Résumé
The impacts of a doubling of atmospheric concentrations of carbon dioxide on intact monoliths of Mediterranean grassland were investigated in a set of growth chambers that attempted to simulate climatic field conditions. The growing season used for the tests was six months in duration. Variations in community structure were continuously observed and quantified into values for species richness and cover. Neither species richness nor plant cover changed in response to the elevated levels of CO sub(2). Night respiration was two-fold higher for the elevated concentrations. Although a certain downward adjustment of net photosynthesis was observed, net canopy photosynthesis was greater for the elevated levels of CO sub(2). This stimulation of net photosynthesis was compensated for by increased respiration.