Fire reduces taxonomic and functional diversity in Neotropical moist seasonally flooded forests

Abstract

Fires are recurrent in moist tropical savannas, but in recent decades, Neotropical forests have become more affected due to the increased frequency of fires and the extent of burned areas. Currently, there is still limited knowledge on whether and how these disturbance events generate changes in taxonomic and functional diversity that can ultimately lead to the degradation and loss of resilience of tropical forests. To understand the response of Neotropical moist seasonally flooded forests to fire and the impact on taxonomic and functional diversity, we studied forests affected by fires with three degrees of severity and intensity: unburned, severity and intensity burned, and high severity and intensity burned. Regardless of the severity, fire generates a high taxonomic and functional homogenization in the tree and palm community by reducing α and β taxonomic and functional diversity and increasing functional homogenization by filtering species with similar traits. We found that adults with fire avoidance traits, such as deciduousness, and persistence traits, such as resprouting ability, were the ones that better survived the fire. Fire significantly reduced the abundance of evergreen species and those that were dispersed by zoochory. Our findings provide insight into the functional trajectory of Neotropical moist seasonally flooded forests after the fire, indicating that even moderate fire events may lead to a homogenization of these ecosystems and threaten their persistence.