Biomass (ecology)

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For the eco-industrial use of the term, which includes dead material used for biofuels, see biomass

An Antarctic krill, whose species comprises roughly 0.66% of the Earth's biomass, the highest of any single animal species.^[1]

In ecology, biomass refers to the accumulation of life that is possibly living matter.^[2] That is, it is the total living biologica (usually measured per square metre or square kilometre). This means that only 30% of the weight of any creature is counted, the rest being water.

The most successful animal, in terms of biomass, is the Antarctic krill, Euphausia superba, with a biomass of probably over 500 million tons, roughly twice the total biomass of humans. The entire earth contains about 75 billion tons of biomass^{[dubious – discuss]}, or 0.00000000126% of the total mass of the Earth. Humans comprise about 100 million tons (0.13%) of the Earth's biomass^[3], domesticated animals about 700 million (1.0%), and crops about 2 billion tons or 2.7% of the Earth's biomass.^{[citation needed]} The total biomass of bacteria is estimated to equal that of plants ^[4].

Biomass may also be a measure of the dried organic mass of an ecosystem. As the trophic level increases, the biomass of each trophic level decreases. That is, producers (grass, trees, scrubs, etc.) have a much higher biomass than animals that consume them (deer, zebras, insects, etc.). The level with the least biomass is the highest predators in the food chain (foxes, eagles, etc.) Biomass is also related to net primary productivity (NPP). Factors which limit NPP and thus mean biomass accumulates only slowly.

Factors which encourage NPP and thus tend to increase biomass are the converse of these.