Comparative effects of elk herbivory and 1988 fires on northern Yellowstone National Park grasslands
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Authors: F. J. Singer, and M. K. Harter
Date: 1996
Journal: Ecological Applications
Volume: 6
Number: 1
Pages: 185-199
Summary of Methods: The authors present data on the effects of elk (Cervus elaphus) herbivory on grassland species composition, biomass production, and forage quality, and to document any changes in ungulate-grassland interactions caused by the autumn wildfires. The 1988 Yellowstone wildfires increased grass biomass by approximately 20% and increased the digestibility in one of three grasses. Protein, cellulose, and macronutrients in grasses were unaffected by fire. Elk preference for burned grasslands during the second and third winters following the fires, however, suggested that elk gained some benefits from burned grasslands, perhaps due to greater foraging efficiency. Protein concentration was enhanced an average of 21%, digestibility was increased 7%, macronutrients concentrations were increased, and N yield was increased an average of 22% on grazed versus ungrazed areas. No interactions were observed between elk herbivory and burning on the Blacktail Plateau. Burning did not affect N levels in either grazed or ungrazed grasslands, probably because litter accumulations on the study sites, even unprotected sites, were still far less than in tallgrass prairie. The authors attribute the lack of nutrient enhancement by the fires of 1988 on the Blacktail Plateau to elk herbivory, the relatively low accumulation of aboveground material, and the relative high speed of the frontfire, and the resultant cool burning.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: elk, cervus elaphus, forage quality, fire effects, ungulate winter range, grazing, grasslands, herbivory, yellowstone national park
Annotation: In 1986 and 1987, prior to the fires, 20 plots were randomly located on ungrazed (exclosed) sites and 20 plots on grazed sites adjacent to the 2-ha elk exclosures. ,All herbaceous and subshrub aboveground biomass was clipped from the plots at peak standing crop (late July) and sorted by species.,Forage quality was sampled in mid-July 1986, 1989, and 1990.,Soil moisture and temperature were recorded bi-weekly from late April through early September of 1990.,7 aerial counts of elk were made from aircraft during midwinter (December-February), two winters prefire (1986-1987, 1987-1988) and three winters postfire (1988-1989, 1989-1990, and 1990-1991).,Grazing intensity not specified.
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