Postfire restoration seeding success increases with early fall seeding and simulated precipitation in the Great Basin Desert of North America

Abstract

Climate forecasts and disturbance mapping increasingly inform strategies for ecological restoration practices. Our study objectives were to understand how a postfire rehabilitation seed mix responds to fire, seeding timing, and changes in fall precipitation timing due to climate change. We planted seeds commonly used in the Great Basin Desert of North America on soil cores in a randomized block design. We imposed two experimental treatments, experimental fire (burned seedbeds or unburned seedbeds) and timing of seeding with simulated precipitation (early September vs. mid‐October) in a two‐way factorial design. We measured seedling emergence (1 month posttreatment), plant density, biomass, and seed production. Early seeding and precipitation reduced seedling emergence over 2‐fold but increased total plant density (3‐fold), biomass (13‐fold), and seed production (140‐fold) compared to delayed seeding and precipitation applications. Antelope bitterbrush was the only species with a negative response to early seeding and precipitation, with a decrease in both density and biomass (over 2‐fold) by the end of the study. Burned seedbeds overall had little effect on measured outcomes for the total plant community. Burned seedbeds decreased forb seedling emergence 2‐fold and alfalfa and Lewis blue flax density almost 3‐fold but increased overall forb seed production 7‐fold while other species and functional groups had minimal responses. Earlier seeding and precipitation interacted with the effects of burned seedbeds to increase biomass of Wyoming big sagebrush and western yarrow. The positive response of species to earlier fall seeding and precipitation underscores the importance of adapting our restoration practices for changing climate conditions.