No description available.

Thesis (M.Sc.)(Wildlife Management)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

No description available.

Re-introducing heterogeneity to native North American rangelands is imperative to maintaining grassland biodiversity, and it has been suggested that using a variety of cattle grazing intensities on the landscape could accomplish this. I used generalized linear mixed models to describe the effects of grazing intensity on vegetation structure, plant species diversity and plant communities over four years. I used the Mantel test and non-metric multidimensional scaling to illustrate changes in plant communities with varying grazing intensities and over time. Effects of grazing were cumulative and changed over time, upland and lowland habitats responded differently to grazing intensity, and heterogeneity was maximized at the landscape scale under a variety of grazing intensities. When conservation is the primary goal, a variety of grazing intensities on the landscape can be used to increase heterogeneity, and therefore grassland biodiversity.

No description available.

Re-introducing heterogeneity to native North American rangelands is imperative to maintaining grassland biodiversity, and it has been suggested that using a variety of cattle grazing intensities on the landscape could accomplish this. I used generalized linear mixed models to describe the effects of grazing intensity on vegetation structure, plant species diversity and plant communities over four years. I used the Mantel test and non-metric multidimensional scaling to illustrate changes in plant communities with varying grazing intensities and over time. Effects of grazing were cumulative and changed over time, upland and lowland habitats responded differently to grazing intensity, and heterogeneity was maximized at the landscape scale under a variety of grazing intensities. When conservation is the primary goal, a variety of grazing intensities on the landscape can be used to increase heterogeneity, and therefore grassland biodiversity.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2007. / Thesis documentation sheet inserted. Includes appendix of four papers and manuscripts co-authored with others. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

Thesis (Ph.D.) - University of Glasgow, 1996. / Ph.D. thesis submitted to the Environmental Sciences Department, Scottish Agricultural College, 1996. Includes bibliographical references. Print version also available.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Includes bibliographical references. Also available electronically via World Wide Web in PDF format.

Tallgrass prairie restorations generally aim to reconstruct native plant assemblages altered by disturbance to a composition of species characteristic of undegraded communities the region. Most prairie restorations, however, lack large herbivores such as Bison bison and Cervus canadensis, therefore leaving herbivory to Odocoileus virginanus, other small mammals, and insects. Although insects are more abundant by comparison, it is hypothesized that their influence as ecological drivers is often obscured by fire, grazing, and climate. Previous study in remnant prairie has shown that insects eat very little of above net primary productivity (ANPP), however they can alter the forb:grass ratio in prairies. Nonetheless, studies have shown that younger plants (particularly forbs) are more susceptible to insect herbivory due to higher nitrogen (N) content and physical and chemical defenses not yet fully developed. This research used an experimental approach (insecticide application) to reducing insect abundance and ectophagy to determine whether insects preferentially feed on forbs, alter forb:grass ratios, and affect diversity and aboveground net primary productivity (ANPP) in young (1-2 y) and more established (7-8 y) restored prairies. Ectophagy measurements showed that forbs were preferred over C4 grasses. Reduced herbivory decreased diversity of forbs and sown grasses, decreased percent cover of forbs, and species richness of sown grasses, and increased evenness in the youngest prairie. Contrary to expectations, ANPP and forb:grass ratios were not affected by treatment. Nevertheless, interactions between year and restoration age were often significant, suggesting that climate variability between seasons and maturity of community may influence how insect herbivores affect restored prairie. There was a positive correlation between herbivore morphospecies richness and sown forb richness. Insect communities were also characterized in restored prairies to evaluate treatment success. Insects were collected by sweep-netting. I collected 10 orders, 83 families, and 150 morphospecies. The largest number of species present was from Hemiptera (suborder Auchenorrhyncha). Species richness decreased through time. Pesticide application reduced diversity of families. Ectophagous insect abundance and richness were impacted by treatment, but piercing-sucking herbivores (Hemiptera) did not respond to insect reduction treatment. Predator/parasitoid insects were also reduced by treatment, indicating a larger sensitivity at higher trophic levels. Like plant diversity, interactions between restoration age and year affected almost all insect variables, suggesting that insect populations are dynamic and sensitive to nearby land-use.