Bison and fire: Landscape analysis of ungulate response to Yellowstone's fires

摘要

A simulation model of bison survival under different scenarios of winter severity, fire size, fire pattern and population size was run. Previous work had shown the model to be realistic. The overriding factor influencing bison winter survival in the model was winter severity. This factor had significant interactions with fire size and population size as well, further reducing survival in all cases. Increasing fire size reduced survival the first year after a simulated fire, but increased survival two years after the fire. This was due to enhanced forage production in burned areas the second year. A threshold effect on survival was noted at fire sizes greater than 60% of the simulated landscape, a number which is critical in disturbance propagation in landscapes. There was no biologically important effect of fire pattern (random vs. clumped) on survival.