Community characteristics of a subtropical evergreen broad-leaved forest in Huangshan, Anhui Province, East China

Abstract

Located in the subtropical monsoon climate zone, Huangshan is one of the high mountains in eastern China and lies in the transition zone of north-south flora. It is considered a refuge of flora and fauna during the Quaternary maximum glaciation. Zonal vegetation is classified as evergreen broad-leaved forest with a vertical distribution pattern. It is not only one of China's Biodiversity Conservation Priority Areas, but also one of the World's Cultural and Natural Heritage Sites and a world famous scenic spot. In 2014, we established a large-scale forest dynamics plot with an area of 10.24 ha in Huangshan based on international protocols (Smithsonian Tropical Research Institute, Center for Tropical Forest Science, CTFS) and completed the first field survey. The investigation aimed at revealing community characteristics by analyzing species composition, flora characteristics, diameter class structure, and spatial distribution patterns. We recorded 191 species of vascular plants, belonging to 59 families and 129 genera, in the plot. Among these, trees (DBH >= 1 cm) belonged to 46 families, 97 genera and 153 species. The number of family and genera with tropical distributions accounted for 65.79% and 45.36% of the total taxa, respectively, while those with temperate distributions accounted for 34.21% and 51.55%, respectively. A number of rare and endangered species occurred in the plots, including six species classified as Class II of State Key Protected Wild Plants, seven threatened species (VU) from the China's Biodiversity Red List: Higher Plant, one species defined in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (Appendix II), and 64 endemic species to China, indicating their values for protection and research. We also found that the number of species increased sharply with increasing scale when the scale was less than 2,150 m(2), while at a higher resolution its rate of increase decreased significantly. When the scale was larger than 57,950 m2, the rate of increase declined slightly. Rare species (N = 69, less than 1 ind./ha) reached 45.10% of the total number of individuals. Members of Fagaceae and Ericaceae comprised more than half of the total importance values (IV). The IV of Castanopsis eyrei, a constructive species, was 26.25%, and followed by Eurya nitida (7.63%), Rhododendron ovatum (7.6%), Pinus massoniana (6.29%) and Loropetalum chinense (4.83%). The mean DBH for all the individuals was 4.10 cm, and small sized trees dominated the plot. The emergent layer was divided into two sub-layers, individuals of C. eyrei were dominant in both layers, while P. massoniana was a subdominant species. Castanopsis eyrei, E. nitida, R. ovatum and P. massoniana had a significant clustered distribution.