Climatic control of primary forest structure and DBH–height allometry in Northeast China

Northeast (NE) China harbors all major forest types in northern East Asia. We sampled 68 plots from all primary forest types across NE China to characterize the regional pattern of forest structure in relation to climate. The results indicated that forest structure and biomass differed greatly among forest types, and these differences were mainly a result of heat gradient. As heat increased, stem density decreased while diameter at breast height (DBH), tree height, total basal area, stand volume and biomass increased. Local site condition also had an important effect on forest structure. DBH–height relationship was significantly modulated by climate. With increasing winter coldness stress, a higher proportion of biomass was allocated for diameter growth than height growth. Our results provide evidences for climatic control of forest structure and DBH–height allometry across large scale.