Human Appropriation of Net Primary Production (HANPP) in an Agriculturally-Dominated Watershed, Southeastern USA

Abstract

Human appropriation of net primary production (HANPP) quantifies alteration of the biosphere caused by land use change and biomass harvest. In global and regional scale assessments, the majority of HANPP is associated with agricultural biomass harvest. We adapted these methods to the watershed scale and calculated land cover change and HANPP in an agricultural watershed in 1968 and 2011. Between 1968 and 2011, forest cover remained near 50% of the watershed, but row crop decreased from 26% to 0.4%, pasture increased from 19% to 32%, and residential area increased from 2% to 10%. Total HANPP decreased from 35% of potential Net Primary Productivity (NPP) in 1968 to 28% in 2011. Aboveground HANPP remained constant at 42%. Land use change accounted for 86%–89% of HANPP. Aboveground HANPP did not change despite the major shift in agricultural land use from row crop and pasture. The HANPP and land use change in Doddies Creek watershed reflects changing land use patterns in the southeastern US, driven by a complex interaction of local to global scale processes including change in farm viability, industrialization of agriculture, and demographic shifts. In the future, urbanization and biofuel production are likely to become important drivers of HANPP in the region. At the watershed scale, HANPP can be useful for improving land use decisions and landscape management to decrease human impact on the ecosystem and ensure the flow of ecosystem services.