Question

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

Answer 1

The pyramidal representation of trophic levels of different organisms based on their ecological position [producer to final consumer] is called as an ecological pyramid.

Pyramid of biomass is usually determined by collecting all organisms occupying each trophic level separately and measuring their dry weight.

This overcomes the size difference problem because all kinds of organisms at a trophic level are weighed. Biomass is measured in g/m2.

Hence the biomass of a species is expressed in terms of fresh or dry weight. Measurement of biomass in terms of dry weight is more accurate.