Broadcast Seeding Fails to Enhance Native Plant Recovery 17 Years after a Mojave Desert Wildfire

Abstract

Increasing wildfire activity, partly associated with invasion of fuel-producing, non-native grasses, has stimulated interest in developing ecological restoration strategies to accelerate native plant recovery after wildfire in western North American deserts. Using plant community assessments from 1–3 (2009–2011) and 16 years (2024) after seeding, we examined effects of broadcast seeding five native species across 40 ha after the 2007 Bonnie Springs Fire (southern Nevada, Mojave Desert). Seeding did not increase the density or cover of seeded species in any year, nor did we detect many seeded species in soil seed banks (only one occurrence of one species). Moreover, there was little evidence that the activity of seeding influenced non-seeded, native or non-native species composition. By 2024, 17 years post-fire and 16 years post-seeding, native plant cover and species richness (100 m2) in the burned area, irrespective of seeding, remained only half the amount in unburned reference habitat while non-native cover was 2–3 times higher. Despite including locally sourced, readily germinable seed, selecting species capable of being initial post-disturbance colonizers, and receiving above average rainfall in two of the first three post-seeding years, seeding did not enhance native species establishment. Developing timely, reliable practices for seeding after desert wildfires may require further work regarding the degree to which seed availability limits recovery (relative to other factors such as site conditions), whether natural early colonizers are best for seeding, factors that influence germination ecology of candidate species, and if pairing other treatments with seeding can increase effectiveness.