Abstract: Working lands provide food, fiber, fuel and other resources for human use and account more than 50% of the land in the continental United States. Prior assessments of habitat value frequently omit the most intensively managed working lands (i.e., row crops). We hypothesize that the full range of working lands contribute a significant proportion of habitat for native species. We developed a 30m national habitat condition model to test these hypotheses. This approach provides a repeatable design that utilizes nationally available geospatial and empirical biodiversity data to calibrate and validate the model. We divide the conterminous US (CONUS) by land cover type into natural and cultivated lands and then spatially map fragmentation, multiple anthropogenic stressors, proximity to aquatic habitat, and vegetation departure from pre-European conditions. Each map layer was then scored for site impact and distance decay, and combined into a final Habitat Condition Index (HCI). National Heritage Program (NHP) field observations providing scored relative ecological conditions and bird distribution data were used for HCI calibration and validation, tested both at the full CONUS and regional scales.
Results/Conclusions
Initial results indicate that most working lands provide habitat for native species. We observe that intensively managed agriculture (i.e., row crops), particularly when planted in large, homogeneous areas, provide considerably lower habitat value than silviculture or hay/pasture. However, as previous research has suggested, a heterogeneous mix of agriculture practices can increase habitat value of croplands. Validation of the HCI dataset using NHP data showed higher accuracy at the regional scale (70% accuracy), than at CONUS scale (62%). Because the regional-scale models allowed for variation in parameters, this result suggests strong regional variation in the impact upon habitat quality of anthropogenic structures, fragmentation, and proximity to water. From a conservation standpoint, the HCI supports previous research that working lands can deliver considerable ecological benefit, and thus may be critical in species or system management, particularly in some configurations of intensity and heterogeneity. Here, we find that not only may working lands serve as a viable buffer or connector between preserved natural lands, but serve as habitats for native species unto themselves.