erwin, T.L. 1982. Responses in Abundance and Diversity of Cornfield Carabid Communities to Differences in Farm Practices. Ecology 63: 900-904.

Duffey, E., Morris, M.G., Sheail, J., Ward, L.K., Wells, D.A. and Wells, T.C.E. 1974. Grassland Ecology and Wildlife Management. Chapman and Hall Ltd., London, United Kingdom.

Dufrêne, M., Baguette, M., Desender, K. and Maelfait, J.-P. 1990. Evaluation of Carabids as Bioindicators: A Case Study in Belgium. In The Role of Ground Beetles in Ecological and Environmental Studies. Edited by N. E. Stork. Intercept Ltd., Andover, United Kingdom. pp. 377-381.

Duncan, P. and Jarman, P.J. 1993. Conservation of Biodiversity in Managed Rangelands, with Special Emphasis on the Ecological Effects of Large Grazing Ungulates, Domestic and Wild. In Grasslands For Our World. Edited by M. J. Baker. SIR Publishing, Wellington, New Zealand. pp. 776-783.

Dusek, G.L. 1975. Range Relations of Mule Deer and Cattle in Prairie Habitat. The Journal of Wildlife Management 39: 605-616.

Ehrlich, W.A., Poyser, E.A. and Pratt, L.E. 1957. Reconnaissance Survey of Carberry Area in Manitoba. Report of Reconnaissance Soil Survey of Carberry Map Sheet Area. Manitoba Soils Report No. 7.

Environment Canada 2010. "National Climate Data and Information Archive." [online]. Available from http://www.climate.weatheroffice.gc.ca/ [accessed January 14, 2011].

Epstein, M.E. and Kulman, H.M. 1990. Habitat Distribution and Seasonal Occurrence of Carabid Beetles in East-central Minnesota. American Midland Naturalist 123: 209-225.

222 Eyre, M.D., Lott, D.A. and Garside, A. 1996. Assessing the Potential for Environmental Monitoring Using Ground Beetles (Coleoptera: Carabidae) with Riverside and Scottish Data. Annales Zoologici Fennici 33: 157-163.

Fichter, E. 1941. Apparatus for the Comparison of Soil Surface Arthropod Populations. Ecology 22: 338-339.

Finnamore, A.T. 1992. Arid Grasslands - Biodiversity, Human Society, and Climate Change. Canadian Biodiversity 2: 15-23.

Finnamore, A.T., Buckle, D., Buddle, C.M., and Hamilton, K.G.A. 2000. The effects of grazing and exotic grasses (crested wheat grass) on the ecological integrity of upland prairie communities of spiders, leafhoppers, and predatory wasps (Poaceae; Arthropoda: Solfugae, Opiliones, Araneae, Homoptera, Hymenoptera). Report prepared for Parks Canada, Department of Canadian Heritage.

Fisher, C.E. and Marion, P.T. 1951. Continuous and Rotation Grazing on Buffalo and Tobosa Grassland. Journal of Range Management 4: 48-51.

Fisher, R.A., Corbet, A.S. and Williams, C.B. 1943. The Relation Between the Number of Species and the Number of Individuals in a Random Sample of an Animal Population. The Journal of Animal Ecology 12: 42-58.

Fleischner, T.L. 1994. Ecological Costs of Livestock Grazing in Western North America. Conservation Biology 8: 629-644.

Flores, D. 1991. Ecology and Bison Diplomacy: The Southern Plains from 1800 to 1850. The Journal of American History 78: 465-485.

Foelix, R.F. 1982. Biology of Spiders. Harvard University Press, Cambridge, England.

Freitag, R., Hastings, L., Mercer, W.R. and Smith, A. 1973. Ground Beetle Populations Near a Kraft Mill. Canadian Entomologist 105: 299-310.

Gibson, C.W.D., Hambler, C. and Brown, V.K. 1992. Changes in Spider (Araneae) Assemblages in Relation to Succession and Grazing Management. Journal of Applied Ecology 29: 132-142.

Green, J. 1999. Sampling Method and Time Determines Composition of Spider Collections. Journal of Arachnology 27: 176-182.

Greenslade, P.J.M. 1963. Daily Rhythms of Locomotor Activity in Some Carabidae (Coleoptera). Entomologia Experimentalis et Applicata 6: 171-180.

223 Greenslade, P.J.M. 1964. Pitfall Trapping as a Method for Studying Populations of Carabidae (Coleoptera). The Journal of Animal Ecology 33: 301-310.

Hadley, M. 1993. Grasslands for Sustainable Ecosystems. In Grasslands For Our World. Edited by M. J. Baker. SIR Publishing, Wellington, New Zealand. pp. 12-18.

Halsall, N.B. and Wratten, S.D. 1988. The Efficiency of Pitfall Trapping for Polyphagous Predatory Carabidae. Ecological Entomology 13: 293-299.

Hart, R.H., Samuel, M.J., Test, P.S. and Smith, M.A. 1988. Cattle, Vegetation, and Economic Responses to Grazing Systems and Grazing Pressure. Journal of Range Management 41: 282-286.

Hayes, G.F. and Holl, K.D. 2003. Site-Specific Responses of Native and Exotic Species to Disturbances in a Mesic Grassland Community. Applied Vegetation Science 6: 235-244.

Hobbs, N.T., Schimel, D.S., Owensby, C.E. and Ojima, D.S. 1991. Fire and Grazing in the Tallgrass Prairie: Contingent Effects on Nitrogen Budgets. Ecology 72: 1374- 1382.

Hoernemann, C.K., Johnson, P.J. and Higgins, K.F. 2001. Effects of grazing and haying on arthropod diversity in North Dakota Conservation Reserve Program grasslands. Proceedings of the South Dakota Academy of Science 80: 283-308.

