Biodiversity Risk in the US: Evidence and Implications of Spatial Autocorrelation

Abstract

This study develops a Modified Index (MODEX) to assess biodiversity risk for all 50 states in the United States (US). The MODEX is an adaptation of the National Biodiversity Risk Assessment Index (NABRAI), which was designed to provide estimates of relative biodiversity rankings among nations rather than for comparison of biodiversity risk among political units within a single country. The MODEX ranking of US states differs from previous biodiversity indices: some states that rank low on indices for threatened species are ranked high in terms of biodiversity risk when using the MODEX because of increased pressure activities. Results show that Illinois, Kentucky, Kansas, Rhode Island, and Maryland can be classified as high-risk states due to: (1) high population densities, (2) a high percentage of threatened and endangered species, and (3) a high percentage of land devoted to agriculture and infrastructure development. A map of MODEX values show that states in the same regions of the US have similar biodiversity risk. This is confirmed by statistical tests for spatial autocorrelation. Further, statistical cluster analysis was performed to identify meaningful groups of states that are similar based on the MODEX values and to verify the results of the spatial autocorrelation tests. These findings support the idea that biodiversity risk transcends arbitrary political boundaries. Thus, coordinating conservation funding and policy efforts in the US at both state and federal levels may be necessary to reduce biodiversity risk. Improved knowledge of relative biodiversity risk of political units within a country can help inform public policy aimed at prioritizing and coordinating conservation funding.