Drivers of desert plant communities: Interactions of small mammal folivory and fire in the Great Basin Desert

Background/Question/Methods

Historically, North American deserts have been relatively resistant to fire. In recent years, however, the introduction of invasive plants, particularly fire tolerant grasses, is increasing the frequency, size, and lasting impacts of desert wildfires. Past studies have discovered that rodent consumers provide some biotic resistance towards plant invasions, but the influence of this biotic resistance on plants at the seedling stage of development is unclear. This study followed the survival of both native and invasive seedlings in the Great Basin Desert over the course of 7 days in the 2 years following a burn treatment. By experimentally excluding small mammal consumers and conducting burn treatments in a factorial design in five randomly replicated blocks, it was possible to document the synergistic effects of fire disturbance and small mammal exclusion on the establishment of the plant communities.

Results/Conclusions

Both small mammal folivory and burning had a detrimental impact on the survival of the seedlings. In the year following the fire, the overall survival was the lowest, in burned plots that were open to small mammals. The overall survival was low the first year following the burn, with no treatment achieving a survival rate of higher than 60% by the end of the 7 days. The hardest hit seedlings were the desert bitterbrush, alfalfa, four wing saltbush and sagebrush. In the burned plots that were open to small mammals, the seedlings of these species had been consumed within 2 days of the study. However, survival was much higher 2 years following the burn, with the overall survivorship never dropping below 40% in any of the treatment plots. The survival rates between the different treatments was also very similar in the 2^nd year following the fire. These results provide insight into the influence that small rodents have on plant community establishment following a fire. Understanding of these influences can be used to implement managerial initiatives that may help in increasing the success rates of land rehabilitation.