Page:Niger Delta Ecosystems- the ERA Handbook, 1998.djvu/108

People and Resource Use Conflicts more often in the combinations of atoms that are molecules. We know of 93 naturally occurring elements, the most common in living matter being carbon, oxygen and hydrogen.

In healthy, viable ecosystems, resources are constantly being recycled in a complexity of inter-related cycles. For instance nutrients in soil are taken up by plants, and the plants grow, die and decay to become part of the soil to nourish new plants. Within this process, the element nitrogen is taken up by plant roots as a vital nutrient and released again into the soil by the micro-organisms which are the agents of decay. These are two simple inter-related cycles in an ecosystem, but they are part of increasingly large resource-cycles, the largest of all being the Biosphere in which we live.

The recycling of resources is facilitated by both living and non-living processes. For instance, water is re-cycled through plants by transpiration which is a living process, but taken up into the air from the surfaces of leaves to become clouds by evaporation which is a non-living process. Similarly, elephants drink water as a living process, while the percolation of water through soil and into rivers is a non-living process. 106