The mass of living matter at a trophic level in an area at any time is called:

Each trophic level has a certain mass of living material at a particular time called the standing crop. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area. The biomass of a species is expressed in terms of fresh or dry weight.

The amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, and so on, that are present in the soil at any given time, is referred to as the standing state.

Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute the detritus, which is the raw material for decomposition.

Humus is a dark-coloured amorphous substance, which is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature, it serves as a reservoir of nutrients.