Abstract
The increasing frequency of wildfires in Southern California’s Mediterranean-type habitats has been facilitating the displacement of native plants by invasive annuals. Black mustard ( Brassica nigra ) is an abundant, allelopathically harmful, invasive forb, which readily colonizes soil niches following most disturbances. Wildfires, however, are unlike other forms of disturbance because they can fundamental alter plant-soil interactions through both physical and chemical changes in the soil. Here, a comparative field study of burned and unburned sites suggests that the Woolsey Fire – the largest wildfire ever recorded in California’s Santa Monica Mountains – inhibited dispersal of B. nigra and changed how it interacts with other plant species in the second year of post-fire recovery. More surprisingly, native plants were more likely to replace B. nigra than non-native plants in burned sites. These results indicate the possibility of post-fire seeding with specific “fire follower” native plant species may allow native flora to occupy soil niche space until longer-lived, competitive native shrubs establish.
Commonness and rarity of alien and native plant species - the relative roles of intraspecific competition and plant-soil feedback
