Niche characterization and distribution of Sikkim Himalayan <Begonia> (Begoniaceae), India: a niche modeling approach

Understanding species’ ecological niches and distribution patterns is crucial for biodiversity conservation and management, particularly in ecologically sensitive regions. We used an NDVI-based ecological niche modeling (ENM) approach for Begonia species for this purpose, where we achieved high predictive accuracy (AUC: 0.82–0.97). Niche breadth analysis revealed a positive correlation (r = 0.747, p = 0.003) between broader niche breadth and larger predicted distribution areas, aligning with the notion that better-performing models tend to capture either highly specialized (narrow-breadth) or ecologically flexible (broad-breadth) niches. Models for Begonia picta, B. panchtharensis, B. sikkimensis, and B. xanthina were classified as fair (0.8 < AUC < 0.9), and exhibited broader niche breadth, with ranges extending from the western Himalaya to the eastern Himalaya, encompassing Nepal, Bhutan, and China. In contrast, B. satrapis, B. gemmipara, and B. nepalensis showed very good model performance (AUC > 0.95) but had the narrowest niche breadth (0.102–0.195), suggesting specialized habitat requirements and restricted distributions. Given their limited ecological flexibility and smaller suitable areas, these species warrant immediate conservation attention to mitigate extinction risks.