Holt, J.A., Bristow, K.L. and McIvor, J.G. 1996. The Effects of Grazing Pressure on Soil Animals and Hydraulic Properties of Two Soils in Semi-Arid Tropical Queensland. Australian Journal of Soil Research 34: 69-79.

Hubbard, W.A. 1951. Rotational Grazing Studies in Western Canada. Journal of Range Management 4: 25-29.

Knisley, C.B. 1987. Habitats, Food Resources, and Natural Enemies of a Community of Larval Cicendela in Southeastern Arizona (Coleoptera: Cicindelidae). Canadian Journal of Zoology 65: 1191-1200.

Lang, A., Filser, J. and Henschel, J.R. 1999. Predation by Ground Beetles and Wolf Spiders on Herbivorous Insects in a Maize Crop. Agriculture, Ecosystems and Environment 72: 189-199.

Larochelle, A. and Larivière, M.-C. 2003. A Natural History of the Ground-Beetles (Coleoptera: Carabidae) of America North of Mexico. Pensoft Publishers, Moscow-Sofia.

224 Lauenroth, W.K. and Milchunas, D.G. 1992. Short-Grass Steppe. In Natural Grasslands. Introduction and Western Hemisphere. Edited by R. T. Coupland. Elsevier Science Publishers, Amsterdam. 8A.

Lauenroth, W.K., Milchunas, D.G., Dodd, J.L., Hart, R.H., Heitschmidt, R.K. and Rittenhouse, L.R. 1994. Effects of Grazing on Ecosystems of the Great Plains. In Ecological Implications of Herbivory in the West. Proceedings of the 42nd Annual Meeting of the American Institute of Biological Sciences. Edited by M. Vavra, W. A. Laycock and R. D. Pieper. Society of Range Management, Denver, Colorado, U.S.A. pp. 69-100.

Laycock, W.A. and Conrad, P.W. 1967. Effect of Grazing on Soil Compaction as Measured by Bulk Density on a High Elevation Cattle Range. Journal of Range Management 20: 136-140.

Leech, R. 1972. A Revision of the Nearctic Amaurobiidae (Arachnida: Araneidae). Memoirs of the Entomological Society of Canada 84.

Lenoir, L. and Lennartsson, T. 2010. Effects of Timing of Grazing on Arthropod Communities in Semi-Natural Grasslands. Journal of Insect Science 10: 1-20.

Levi, H.W. 1954. Spiders of the Genus Euryopis from North and Central America (Araneae, Theridiidae). American Museum Novitates 1666.

Levi, H.W. 1957a. The Spider Genera Enoplognatha, Theridion, and Paidisca in America North of Mexico (Araneae, Theridiidae). Bulletin of the American Museum of Natural History 112: 1-124.

Levi, H.W. 1957b. The Spider General Crustulina and Steatoda in North America, Central America, and The West Indies (Araneae, Theridiidae). Bulletin of the Museum of Comparative Zoology 117: 367-424.

Levi, H.W. 1980. The Orb-Weaver Genus Mecynogea, the Subfamily Metinae and the Genera Pachygnatha, Glenognatha and Azilia of the Subfamily Tetragnathinae North of Mexico (Araneae: Araneidae). Bulletin of the Museum of Comparative Zoology 149.

Levi, H.W. 1981. The American Orb-Weaver Genera Dolichognatha and Tetragnatha North of Mexico (Araneae: Araneidae, Tetragnathinae). Bulletin of the Museum of Comparative Zoology 149: 271-318.

Levi, H.W. and Levi, L.R. 1962. The Genera of the Spider Family Theridiidae. Bulletin of the Museum of Comparative Zoology 127: 3-71.

Lindroth, C.H. 1961-1969. The Ground-Beetles (Carabidae, excl. Cicindelinae) of Canada and Alaska. Entomologiska Sällskapet, Lund, Sweden.

225 Lodge, R.W. 1954. Effects of Grazing on the Soils and Forage of Mixed Prairie in Southwestern Saskatchewan. Journal of Range Management 7: 166-170.

Loreau, M. 1994. Ground Beetles in a Changing Environment: Determinants of Species Diversity and Community Assembly. In Biodiversity, Temperate Ecosystems, and Global Change. Edited by T. J. B. Boyle and C. E. B. Boyle. Springer-Verlag, Berlin. 20: 77-98.

Lövei, G.L. and Sunderland, K.D. 1996. Ecology and Behavior of Ground Beetles (Coleoptera: Carabidae). Annual Review of Entomology 41: 231-256.

Luff, M.L. and Rushton, S.P. 1989. The Ground Beetle and Spider Fauna of Managed and Unimproved Upland Pasture. Agriculture, Ecosystems and Environment 25: 195-205.

Lym, R.G. and Kirby, D.R. 1987. Cattle Foraging Behavior in Leafy Spurge (Euphorbia esula)-Infested Rangeland. Weed Technology 1: 314-318.

MacArthur, R.H. 1957. On the Relative Abundance of Bird Species. Proceedings of the National Academy of Sciences of the United States of America 43: 293-295.

Maddison, W. and Proszynski, J. (2007). "Jumping Spiders of the World." [online]. Available from www.salticidae.org

Maelfait, J.-P. and Desender, K. 1990. Possibilities of Short-Term Carabid Sampling for Site Assessment Studies. In The Role of Ground Beetles in Ecological and Environmental Studies. Edited by N. E. Stork. Intercept Ltd., Andover, United Kingdom. pp. 217-225.

Magurran, A.E. 1988. Ecological Diversity and Its Measurement. Princeton University Press, Princeton, New Jersey, USA.

