Colonization–persistence trade-offs shape changes on vegetation island community assembly in campo rupestre under fire disturbance

Abstract

We studied neglected island plant communities on rock outcrops (vegetation islands or patches) that harbor many endemic species. We assessed how the post-fire habitat conditions (factor related to habitat filtering), the patch area and substrate depth (factors related to resource availability and environmental filtering), and the patch distance (spatial factor related to dispersal limitation) shape the plant community attributes, life forms and persistence–reproduction trade-offs in a campo rupestre in the Chapada Diamantina, Brazil. Two years after a wildfire, we sampled 82 vegetation islands in two habitat conditions based on fire disturbance (burned and unburned). We verified high plant mortality caused by wildfire. All succulent and desiccation-tolerant chamaephytes died, but while the desiccation-tolerant chamaephyte recolonized burned vegetation islands by seedling recruitment, the succulent chamaephyte lack regeneration after disturbance, demonstrating their vulnerability to fire disturbances. The post-fire recovery was driven by obligate resprouters (hemicryptophytes and phanerophyte), post-fire colonizers (therophytes and phanerophytes), facultative seeders (phanerophytes), and desiccation-tolerant obligate seeders (chamaephytes). Despite the similar species richness between burned and unburned vegetation islands, the fire-habitat conditions determined changes in species composition and persistence–reproduction trade-offs. We demonstrated that random processes related to the colonization-survival and persistence–reproduction trade-offs can be a strong biotic factor shaping vegetation islands on rocky outcrops beyond environmental filtering and dispersal limitation. Our study is the first to investigate the fire effects on vegetation islands in rock outcrops and reveal the desiccation-tolerant obligate seeder as a novel post-fire regeneration strategy, that has a central role in the vegetation island community assembly.