The effects of prescribed fires in different seasons on small mammals in a Sierra Nevada mixed conifer forest.

摘要

Prescribed fire is an important management practice used to restore natural fire regimes in Sierra Nevada mixed conifer forests where fire has been suppressed over the last century. It is not well known, however, how the timing of prescribed fire affects wildlife species. I compared the effects of prescribed fires during the early season (spring and early summer) with those during the late season (late summer and fall) on small mammal populations using model selection and inference methods. In Chapter 1, I examined the effects of prescribed fire treatments on small mammal movements. In Chapter 2, I evaluated the effects of prescribed fire treatments on small mammal population demographics. In Chapter 3, I explored small mammal habitat relationships following prescribed fire treatments.; Lodgepole chipmunk (Neotamias speciosus) movements differed between years, but there was no effect of prescribed fires on their movements (Chapter 1). Deer mouse (Peromyscus maniculatus) movements differed between age groups within years. Prescribed fire treatments did not affect deer mouse movements, except when only adult female deer mouse movements were analyzed. Year effects were more important than fire effects on lodgepole chipmunk densities, total small mammal biomass, deer mouse densities, and deer mouse age ratios (Chapter 2). Prescribed burning had a positive effect on deer mouse pregnancy ratios, and there was only limited support for an effect of year on these ratios. There was essentially no support for different effects of fire depending on the season of fire on total small mammal biomass and deer mouse densities, and only limited support for these effects on lodgepole chipmunk densities, deer mouse age ratios, and deer mouse pregnancy ratios. The prescribed fire treatments differentially impacted small mammal habitat components depending on the season of the fire (Chapter 3). However, there were few significant relationships between these habitat components and deer mouse densities, lodgepole chipmunk densities or small mammal species richness. Overall, year effects often had the greatest influence on the small mammal populations examined, and there were few strong differences between the effects of early season fires and late season fires on these populations.