Manitoba Conservation (2010). "Critical Wildlife Habitat Program - Mixed Grass Prairie Inventory Project " [online]. Available from http://www.gov.mb.ca/conservation/wildlife/habcons/cwhp/index.html [accessed March 8, 2011].

Marc, P., Canard, A. and Ysnel, F. 1999. Spiders (Araneae) Useful for Pest Limitation and Bioindication. Agriculture, Ecosystems and Environment 74: 229-273.

Maurer, R. 1974. Die Vielfalt der Käfer- und Spinnenfauna des Wiesenbodens im Einflußbereich von Verkehrsimmissionen. Oecologia 14: 327-351.

McHugh, T. 1972. Grassland and Buffalo. In The Time of the Buffalo. Edited by. Alfred A. Knopf, Inc., New York. pp. 18-26.

226 McIlvain, E.H. and Savage, D.A. 1951. Eight-Year Comparisons of Continuous and Rotational Grazing on the Southern Plains Experimental Range. Journal of Range Management 4: 42-47.

McNaughton, S.J. 1993. Grasses and Grazers, Science and Management. Ecological Applications 3: 17-20.

Merrett, P. and Snazell, R. 1983. A Comparison of Pitfall Trapping and Vacuum Sampling for Assessing Spider Faunas on Heathland at Ashdown Forest, South- East England. Bulletin of the British Arachnological Society 6: 1-13.

Millidge, A.F. 1981a. The Erigonine Spiders of North America Part 3. The Genus Scotinotylus Simon (Araneae: Linyphiidae). Journal of Arachnology 9: 167-213.

Millidge, A.F. 1981b. A Revision of the Genus Gonatium (Araneae: Linyphiidae). Bulletin of the British Arachnological Society 5: 253-277.

Millidge, A.F. 1983. The Erigonine Spiders of North America Part 6. The Genus Walckenaeria Blackwall (Araneae: Linyphiidae). Journal of Arachnology 11: 105-200.

Moring, J.B. and Stewart, K.W. 1994. Habitat Partitioning by the Wolf Spider (Araneae, Lycosidae) Guild in Streamside and Riparian Vegetation Zones of the Conjejos River, Colorado. The Journal of Arachnology 22: 205-217.

Morris, M.G. 1971. The Management of Grassland for the Conservation of Invertebrate Animals. In The Scientific Management of Animal and Plant Communities for Conservation. The 11th Symposium of the British Entomological Society, University of East Anglia, Norwich 7-9 July, 1970. Edited by E. Duffey and A. S. Watt. Blackwell Scientific Publications, Oxford, United Kingdom. pp.527-552.

Muma, M.H. and Muma, K.E. 1949. Studies on a Population of Prairie Spiders. Ecology 30: 485-503.

Munroe, E. 1956. Canada as an Environment for Insect Life. The Canadian Entomologist 88: 372-476.

New, T.R. 1998. The Role of Ground Beetles (Coleoptera: Carabidae) in Monitoring Programmes in Australia. Annales Zoologici Fennici 35: 163-171.

Niemelä, J., Spence, J.R. and Spence, D.H. 1992. Habitat Associations and Seasonal Activity of Ground-Beetles (Coleoptera, Carabidae) in Central Alberta. The Canadian Entomologist 124: 521-540.

227 O'Neill, K.M., Olson, B.E., Rolston, M.G., Wallander, R., Larson, D.P. and Seibert, C.E. 2003. Effects of livestock grazing on rangeland grasshopper (Orthoptera: Acrididae) abundance. Agriculture, Ecosystems and Environment 97: 51-64.

Opell, B.D. and Beatty, J.A. 1976. The Nearctic Hahniidae (Arachnida: Araneae). Bulletin of the Museum of Comparative Zoology 147: 393-433.

Paquin, P. and Dupérré, N. 2003. Guide d‟Identification des Araignées (Araneae) du Québec. Fabreries 11: 251 pps.

Patenaude, A. 2007. Diversity, composition and seasonality of wild bees (Hymenoptera: Apoidea) in a northern mixed-grass prairie preserve. M.Sc. Thesis. Department of Entomology. University of Manitoba. Winnipeg. 235 pps.

Pétillon, J., Georges, A., Canard, A. and Ysnel, F. 2007. Impact of Cutting and Sheep Grazing on Ground-Active Spiders and Carabids in Intertidal Salt Marshes (Western France). Animal Biodiversity and Conservation 30: 201-209.

Petit, S. and Usher, M.B. 1998. Biodiversity in Agricultural Landscapes: The Ground Beetle Communities of Woody Uncultivated Habitats. Biodiversity and Conservation 7: 1549-1561.

Platnick, N.I. and Dondale, C.D. 1992. The Ground Spiders of Canada and Alaska. Araneae: Gnaphosidae. Canada Communications Group - Publishing, Ottawa, Ontario, Canada.

Plumb, G.E. and Dodd, J.L. 1993. Foraging Ecology of Bison and Cattle on a Mixed Prairie: Implications for Natural Area Management. Ecological Applications 3: 631-643.

Pristavko, V.P. and Zhukovets, E.M. 1988. Spiders (Aranei) as Objects of Ecological Monitoring in the Berezinskiy Nature Reserve. Entomological Review 67: 26-32.

Risser, P.G. 1988. Diversity In and Among Grasslands. In Biodiversity. Edited by E. O. Wilson. National Academy Press, Washington, D.C. pp. 176-180.

Riveros, F. 1993. Grasslands For Our World. In Grasslands For Our World. Edited by M. J. Baker. SIR Publishing, Wellington, New Zealand. pp. 6-11.

