How is GPP measured?
The amount of energy that plants can trap from the sun is referred to as gross primary production (GPP). An indirect way of measuring this is to measure the mass of carbon that a plant takes in during photosynthesis.
Which ecosystem has highest productivity?
After Tropical Rainforests, Estuaries and Swamps / Marshes, the highest primary productivity is found in coral reefs, algal beds and temperate forests.