Plants, roots and ion absorption

Abstract

The view of ecology adopted here is that it comprises the study of ecosystems and their surroundings. Plants are thus seen in relation to the cluster of organisms most closely associated with them and to their environment. Plants are located in an environmental complex of energy, atmosphere and soil. Within an ecosystem context, plants have three principal functions:

• (a) Absorption of photosynthetically active radiation which is applied to the synthesis of carbon-to-carbon bonds. Compounds synthesised in this way serve as the only energy currency for the ecosystem.

• (b) Absorption and assimilation of ions as a source of essential elements for the ecosystem. Photosynthesis is necessary for ion absorption and assimilation, and ions are an essential part of the photosynthetic system and all other metabolism.

• (c) Plants process water on a sufficiently large scale to make a large contribution to the hydrological cycle of the Earth. Some of this water use is ancillary to photosynthesis, general metabolism and the fabric of plant structure. Much is involved with the special place of plants in unavoidably intercepting solar heat while simultaneously optimising gas exchange. Leaves are cooled by evaporative water loss.