Robinson, J.V. 1981. The Effect of Architectural Variation in Habitat on a Spider Community: An Experimental Field Study. Ecology 62: 73-80.

Rodríguez, J.P., Pearson, D.L. and Barrera R., R. 1997. A Test for the Adequacy of Bioindicator Taxa: Are Tiger Beetles (Coleoptera: Cicindelidae) Appropriate Indicators for Monitoring the Degradation of Tropical Forests in Venezuela? Biological Conservation 83: 69-76.

228

Rogler, G.A. 1951. A Twenty-Five Year Comparison of Continuous and Rotation Grazing in the Northern Plains. Journal of Range Management 4: 35-41.

Rypstra, A.L., Carter, P.E., Balfour, R.A. and Marshall, S.D. 1999. Architectural Features of Agricultural Habitats and Their Impact on the Spider Inhabitants. The Journal of Arachnology 27: 371-377.

Samson, F.B. and Knopf, F.L. 1994. Prairie Conservation in North America. Bioscience 44: 418-421.

Smith, C.C. 1940. The effect of over-grazing and erosion upon the biota of the mixed- grass prairie of Oklahoma. Ecology 21: 381-397.

Spedding, C.R.W. 1971. Grassland Ecology. Oxford University Press, London, United Kingdom.

Spellerberg, I.F. 1991. Biological Indicators. In Monitoring Ecological Change. Edited by. Cambridge University Press, Cambridge, United Kingdom. pp. 93-111.

Standen, V. 2000. The Adequacy of Collecting Techniques for Estimating Species Richness of Grassland Invertebrates. Journal of Applied Ecology 37: 884-893. Steuter, A.A. and Hidinger, L. 1999. Comparative Ecology of Bison and Cattle on Mixed-Grass Prairie. Great Plains Research 9: 329-342.

Sveinson, J.M.A., Brook, R.K. and Thompson, B.A. 2001. Yellow Quill Mixed-Grass Prairie Vegetation Inventory and Mapping. The Nature Conservancy of Canada, Manitoba Region: 38 pps.

Systat. 2004. Systat 11 Statistics. Systat Software Inc., Richmond, CA. ter Braak, C.J.F. and Smilauer, P. 2002. CANOCO Reference Manual and CanoDraw for Windows version 4.5. Microcomputer Power, Ithaca, NY.

Thiele, H.-U. 1977. Carabid Beetles in Their Environments: A Study on Habitat Selection by Adaptations in Physiology and Behaviour. Springer-Verlag, Berlin.

Topping, C.J. and Sunderland, K.D. 1992. Limitations to the Use of Pitfall Traps in Ecological Studies Exemplified by a Study of Spiders in a Field of Winter Wheat. Journal of Applied Ecology 29: 485-491.

Turnbull, A.L. 1966. A Population of Spiders and Their Potential Prey in an Overgrazed Pasture in Eastern Ontario. Canadian Journal of Zoology 44: 557-583.

Ubick, D., Paquin, P., Cushing, P.E. and Roth, V. (Eds.) 2005. Spiders of North America - An Identification Manual. American Arachnological Society. 377 pps.

229

Uetz, G.W. 1979. The Influence of Variation in Litter Habitats on Spider Communities. Oecologia 40: 29-42.

Uetz, G.W. and Unzicker, J.D. 1976. Pitfall Trapping in Ecological Studies of Wandering Spiders. Journal of Arachnology 3: 101-111.

Vinton, M.A. and Hartnett, D.C. 1992. Effects of bison grazing on Andropogon gerardii and Panicum virgatum in burned and unburned tallgrass prairie. Oecologia 90: 374-382. Wallis, C.A. 1982. An Overview of the Mixed Grasslands of North America. In Grassland Ecology and Classification Symposium Proceedings. Edited by A. C. Nicholson, A. McLean and T. E. Baker. British Columbia Ministry of Forests, Victoria, B.C. pp. 195-208.

Wallis, J.B. 1961. The Cicindelidae of Canada. University of Toronto Press, Toronto, Canada.

Watts, J.G., Burgess, L.W. and Huddleston, E.W. 1993. Invertebrate Pests, Plant Pathogens and Beneficial Organisms in Extensive Natural Grassland. In Grasslands For Our World. Edited by M. J. Baker. SIR Publishing, Wellington, New Zealand pp. 284-289.

Weaver, J.E. 1954. North American Prairie. Johnsen Publishing Company, Lincoln, Nebraska, USA.

Weaver, J.E. and Albertson, F.W. 1956. The Great Plains and the Mixed Prairie. In Grasslands of the Great Plains. Edited by. Johnsen Publishing Company, Lincoln, Nebraska.

Weaver, J.E. and Clements, F.E. 1938. Plant Ecology. McGraw-Hill Book Company Inc., New York.

Willatt, S.T. and Pullar, D.M. 1984. Changes in Soil Physical Properties Under Grazed Pastures. Australian Journal of Soil Research 22: 343-348.

Work, T.T., Buddle, C.M., Korinus, L.M. and Spence, J.R. 2002. Pitfall Trap Size and Capture of Three Taxa of Litter-Dwelling Arthropods: Implications for Biodiversity Studies. Environmental Entomology 31: 438-448.

Zahn, A., Juen, A., Traugott, M. and Lang, A. 2007. Low Density Cattle Grazing Enhances Arthropod Diversity of Abandoned Wetland. Applied Ecology and Environmental Research 5: 73-86.

230 Zulka, K.P., Milasowszky, N. and Lethmayer, C. 1997. Spider Biodiversity Potential of an Ungrazed and a Grazed Inland Salt Meadow in the National Park 'Neusiedler See-Seewinkel' (Austria): Implications For Management (Arachnida: Araneae). Biodiversity and Conservation 6: 75-88.

