Field evidence reveals conservative water use of poplars under high aerosol conditions in Beijing

Anthropogenic aerosols could alter multiple meteorological processes such as radiation regime and air temperature, thereby modifying plant transpiration. However, the lack of field observations at the leaf- and plant-level hinders our ability to understand how aerosols could affect plant water use. Aerosol concentrations in northern China fluctuates periodically over a wide range. Taking advantage of this unique natural experiment opportunity, we conducted a full series of supporting physiological and environmental measurements to explore aerosols' effect on leaf transpiration and sap flow in the field using poplar trees (Populus × canadensis Moench). We found that high aerosol concentrations suppressed sun-leaf transpiration by reducing leaf-to-air vapor pressure deficit (VPDleaf) while not affecting shade-leaf transpiration, mainly because the negative effect of reduced VPDleaf on transpiration offset the positive effects of the increased stomatal conductance (gs). As aerosol ...