Floristic Characteristics and Biodiversity Patterns in the Baishuijiang River Basin,China

A case study was conducted on the forest ecosystem in the Baishuijiang River basin of China to reveal the influences of environmental factors and human disturbance on the floristic characteristics and biodiversity patterns. Field surveys of the floristic composition, environmental factors, and disturbance factors were conducted along an elevation gradient, and the relationships between biodiversity pattern and environmental factors were analyzed using CCA (canonical correspondence analysis). The results showed that the floristic composition of higher plants consisted of 197 families, 796 genera, 2165 species, 19 subspecies, 239 varietas, and 12 forma, and it was characterized by the multi-geographic composition and by the transition from tropical to temperate zones. Along an elevation gradient, the variations in α and β diversity were best described by a bimodal curve, and the peak values occurred at middle elevations. The CCA indicated that the elevation had the greatest influence on the biodiversity pattern, followed by the topographic index, slope direction, slope, slope position, slope shape, and vegetation coverage. In addition, human disturbance has greatly impacted the floristic composition and biodiversity patterns, and the biodiversity indices were higher with intermediate disturbance at middle elevations compared to higher and lower disturbances at low and high elevations, respectively. This reflected a disturbance–diversity pattern and thus revealed the obvious importance to maintain the intermediate disturbance for biodiversity conservation.