We are studying the metabolic adaptation of plants to temperature along an altitudinal gradient. Seven sites were selected for study, progressing from near the mouth of Provo Canyon (Utah County, UT) to just below the summit of Bald Mountain in the Uintas (Summit County, UT). We used HOBO H8 Pro-Series data loggers to record the hourly temperatures at each site throughout the 2000 growth season, from June through August. We identified two herbaceous and one woody species or congeneric species growing at every site, and collected growing tissue for calorimetric analysis. The species used were Achillea millefolium L., Castilleja spp., and Salix spp. Metabolic heat rates and CO2 evolution rates were obtained at 5, 12, 19, 26, and 33 degrees C. The data show clear differences in metabolic response between plants of the same species growing at different altitudes. The hourly temperature data show that each site is characterized by a different range of temperatures experienced by plants during the growing season. We hypothesize that the mean temperature and temperature range will be correlated to the metabolic response of the plants. This hypothesis leads to a better understanding of metabolic adaptation of plants. The temperature loggers are currently in Salt Creek Canyon near Nephi (Utah County, UT), and we hope to correlate these data to previous calorimetric measurements on sagebrush grown in the canyon.

Key words: altitude, calorimetry, metabolism, respiration, temperature, treelines