Species composition, diversity, and stand structure of tropical lower montane forests resulting from various human impacts on the Shan Plateau, eastern Myanmar

Abstract

We observed species composition, diversity, and stand structure in the tropical lower montane forests of a hilly region in eastern Myanmar and examined the impacts of anthropogenic disturbances on the forest stands. From our survey of 58 sample plots (30 m30 m), we categorized four stand types using nonmetric multi-dimensional scaling (NMS) ordination. The four stand types exhibited significant contributions of various anthropogenic impacts, reflecting differences in local livelihoods within different varying landscapes. Anthropogenic disturbances, especially the extraction of firewood, can significantly affect the stand structure of forests and, in turn, the species composition and tree diversity. Some early successional species such as Phyllanthus albizzioides and Albizia odoratissima became indicator species of highly disturbed forests. As firewood is mainly extracted from privately owned forests rather than communal forests, land tenure was also an important factor governing the intensity of anthropogenic disturbances. Species richness and diversity values decreased in stand types exposed to more severe anthropogenic disturbances. Stem density was significantly higher in highly disturbed forests. This was a result of higher numbers of multi-stemmed individuals, which revealed the effect of cutting larger stems for firewood extraction. In old secondary forests, the lack of young trees under the canopy may threaten future forest regeneration. Depending on varying forest conditions and the local populationʼs input, different forest management activities should be applied to forests to optimize production and protection for the local community.