Ecological Aspects of Transpiration. I. Pike's Peak Region: Climatic Aspects

1. A comparison of the plains, montane, and alpine climates of the Pike's Peak region showed that: (a) air and soil temperatures, saturation deficit, and evaporation decrease with increased altitude; (b) radiant energy, relative humidities, rainfall, and holard are usually greater at higher elevations; (c) wind movement is constantly highest in the alpine region, with the plains next, and the montane zone ordinarily the lowest. 2. A comparison of the functional responses of plants in these three climates showed: (a) a decrease of transpiration with increased altitude; (b) a decrease of growth rate with increased altitude. 3. The transpiration curve showed a closer correlation with the air temperature and the relative humidity curves than with any of the other factors measured. 4. Evaporation was approximately five times as great as transpiration in the three regions. 5. Vegetation does not respond to any one factor, but rather to all of the climatic conditions.