A recent research paper published in Tree Physiology describes the coordination of hydraulic and gas exchange traits across subtropical woody species.

Terrestrial plants must exchange large volumes of water to obtain the atmospheric CO₂ required for growth. A reliable and timely supply of water is therefore necessary to maintain adequate stomatal conductance and photosynthesis. Therefore, tight across-species coordination between gas exchange and water transport through stem and leaves should be observed in most cases. However, inconsistent results were reported in previous studies.

A research group led by Professor YE Qing at South China Botanical Garden of Chinese Academy of Sciences conducted researches on this issue. In their study, hydraulic efficiency in stem and leaf, and gas exchange traits were measured for 33 co-occurring subtropical woody species. Due to the complex leaf anatomical structures, water transport pathway in leaf was divided into two parts: water transport within xylem and outside xylem. They found that compared to leaf outside-xylem hydraulic conductance, leaf xylem hydraulic conductance and stem hydraulic conductivity were more closely coordinated with leaf gas exchange traits. Their study highlights the key roles of stem and leaf xylem water-transport efficiency in affecting stomatal conductance and photosynthetic capacity across co-occurring forest species.

For further reading, please find the paper entitled “Water transport from stem to stomata: the coordination of hydraulic and gas exchange traits across 33 subtropical woody species” at https://doi.org/10.1093/treephys/tpz076.