In
ecology,
productivity or
production refers to the rate of generation of
biomass in an
ecosystem. It is usually expressed in units of
mass per unit surface (or volume) per unit time, for instance
grams per square metre per
day (g m
-2 d
-1). The mass unit may relate to
dry matter or to the mass of
carbon generated. Productivity of
autotrophs such as
plants is called
primary productivity, while that of
heterotrophs such as
animals is called
secondary productivity.