Limitations to Postfire Seedling Establishment: The Role of Seeding Technology, Water Availability, and Invasive Plant Abundance

Abstract

Seeding rangeland following wildfire is a central tool managers use to stabilize soils and inhibit the spread of invasive plants. Rates of successful seeding on arid rangeland, however, are low. The objective of this study was to determine the degree to which water availability, invasive plant abundance, and seeding technology influence postfire seedling establishment. Across four fire complexes, whole plots were either seeded using a rangeland drill, seeded by hand where seeds could be placed at an exact depth, or left as unseeded controls. Irrigation and weeding treatments were applied to subplots within whole plots in an incomplete factorial design. In three of the four fires, seeding method was the single factor limiting establishment with seedling density over sevenfold higher in the hand-seeded compared to the drill-seeded treatments. In contrast to our hypotheses, water and weeding had no positive effect on seedling establishment in any of the four fires; however, background weed density was relatively low. The native community recovered at all sites with minimal bunchgrass mortality. These results strongly suggest a need for a decision framework that evaluates postfire seeding needs relative to natural recovery. Based on these initial results, it appears modest improvements in seeding technology may yield substantial increases in seeding success.