Expanding remote sensing of forest resources

This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends remote sensing and ground surveys.

Exact knowledge about the location and the overall condition of forest resources including tree types (thus up-to-date forest inventories) can be ascertained allowing accurate, timely and cost-effective decision making processes to be developed. Remote sensing also provides adequate and rapid damage assessment for different stages of stress due to pollution, lack of water, insect damage and other causes. Pre- and post- forest fire mapping or during the event, for instance, supports successful fire management programmes. The ecosystem changes resulting from such disturbances can then be chronologically recorded. Forest productivity can also be assessed and aided. Identifying biophysical conditions such as climatic conditions that could be suitable for tree species regeneration is used for identifying where to best establish tree plantations for afforestation programmes and for re-establishing endemic species. Similarly, by imaging the vegetation condition at the specific time of the satellite overpass with the respective ground and aircraft observations and models of vegetation behaviour, comprehensive and quantitative pictures of the vegetation condition and their response to changing environmental conditions can be ascertained to location. Furthermore, methods to determine the total phytomass and to estimate the annual net primary productivity and the net change in carbon storage for the vegetation can be calculated as well. The same principles can be applied to agricultural needs.

These applications allow the forest manager to manage from the office rather than spending a significant portion of their time travelling to different parts of the forested area. Dispatch of personnel such as timber markers and surveyors becomes more efficient and even non-essential. Likewise, planning and supervising logging operations, road construction, fire prevention and suppression and timber stand improvement work can be done more cost effectively. The collected data from remote sensing as well as data from other sources ( e.g. cartography) can finally be incorporated into a GIS and serve as models to guide timber harvesting, fire management activities, or predict fuel wood and other resources supply. Other priorities, such as providing sufficient wildlife habitats, ensuring recreational opportunities and minimizing visual impacts of harvesting, can be achieved as well.

Monitoring tropical rainforest deforestation in concert with field surveys has been one of remote sensing's outstanding contributions. In India, for instance, studies have shown that the actual rate of deforestation is ten times higher than that estimated by the UN Food and Agricultural Organization (FAO). Moreover, satellite images show that areas legally designated as forest land are virtually treeless. The latest FAO study which used high resolution satellite data estimated the annual deforestation rate at 15.4 million hectares.