This study assessed the influence of terrestrial invertebrate abundance and vegetation characteristics on northwest Minnesota greater prairie chicken brood success. Radio telemetry was used to determine movements of greater prairie chicken hens and their broods. Invertebrate abundance indices were collected using a sweep net and vegetation data were recorded with overhead and dot-board photographs. Invertebrates were dried, sorted by size and order, and weighed and counted. Vegetation was classified according to life form and height was measured. Greater prairie chicken broods appear to use those habitats most readily available with increased invertebrate resources. Invertebrate biomass was not related to the occurrence of uncultivated forbs which averaged < 17% in Minnesota habitats where greater prairie chicken broods were located. Relatively undisturbed grasslands produce sufficient invertebrate resources to fledge greater prairie chicken chicks. However, location data and invertebrate-habitat indices suggest increased brood success would be likely with improved habitat placement/availability and irregular disturbance regimes that produce beneficial mixed grass/forb vegetation attractive to both greater prairie chicken broods and their invertebrate prey.

Wetlands are very valuable ecosystems as they play an integral role in wildlife habitat, water management and greenhouse gas exchange. The exchange of carbon dioxide between prairie wetlands and the atmosphere is poorly understood. The purpose of this study was to identify rates and trends in the growing season carbon dioxide flux from the riparian and open-water zone of a prairie pothole wetland. In addition to providing core open water and riparian zone CO2 flux measurements, relationships between variations in CO2 flux and characteristics of the wetland’s biological, biochemical and hydrometeorological state were assessed. The CO2 effluxes from the pond during the summer of 2006 were approximately four times greater than in 2005, but were much lower in the early fall. Algal chlorophyll-a concentrations were greater in 2005 than 2006 for all three algal assemblages. The mean chlorophyll-a concentrations in 2005 for epiphyton, phytoplankton and metaphyton were 2.75 ± 0.62 g m-2, 87 ± 24 µ L-1, and 318 ± 187 g m-2 respectively. In 2006 mean concentrations for the same assemblages were 0.008 ± 0.001 g m-2, 8 ± 2 µ L-1, and 27 g m-2 respectively. The amount of DOC in the open water in August of 2005 (140 mg DOC L-1) was 70 times greater than in July of 2005 (2 mg DOC L-1). DOC ranged from 30 to 52 mg DOC L-1 in 2006. Although highly productive, the pond proper appeared to be a source of DOC which is concurrent with literature from littoral zone and shallow inland waters. Soil respiration increased upslope from the wetland to the cropped upland in 2005. Net ecosystem exchange was greater in the cattail ring surrounding wetland than the grass and sedge zone beyond the cattails. The riparian vegetation may have been water stressed in late-July (at the climax of the dry period) when net ecosystem exchange decreased. Diurnal net ecosystem exchange in the riparian zone indicates uptake during the day and emissions at night. From this data it appears that the riparian zone may have acted as a CO2 sink in June, July and August and a source in April.

Brush encroachment is a serious problem on pastures in Western Canada. It results in a loss of productivity and habitat for wildlife. Sixty-seven pastures were visited in Manitoba, Saskatchewan and Alberta. Approximately half were privately owned lands and the remainder were public lands. Each field sampled was divided into grass, shrub and forest strata, within each stratum vegetation cover was noted and biomass and soil samples were taken. A historical reconstruction was created using aerial photos dating back to the 1940s up until most recent photos available. Six cover classes were delineated and patch statistics were calculated. Information on historical management practices were obtained also. It was determined that woody encroachment is occurring on pastures, but no significant trends found between environmental factors and encroachment. Therefore it was concluded that management probably has the greatest impact on the occurrence and extent of woody encroachment.

There is little information comparing the impacts of bison and cattle grazing in the northern mixed-grass prairies; understanding which grazer to use for management is important. I collected data in sites grazed by bison or cattle using point counts to survey the songbird community, and habitat structure measurements. I used generalized- and non-linear mixed models to determine the relationships between grazers and habitat or songbird communities. Bison and cattle grazing caused changes in habitat structure, including decreased vegetation height and litter depth. Sprague’s pipits declined more steeply with bison grazing than with cattle grazing. 0.4 AUM/ha was an important threshold, because chestnut-collared longspurs increased in abundance at this stocking rate, and grasshopper sparrows decreased in abundance at this stocking rate. Either grazer is appropriate for managing for grassland birds. There is also an opportunity to encourage surrounding landowners to manage their lands for the benefit of wildlife.