231 APPENDICES Appendix 1. Total catch of spiders collected in pitfall traps in each paddock and treatment of the primary experiment on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba in 2005. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Agelenopsis actuosa 0 0 3 3 0 2 2 4 7 Agelenopsis utahana 2 0 0 2 0 0 1 1 3 Agroeca pratensis 0 1 0 1 1 4 0 5 6 Alopecosa aculeata 10 13 43 66 8 17 177 202 268 Araneus trifolium 0 0 0 0 0 1 0 1 1 Arctosa rubicunda 12 0 0 12 11 0 3 14 26 Callilepsis pluto 0 0 0 0 2 0 0 2 2 Castianeira descripta 2 0 4 6 1 0 3 4 10 Castianeira longipalpa 2 5 2 9 5 23 6 34 43 Ceraticelus crassiceps 0 0 0 0 0 0 4 4 4 Ceraticelus laetus 0 0 0 0 0 0 2 2 2 Ceraticelus minutus 0 0 0 0 0 1 0 1 1 Ceratinella brunnea 0 2 4 6 0 3 0 3 9 Ceratinella sp. 0 0 0 0 0 0 1 1 1 Ceratinops crenatus 2 0 0 2 0 0 0 0 2 Ceratinops latus 0 1 0 1 6 4 2 12 13 Ceratinopsis nigriceps 0 0 0 0 0 0 1 1 1 Chrysso pelyx 0 0 0 0 1 0 0 1 1 Cicurina arcuata 2 0 0 2 0 1 0 1 3 Clubiona kiowa 3 0 5 8 6 3 7 16 24 Coloncus siou 24 5 77 106 26 30 23 79 185 Dictyna terrestris 0 0 5 5 0 0 2 2 7 Drassodes neglectus 0 1 8 9 4 1 11 16 25 Enoplognatha marmorata 2 0 0 2 0 0 0 0 2 Eperigone tridentata 1 0 0 1 0 0 0 0 1

232 Appendix 1 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Eperigone trilobata 0 0 0 0 0 1 0 1 1 Erigone aletris 6 2 0 8 0 0 0 0 8 Erigone atra 5 1 0 6 0 0 1 1 7 Erigone psychrophila 1 0 0 1 1 0 0 1 2 Eris militaris 0 0 0 0 0 0 0 0 0 Ero canionis 0 0 0 0 1 0 0 1 1 Euophrys monadnock 1 0 0 1 0 0 0 0 1 Euryopis gertschi 2 0 0 2 34 0 0 34 36 Euryopis pepini 5 2 6 13 2 14 5 21 34 Evarcha hoyi 0 0 0 0 2 0 1 3 3 Gnaphosa muscorum 2 1 1 4 0 0 8 8 12 Gnaphosa parvula 0 0 1 1 1 0 3 4 5 Grammonota capitata 8 4 1 13 3 9 5 17 30 Habronattus altanus 8 1 1 10 5 2 1 8 18 Habronattus americanus 0 1 1 2 0 0 0 0 2 Habronattus borealis 4 3 12 19 1 4 1 6 25 Habronattus cognatus 1 3 3 7 1 0 0 1 8 Habronattus decorus 0 0 1 1 0 0 0 0 1 Halorates plumosus 0 0 0 0 2 0 0 2 2 Haplodrassus bicornis 0 0 0 0 3 0 1 4 4 Haplodrassus hiemalis 0 2 0 2 0 0 0 0 2 Haplodrassus signifer 3 1 5 9 7 0 4 11 20 Hogna frondicola 0 5 4 9 0 12 5 17 26 Hypsosinga rubens 1 0 1 2 0 0 1 1 3 Islandiana longisetosa 1 0 2 3 1 0 2 3 6 Larinia borealis 1 0 0 1 0 0 0 0 1 Lepthyphantes alpinus 5 0 3 8 5 7 4 16 24 Maso sundevallii 0 0 0 0 1 0 3 4 4

233 Appendix 1 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Micaria laticeps 5 4 18 27 13 16 19 48 75 Neoscona arabesca 0 0 0 0 0 1 0 1 1 Ozyptila sincera canadensis 0 0 0 0 0 0 1 1 1 Pardosa distincta 44 306 395 745 1070 1944 526 3540 4285 Pardosa mackenziana 1 0 0 1 0 0 0 0 1 Pardosa moesta 3 2 6 11 5 23 23 51 62 Pellenes wrighti 0 0 0 0 0 1 0 1 1 Phiddipus borealis 0 0 6 6 0 0 0 0 6 Phiddipus johnsoni 0 0 4 4 2 1 3 6 10 Phiddipus purpuratus 0 0 2 2 0 0 0 0 2 Phrurotimpus borealis 1 1 1 3 1 0 0 1 4 Phrurotimpus certus 0 1 0 1 0 0 0 0 1 Pirata minutus 1 0 0 1 0 0 0 0 1 Pocadicnemis americana 0 0 0 0 10 4 6 20 20 Schizocosa mccooki 17 24 58 99 5 15 2 22 121 Scotinotylus alpinus 0 0 0 0 1 0 0 1 1 Sergiolus capulatus 0 2 0 2 0 0 0 0 2 Steatoda americana 0 0 2 2 0 0 0 0 2 Tenneseelum formicum 3 0 0 3 1 0 0 1 4 Tetragnatha laboriosa 0 0 1 1 0 0 0 0 1 Thanatus coloradensis 2 5 6 13 7 2 2 11 24 Thanatus formicinus 0 0 0 0 0 1 0 1 1 Thanatus rubicellus 4 4 5 13 13 8 10 31 44 Thanatus striatus 0 0 1 1 0 1 0 1 2 Theridion prataeum 0 0 1 1 1 1 3 5 6 Tibellus duttoni 0 0 0 0 0 1 0 1 1 Titanoeca silvicola 4 0 1 5 0 0 0 0 5 Trochosa terricola 0 0 0 0 0 0 1 1 1

