Interspecific Habitat Suitability of Four Southeast Asian Spiny Climbing Palms (Korthalsia) Through Species...

Rattans of the genus Korthalsia are ecologically and economically important non-timber forest resources in Southeast Asia, yet their conservation is limited by knowledge of species-specific distribution patterns and environmental constraints. We modeled the potential distributions of four Korthalsia species (K. flagellaris, K. laciniosa, K. rigida, and K. scortechinii) using species distribution models (SDMs). Models were fitted in R using the sdm package, and ensemble maps were generated by combining predictions from Random Forest (RF), Generalized Linear Models (GLMs), Generalized Additive Models (GAM), and GLMnet. The top predictors influencing habitat distribution included soil physical structure, atmospheric moisture demand, and canopy light availability. The dominance of these factors reflects three distinct and non-interchangeable environmental axes that regulate belowground moisture dynamics, atmospheric constraints on gas exchange, and the energetic requirements for recruitment. All four species ensemble models significantly outperformed the null model, and spatial block cross-validation (k = 5, 200 km blocks) indicated a marginal drop in area under the curve (AUC) values, confirming a predictive signal under geographically independent evaluation. Ensemble suitability maps identified Peninsular Malaysia, Borneo, and Sumatra as centers of predicted habitat. Core habitat was estimated to be less than 0.6% of total suitable area for all species, ranging from 980 km² (K. scortechinii) to 19,256 km² (K. rigida), with anthropogenic modification exceeding 50% in the core habitat in K. flagellaris and K. rigida. These results provide the first species-specific baseline for these Korthalsia across Southeast Asia, supporting more targeted conservation and restoration planning under varying habitat constraints.