Exploring The Effects Of Heat and Drought on Conifer Trees: From Semi-Arid Woodlands to Coast Redwoods
Periods of low precipitation and increasing atmospheric temperature are having adverse effects on tree and forest growth and survival in part via limitations upon photosynthesis. Understanding how different species and plant functional types will physiologically respond to the combination of drought and heat is therefore critical for modeling and predicting the fate of trees and forests under future climate conditions. In addition, climate is changing at a faster pace than the slow natural adjustment rates of most species to their rapidly shifting habitat conditions, especially for long-lived tree species, which poses a major challenge for management, conservation, and preservation strategies and policies. Therefore the current traditional conservation/preservation methods, such as providing migration corridors and increasing suitable habitat at range margins will need to be supplemented with a more direct, innovative, and adaptive approach. One such approach is that of managed migration, which is the intentional translocation of species outside their current habitat in order to reduce anticipated loss of biodiversity caused by climate change related stress. This dissertation addresses these problems through the experimental examination of heat, drought, and the combination of heat and drought on two conifer species that have differing drought tolerances, which can serve as global models for a range of physiological mechanisms to deal with water and heat stress, as well as a social science investigation into the preservation of an iconic conifer tree, the coast redwood into Oregon via managed migration.