234 Appendix 1 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Tutelina similis 0 0 0 0 0 1 0 1 1 Walckenaeria communis 4 0 0 4 1 2 1 4 8 Xysticus ampullatus 6 9 15 30 18 9 45 72 102 Xysticus auctificus 0 2 0 2 0 0 0 0 2 Xysticus canadensis 1 0 0 1 0 0 0 0 1 Xysticus cunctator 1 0 1 2 0 0 3 3 5 Xysticus emertoni 0 0 0 0 0 1 0 1 1 Xysticus ferox 1 0 3 4 0 5 5 10 14 Xysticus gulosus 3 7 7 17 4 11 0 15 32 Xysticus luctans 4 1 5 10 8 0 10 18 28 Xysticus montanensis 1 2 1 4 1 0 1 2 6 Xysticus nigromacullatus 0 0 1 1 0 0 0 0 1 Xysticus pellax 0 1 2 3 10 9 4 23 26 Xysticus triguttatus 2 0 0 2 3 1 0 4 6 Zelotes exiguoides 0 2 0 2 0 2 1 3 5 Zelotes fratris 0 0 1 1 1 0 1 2 3 Zelotes hentzi 2 1 5 8 4 2 6 12 20 Zelotes lasalanus 11 15 7 33 7 10 4 21 54 Zelotes puritanus 0 1 0 1 0 0 0 0 1 Totals 237 444 748 1429 1327 2211 967 4505 5934

235 Appendix 2. Total catch of spiders collected in pitfall traps in each paddock and treatment of the primary experiment on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba in 2006. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Agelenopsis actuosa 0 0 0 0 0 1 0 1 1 Agelenopsis potteri 0 0 1 1 0 0 1 1 2 Agelenopsis utahana 1 2 0 3 0 2 0 2 5 Agroeca pratensis 0 0 0 0 1 1 2 4 4 Agyneta allosubtilis 0 0 1 1 0 0 0 0 1 Alopecosa aculeata 22 23 69 114 37 73 293 403 517 Araneus pratensis 0 0 0 0 1 0 0 1 1 Arctosa rubicunda 19 2 0 21 22 2 2 26 47 Castianeira descripta 11 15 2 28 2 1 1 4 32 Castianeira longipalpa 3 5 4 12 0 9 9 18 30 Ceraticelus laetus 0 0 1 1 0 2 1 3 4 Ceratinops crenatus 0 0 0 0 0 2 0 2 2 Ceratinops latus 0 1 0 1 0 0 0 0 1 Ceratinopsis interpres 0 0 0 0 0 0 1 1 1 Cicurina arcuata 1 0 0 1 1 2 6 9 10 Clubiona kiowa 3 2 5 10 2 0 2 4 14 Clubiona moesta 0 1 0 1 0 0 0 0 1 Coloncus siou 0 0 5 5 0 3 1 4 9 Drassodes neglectus 1 5 12 18 3 1 17 21 39 Enoplognatha marmorata 0 0 0 0 0 0 1 1 1 Eperigone trilobata 0 0 1 1 0 0 3 3 4 Erigone aletris 0 0 1 1 0 0 0 0 1 Erigone atra 0 2 0 2 0 0 0 0 2 Eris militaris 0 0 0 0 0 1 0 1 1 Euryopis gertschi 2 0 0 2 21 0 0 21 23 Euryopis pepini 3 0 0 3 1 2 1 4 7

236 Appendix 2 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Evarcha hoyi 0 0 1 1 4 0 2 6 7 Geolycosa missouriensis 0 0 0 0 1 0 0 1 1 Gnaphosa muscorum 1 2 2 5 1 1 6 8 13 Gnaphosa parvula 1 0 0 1 0 0 1 1 2 Grammonota capitata 2 4 0 6 3 11 2 16 22 Habronattus altanus 10 6 5 21 8 2 1 11 32 Habronattus americanus 0 1 0 1 0 1 0 1 2 Habronattus borealis 6 9 11 26 3 2 0 5 31 Habronattus cognatus 4 2 1 7 4 0 0 4 11 Hahnia cinerea 0 1 1 2 4 4 0 8 10 Halorates plumosus 0 0 0 0 0 1 0 1 1 Haplodrassus bicornis 2 0 0 2 4 0 0 4 6 Haplodrassus signifer 4 16 4 24 19 9 0 28 52 Hogna frondicola 2 8 6 16 14 13 23 50 66 Hypsosinga rubens 1 2 0 3 0 0 0 0 3 Larinia borealis 1 0 0 1 0 0 1 1 2 Lepthyphantes alpinus 0 2 3 5 2 20 5 27 32 Maevia inclemens 0 0 0 0 0 0 1 1 1 Micaria gertschi 0 0 0 0 0 1 0 1 1 Micaria laticeps 2 5 11 18 3 5 4 12 30 Micaria longipes 1 0 0 1 0 0 0 0 1 Misumenops celer 0 1 1 2 0 0 0 0 2 Neoantistea agilis 1 0 0 1 0 0 0 0 1 Nodocion mateonus 0 1 0 1 0 0 0 0 1 Ozyptila sincera 0 0 0 0 0 0 2 2 2 canadensis Pardosa distincta 154 276 334 764 420 772 390 1582 2346 Pardosa fuscula 1 0 1 2 0 0 0 0 2 Pardosa mackenziana 0 2 0 2 0 0 0 0 2

