9604497 Smith The ecophysiological effects of multiple stress factors have been recognized as an important omission in studies of plant adaptation to the environment and effects on abundance and distribution patterns. Cold temperatures, in combination with high sunlight levels, is a particularly important combination of stress factors that results in severe inhibition of photosynthesis in numerous agricultural and the few native species that have been studied. This project will investigate the adaptive responses of native alpine/subalpine plants to one of the most extreme, naturally-occurring combinations of low temperature and high sunlight found in any habitat. By evaluating plant responses to this extreme stress combination, we hope to establish an estimate of the maximum adaptive capabilities to this multiple-stress scenario that currently exists among terrestial vascular plants. The study will focus on photosynthetic responses that we believe are critical to plant survival under these extreme multiple-stress conditions. In addition, the impact of future changes in global climate on cold temperature photoinhibition will be evaluated using two atmospheric parameters which are known measures of global atmospheric change, atmospheric warming and increases in UV radiation. The results will be evaluated on a leaf, whole-plant, and landscape level.
