Foraging intensity of large herbivores may exert an indirect top-down ecological force on soil microbial communities via changes in plant litter inputs. We investigated the responses of the soil microbial community to elk (Cervus elaphus) winter range occupancy across a long-term foraging exclusion experiment in the sagebrush steppe of the North American Rocky Mountains, combining phylogenetic analysis of fungi and bacteria with shotgun metagenomics and extracellular enzyme assays. Winter foraging intensity was associated with reduced bacterial richness and increasingly distinct bacterial communities. Although fungal communities did not respond linearly to foraging intensity, a greater β-diversity response to winter foraging exclusion was observed. Furthermore, winter foraging exclusion increased soil cellulolytic and hemicellulolytic enzyme potential and higher foraging intensity reduced chitinolytic gene abundance. Thus, future changes in winter range occupancy may shape biogeochemical processes via shifts in microbial communities and subsequent changes to their physiological capacities to cycle soil C and N.
Bibliographical noteFunding Information:
We sincerely thank Eric Cole of the National Elk Refuge for providing access to field sites. The authors also thank Joseph Zak and Thad Stanley for field assistance as well as Sydney Salley for her invaluable laboratory assistance. This research was supported by the School of Natural Resources & Environment at the University of Michigan.
© 2017 John Wiley & Sons Ltd/CNRS
- community assembly
- extracellular enzyme
- functional gene