Effects of moose browsing on decomposition rates of birch leaf litter in a subarctic stream
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Authors: J. G. Irons, III, J. P. Bryant, and M. W. Oswood
Date: 1991
Journal: Canadian Journal of Fisheries and Aquatic Science
Volume: 48
Number:
Pages: 442-444
Summary of Methods: The effects of moose (Alces alces) browsing on nitrogen concentrations and decomposition rates of paper birch (Betula resinifera) leaf litter were measured in a subarctic headwater stream near Fairbanks, Alaska (65° N, 146° W). Senescent leaf samples were collected from moose browsed and unbrowsed paper birch trees. Three grams of leaves were placed in 25 packs in mesh bags in the stream. Approximately every two weeks for almost 11 weeks, five packs were taken out for analysis, which included decomposition rates and condensed tannin and nitrogen concentrations.
Article Summary / Main Points: Leaves collected from browsed trees decomposed faster, had higher nitrogen content and leached tannin more rapidly than leaves from the unbrowsed birch trees. Faster loss of tannin through leaching and higher foliar nitrogen concentration apparently caused birch detritus to be processed more rapidly by stream biota, potentially increasing secondary production of stream consumers. Hence, moose browsing was associated with increasing the food quality of birch leaf litter by reducing tannins and increasing nitrogen concentrations, linking terrestrial herbivory and aquatic food webs.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 229 Interior Alaska Lowlands 231 Interior Alaska Highlands
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: browse chemistry, tannin levels, aquatic food webs, herbivory, invertebrate utilization
Annotation: Leaves were collected after browsing, but neither timing nor intensity of browsing was measured in this study. Insect herbivory was thought not to have occurred on the collected leaves, but it was not verified. However, many recent studies have demonstrated that herbivory does increase the quality of litter and these results, although perhaps incomplete, should be viewed as part of the larger picture on the effects of herbivory on litter quality.
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