The global Sulphur cycle is a good example to illustrate linkage between the air, water, and soil. Like the nitrogen cycle, it also illustrates the key role played by microorganisms. There are at least four major inputs of sulphur into the atmosphere from land— volcanic activity, soil dust, industrial activity and activity of sulphur bacteria which releases H2S into the [...]
The chemical elements tend to circulate in the biosphere in characteristic paths from environment to organisms and back to the environment. These more or less circular paths of the chemical elements are known as the Biogeochemical cycles. These cycles of chemical elements involve biological organisms and their geological environment. Hence, they are collectively referred to as biogeochemical In this term [...]
The trophic level concept was first given by Lindeman (1942). According to him, a food chain consisted of steps— primary producers, herbivores, carnivores— that he referred to as trophic levels. Trophic literally means feeding, so trophic levels are the positions or levels at which organisms of an ecosystem feed. In complex natural communities, organisms obtain their food from plants through [...]