Rafael B. Andrade

Wildfires in bamboo-dominated Amazonian forest: impacts on above-ground biomass and biodiversity.

Fire has become an increasingly important disturbance event in south-western Amazonia. We conducted the first assessment of the ecological impacts of these wildfires in 2008, sampling forest structure and biodiversity along twelve 500 m transects in the Chico Mendes Extractive Reserve, Acre, Brazil. Six transects were placed in unburned forests and six were in forests that burned during a series of forest fires that occurred from August to October 2005. Normalized Burn Ratio (NBR) calculations, based on Landsat reflectance data, indicate that all transects were similar prior to the fires. We sampled understorey and canopy vegetation, birds using both mist nets and point counts, coprophagous dung beetles and the leaf-litter ant fauna. Fire had limited influence upon either faunal or floral species richness or community structure responses, and stems <10 cm DBH were the only group to show highly significant (p = 0.001) community turnover in burned forests. Mean aboveground live biomass was statistically indistinguishable in the unburned and burned plots, although there was a significant increase in the total abundance of dead stems in burned plots. Comparisons with previous studies suggest that wildfires had much less effect upon forest structure and biodiversity in these south-western Amazonian forests than in central and eastern Amazonia, where most fire research has been undertaken to date. We discuss potential reasons for the apparent greater resilience of our study plots to wildfire, examining the role of fire intensity, bamboo dominance, background rates of disturbance, landscape and soil conditions.

Quantifying responses of dung beetles to fire disturbance in tropical forests: the importance of trapping method and seasonality.

Understanding how biodiversity responds to environmental changes is essential to provide the evidence-base that underpins conservation initiatives. The present study provides a standardized comparison between unbaited flight intercept traps (FIT) and baited pitfall traps (BPT) for sampling dung beetles. We examine the effectiveness of the two to assess fire disturbance effects and how trap performance is affected by seasonality. The study was carried out in a transitional forest between Cerrado (Brazilian Savanna) and Amazon Forest. Dung beetles were collected during one wet and one dry sampling season. The two methods sampled different portions of the local beetle assemblage. Both FIT and BPT were sensitive to fire disturbance during the wet season, but only BPT detected community differences during the dry season. Both traps showed similar correlation with environmental factors. Our results indicate that seasonality had a stronger effect than trap type, with BPT more effective and robust under low population numbers, and FIT more sensitive to fine scale heterogeneity patterns. This study shows the strengths and weaknesses of two commonly used methodologies for sampling dung beetles in tropical forests, as well as highlighting the importance of seasonality in shaping the results obtained by both sampling strategies.

Responses of leaf-litter ant communities to tropical forest wildfires vary with season

Fire is an important land-management tool in tropical forest landscapes. However, these fires sometimes escape into surrounding forests (Uhl & Buschbacker 1985), and are one of the most severe disturbances threatening tropical forest biodiversity (Barlow et al 2006). These forest fires have become more frequent over the last decades due to the combined effect of selective logging, fragmentation and abnormal droughts that increase the flammability of forests, and agriculture expansion that brings the ignition sources (Aragao & Shimabukuro 2010).

Tropical forest fires and biodiversity: dung beetle community and biomass responses in a northern Brazilian Amazon forest

The Brazilian Amazon is under threat from more frequent and intense forest fires, with a few studies showing negative consequences for forest integrity and the biodiversity. However, the impacts of this disturbance on tropical forests remain mostly unknown. We investigate the impacts of forest fires on community parameters and biomass of dung beetles, a cost-effective indicator of disturbance and overall biodiversity, in the northern Brazilian Amazon. Our results indicate that burned forests harbor a modified dung beetle community, with altered abundance, community composition, and structure. Burned forest samples had lower total biomass and were dominated by small-bodied dung beetles. Large-bodied tunneler species were negatively impacted, responding to changes in environmental characteristics such as soil compaction. Lower biomass and higher predominance of smaller species in burned forest is likely to impact dung beetle-mediated ecological functions, such as nutrient cycling and seed dispersal. Our results support that forest fires in the Brazilian Amazon pose a serious threat to local biodiversity and habitat integrity.