Environmental Controls of Foliar Respiration in Arctic Tundra Plants

The Arctic is warming at rapid, unprecedented rates, causing cascading ecological and environmental changes that threaten to destabilize the vast amounts of carbon stored in the vegetation and soils of the tundra. Foliar gas exchange, which is responsible for the initial fixation of carbon, is likely to respond to warming and associated environmental change in tundra plants, though the direction and degree of these responses are not well studied. This dissertation aims to quantify multiple cellular and leaf-level processes underlying carbon cycling in tundra plants, and to address the responses of these processes to abiotic and biotic effects of warming in the Arctic. To assess the impact of environmental change on foliar gas exchange physiology of tundra plants, a series of empirical studies were conducted on common and abundant plant species located near Toolik Lake, on the North Slope of Alaska. Long-term manipulated treatment plots that simulate the effects of climate change in this region, including elevated growth temperature and increased soil nutrient availability, served as the research setting for multiple experiments that addressed the response of variables such as foliar photosynthesis, respiration, photorespiration, mitochondria and chloroplast size and density, and physical lea