Moose browsing and soil fertility in the boreal forests of Isle Royale National Park
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Authors: J. Pastor, B. Dewey, R. J. Naiman, P. F. McInnes, and Y. Cohen
Date: 1993
Journal: Ecology
Volume: 74
Number: 2
Pages: 467-480
Summary of Methods: Pastor et al. studied the effect of moose (Alces alces) browsing on the nutrient cycles of boreal forests using three, 40-year old exclosures on Isle Royale, Michigan. Soil nutrient availability and microbial activity, including exchangeable cations, total carbon and nitrogen, nitrogen mineralization rates, and microbial respiration rates were uniformly higher in exclosures than outside. These differences were more significant where browsing intensity was high and less often significant where was browsing intensity was low. Differences in litter quantity and quality were caused by an increased abundance of unbrowsed spruce outside the exclosures. In the long term, high rates of moose browsing depress N mineralization and net primary production through the indirect effects on recruitment into the tree stratum, and subsequent depression of litter N return and litter quality. These results suggest that the effects of herbivores on ecosystems may be amplified by positive feedbacks between plant litter and soil nutrient availability.
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: moose, alces alces, boreal forests, exclosures, food webs, herbivory, nitrogen cycling, nitrogen mineralization
Annotation: Three exclosures (which only exclude moose, not snowshoe hare) were in upland forests; 1) Windigo= moose densities of 4.6 animals/km2, 2) Siskiwit Camp= moose densities of 1.5 animals/km2, and 3) Daisy Farm= moose densities of 3.4 animals/km2.
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