COS 57-7
Increasing fire frequency effects on butterfly communities of southeastern Amazon forests
Fire frequencies are increasing in the southeastern Amazon, with negative consequences for the integrity of tropical forests and the biodiversity that they contain. This change in fire regimes is the result of interactions between land use change and drought frequency, and has substantial consequences for tropical forest structure, function, and biodiversity. However, the effects of increasing fire frequency on local biodiversity remain essentially unknown. We studied the impacts of forest fires on communities of fruit-feeding butterflies (Nymphalidae), a group of insects known to be efficient indicators of forest integrity and diversity of other taxa. Samples were conducted in 50-ha experimental plots of burned transitional forest at the Cerrado (neotropical savanna)/Amazonia region ecotone, one of the most threatened habitats. Baited funnel traps were set in a control plot, a thrice-burned plot (in 2004, 2007, and 2010) and a plot burned six times (in 2004, 2005, 2006, 2007, 2009, and 2010). We compared abundance, species richness, species composition and structure among the three treatments.
Results/Conclusions
Results indicate a considerable impact of forest fires on butterfly communities. Diversity parameters showed significant differences between control and burned plots, but not between burned treatments. Species accumulation curves showed burned forest with lower abundance but higher species richness, due to the invasion of Cerrado and grassland species in the burned forest. Fire also affected structure and composition (nMDS analysis, Anosim R = 0.22, p < 0.05). We found community species and sub-family composition patterns reflecting changes associated with fire disturbance: lower abundance or local extinction of forest specialist species (e.g. Memphis philumena, M. polycarmes, Pareuptychia sp., Zaretis itys), increase in species associated with grasses (Satyrinae) and Cerrado specialist species (e.g. Hamadryas feronia) (PCA analysis, chi-quare c2 = 22.60, p < 0.001). Micro-climatic alterations due to burning (e.g. higher sunlight incidence and lower humidity) are likely benefiting species with higher tolerance to open habitats, indicating that fire can have significant impacts on tropical insect diversity. Our findings corroborate the hypothesis that increases in fire frequency, along with other factors such as severe drought, can transition Amazon forests to a possible alternate degraded forest or grassland state, with alarming impacts on tropical insect biodiversity.