question_answer

What do you mean by the term 'standing crop' in an ecosystem? Draw a pyramid of biomass, where a small standing crop of phytoplanktons supports a large standing crop of zooplanktons in the sea.

Or

An ecosystem can support only a limited number of trophic levels. Explain.

Answer:

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

In a sea ecosystem, pyramid of biomass for smat standing crop of phytoplanktons supporting a large standing crop of zooplanktons is as follows

PP-Primary Producers

PC-Primary Consumers

Or

Flow of energy in an ecosystem determines the diversity as well as density of organisms. According to Lindeman's (1942) 10% law, only 10% of energy is transferred from one trophic level to the next trophic level and nearly 90% of energy is lost. If more trophic levels will be present, the residual energy will be limited and will decrease to an extent that it will not be able to support further trophic levels. Therefore, an ecosystem can support only a limited number of trophic levels.