Identifying the drivers of tree growth is essential for our understanding forest dynamics. Trait data are frequently used to identify these drivers. However, successfully linking traits to plant demographic performance likely requires the consideration of important contextual and individual‐level information that is often ignored in trait‐based ecology. 

In a study published in Journal of Ecology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) show that the relationships between traits and tree growth are the outcome of several contexts and best studied at the individual-level, which is generally not the approach taken in trait-based tree community ecology. 

The researchers combined detailed individual-level tree growth, biotic neighborhood and trait data with local climatic data over a period of 9 years in the 20-ha Xishuangbanna forest dynamics plot (FDP) in a seasonal tropical rain forest of southwest China. 

They estimated how the leaf mass per area (LMA), tree height, wood specific resistance and leaf area of species and local neighborhood effects shape the observed response in tree growth through a consideration of individual- and species-level trait variation and seasonal drought effects on the growth of 36 tropical tree species over 8 years. 

They found that both the climatic and local biotic contexts were important drivers of tree demographic performance and had interactive effects, thus the understanding of the importance of one driver is faulty without a consideration of the other. 

Furthermore, they found that individual-level trait data generally provided stronger and alternative models of tree growth as compared to models parameterized using species-level average data. 

"We here show that we can improve the development of models of tree demographic performance upon the basis of traits, by considering individual‐level trait variation as well as phenotypic and climatic contexts," said Prof. CAO Min, principal investigator of the study. 

20-ha Xishuangbanna forest dynamics plot (Image by DENG Yun)