Life stages and habitat types alter the relationships of tree growth with leaf traits and soils in an old-growth temperate forest

Knowledge of the leaf trait-growth rate relationship is essential for assessing plant physiological performance in forest ecosystems. Intraspecific leaf trait variation may have different effects on tree growth at various spatial and temporal scales. Plant functional-group and life-stage approaches have the potential to clarify the specific roles to understand the biodiversity-ecosystem functioning relationship. Our research determined the significance of leaf traits and soil variation in broadleaf and coniferous tree growth across different life stages and habitat types. In a 9 ha Liangshui forest dynamic plot in Northeast China, we used linear mixed-effects models (LMMs) to model tree growth as a function of leaf traits and soil variables in three habitat types with different soil organic matter and slope conditions. Tree growth in the broadleaf saplings was more significantly influenced by leaf traits and soil variation than that in the adults. On the other hand, the growth of coniferous adults was more significantly influenced by leaf traits and soil variation than that of the saplings. The influence of leaf traits on the growth of broadleaf saplings was dependent on the habitat type. Soil variation had positive effects on the growth of broadleaf saplings and coniferous adults in the high-nutrient habitat type. Different functional types can provide different insights into the influence of leaf traits on tree growth. To apply leaf traits to forest management, the relationships of plant functional types, life stages, and local environments with tree growth need to be carefully considered, particularly in mixed-species forests with varying tree sizes.