Tree hydraulics equipment for assessing tree drought mortality under future climate conditions

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Tree mortality rates are increasing globally, and in Canada, large tracts of aspen stands are dying due to drought stress associated with climate warming. While drought-related forest decline is expected to become more common as temperatures rise, increasing growth temperatures and CO2 concentrations alter tree biomass allocation and water transport physiology, which could make trees either more or less vulnerable to drought stress in the future. This proposal will fund a high-pressure flow meter for measuring how future climate scenarios alter aspen water transport capacity in roots, stems and leaves. Aspen will be grown at each of three temperature regimes (ambient temperatures, +4 and +8 degrees Celsius) and either current ambient or twice-ambient atmospheric CO2 concentrations (390 ppm or 780 ppm) in the Biotron at Western University, and subjected to a drought treatment. The high-pressure flow meter will facilitate rapid measurements of resistance to water flow in plant tissues, allowing my lab to determine how drought progressively affects water transport in trees acclimated to different growth environments. The research will address crucial problems for forest managers in projecting Canada's forest growth and health in a changing climate by providing insight into whether drought-induced aspen mortality will increase in severity in the future. This study will also help identify which physiological traits improve aspen drought tolerance under a suite of growth conditions, allowing breeders to develop more stress resistant tree varieties for biomass and biofuel purposes, and helping fill a basic knowledge gap on the plasticity of plant hydraulic characteristics to the environment. The grant will support the immediate training of a Masters student in plant water relations and climate stress effects on Canada's forests, as well as facilitating future undergraduate and graduate student training in pressing forestry-related issues. This grant will allow me to buy equipment crucial to the development of my research program as an early career researcher and facilitate cutting-edge research to continue my lab's record of publishing high-quality global change research in premier journals.