Modelling current and future potential distribution of medicinal orchids in Darjeeling eastern Himalaya

Abstract

Species distribution modelling remains a valuable tool for managing conservation practices for medicinal plants. As climate change threatens the planet’s biodiversity, it has become imperative to investigate its impact on our important bioresources. We studied the distribution of two medicinally essential orchid taxa, Crepidium acuminatum and Satyrium nepalense, in the Darjeeling Himalayan region using MaxEnt modelling. AUC (Area Under the Curve) and the TSS (True Skill Statistic) value for the models was calculated to gauge model performance. The models generated via MaxEnt performed excellently with > 0.9 AUC value and 0.6 to > 0.85 TSS value. The most influential factor affecting the distribution of C. acuminatum seems to be precipitation, whilst the factor affecting S. nepalense is altitude. The current potential habitat of C. acuminatum and S. nepalense was 385.25 km² (12.51%) and 245.25 km² (7.96%), respectively. Of the total current potential habitat, only 108.75 km² (3.53%) and 61.5 km² (2.0%) were of good habitat suitability for C. acuminatum and S. nepalense, respectively. Similarly, only 100.5 km² (3.26%) and 43.5 km² (1.41%) were of excellent habitat suitability for C. acuminatum and S. nepalense, respectively. Hence, Maxent identified highly suitable regions for the conservation of both species. The model predicts that for C. acuminatum, the total suitable habitat may decrease by as much as 113.25 km^2. In contrast, for S. nepalense, the total suitable habitat may increase by as much as 230.25 km² in future scenarios. However, when suitable habitat increases in certain regions for both species, the habitat is usually of poor suitability. This reflects the strong effect of climate change on the future of medicinal plants, particularly orchids. Hence, this indicates the need for better monitoring and holistic conservation strategies.