Philip De Witt

Ungulate guild dynamics: Mechanisms and consequences for aspen-parklands

Multi-ungulate communities can be structured by competition and facilitation, but few studies explore the interactions by which these processes occur or the subsequent implications for plant communities. Using paddock experiments conducted in central Alberta, I evaluated how previous and concurrent grazing influences resource selection and intake in a native assemblage containing bison (Bison bison), wapiti (Cervus elaphus), and mule deer (Odocoileus hemionus). Bison were unaffected by concurrent grazing, whereas previous grazing reduced daily intake. By altering the activity and resource selection of wapiti and deer, bison facilitated the daily intake of wapiti and displaced deer. When foraging simultaneously, behavioural interactions reduced forage utilization and homogenized the spatial distribution of forage. Although sequential grazing decreased the spatial heterogeneity of graminoid biomass in most scenarios, sequential grazing generally increased the patchiness of forbs. My research demonstrates that behavioural interactions have implications for ungulate assemblages and forage biomass in aspen parklands.