Distribution patterns of medicinal plants along an elevational gradient in central Himalaya, Nepal

This study aimed to compare the distribution patterns and trends of plant parts used among different groups of medicinal plants, geographical regions, and between medicinal plants and all vascular plants. We used the published sources for elevation records of 2,331 medicinal plant species to interpolate presence between minimum and maximum elevations and estimated medicinal plant richness for each 100-m elevational band. Monte Carlo simulations were used to test whether differences in elevational distribution between different groups of medicinal plants were significant. Total number of medicinal plants as well as different groups showed unimodal relationship with elevation. The elevational distributions of medicinal plants significantly differ between regions and between medicinal plant groups. When comparing the richness of all medicinal plants to all vascular plants, Monte Carlo simulations indicated that the numbers of medicinal plants are higher than expected at low elevations. The highest richness of medicinal plants at low elevation could be possibly due to favorable environmental factors such as high temperature, rainfall, sunlight or due to higher density of human population and thus higher pressure on use of any plants in lower elevations.