2.5.10 (HL)—Productivity patterns in succession

Net productivity is gross production minus community respiration: NP = GP − R.

Early succession has sparse producers and low respiration, so NP can be strongly positive. Later GP may be high, but plants, consumers and decomposers respire more, bringing NP toward zero.

Early in succession, GP is low but community respiration is lower, so positive NP allows biomass to accumulate. Later, GP may be high, but respiration by a larger community nearly balances it, so NP approaches zero.

A climax community can contain a large biomass while NP is near zero because gross production is balanced by community respiration.

Productivity is a rate, not stored biomass; do not infer NP from stock size alone.