Plant hydraulics

How plants respond to water limitations affects both carbon uptake and evapotranspiration, which in turn has important effects on water availability and on the weather (through land-atmosphere interactions). Ecology and hydrology have long used conceptual models that treat this plant response as depending on soil moisture, ignoring the movement of water through the plants (plant hydraulics). But this neglects the plant physiology at play. Our group is interested in understanding how plant hydraulics affects vegetation's overall response to water stress, and how different soil and plant properties affect plant water cycling. In past studies, we have studied how plant hydraulics affects the apparent sensitivity of stomatal conductance to either vapor pressure deficit or soil moisture (which affects our expectations about future drought responses, given increasing VPD with temperatures), how soil and plant traits affect the likelihood of drought causing increases (rather than the commonly assumed decreases) of evapotranspiration, and how the diversity of hydraulic traits at a site affects drought response. We have also studied (and are studying) how plant and soil traits affect the impact of drought on fuel moisture, and how that feeds back to wildfire risk in the Western United States. Because of the lab's general interest in understanding the effect of variability in traits, we also have worked and are working on mapping plant traits. The group is also interested in understanding how water stress interacts with carbon allocation, how vegetation water potential can be used to infer root water uptake that is difficult to measure directly, and many other questions related to plant water use.