Theses and Dissertations Collection

The first-year seedling stage is vital in terms of determining species distributions and migration under a changing climate, yet conifers experience the highest rates of mortality during their first year and it is the tree life stage least studied. In this study, we compared anatomical and theoretical functional traits of Pseudotsuga menziesii, Larix occidentalis, and Pinus ponderosa to in vitro measurements and in vivo visualization of vulnerability to embolism. Theoretical measurements suggest that vulnerability to embolism varies greatly for each species over the first 10 weeks of growth and so the timing of drought onset is critical in regards to potential resistance to hydraulic dysfunction in seedlings. Additionally, in vivo imaging of embolism during desiccation indicated that in planta resistance to hydraulic dysfunction cannot necessarily be inferred from results based on standard in vitro laboratory methodologies.