Patterns and changes of land use and land-use efficiency in Africa 1980-2005: an analysis based on the human appropriation of net primary production framework

摘要

African land systems play a decisive role in addressing future sustainability challenges for food and energy supply-in Africa and potentially elsewhere. Knowledge on the magnitude and efficiency of current land use and its socio-economic frame conditions is scarce but required to provide an appropriate basis for estimating production potentials and efficiency improvements. We apply the human appropriation of net primary production (HANPP) framework to analyze African land systems and their dynamics between 1980 and 2005. HANPP measures human-induced changes in ecological biomass flows and allows analyzing the efficiency with which humans use the natural resource NPP (Net Primary Production). In 2005, African HANPP amounts to 20 %, which is below the global average of 23 %, and has grown significantly (+55 %) since 1980. HANPP efficiency (i.e., the ratio of used biomass extraction to total HANPP) is low (35 %) in contrast to the global average of 48 %. Large regional variations (ranging from 18 % in Central Africa to > 100 % in Northern Africa) and only small improvements of +11 % on average have been observed. In the study period, the growth of HANPP has been mostly driven by land-use expansion. We conclude that the observed low HANPP efficiency in Africa suggests that there may be potentials for improving the efficiency of biomass production on existing land-uses rather than increasing output trough further land expansion. We discuss policy implications that could help better utilizing existing potentials to increase land-use efficiency in a sustainable manner.