Speaker: Dr. Daniel Beverly
Increases in temperature and vapor pressure deficits, along with shifting precipitation regimes, have broad but substantial effects on ecological function and productivity. Of the processes most impacted, gas exchange, stomatal conductance (GS), and leaf water potential (ΨL) are some of the most complex to predict. The difficulties are multifaceted, but data needed to disentangle these ecophysiological processes rarely embody the same temporal and spatial resolutions. Moreover, the dearth of data spanning relevant species responses, ecological gradients, and functional groups hinders the ability to scale the biophysical controls of gas exchange.
As a result, much effort has been made to understand how diverse environmental perturbations, from droughts to solar eclipses to cicada outbreaks, influence gas exchange from the leaves to entire ecosystems in eastern deciduous forests. Specifically, recent cicada emergence events have increased soil respiration by altering soil sensitivity to temperature as aeration increases and soil moisture decreases. Further, soil moisture limitations and atmospheric aridity, driven by rising air temperatures, are likely to shift forest composition, but the direction and magnitude remain in question as plant hydraulic strategies and gas exchange responses remain loosely characterized.
This has propelled the initiative to develop a novel soil-root water potential imaging (i.e., electrical resistivity imaging) technique coupled with flux observations to reveal the subsurface hydrological (i.e., rhizosphere) dynamics governing ecosystem-scale gas and energy exchange. This effort has significantly increased continuous plant and soil water potential measurements while aiding in the success of PSInet, the global water potential network. Combining these observations provides a complete suite of measurements to bridge the above- and below-ground mechanisms that directly control carbon sequestration processes that are highly vulnerable to shifting climates.