Trait-based neighbourhood effects on the growth–weather relationships of subtropical trees.

Growth–weather relationships of trees determine the carbon sequestration and productivity in forests. Neighbourhood resource acquisitiveness and functional diversity may influence the growth–weather relationships of the focal trees by changing the availability and utilization efficiency of local resources. To understand this process, we measured daily radial growth and weather in a biodiversity experiment in southeast China (BEF-China) and explored the relationship between neighbourhood functional traits, weather variables, and growth rate of focal trees. We found that whereas neighbours with strong resource acquisitiveness decreased the growth–temperature relationship of deciduous trees, they increased the beneficial effect of weather on growth of evergreen trees. In addition, neighbourhood functional diversity also increased the growth–weather relationships of evergreen species. The negative effects of neighbourhood on deciduous species might be explained by enhanced water loss and competition, while the positive effects on evergreen species might be explained by niche partitioning. We conclude that contrasting ecological strategies between focal trees and their neighbours and the increase of neighbourhood functional diversity enhance tree growth by increasing their growth–weather relationships, especially for evergreen species, which offers an explanation for positive biodiversity–productivity relationships at the neighbourhood scale and provides important reference for planning in forestry.