XVI International Botanical Congess

Our latest inventories of the mangroves of the world suggest that the aerial extent of these ecosystems is about 180,000 sq km (± 10%). South and Southeast Asia inhabit more than 40% of present mangroves. During the last decade (1980-1990) the average annual loss has been about 1%. Our work carried out with accurate mapping techniques at high levels of resolution has shown the evolutionary trends of mangrove ecosystems in tropical Continental Asia, from the Persian Gulf to Vietnam. The general regression of these ecosystems is observed everywhere except in protected areas. Within these conservation areas the mangrove habitats seem to be efficiently preserved or restored in most study sites. However, the present satellite technology (visible, infrared, microwaves) does not allow the detection of important and yet unexplained floristic changes occurring in several parts of Southeast Asia. We give a realistic assessment of the reliability and limitations of satellite technology for mangrove monitoring.