Mangals occur on all tropical coasts and in lagoons (between approximately the 30∞ latitudinal degrees), when a number of environmental conditions are fulfilled (slope, substrate type, water quality, protection against wave action etc.). In spite of their established ecological and derived economical (coastal fisheries, protection against coastal erosion) and direct economical importance (e.g. timber and fuel), they are still threatened because of lack of protection and lack of management. A rational management requires insight into the vegetation dynamics, which cannot be established over a short period, nor retrospectively, unless a time series of aerial photographs is available. This is the case for the Sri Lankan mangal, studied by the VUB. The programme in the proposal aims at the analysis of vegetation dynamics in mangals of S.W. Sri Lanka on basis of aerial photographs (1956-94). Because within mangal vegetation overview and positioning is extremely difficult (yet necessary for the vegetation recording methodology) a global positioning system is required and applied for in the proposal.