Local environment shapes habitat suitability of the endangered mint Dicerandra cornutissima

Abstract

Ecological niche models are shaped by the spatial and environmental scales at which they are built, making environmental grain especially important for range‐restricted species with specialized habitat requirements. We used fine‐scale environmental data at 250 m resolution to estimate the ecological niche characteristics of Dicerandra cornutissima , an endangered mint endemic to xeric scrub and sandhill habitats in central Florida. Using 208 presence‐only localities, we built Maxent models with spatial block cross‐validation and edaphic, topographic, and canopy predictors. The best model performed well (AUC = 0.93) and identified 15,532 ha of high‐suitability habitat, concentrated near the corner of one county, with scattered patches beyond. The most suitable cells had higher clay and elevation, and lower cation exchange capacity, soil organic carbon, and tree canopy cover than the study region overall. Suitability declined with increasing canopy cover, consistent with the species' association with open, fire‐maintained gaps. Field validation confirmed that predicted sites contained characteristic habitat features and co‐occurring species, and identified unoccupied suitable areas, suggesting that historical or contemporary constraints may limit occupancy. Because only 26% of suitable habitat is protected, these unoccupied areas offer a spatially explicit shortlist for future surveys, management, and reintroduction of D. cornutissima .