Himalayan medicinal plant diversity in an ecologically complex high altitude anthropogenic landscape, Dolpo, Nepal

摘要

The conservation of high-altitude medicinal plants is of concern throughout the Himalayan region, because they are important for traditional health care and in large-scale collection for trade. Because little is known regarding their conservation status in relation to the diversity of land-use patterns and habitats, this paper explores patterns of species composition and diversity of medicinal plants in five different pasture types in a traditionally-managed high-altitude landscape in northwest Nepal. Environmental variables, including human activities, strongly affected species composition, diversity and cover-abundance of medicinal plant species. Species richness of rare and commercially threatened medicinal plants (CTMP) showed patterns similar to overall medicinal plant species richness. Sub-alpine meadows, which have intermediate levels of human pressure related to grazing and relatively high levels of resource availability in terms of rainfall and soil nutrients, were richer in medicinal-plant species than alpine meadows. The coexistence of various plant communities under different human management regimes also enhanced landscape-level species diversity by maintaining some species restricted to particular habitat or pasture types. A number of medicinal plant species reported to be resistant to grazing were most abundant in heavily grazed sites. This pattern suggests that medicinal plant species may be positively influenced, to a certain extent, by human activities (mainly grazing). The combination of grazing and high levels of harvesting, however, had a negative impact on diversity and cover-abundance of rare and CTMP species. Maintenance of medicinal plant diversity and cover-abundance is critically dependent on managing grazing and resource harvesting to maintain levels that are both ecologically and economically sustainable. Forage for livestock and medicinal plants for local health care cannot be managed independently; a systems approach is needed, incorporating social management to accommodate the needs of different users. This could be achieved by maintenance of a mosaic landscape, in which different use patterns and pressures, reflecting the values attached to resources by different users and favouring different types of biodiversity, co-exist.