Your search for keyword(s) "soil organic matter" resulted in 4 record(s).

Title: Direct and indirect effects of herbivores on nitrogen dynamics: Voles in riparian areas: Journal: Ecology; Authors: J. M. Sirotnak, and N. J. Huntly; Date: 2000; Summary: This study assessed effects of voles (Microtus) on nitrogen dynamics using exclosures in two riparian meadows (Crystal Bench and Blacktail Deer Creek), in Yellowstone National Park. Results showed that voles affected nitrogen dynamics directly and indirectly. Direct mechanisms included alterations in litter quantity and quality that increased the pool of soil organic nitrogen that was readily mineralizable. However, after several years, and contrary to the authors initial hypothesis, indirect effects of voles became important to nitrogen dynamics. The removal of chroni ...; Agrovoc Control Words: Riparian zones, Rangelands, Wildlife; View more details about this article

Title: Spatial variability of soil properties in the shortgrass steppe: The relative importance of topography, grazing, microsite, and plant species in controlling spatial patterns: Journal: Ecosystems; Authors: I. C. Burke, W. K. Lauenroth, R. Riggle, P. Brannen, B. Madigan, and S. Beard; Date: 1999; Summary: Burke et al. compared changes in soil characteristics, caused by long-term grazing, topography, microsite and plant species, in a Colorado shortgrass steppe plant community. Topography and microsite had greater effects on soil characteristics than grazing and plant species. Grazing tended to enhance coarse particulate organic matter C and N and soil redistribution, while decreasing soil respiration; however, the magnitude of these differences was limited. The authors conclude that 60 years of grazing has had minimal impacts on soil physical and chemical characteristics in this shortgrass st ...; Agrovoc Control Words: Riparian zones, Rangelands, Wildlife; View more details about this article

Title: Soil carbon and nitrogen of Northern Great Plains grassland as influenced by long-term grazing: Journal: Journal of Range Management; Authors: A. B. Frank, D. L. Tanaka, L. Hofmann, and R. F. Follett; Date: 1995; Summary: Three mixed prairie sites in North Dakota were grazed heavily, moderately, or left ungrazed (exclosure) since 1916. These sites provided treatments to study the effects of long-term grazing on soil organic carbon and nitrogen content and to relate changes in soil carbon and nitrogen to grazing induced changes in species composition. Relative cover of blue grama (Bouteloua gracilis) increased from 25% to 86%. In contrast, under moderate grazing, relative cover fluctuated from 15% to 64%, and returned to 16% at last measurement. Total soil nitrogen was greater in the exc ...; Agrovoc Control Words: Riparian zones, Rangelands, Wildlife; View more details about this article

Title: Quantitative effects of grazing on vegetation and soils over a global range of environments: Journal: Ecological Monographs; Authors: D. G. Milchunas, and W. K. Lauenroth; Date: 1993; Summary: Multiple regression analyses were performed on worldwide 236-site data set compiled from studies that compared species composition, aboveground net primary production (ANPP), root biomass, and soil nutrients of grazed vs. protected, ungrazed sites. The authors' objective was to quantitatively assess factors relating to differential sensitivities of ecosystems to grazing by large herbivores. Changes in species composition with grazing were primarily a function of ANPP and the evolutionary history of grazing of the site, with level of consumption third in importance. Changes in species compos ...; Agrovoc Control Words: Riparian zones, Rangelands, Wildlife; View more details about this article