Modeling Habitat Suitability for Stewartia ovata Across the Southeastern United States

Abstract

ABSTRACT Mountain stewartia (Stewartia ovata) is a rare shrub or small tree endemic to the higher elevation regions of Georgia, Tennessee, and Alabama with isolated populations occurring in Kentucky, North Carolina, South Carolina, Virginia, and Mississippi. The species is often misidentified or overlooked by land managers and conservationists. As a result, mountain stewartia's habitat and distribution descriptions are limited for restoration and conservation use. Modeling a species' habitat suitability has become a critical first step in conserving rare and imperiled plant species. These models allow conservationists to locate previously undocumented populations and prioritize populations and habitats for conservation. This study presents a habitat suitability model for mountain stewartia across its known natural range based on maximum entropy (Maxent) modeling with nine environmental predictor variables and 60 occurrences from herbarium records (n=22), research-grade iNaturalist observations (n=25), and other author identified locations (n=3). The resulting habitat suitability map was classified into bins for spatial analysis. A total of 376,030 ha (0.44% of the study area) was designated within the top tier bin with the highest suitable habitat. Further, 133,344 ha (0.16% of the study area) of the top bin was found on publicly owned lands, indicating approximately 35.56% of the highest habitat suitability occurs within public lands. The presented model could allow plant conservationists to prioritize areas for conservation, reintroduction, and may lead to the discovery of previously undocumented populations.