All systems have three main components, viz., elements, states and relations between elements and states. The elements represent objects and each element has properties or states such as number, size, colour etc.
This is applicable in case of ecosystem also. Plants and animals are the elements and they have different states. All systems have inputs and outputs, and in ecosystems both inputs and outputs relate to the flow of energy. The chief input is energy from sunlight.
The green plants utilize the same in the process of photosynthesis to manufacture food. The output is in the form of harvest either by animals or human beings. Obviously, ecosystems have both biotic and abiotic elements.
Biotic elements are represented by plants and animals etc. and human beings. Abiotic elements are represented by sediments, soils, nutrients and water. It is through these elements (biotic and abiotic) that the ecosystem functions and also represents a storage element.
The driving force of the ecosystem is solar energy. This is responsible for the circulation of all materials in the ecosystem and the operation of processes. The input of solar energy is used in the process of photosynthesis by green plants, which thereby make energy available in a usable form to plants themselves (primary producers) and to consumers.
Associated with this process of energy transference is the circulation of nutrients, gases and water from soils and the atmosphere, through the producers to the consumers and finally to human beings or out of the ecosystem entirely.
Thus it is clear that the processes within the ecosystem are closely linked with other environmental systems including nutrient transfer.