Identification of Optimal Understory Cultivation Zones for Five Typical Yunnan Medicinal Herbs Across Integrating Climatic Data and Forest Stand Conditions

This study focuses on five understory medicinal plants in Yunnan Province: Paris polyphylla var. yunnanensis, Polygonatum kingianum, Panax notoginseng, Gastrodia elata, and Dendrobium nobile. Using the MaxEnt model and based on forest management inventory data from Yunnan Province, we investigate the mechanisms by which stand conditions influence the distribution of medicinal plants in forest understory areas and simulate the spatial distribution of suitable habitats for these plants. Results indicated that intergrating forest stand variables significantly improved model accuracy for these species, with average increases in AUC, the true skill statistic, and the continuous Boyce Index by 5.22%, 13.26%, and 3.44%, respectively. The primary climate factors affecting the distribution of P. polyphylla, P. kingianum, P. notoginseng, G. elata, and D. nobile were seasonal precipitation variability, precipitation of wettest month, mean diurnal range, temperature seasonality, mean temperature of driest quarter, respectively, with site type as the dominant forest stand factor for all five plants. While the total area of suitable habitats decreased after incorporating forest stand variables, the distribution of highly suitable areas remained consistent. P. notoginseng and G. elata exhibited strong regional specificity, with P. notoginseng concentrated in southeastern Yunnan and G. elata in northeastern Yunnan. P. polyphylla, P. kingianum, and D. nobile demonstrated relatively broader suitable ranges, with high-suitability areas for P. polyphylla primarily in western and southern Yunnan, P. kingianum mainly in southern and southeastern Yunnan, and D. nobile predominantly in western and southern Yunnan.