Plant hydraulic traits represent strategies of water transport efficiency and safety, affecting the growth, survival and distribution of trees under different environmental conditions.

Although both can contribute to the variation of plant hydraulic traits, the effects of environment and phylogeny have not been clearly distinguished.

In a recent article in Agricultural and Forest Meteorology, a research group led by Professor YE Qing of South China Botanical Garden (SCBG) of Chinese Academy of Sciences (CAS), has made advances in understanding the drivers of the variation of plant hydraulics.

The researchers quantified the variation of ten plant hydraulic traits of Castanopsis fargesii (Fagaceae) from 12 populations along a precipitation (1120-1690 mm y^-1) in subtropical China, they also conducted phylogenetic analyses to test the role of intraspecific phylogeny in the plant hydraulic variation.

The researchers found that, with decreasing precipitation, branch vessel density remained unchanged while vessel diameter declined significantly by 32%, leading to a 74% reduction in theoretical hydraulic conductance. In parallel, leaf vein density and stomatal pore area index declined by 15% and 30%, respectively. Leaf turgor loss point also declined significantly from -1.51 to -2.29 MPa along the precipitation gradient.

Using Blomberg’s K phylogenetic test and phylogenetic principle component analysis, the researchers revealed that the intraspecific phylogeny did not significantly affect the variation of hydraulic traits or the trait-trait relations.

The researchers concluded that precipitation is the main driver of the variation of plant hydraulic traits of this native subtropical tree species.

“Our results suggest that subtropical trees have a high degree of plasticity in terms of hydraulic adjustment, and that Castanopsis fargesii can be used as a potential tree species for reforestation to cope with climate change in subtropical China.” said Dr. LIANG Xingyun, the first author of this study.