237 Appendix 2 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Pardosa moesta 0 3 5 8 5 14 8 27 35 Phiddipus borealis 2 7 1 10 2 0 0 2 12 Phiddipus johnsoni 10 17 8 35 15 6 6 27 62 Phiddipus purpuratus 2 11 8 21 0 0 1 1 22 Phiddipus whitmani 0 3 0 3 1 0 0 1 4 Philodromus histrio 1 1 0 2 0 0 1 1 3 Phrurotimpus certus 0 0 0 0 1 3 1 5 5 Pocadicnemis americana 0 0 1 1 4 10 0 14 15 Schizocosa mccooki 124 67 40 231 26 33 0 59 290 Scotinella pugnata 0 1 0 1 0 2 0 2 3 Scotinotylus pallidus 0 0 1 1 1 1 0 2 3 Sergiolus capulatus 0 0 0 0 0 1 0 1 1 Steatoda americana 1 0 3 4 0 0 1 1 5 Thanatus coloradensis 7 5 10 22 7 3 5 15 37 Thanatus formicinus 0 2 1 3 3 9 4 16 19 Thanatus rubicellus 3 2 7 12 11 3 15 29 41 Theridion prataeum 0 1 0 1 2 1 0 3 4 Titanoeca silvicola 0 0 1 1 0 0 0 0 1 Trochosa terricola 0 0 1 1 0 1 5 6 7 Tutelina similis 0 0 0 0 1 0 0 1 1 Walckenaeria castanea 0 0 0 0 0 0 1 1 1 Walckenaeria communis 0 3 0 3 0 2 0 2 5 Xysticus ampullatus 13 9 6 28 53 1 3 57 85 Xysticus auctificus 2 2 4 8 0 0 0 0 8 Xysticus emertoni 1 0 0 1 0 0 0 0 1 Xysticus ferox 0 0 2 2 0 0 4 4 6 Xysticus gulosus 81 8 20 109 12 8 1 21 130 Xysticus luctans 3 6 5 14 29 15 10 54 68

238 Appendix 2 continued. Grazed Ungrazed Grand Species 27 28 29 Total 27 28 29 Total Total Xysticus montanensis 10 5 6 21 1 1 1 3 24 Xysticus nigromacullatus 0 0 6 6 1 1 0 2 8 Xysticus pellax 12 2 0 14 22 27 0 49 63 Xysticus triguttatus 1 0 0 1 0 0 0 0 1 Zelotes exiguoides 0 0 0 0 2 0 0 2 2 Zelotes fratris 0 0 0 0 0 1 0 1 1 Zelotes hentzi 3 4 2 9 4 18 3 25 34 Zelotes lasalanus 21 26 17 64 26 33 1 60 124 Totals 556 581 638 1775 810 1138 850 2798 4573

239 Appendix 3. Total catch of spiders collected in pitfall traps and by sweep netting in each treatment of the secondary experiment on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba in 2005. Spring Graze Fall Graze Spring & Grand Species Only Only Fall Grazes Total Agelenopsis actuosa 0 0 2 2 Agelenopsis potteri 0 0 2 2 Agelenopsis utahana 2 0 0 2 Agroeca ornata 0 0 1 1 Agroeca pratensis 7 2 0 9 Agyneta allosubtilis 0 1 0 1 Alopecosa aculeata 196 214 224 634 Araneus saevus 0 1 0 1 Araneus trifolium 0 1 1 2 Arctosa rubicunda 16 9 11 36 Callilepsis pluto 1 2 1 4 Castianeira descripta 0 1 2 3 Castianeira longipalpa 12 10 6 28 Centromerus sylvaticus 1 2 1 4 Ceraticelus crassiceps 1 0 0 1 Ceraticelus laetus 1 0 4 5 Ceratinella brunnea 1 2 0 3 Ceratinops crenatus 0 1 0 1 Ceratinops latus 1 2 0 3 Chrysso pelyx 2 0 2 4 Cicurina arcuata 47 7 24 78 Cicurina robusta 1 0 0 1 Clubiona kiowa 5 7 6 18 Clubiona obesa 0 1 0 1 Coloncus siou 19 35 37 91 Dictyna terrestris 2 0 0 2 Drassodes neglectus 14 15 15 44 Enoplognatha marmorata 1 0 0 1 Eperigone tridentata 1 0 0 1 Eperigone trilobata 1 1 0 2 Erigone aletris 2 1 1 4 Erigone atra 1 0 1 2 Euophrys monadnock 0 1 1 2 Euryopis gertschi 2 1 6 9 Euryopis pepini 34 21 13 68 Gnaphosa muscorum 0 6 2 8 Gnaphosa parvula 1 1 0 2 Grammonota capitata 17 19 22 58 Habronattus altanus 2 0 0 2 Habronattus borealis 1 1 2 4 Habronattus cognatus 0 1 2 3

