Refining the cheatgrass-fire cycle in the Great Basin: precipitation timing and fine fuels predict fire trends

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This study investigated the complex relationships among weather, fine fuels, and fire in the Great Basin, USA. It found that cheatgrass cover increased in years with higher precipitation and especially when one of the previous 3 years also was particularly wet. Area burned in a given year was mostly associated with native herb and non-native forb cover, whereas cheatgrass mainly influenced area burned in the form of litter derived from previous years’ growth. Results suggest that the region’s precipitation pattern of consecutive wet years followed by consecutive dry years results in a cycle of fuel accumulation followed by weather conditions that increase the probability of wildfire events in the year when the cycle transitions from wet to dry. These patterns varied regionally but were strong enough to allow us to model annual wildfire risk across the Great Basin based on precipitation alone.