The development of a coupled ecosystem exchange plant hydraulic model to explore drought related plant mortality
Roberts, David Edward
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A goal of global climate change modeling is to predict the impact of climate change on the distribution of global vegetative cover. The primary objective of this research is to study one factor influencing the distribution of vegetative cover, that factor being plant hydraulics. To determine how plant hydraulics might impact vegetative cover, an ecosystem exchange model was coupled with a model of plant hydraulics to explore the hydraulic limitations on plant growth under varying climatic and environmental conditions. The coupled model was tested by comparing simulated transpiration from the coupled model to simulated transpiration from the uncoupled model. A sensitivity analysis was conducted due to the large number of uncertain parameters used in the plant hydraulic component of the model. Upon model validation, simulations were run to determine the impact of soil water potential on transpiration. The model was also used to explore the impact of future IPCC projections of temperature and precipitation on the survivability of two subspecies (ssp. Vaseyana and ssp. Wyomingensis ) of Artemesia Tridentata , a semi-arid desert species. This was done by shifting the timing of spring snow-melt. The coupled model predicted that ssp. Wyomingensis would be more likely to survive than ssp. Vaseyana. This result was expected as ssp. Wyomingensis is found in a dryer and warmer climate than ssp. Vaseyana owing to ssp. Wyomingensis having less vulnerability to cavitation than ssp. Vaseyana .