In an ecosystem, if the Net Primary Productivity (NPP) of the first trophic level is 100x\ (\mathrm{kcal\,m^{-2}})\,\mathrm{yr^{-1}}, what would be the GPP (Gross Primary Productivity) of the third tr

Question

In an ecosystem, if the Net Primary Productivity (NPP) of the first trophic level is 100x\ (\mathrm{kcal\,m^{-2}})\,\mathrm{yr^{-1}}, what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem?

Vishal Gupta · Accepted Answer

B. By the 10% law each trophic level passes on about a tenth of its production. From a producer NPP of 100x, the second level takes in 10x. The official key marks 10x — it treats the third level's gross intake as the energy handed on by the level below it. (Applying the 10% step once more, the third level's own NPP would be x; that is not what was marked.)

Ecosystem

More from this chapter in past papers