Patterns of tropical forest dynamics and human impacts: views from above and below the canopy

Abstract

Tropical forests are influenced by regional and global bio-climatic processes as well as local anthropogenic disturbances. Most studies have ignored the synergistic influence of bio-physical processes operating at large spatial scales and local human use on forest vegetation and fauna. Assessments of forest condition change using time-series of remotely sensed data need to be supported by measurements under the canopy. The Tadoba-Andhari Tiger Reserve (TATR) in India is a protected area that has a long history of human resource extraction and settlements. Like much of South Asia, it has undergone major shifts in rainfall in the last hundred years. We examine trends in forest greenness over two and half decades and assess spatial patterns in rates of change. We also analyze ground based measurements of human impacts on flora and fauna. Trends in forest canopy greenness show two distinct phases: a period of decline from 1980s to mid-90s, followed by a recovery. These trends are a function of initial greenness and are best explained by prevailing climatic regimes, feed-backs from human use, and park management practices and protection. Negative impacts to flora and fauna on the ground were, however, wide-spread during the recovery period and are influenced by proximity to nearest settlement as well as combined distance from all settlements. Remotely sensed data cannot effectively detect these processes under the canopy. There is an urgent need to incorporate monitoring of long-term bio-climatic processes and their interaction with short and long-term effects of human-use and disturbance arising from processes at local, regional and larger spatial scales around protected areas to effectively manage these reserves.