This GSE-FM service option provides a powerful tool for effective forest monitoring and inventory at regional scale using both EO-data and ground based observations. It is especially designed for allocating reliable and up-to-date information over large forest areas. Many regions of the world like wide parts of Russia and the Irkutsk Oblast are covered by vast forests. The countries and administrative regions often have to deal with pressing environmental problems such as frequent forest fires events, illegal logging practices as well as other human activities and natural forest disturbances. Due to the large forest areas, which are often difficult to access or characterized by insufficient infrastructure and severe climate conditions, frequent monitoring of the forest resources is a great challenge. Forest monitoring by the means of ground inventories is rather complicated or even impossible. The use of aerial photographs is also often insufficient and cost-intensive. As a result, forest information available today, often does not correspond to the current situation. This is true for wide parts of Siberia, for example. However, according to their own legislation and to fulfill international obligations up-to-date and reliable information on forest resources are essential. For instance, in order to update the Russian State Forest Account as well as for forest management and monitoring issues an annual update of forest information is obligatory. The use of EO-technologies offers an excellent tool to obtain spatial forest information. Especially for regions covered by vast forest areas the combined use of high and low resolution EO-data is the most promising and cost-efficient strategy. Therefore, this GSE-FM service option follows a two-level strategy:

• Level 1: Low and medium resolution satellite data are used for operational monitoring of forest changes over large areas caused by fires, cutting, and other natural and human induced disturbances. Territories where significant changes occurred are identified at this level.
• Level 2: Both high-resolution satellite data and aerial photos are used for a detailed inventory of all candidates registered by the first level observations. Ground truth data (inventory maps, topography, archive EO data etc.) are used in addition.