Continental estimates of forest cover and forest cover changes in the dry ecosystems of Africa between 1990 and 2000

摘要: AIM This study provides regional estimates of forest cover in dry African ecoregions and the changes that occurred there between 1990 2000, using a systematic sample medium-resolution satellite imagery which was processed consistently across continent. LOCATION The area corresponds to forests woodlands Africa humid semi-arid regions. covers Sudanian Zambezian ecoregions. METHODS A 1600 Landsat subsets, each 20 km × size, were analysed for two reference years: 2000. At site both years, dense tree cover, open other wooded land vegetation identified from analysis imagery, comprised multidate segmentation automatic classification steps followed by visual control national forestry experts. RESULTS Land land-cover estimated at continental ecoregion scales compared with existing pan-continental, local studies. overall accuracy our maps 87%. Between 3.3 million hectares (Mha) 5.8 Mha 8.9 lost, further 3.9 degraded cover. These results are substantially lower than 34 loss reported FAO's 2010 Global Forest Resources Assessment same period area. MAIN CONCLUSIONS Our method generates first consistent robust change known statistical precision scales. reduce uncertainty regarding its dynamics these previously poorly studied ecosystems provide crucial information science environmental policies.