Fire effects on different successional groups of tree species in the southwestern Brazilian Amazon

Aim of study: Human-driven wildfires are frequent events in the Amazon rainforest and can lead to changes in the composition and structure of plant communities. To contribute to this discussion, this work aims to evaluate the fire effect after 10 years on the composition, abundance, and richness of tree species in different successional groups in the southwestern Brazilian Amazon. Area of study: This work was carried out in two forest fragments located in the southwestern Brazilian Amazon, each containing areas affected by a single fire events (burned areas) as well as adjacent unburned areas. Material and methods: In each burned and unburned area, plots measuring 250 x 10 m (2500 m2) were established for sampling the tree species. The individuals sampled were classified into three different successional groups: pioneer species, early secondary species and tolerant species. Main results: The composition of tree species differed between burned and unburned areas, when all tree species were included in the analysis, and when only tolerant species were included. Higher tree abundance was detected in burned areas, considering all species and considering only pioneer and early secondary species separately. Only the richness of early secondary species differed between treatments, with higher values being detected in burned areas. Research highlights: From the results found, we concluded that changes in the proportions of individuals and tree species in the succession groups are still ongoing even after 10 years of fire events.