ABSTRACT
Within ecosystems, primary production is carried out by autotrophic organisms. These organisms, plants, are able to fix carbon by the process of photosynthesis and build biomass by combining this fixed carbon with nutrient elements derived from the environment. The nutrients required for plant growth come from two main sources. The first source is the rock material underlying the soil. This rock may be of local origin, or of remote geology in areas that have been affected by glaciation. Rocks of the earth’s crust contain a variety of the essential mineral nutrients that plants need, but the minerals are bound in complex chemical forms that make them poorly available for plant uptake. By the action of environmental factors (wind, water, and physical disturbance) along with the activities of bacteria, fungi, and plant roots, the surface of rocks can be weathered and degraded to finer particles and the mineral nutrients released in a soluble form that can be accessed by plants. Some of these minerals will be carried in water to streams, rivers, and oceans, imparting fertility to these ecosystems. The second source of nutrients is by the breakdown or decomposition of dead plant and animal remains by microbes and animals. During decomposition, mineral nutrients are released in a soluble form as inorganic ions from the breakdown of the organic complexes within the plant and animal remains. This process is called mineralization, and provides fertility to the ecosystem. Decomposition and mineralization occur in terrestrial, freshwater, and marine ecosystems. In this chapter we will investigate the role that fungi play in these processes (Table 2.1).
