Understory plant diversity assessment of Szemao pine (<i>Pinus kesiya</i> var. <i>langbianensis</i>) plantations in Yunnan, China

Abstract

Sustainability is a key objective for managers of both natural forests and plantations, and biodiversity assessments are important tools to improve conservation of endangered species. Szemao pine ( Pinus kesiya var. langbianensis ) is a native Chinese tree species used in plantations. This study evaluated differences in understory diversity among Szemao pine plantations (SP) and other local current vegetation types: secondary evergreen forests (SE) and abandoned farmlands (AF) in Yunnan Province. Sampling was performed at three elevation ranges, where species richness, species cover, and environmental variables in the herb and shrub layers were measured. We found that indexes for average richness and Shannon–Wiener diversity were higher in SE than in SP, which were in turn higher than in AF, while the index for evenness was higher in SP. These indexes increased with elevation in SP and AF, but were higher at low and medium elevations in SE. Inclusion of environmental factors highlighted elevation differences, with water content (at herb layer) and soil type (at shrub layer) being the most significant variables. In conclusion, plantations of Szemao pine negatively affect understory diversity in Yunnan, and furthermore, only a few rare or threatened species could be found in the plantations. Nature reserves and transplanting could protect threatened species if established before plantations.