Reduction of Tree Cover in West African Woodlands and Promotion in Semi-Arid Farmlands

Brandt, Martin ; Rasmussen, Kjeld ; Hiernaux, Pierre ; Herrmann, Stefanie ; Tucker, Compton J ; Tong, Xiaoye ; Tian, Feng ; Mertz, Ole ; Kergoat, Laurent ; Mbow, Cheikh(START International, Washington, DC, United States)

关键词: AFRICA;    ARID LANDS;    CARBON;    FARMLANDS;    LAND MANAGEMENT;    MODIS (RADIOMETRY);    RAIN;    SATELLITE IMAGERY;    URBAN DEVELOPMENT;    VEGETATION;   

RP-ID  :  GSFC-E-DAA-TN53367

学科分类：地球科学(综合)

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Woody vegetation in farmland acts as a carbon sink and provides ecosystem services for local people, but no macro-scale assessments of the impact of management and climate on woody cover exists for drylands. Here we make use of very high spatial resolution satellite imagery to derive wall-to-wall woody cover patterns in tropical West African drylands. Our study reveals a consist-ently high woody cover in farmlands along all semi-arid and sub-humid rainfall zones (16%), on average only 6% lower than in savannas. In semi-arid Sahel, farmland management increases woody cover to a greater level (12%) than found in neighbouring savannas (6%), whereas farm-lands in sub-humid zones have a reduced woody cover (20%) as compared to savannas (30%). In the region as a whole, rainfall, terrain and soil are the most important (80%) determinants of woody cover, while management factors play a smaller (20%) role. We conclude that agricultural expansion cannot generally be claimed to cause woody cover losses, and that observations in Sahel contradict simplistic ideas of a high negative correlation between population density and woody cover.