Water Use Strategies of Woody Species under Changing Climate

Abstract

Global climate change has shifted rainfall patterns and increased aridity across many environments. These changes can limit the amount of water present in the landscape by increasing the time between precipitation events and altering the timing and amount of meltwater from snowpack. This in turn can alter how plants use precipitation inputs, which is essential to understanding terrestrial ecohydrology. In addition, our understanding of current water use can also help provide context when constructing tree ring chronologies using oxygen stable isotopes, which can provide longer term water use strategies in trees. Thus, my dissertation aims to understand how species are using different water sources to help predict how changes to the water cycle can impact plant-water relations. In Appendix A, I assessed the spatio-temporal patterns of water use between two co-occurring species, one naturally occurring and one expanding into riparian areas, in order to understand how the expanding species impacts soil moisture and potentially streamflow. In Appendix B, I examined how antecedent moisture conditions from melting snowpack can impact tree water use of monsoon rains in forests distributed across a climate gradient within the North American Monsoon region. Lastly in Appendix C, I used current plant water use isotopes to evaluate the oxygen isotope model in wood cellulose in tree rings. Together, these findings provide a better understanding of tree water use so that we can leverage this information to increase the robustness of climate reconstructions and predictions.