The Congo basin is the second largest tropical forest in the world, and intimate knowledge of forest characteristics and change is crucial to good management. Recent advances in satellite monitoring have dramatically improved the quality of forest maps; the Congo State of the Forest report of 2010 published a detailed vegetation map while a more recent global study from the University of Maryland tracks deforestation and forest cover change.
Forest mapping uses the earth’s satellites to identify forest vegetation over a large area. Landsat satellites orbit the earth with a 30 meter swath and circle a point on earth once every 16 days. MODIS satellites are lower resolution (250 meters) but orbit every day. In tropical areas, satellite photos are often obscured by clouds, but mosaic images of multiple satellite views over time can overcome this problem. Forests can be mapped from satellite images by using the reflectance in the different color bands of the satellite sensors to identify vegetation. Similarly, the change in forest pixels to non forest pixels can be used to measure deforestation and forest cover change. In 2008, NASA made much of their satellite data freely available over the internet; high resolution data is also freely available from Google Earth Engine.
In the Congo basin, the Central Africa Regional Program for the Environment of USAID provides interactive GIS and forest mapping (CARPE Mapper). Other programs include REDD+, regional capacity building, and more. The CARPE program collaborates with OSFAC, the Observatoire Satellital des Forêts d’Afrique Centrale, started in 2000 to share satellite data throughout the region. OSFAC contributes to regional landscape planning by producing reliable and useful map and land cover information for managers and decision-makers, using its regional network to improve data availability and build capacity across Central Africa. Other groups involved in forest mapping in the Congo basin include Woods Hole Research Center and the WRI Congo Basin forest atlases, which include detailed information on land use, timber and mining concessions, and protected areas.
Results from an analysis of forest cover change using Landsat data found total forest loss of 2.3% over the decade of 2000-2010. Forest loss centered in areas of dense population and mining; loss also increased in the second half of the data. The mean patch area of forest clearing was 1.4 hectares, suggesting that shifting cultivation continues to be a major driver of deforestation in the humid forest of the region.
Satellite mapping is an important step to establish baseline deforestation and forest carbon levels for REDD+. In the DRC, Yale F&ES researcher Peter Umunay (MFS ‘14) developed allometric equations to more accurately quantify the forest carbon in humid forest of the region.
CARPE. (n.d.) Central Africa Regional Program for the Environment. Retrieved from http://carpe.umd.edu/index.php
Potapov, P.V., Turubanova, S.A., Hansen, M.C., Adusei, B., Broich, M., Altstatt, A., Mane, L., and Justice, C.O., Quantifying forest cover loss in Democratic Republic of the Congo, 2000-2010, with Landsat ETM+ data, Remote Sensing Environment, 2012, 122, 106-116