This study considered the long term effects and interaction between burning and grazing in the northern mixed-grass prairies on the grassland songbird community. Point counts were conducted to assess songbird species abundances in burned-grazed, burned-ungrazed, unburned-grazed, and unburned-ungrazed pastures along with habitat structure (litter depth, vegetation height and density) over a five year period; from the first year post burn in 2007 until the fifth year post burn in 2011. Generalized linear mixed models were used to analyse the interaction between year, burning, and grazing for songbird abundances and habitat structure. As time since burned increased, species abundances in burned-grazed pastures have become more similar with those in unburned-grazed while abundances in burned-ungrazed are becoming increasingly similar to those in unburned-ungrazed pastures. The effects of burning are different than those of grazing and both disturbances should be utilised in grassland management when possible.

Wetlands are very valuable ecosystems as they play an integral role in wildlife habitat, water management and greenhouse gas exchange. The exchange of carbon dioxide between prairie wetlands and the atmosphere is poorly understood. The purpose of this study was to identify rates and trends in the growing season carbon dioxide flux from the riparian and open-water zone of a prairie pothole wetland. In addition to providing core open water and riparian zone CO2 flux measurements, relationships between variations in CO2 flux and characteristics of the wetland’s biological, biochemical and hydrometeorological state were assessed. The CO2 effluxes from the pond during the summer of 2006 were approximately four times greater than in 2005, but were much lower in the early fall. Algal chlorophyll-a concentrations were greater in 2005 than 2006 for all three algal assemblages. The mean chlorophyll-a concentrations in 2005 for epiphyton, phytoplankton and metaphyton were 2.75 ± 0.62 g m-2, 87 ± 24 µ L-1, and 318 ± 187 g m-2 respectively. In 2006 mean concentrations for the same assemblages were 0.008 ± 0.001 g m-2, 8 ± 2 µ L-1, and 27 g m-2 respectively. The amount of DOC in the open water in August of 2005 (140 mg DOC L-1) was 70 times greater than in July of 2005 (2 mg DOC L-1). DOC ranged from 30 to 52 mg DOC L-1 in 2006. Although highly productive, the pond proper appeared to be a source of DOC which is concurrent with literature from littoral zone and shallow inland waters. Soil respiration increased upslope from the wetland to the cropped upland in 2005. Net ecosystem exchange was greater in the cattail ring surrounding wetland than the grass and sedge zone beyond the cattails. The riparian vegetation may have been water stressed in late-July (at the climax of the dry period) when net ecosystem exchange decreased. Diurnal net ecosystem exchange in the riparian zone indicates uptake during the day and emissions at night. From this data it appears that the riparian zone may have acted as a CO2 sink in June, July and August and a source in April.

Brush encroachment is a serious problem on pastures in Western Canada. It results in a loss of productivity and habitat for wildlife. Sixty-seven pastures were visited in Manitoba, Saskatchewan and Alberta. Approximately half were privately owned lands and the remainder were public lands. Each field sampled was divided into grass, shrub and forest strata, within each stratum vegetation cover was noted and biomass and soil samples were taken. A historical reconstruction was created using aerial photos dating back to the 1940s up until most recent photos available. Six cover classes were delineated and patch statistics were calculated. Information on historical management practices were obtained also. It was determined that woody encroachment is occurring on pastures, but no significant trends found between environmental factors and encroachment. Therefore it was concluded that management probably has the greatest impact on the occurrence and extent of woody encroachment.

There is little information comparing the impacts of bison and cattle grazing in the northern mixed-grass prairies; understanding which grazer to use for management is important. I collected data in sites grazed by bison or cattle using point counts to survey the songbird community, and habitat structure measurements. I used generalized- and non-linear mixed models to determine the relationships between grazers and habitat or songbird communities. Bison and cattle grazing caused changes in habitat structure, including decreased vegetation height and litter depth. Sprague’s pipits declined more steeply with bison grazing than with cattle grazing. 0.4 AUM/ha was an important threshold, because chestnut-collared longspurs increased in abundance at this stocking rate, and grasshopper sparrows decreased in abundance at this stocking rate. Either grazer is appropriate for managing for grassland birds. There is also an opportunity to encourage surrounding landowners to manage their lands for the benefit of wildlife.

This study considered the long term effects and interaction between burning and grazing in the northern mixed-grass prairies on the grassland songbird community. Point counts were conducted to assess songbird species abundances in burned-grazed, burned-ungrazed, unburned-grazed, and unburned-ungrazed pastures along with habitat structure (litter depth, vegetation height and density) over a five year period; from the first year post burn in 2007 until the fifth year post burn in 2011. Generalized linear mixed models were used to analyse the interaction between year, burning, and grazing for songbird abundances and habitat structure. As time since burned increased, species abundances in burned-grazed pastures have become more similar with those in unburned-grazed while abundances in burned-ungrazed are becoming increasingly similar to those in unburned-ungrazed pastures. The effects of burning are different than those of grazing and both disturbances should be utilised in grassland management when possible.

Thesis (M.S.)--Eastern Illinois University, 2008. / Includes bibliographical references (leaves 30-32).