Leaves are the main photosynthetic organs of plant. The trade-off between leaf mass and leafing intensity reflects an important adaptive strategy of the plant to the environment. Studies of the mechanisms of such a trade-off under global climate-change scenarios will help in better understanding the responses of plants to environmental fluctuations. In this study, we used the standardized major axis estimation method to examine the relationship between leaf mass and leafing intensity within current-year twigs from 48 tree species sampled from 4 mountains in temperate regions of China. The trade-off between leaf mass and leafing intensity was allometric for all twigs and those from a deciduous broadleaf forest, simple broad leaf species and understorey broadleaf species but isometric for twigs from coniferous and mixed coniferous broadleaf forests, evergreen and deciduous broadleaf species, compound broadleaf species and canopy broadleaf species. Thus, the trade-off between leaf size and leafing intensity is not ubiquitous for species of different leaf forms and life forms, canopy status, or species from different forest types.