Compound-leaf form has long been hypothesized to be responsible for higher photosynthetic and growth rates of compound-leaved tree species, but the underlying physiological mechanisms are largely unknown.
Dr. SONG Jia and Prof. HAO Guangyou at the Institute of Applied Ecology (IAE), the Chinese Academy of Sciences (CAS) studied functional traits concerning xylem hydraulics and photosynthesis of five compound-leaved tree species in Changbai Mountain of northeastern China.
The researchers found strong positive correlations between hydraulic conductivity, photosynthetic rate and compound leaf area, and both stem hydraulic conductivity and whole-shoot hydraulic conductance increased with the increase of compound leaf area.
The results supported their hypotheses that larger compound leaf size would be associated with higher hydraulic conductance, increased efficiency of carbon assimilation and greater photosynthetic productivity.
Compound-leaved tree species often have larger leaves than simple-leaved tree species. But the advantages associated with larger leaf size can be traded off by a greater susceptibility to freeze-thaw induced hydraulic dysfunction.
In other words, the study suggests that, compared with simple-leaved tree species, compound-leaved tree species' competitive advantages to capture light and transport water are more likely to achieve under favorable habitat conditions.
These findings may contribute to a better utilization of this important type of trees in forestry.