Presentation description

As climate change raises global temperatures, droughts are becoming more frequent and plants are left increasingly water stressed. Drought stress impacts the water transport system of plants (i.e. the water conducting vessels) from the roots up to the leaves. As plants become more drought stressed, gas bubbles, or emboli, form in the vessels, blocking off water transport, thus reducing the plant's hydraulic conductance. Interestingly, different parts of a tree differ in how vulnerable they are to drought stress. While this has mostly been studied in branches, less is known about how the conductance of leaves and roots are affected by drought. Understanding these differences is crucial for predicting how the whole-plant water transport capacity changes in response to drought.
With this project, I ask how drought stress impacts the hydraulic conductance of leaves, branches and roots in mature aspen trees?
Creating an experimental drought in a stand of aspens in Northern Utah allowed us to compare the drought impacts on the hydraulic conductance of different tree organs. We measured the maximum (Kmax) and native leaf hydraulic conductance (Knative) in the field alongside water potentials and leaf area for every sample. Additionally, we took 48 branch samples back to the lab to measure Knative and Kmax. Finally, we measured 11 roots sampled near the drought experiment.
We found limited effects of drought treatments on the conductance of leaves and branches, likely due to the drought not being particularly severe yet at the time of measurement.
Despite the limited drought impacts, our findings invite further investigation into how aspens remain healthy during periods of drought. Further measurements over a longer period of time, as well as combined with other parameters (e.g. soil, growth, phenology, photosynthesis) could put these results in a larger context and give more insights into drought impacts, or the lack thereof, on trees.