The degree to which variation in plant distribution is predictable from topographic variation is of considerable current interest. Dr. Cao Min and his colleagues of Xishuangbanna Tropical Botanical Garden (XTBG) investigated the question by analyzing the data of the 13 dominant tree species in a 20-ha dipterocarp tropical seasonal rain forest in Xishuangbanna, Yunnan, southwest China. Canonical correspondence analysis was used to analyze the relationship between species distribution and environmental variables.

　 The researchers modeled the environmental component using mean elevation, convexity and mean slope of each 400-m2 quadrat and the spatial component with a more flexible model, principal coordinates of neighbour matrices (PCNM).They hypothesized that the spatial patterns of species correlate (negatively or positively) with the topographic variables (slope, elevation, convexity and aspect).

　 The researchers were further interested in the relative contributions of topographic and spatial variables to the species distribution and the degree to which variation in a species distribution can be predicted from environmental and spatial variables.

　 Their study concluded that topographic variables are important factors for the distribution pattern of trees in tropical seasonal rainforest in Xishuangbanna. Amongst the four topographic variables, the convexity and elevation were the two most important factors contributing the distribution patterns of tree species in the plot. Topography alone explained 20%, 24% and 5% of the total variation of species abundance for saplings, poles and adults, respectively.

The study entitled “Topography related spatial distribution of dominant tree species in a tropical seasonal rain forest in China” has been published in Forest Ecology and Management, 262(8): 1507-1513, doi:10.1016/j.foreco.2011.06.052

Abstract http://www.sciencedirect.com/science/article/pii/S0378112711004269