Post-Wildfire Vegetation Response on Diverse Rangelands in Northeast California: Does Livestock Grazing Management Matter?

Abstract

Wildfires are increasing in size and frequency and are affecting federal lands used for livestock grazing across the western United States. A recommended approach to post-wildfire grazing policy is to rest fire-affected areas from grazing for two growing seasons following a burn; however, this guideline does not consider biophysical factors that influence vegetation recovery after fire. We examined responses of Bromus tectorum, annual graminoids, perennial graminoids, and species diversity to grazing management strategies (rested from livestock grazing one or two growing seasons after fire vs. grazing the growing season after fire) from 1-16 years after wildfire among sites that differed in biophysical factors, including burn severity, precipitation, temperature, and juniper presence. Vegetation cover data was collected at 106 sites that were burned in 18 diverse fires on northeast California rangelands. Overall, rest from livestock grazing increased perennial graminoid cover and areas not rested from livestock grazing had lower species diversity 16 years after fire. Annual graminoid cover and B. tectorum cover decreased with precipitation and increased with burn severity. Perennial graminoid cover was positively correlated with juniper presence and time since fire and negatively correlated with temperature and burn severity. Species diversity increased with precipitation, decreased with temperature, and increased slightly over time in severely burned areas rested from grazing. This broad scale research offers tools to aid livestock grazing management decisions following wildfire.