Joining laboratory, greenhouse, and field approaches to improve our understanding of fire effects on seed germination in Great Basin, Colorado Plateau, and Sonoran deserts
Our findings suggest that all deserts exhibited vulnerability to increasing fire disturbance because relatively low soil seed densities may not provide enough propagules for revegetation. Therefore, seeding of these communities may be especially important. In the cold deserts, this susceptibility was further evidenced by the fact that aboveground community composition in fire-affected areas was significantly different from the nearby unburned community even 30 years after fire and burned communities were associated with non-native species. That said, native species did exist in seed banks of burned sites and some taxa, like Sporobolus sp., occurred in high densities. Therefore, caution may be needed when using herbicide treatments to control exotic species as there may be unintended consequences of decreasing desirable species. In contrast, our warm desert sites exhibited less change in terms of seed densities, species richness and aboveground community composition following fire. In the face of more frequent fires, the lack of shrub seeds in the seed bank of all deserts was notable and we found no evidence of greater seed densities or unique species assemblages associated with shrub microsites.