Effects of Tropical Forest Degradation on Amazon Forest Phenology

Anthropogenic disturbances in tropical forests cause short-and long-term alterations in forest structure, species composition, and successional processes. However, improved understanding of the impacts of disturbance on forest functioning is needed to support forest management and conservation. In this study, we investigated the phenological responses of two sites in the Brazilian Amazon to forest degradation (selective logging and forest fires). We used MODIS-derived time-series to assess pre- and post-disturbance trajectories of two vegetation indices: Normalized Burn Ratio (NBR) and Enhanced Vegetation Index (EVI). We found that our study sites present different VI seasonality, and that selective logging did not cause phenological shifts. Fires, on the other hand, caused explicit EVI shifts in the transition from wet to dry season in the driest site and barely no shifts in the wettest site, and yearlong NBR shifts compared to intact forests at both sites. Changes in the magnitude and timing of phenological events highlight human-induced changes in tropical forests functioning. If widespread, these shifts may have large-scale implications for carbon sink stability in tropical regions.