Human Appropriation of Net Primary Productivity (HANPP) in Texas: A Statewide Analysis of Sustainability in the Agricultural and Timber Sectors

Abstract

The sustainability of the Texas agricultural and timber sectors is measured using the ratio of human appropriation of net primary productivity (HANPP) to available net primary productivity (NPP) on a county-by-county basis for the entire state. By combining NPP and HANPP, a measure of ecologic sustainability in terms of carbon dynamics is achieved. This is based on a six-year average from 2000 to 2005 obtained from the NASA MODIS sensor, as well as the calculated NPP harvested from agricultural and timber activities reported by USDA Agricultural and Texas Forest Department timber statistics covering the same years. The spatial pattern of NPP in Texas is strongly influenced by moisture availability and is naturally highest in the Gulf Coastal Plains, and parts of east Texas. Areas of artificially-high NPP can often rival or surpass naturally occurring NPP and occur primarily due to irrigation, such as in the Panhandle and lower Rio Grande Valley. Human appropriation of this carbon is greatest in the Panhandle and lower Rio Grande Valley where, in many counties, >45% of all carbon produced is appropriated. HANPP values throughout the rest of the state are moderate (10-24%) corresponding well with global and national HANPP literature. These results support two conflicting findings: increased HANPP indicates decreased ecological sustainability, but is also a measure of increased agricultural efficiency.