Wood characteristics, especially wood density, have been traditionally regarded as core plant functional traits because of their importance for mechanical support, defence, architecture, hydraulics, carbon gain and growth potential of plants.However, across a wide range of species, wood density is usually weakly correlated with growth rate.

 Prof. Cao Kunfang and his research team of Xishuangbanna Tropical Botanical Garden (XTBG) examined the covariation in wood density and xylem anatomical traits, together with tree growth rate and adult stature among 40 coexisting tree species in an Asian tropical forest, southwestern China. By using phylogenetically independent contrasts, the researchers examined whether those traits show coordinated variation at multiple divergences across the phylogenetic tree.

The aims of the study were to (i) evaluate the covariation of xylem anatomical traits among co-occurring tree species, and its potential in constraining variation in high-order traits, such as tree growth rate and adult stature, and (ii) test the hypothesis that xylem anatomical traits are better predictors of tree growth rate and adult stature than wood density.

The researchers found that xylem anatomical traits have a more significant influence on whole-plant performance due to their direct association with stem hydraulic conductivity, whereas wood density is decoupled from hydraulic function due to complex variations in xylem components.

The study entitled “Hydraulic conductivity traits predict growth rates and adult stature of 40 Asian tropical tree species better than wood density” has been published online in Journal of Ecology, DOI: 10.1111/j.1365-2745.2011.01939.x

Plots data were provided by the Xishuangbanna Station for Tropical Rain Forest Ecosystem Studies (XSTRFE) of Chinese Ecosystem Research Network (CERN). The work was financially funded by the National Natural Science Foundation of China (No. 31000237, 31170315) and West Light Foundation of the Chinese Academy of Sciences.