Seasonal changes in photosynthetic activity of snow tussocks (Chionochloa spp.) along an altitudinal gradient in Otago, New Zealand

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Abstract
Photosynthetic characteristics were studied in Chionochloa rigida, an altitudinally widespread snow tussock and a closely related high-altitude species C. macra. Along a gradient from near sea level to 1600 m there were no consistent differences in maximum photosynthetic capacity which averaged 4.5 μmol CO2 m-2s-1. The photosynthetic temperature optimum ranged between 15 and 18°C and there was only a limited capacity for seasonal adjustment. Net photosynthesis was light-saturated at about 500 μmol photons m-2s-1. In winter, the photosynthetic capacity decreased significantly with increasing altitude of origin of the snow tussocks. A transplant experiment indicated this was partly genetically controlled.