Climatic control on forests and tree species distribution in the forest region of northeast China

North-east (NE) China covers considerable climatic gradients and all major forests types of NE Asia. In the present study, 10 major forest types across the forest region of NE China were sampled to investigate forest distribution in relation to climate. Canonical correspondence analysis (CCA) revealed that growing season precipitation and energy availability were primary climatic factors for the overall forest pattern of NE China, accounting for 66% of the explanatory power of CCA. Conversely, annual precipitation and winter coldness had minor effects. Generalized additive models revealed that tree species responded to climatic gradients differently and showed three types of response curve: (i) monotonous decline; (ii) monotonous increase; and (iii) a unimodal pattern. Furthermore, tree species showed remarkable differences in limiting climatic factors for their distribution. The power of climate in explaining species distribution declined significantly with decreasing species dominance, suggesting that the distribution of dominant species was primarily controlled by climate, whereas that of subordinate species was more affected by competition from other species.