240 Appendix 3 continued. Spring Graze Fall Graze Spring & Grand Species Only Only Fall Grazes Total Hahnia cinerea 1 16 12 29 Haplodrassus hiemalis 1 2 1 4 Haplodrassus signifer 4 13 6 23 Hogna frondicola 15 11 9 35 Islandiana longisetosa 2 2 2 6 Lepthyphantes alpinus 17 31 17 65 Maso sundevallii 1 0 1 2 Micaria laticeps 18 23 19 60 Micaria pulicaria 0 0 1 1 Neoantistea agilis 1 0 0 1 Ozyptila sincera canadensis 3 5 0 8 Pardosa distincta 837 1004 1185 3026 Pardosa moesta 11 9 30 50 Pardosa ontariensis 0 1 0 1 Phiddipus borealis 0 1 0 1 Phiddipus johnsoni 8 7 10 25 Phiddipus purpuratus 1 1 0 2 Phiddipus whitmani 0 1 0 1 Phrurotimpus borealis 1 0 0 1 Phrurotimpus certus 2 4 0 6 Pirata minutus 0 0 1 1 Pocadicnemis americana 7 11 12 30 Schizocosa mccooki 7 3 5 15 Scotinotylus alpinus 0 0 1 1 Scotinotylus pallidus 4 1 0 5 Sergiolus capulatus 2 0 0 2 Steatoda americana 1 0 0 1 Tenneseelum formicum 0 1 0 1 Tetragnatha laboriosa 0 1 2 3 Thanatus coloradensis 19 11 14 44 Thanatus formicinus 8 10 9 27 Thanatus rubicellus 6 8 5 19 Thanatus striatus 1 0 0 1 Theridion prataeum 1 2 3 6 Trochosa terricola 4 0 3 7 Walckenaeria castanea 1 0 0 1 Walckenaeria communis 6 3 1 10 Walckenaeria digitata 0 0 4 4 Walckenaeria directa 0 0 1 1 Walckenaeria pallida 1 0 0 1 Walckenaeria spiralis 2 0 0 2 Xysticus ampullatus 52 63 65 180 Xysticus cunctator 1 7 4 12 Xysticus emertoni 1 1 1 3

241 Appendix 3 continued. Spring Graze Fall Graze Spring & Grand Species Only Only Fall Grazes Total Xysticus ferox 3 1 0 4 Xysticus gulosus 2 0 6 8 Xysticus luctans 26 23 23 72 Xysticus luctuosus 0 1 0 1 Xysticus montanensis 2 1 2 5 Xysticus pellax 1 1 0 2 Xysticus triguttatus 0 1 0 1 Xysticus winnipegensis 0 1 0 1 Zelotes exiguoides 0 2 1 3 Zelotes fratris 0 1 2 3 Zelotes hentzi 9 7 10 26 Zelotes lasalanus 9 21 17 47 Totals 1491 1679 1874 5044

242 Appendix 4. Total catch of spiders collected in pitfall traps and by sweep netting in each treatment of the secondary experiment on the Yellow Quill Mixed Grass Prairie Preserve, Manitoba in 2006. Spring Graze Fall Graze Spring & Grand Species Only Only Fall Grazes Total Agelenopsis actuosa 0 2 1 3 Alopecosa aculeata 165 109 78 352 Arctosa rubicunda 14 3 6 23 Callilepsis pluto 2 1 0 3 Castianeira descripta 0 1 0 1 Castianeira longipalpa 1 13 1 15 Ceraticelus laetus 1 1 0 2 Ceratinops crenatus 1 0 0 1 Ceratinopsis nigriceps 1 0 0 1 Cicurina arcuata 4 3 7 14 Cicurina robusta 0 0 1 1 Clubiona kiowa 4 0 3 7 Clubiona obesa 1 0 0 1 Coloncus siou 0 1 0 1 Drassodes neglectus 14 10 4 28 Eperigone trilobata 1 0 1 2 Euryopis gertschi 4 4 0 8 Euryopis pepini 2 0 1 3 Gnaphosa muscorum 6 3 4 13 Grammonota capitata 6 3 3 12 Habronattus altanus 1 0 0 1 Habronattus borealis 0 0 1 1 Habronattus cognatus 1 1 1 3 Hahnia cinerea 0 9 0 9 Halorates plumosus 1 0 0 1 Haplodrassus signifer 7 6 6 19 Hogna frondicola 14 11 3 28 Hypsosinga rubens 0 0 1 1 Lepthyphantes alpinus 10 10 1 21 Micaria laticeps 3 3 2 8 Microlinyphia mandibulata 0 1 0 1 Misumenops celer 1 0 0 1 Neoantistea agilis 1 0 0 1 Ozyptila sincera canadensis 0 1 0 1 Pardosa distincta 141 140 86 367 Pardosa fuscula 0 0 1 1 Pardosa moesta 5 8 1 14 Pardosa ontariensis 1 0 0 1 Phiddipus borealis 0 0 1 1 Phiddipus johnsoni 33 41 41 115 Phiddipus purpuratus 1 0 3 4

243 Appendix 4 continued. Spring Graze Fall Graze Spring & Grand Species Only Only Fall Grazes Total Phiddipus whitmani 2 0 1 3 Philodromus histrio 0 0 1 1 Phrurotimpus certus 1 0 0 1 Pirata canadensis 1 0 0 1 Pocadicnemis americana 1 2 0 3 Schizocosa mccooki 9 4 8 21 Scotinotylus pallidus 1 1 1 3 Sergiolus capulatus 0 1 0 1 Thanatus coloradensis 22 12 6 40 Thanatus formicinus 6 2 2 10 Thanatus rubicellus 24 7 7 38 Trochosa terricola 4 3 3 10 Walckenaeria communis 0 1 0 1 Walckenaeria digitata 1 0 0 1 Walckenaeria spiralis 0 1 0 1 Xysticus ampullatus 17 10 10 37 Xysticus elegans 0 4 1 5 Xysticus emertoni 1 1 2 4 Xysticus ferox 1 0 0 1 Xysticus gulosus 3 2 4 9 Xysticus luctans 31 20 11 62 Xysticus montanensis 1 2 0 3 Xysticus pellax 2 5 1 8 Xysticus triangulosus 1 0 0 1 Zelotes fratris 1 2 0 3 Zelotes hentzi 3 3 3 9 Zelotes lasalanus 9 17 21 47 Zelotes puritanus 0 1 0 1 Totals 589 486 340 1415

244