Effects of dormant- vs. growing-season fire in shortgrass steppe: Biological soil crust and perennial grass responses

This research experimentally examined seasonal effects of fire on biological soil crusts and perennial grasses in shortgrass steppe. We predicted dormant-season fire would have greater negative effects on biological soil crusts than fire during the growing season, but less of an impact on perennial grasses than fire during the growing season. Treatments were dormant- and growing-season fires and unburned reference condition plots. Response variables included biological soil crust and grass percent ground cover, and crust nitrogen fixation and chlorophyll a content. Results indicated shortgrass steppe can recover from fire in three to 30 months, dependent on fire season. Burning during the dormant-season had little effect on grass cover, but decreased nitrogen fixation and reduced chlorophyll a content in crusts. Growing-season fire negatively impacted grass cover, but reduced the impact of fire on soil crusts. Most of the fire effects in this study were of relatively short duration and strongly tied to weather patterns.