In the south-eastern Amazon, positive feedbacks between land use and severe weather events are increasing the frequency and intensity of fires, threatening local biodiversity. We sampled fruit-feeding butterflies in experimental plots in a south-eastern Amazon forest: one control plot, one plot burned every 3 y, one plot burned yearly. We also measured environmental parameters (canopy cover, temperature, humidity). Our results show no significant differences in overall species richness between plots (34, 37 and 33 species respectively), although richness was lower in burned plots during the dry season. We found significant differences in community composition and structure between control and burned plots, but not between burned treatments. In the control plot, forest-specialist species represented 64% of total abundance, decreasing to 50% in burned every 3 y and 54% in yearly burned plots. Savanna specialist species were absent in the control plot, but represented respectively 8% and 3% of total abundance in burned plots. The best predictor of the change in spatial community patterns and abundance of forest specialists was canopy cover. Although we found high resilience to forest burning in many species, our study suggests that fire disturbance can still be a threat to forest specialists due to changes in microclimate.
Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake
Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake
Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. The current study utilized a 1999–2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil.