A Case Study Examining the Relationship Between Human Appropriation of Net Primary Productivity and Landscape Patterns in the U.S. Great Lakes Basin

Abstract

Human appropriation of net primary productivity (HANPP) has been proposed as a measure of human pressures on biodiversity; it represents the proportion of energy flow that was historically available to wildlife food webs but has been appropriated for human use, primarily through the harvesting of primary production. This study examined the spatial relationship between HANPP of managed terrestrial landscapes and two abiotic proxy metrics for biodiversity–landscape diversity and local connectedness. Our objectives were 1) to quantify patterns of HANPP in forestlands and croplands, comparing the extraction of NPP in a recent decade against the potential natural vegetation that largely existed on the US side of the Great Lakes prior to European settlement; and 2) to assess spatial patterns of HANPP in comparison to landscape diversity and local connectedness at the county scale across the region. Our analysis considered above and below-ground compartments of NPP and focused on the percent of potential NPP being appropriated (%HANPP0). The mean areaweighted %HANPP0 across our study region was 45%, with the lowest %HANPP0 occurring in counties with >50% forest cover. We observed a significant (p<0.001) but weak, negative relationship between %HANPP0 and county means of landscape diversity (r=-0.53, r2=0.28) and a significant (p<0.001), moderate, negative relationship between %HANPP0 and local connectedness (r =-0.61, r2=0.36). Our findings are comparable to global estimate of HANPP on croplands and forestlands, and support previous research indicating HANPP negatively impacts biodiversity. We concluded the calculation of HANPP could be used as an additional tool for conservation professionals during regional-scale landuse planning or conservation decision-making, particularly in mixed-use landscapes that exhibit potential to support biodiversity based on abiotic proxy measures and have high amounts of primary production harvest.