s:1659:"TI Trees on farm: analysis of global extent and geographical patterns of Agroforestry 
AU Zomer R A 
AU Trabucco A 
AU Place F 
AU Coe, R. 
AB Agroforestry, the inclusion of woody pere nnials within farming systems, has been both a traditional landuse approach developed by subsistence farmers throughout the tropics, and a livelihood option promoted by landuse managers and international development efforts. Agroforestry system s range from subsistence livestock and pastoral systems to home gardens, alley in tercropping, and biomass plantations with a wide diversity of biophysical conditions a nd socio-ecological characteristics. The extent of its practice has never been quant ified leading to widely varied estimates about its importance. This paper is the first attempt to quan tify the extent of agroforestry at the global level. A geospatial analysis of remote sensi ng derived global datasets investigated the correspondence and relati onship of tree cover, popula tion density and climatic conditions within agricultural land at 1 km resolution. Among the key results are that agroforestry is a significant feature of agricu lture in all regions, th at its extent varies significantly across different regions (e.g. more significant in Central America and less in East Asia), that tree cover is str ongly positively related to humidity, and that there are mixed relationships between tr ee cover and population density depending on the region. This first analysis suggests that patterns of tree cover are influenced by a range of factors we were not able to ex amine at the global scale and a number of follow up analyses are recommended. 
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