全球智库信息集成服务系统

The loss of tree cover over extensive areas of the humid tropics is a global phenomenon with important implications for the health and prosperity of forest ecosystems, as well as the local people and economies that depend on their resources.

Accurate, consistent and timely data on the location and extent of major changes in forest ecosystems is essential to governments and civil society groups that are working to understand and address the impacts of forest loss. Until recently, global forest cover assessments typically had to rely on disparate data sets of uncertain quality and accuracy. However, improved mapping techniques and satellite observations can now, for the first time, produce reliable, cost-effective measurements of forest cover change. This new capability represents a turning point in environmental monitoring and the use of satellite information to improve management of the world's forests.

Since 2000, remotely sensed data have been available free of cost from the MODIS (MODerate Resolution Imaging Spectro-radiometer) sensor, operated by NASA. MODIS land data are detailed enough (250 and 500 meters) to detect major land cover conversion events. Near-daily data updates for the entire surface of the Earth allow for timely detection and documentation of change.