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4.5.10 GROSS PRIMARY PRODUCTIVITY, NET PRIMARY PRODUCTIVITY AND PLANT RESPIRATION

NPP = Net Primary Productivity (amount of stored chemical energy the plant has to use for growth. This is directly proportional to biomass)

GPP = Gross Primary Productivity (amount of stored chemical energy the plant earns through photosynthesis)

R = Respiration (amount of energy lost through respiration, i.e. heat, lost as CO2 etc)

Best analogy is a salary. GPP is the amount of stored chemical energy the plant earns through photosynthesis. R is like income tax. The plant has to pay “respiration tax” because it can’t photosynthesis at night & not all parts of the plant are capable of photosynthesis. NPP = disposable income: what the plant has to spend after paying tax.