stem ecology is often concerned with both energetics and materials as key ts of ecological dynamics. These differ in that: om sunlight that is fixed by a plant through photosynthesis, the energy may be used by ny organism in the food web, while nitrogen is only used by plants. om sunlight that is fixed by a plant through photosynthesis, the energy can only be used nce after which it is lost as work and heat. The nitrogen a plant acquires from the soil is sed for making plant or consumer tissue only once. rom sunlight that is fixed by a plant through photosynthesis, the energy can only be used nce after which it is lost as work and heat. The nitrogen a plant acquires from the soil can e used in plant tissue, used by consumers, returned to the soil, and reacquired by the ant multiple times.

The relationship between biotic community and abiotic environment is ecosystem and the study of ecosystem is called ecology. Ecology involves the cycling of minerals as well as materials in all the three spheres of Earth- atmosphere, lithosphere and Hydrosphere.