WILDFIRE IMPACTS ON VEGETATION STRUCTURE IN THE BRAZILIAN ATLANTIC FOREST 8 YEARS AFTER A FIRE

Wildfire impacts on vegetation structure in the Brazilian Atlantic Forest

Abstract

Wildfires are a severe threat to biodiversity, especially in fire-sensitive ecosystems such as tropical rainforests. We assessed differences in vegetation structure between burned and unburned Brazilian Atlantic Forest fragments eight years after a wildfire. We expected higher tree mortality, a greater abundance of ferns, and reduced canopy cover in burned areas, reflecting limited forest recovery. Although the number and basal area of snags (standing dead trees) did not differ between areas, burned forests had fewer living trees, more snags per plot, and a greater number of fallen trees. Living trees in unburned areas exhibited larger basal areas, whereas snags were larger in burned areas. Canopy cover was lower and more variable in burned sites. In the understory, Neotropical bracken fern dominated burned forests, while herbaceous plants and palms were more frequent in unburned areas. The results indicate that fire impacts persist nearly a decade after disturbance, as evidenced by the higher abundance and basal area of standing and fallen dead individuals, confirming fire as a key agent of structural alteration in tropical forests. Additionally, the dominance of superdominant species and the low canopy cover may compromise natural regeneration. However, the remaining snags, as well as the living trees, in the burned forest may act as perches, facilitating seed rain. Concluding, our results indicate that natural regeneration is not sufficient, and active restoration strategies should be employed for the recovery of burned Neotropical rainforests.