2,500
g C/m²/yr
48
%
52
%
52
%
2,500
g C/m²/yr
48
%
52
%
52
%
The Gross Primary Productivity (GPP) Calculator computes the total amount of carbon fixed by photosynthesis in an ecosystem. GPP represents the total energy captured by autotrophs before any is lost to respiration. It is the starting point for understanding energy flow through an ecosystem.
GPP is measured using techniques like eddy covariance flux towers, satellite remote sensing, and gas exchange chambers. This calculator uses the relationship GPP = NPP + Respiration to derive GPP from its two components. GPP is a critical metric in global carbon cycle research and climate modeling.
Gross Primary Productivity is calculated as:
GPP = NPP + Ra
Where:
The respiration fraction shows what percentage of total photosynthesis is used by plants for their own metabolism versus what is stored as biomass.
Inputs
Results
GPP = 1300 + 1200 = 2500 g C/m2/yr. Plants use 48% of total photosynthesis for respiration.
Inputs
Results
Tropical forests have very high GPP but also high respiration due to warm temperatures, so 55% is respired.
GPP is the total carbon fixed by photosynthesis, while NPP is the carbon remaining after autotrophic respiration. GPP = NPP + Respiration. Think of GPP as gross income and NPP as net income after operating costs (respiration) are paid.
GPP is commonly estimated using eddy covariance flux towers that measure CO2 exchange between ecosystems and the atmosphere. It can also be estimated from satellite data using light use efficiency models, or from gas exchange measurements on individual leaves or chambers.
Tropical forests receive abundant light and water year-round, driving very high photosynthesis (GPP). However, high temperatures also increase respiration rates significantly. As a result, plants may respire 50-60% of GPP, leaving moderate NPP despite very high gross production.
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