Soil water availability is an important mechanism filtering plant species. Twenty-five herbaceous dicot species were grown under controlled conditions in order to measure a suite of physiological traits associated with a plant’s water economy. Belluau and Shipley identify five traits related to gas exchange that define the ability to acquire resources (when water is not limiting) or conserve water (when it is limiting).
Stomatal conductance and net photosynthesis measured at soil field capacity, water use efficiency, stomatal conductance and soil water potential (measured when leaves begin to wilt), best predicted different levels of drought tolerance or avoidance in herbaceous dicots. Together, these traits predict different levels of drought tolerance or avoidance in herbaceous dicots, and, for the first time, elucidate the direct and indirect pathways linking traits to habitat affinities.