Ecological Aspects of Assimilation and Primary Production in Humid and Arid Areas

Abstract

Photosynthesis by autotrophic green plants—the producers—is the essential prerequisite for all life on earth and initiates the material cycle and energy flow within every ecosystem. In this process, atmospheric CO₂ is taken up by the chloroplasts and, with the aid of absorbed light energy, is converted to organic compounds, mostly carbohydrates; during this process storage of chemical energy takes place. Intermediate compounds with three carbon atoms may be formed; this is therefore known as C₃-photosynthesis. In C₃ plants fixation of CO₂ and absorption of the light necessary for the synthesis take place in the same chloroplast. It has been found that the situation is different in some tropical plants in which CO₂ fixation takes place in the chloroplasts of the mesophyll, with the formation of malate as an intermediate product.