In areas using both evergreen and deciduous trees for timber plantations, understanding their differences in water consumption and response to change in environmental conditions could be helpful for species selection.
Researchers from Plant Physiological Ecology Group of Xishuangbanna Tropical Botanical Garden (XTBG) studied the whole-tree water use and crown conductance response to vapor pressure deficit in 10 deciduous and 11 evergreen broadleaf timber tree species in a site of Southwest China with a tropical seasonal climate.
The researchers compared crown conductance sensitivity to the vapor pressure deficit and water consumption between evergreen and deciduous timber species during the wet season.
They found that tropical evergreen timber trees have more sensitive crown conductance response to vapor pressure deficit than deciduous ones. Tropical evergreen trees also have larger daily water consumption than deciduous ones.
Further, evergreen trees had larger daily water consumption than deciduous trees mainly because of their higher peak sap flux density and crown conductance (i.e. maximum or reference crown conductance). Higher reference crown conductance is associated with higher crown conductance sensitivity. The sap flux density is facilitated by their larger sapwood area (i.e., larger xylem area for water transport and storage).
Based on the results, the researchers recommend a potential management possibility. They suggested that plantations with less evergreen species and more deciduous species could be used to enhance water conservation for plantation systems in the tropical regions with a monsoonal climate and increasing water deficit, which needs to be tested at the plantation level.