Spatial structures in a Secondary Forest in Changbai Mountains Northeast China

This paper presents an analysis of the spatial patterns of 16 different tree species in an uneven-aged forest in Northeastern China. In order to better understand the spatial structure of a tree community, variation partitioning analysis was used to estimate the relative contributions of environmental factors and spatial gradient to spatial structures of community and specified tree species. The results showed that the size distribution index (DI) was largest in Populus davidiana (-0.003488) and smallest in Acer mono (-0.081279). Betula platyphylla, Betula costata, Populus ussuriensis and Populus davidiana had unimodal dbh distributions. In contrast, other species showed a reversed J-shaped distribution. Most of the tree species showed a clumped distribution at most scales except for Pinus koraiensis and Quercus mongolica. Dominant trees of Pinus koraiensis and Quercus mongolica and smaller trees of Quercus mongolica tended to random spatial distributions at almost all scales. 19 species pairs showed interactions between seedlings and adults, accounting for 21% of totals, and there were no significant associations detected among other species pairs. A permutation test indicated that soil moisture and soil pH are key environmental factors regulating the spatial structure of the community and individual tree species. Environment factors greatly affected the spatial distribution of Acer barbinerve, Acer pseudosieboldianum, Picea jezoensis and Fraxinus mandshurica, but there was little effect on other tree species. Altogether 21% of the variation in community structure could be accounted by environment variables.