Practice question

Food-web connectance is the fraction of possible feeding links that are actually realized, calculated as actual links divided by potential links. If directed links among S species are allowed, potential links may be S², S(S−1), or another denominator depending on whether cannibalism and basal species are included. Because conventions differ, comparisons require the same definition and sampling effort. Connectance influences possible pathways for energy flow and indirect effects, but observed values can decline artificially as more poorly resolved species are added. Energy budgets must distinguish stocks from rates: standing biomass can remain high or low even when production and transfer through that compartment are rapid. Matter can cycle repeatedly through producers, consumers, and decomposers, whereas usable energy requires continuous external input because respiration degrades it to heat. The amount reaching a consumer level depends jointly on resource production, the fraction consumed, assimilation efficiency, and conversion of assimilates into new biomass.