Conserving a network of representative physical environments is a strategy that could conserve species both now and into the future, while allowing them to move in response to the climate. The key to implementing such a strategy is to define the physical environments in a way that is maximally relevant to species. We created comprehensive maps of geology, elevation zones, and landforms for the Eastern U.S. and then examined the relationships between these factors and 3434 rare species at 85,613 locations. Based on an index of importance derived from the number of species samples and an index of the percent above expected that a species was found on a feature, most species showed strong preferences for specific settings: 78% for specific geology classes, 70% for specific landforms, and 62% for elevation zones. More distinctive features tended to have more preferential species: calcareous, ultramafic, and coarse sand geologies; steep slopes and wet flat landforms; high altitude and coastal elevations. Our results suggest that the correspondence - whether causal or coincidental – between species and enduring features was substantial, and thus incorporating enduring features into conservation network designs could improve the long-term effectiveness of conservation areas. Examination of how well the current network of conservation lands represented the enduring features revealed biases towards high elevations and acidic geologies. Low elevations (6%), followed by calcareous (5%) and ultramafic (2%) geologies had the lowest representation. To adjust for this, we identified under-represented features in each of the 13 ecoregions and for the region as a whole.
