Dissertation Research: Climate Change, Hydraulic Function, and Ecotypic Variation in Spatially Isolated Ponderosa Pine Populations

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DeLucia 9800932 The change in climate expected in the next century will challenge the capacity of trees to acclimate to increased temperatures and aridity. The dry atmospheric conditions of an and climate increase evaporation from the leaf surfaces of a plant (transpiration), increasing moisture requirements. The PIs used a geographic comparison of Ponderosa pine populations growing on a climate gradient as a proxy for differences between the current and future climate. The PIs found that trees growing in a warm, dry versus a cool, moist climate increased biomass allocation to sapwood (water conducting tissue) relative to leaves. To determine if these changes in tree structure may be physiological and evolutionary adaptations to an and climate, we propose to examine four research questions. First, does increased allocation to sapwood relative to leaves increase transpiration in and trees? Second, does increased allocation to sapwood reduce the probability of dehydration during prolonged summer droughts? Third, does increased allocation to sapwood provide greater water storage in and trees? Fourth, does the physiological and structural response of Ponderosa pine to aridity have an underlying genetic basis? The proposed research will establish direct links between tree structure and function and permit predictions to be made about the physiological and evolutionary potential of Ponderosa pine to respond to climate change.