Which one of the following ecosystems has the highest net primary

Which one of the following ecosystems has the highest net primary productivity?

Rainforest
Extreme desert
Lakes and streams
Mid-latitude grassland
This question was previously asked in
UPSC Geoscientist – 2020
The correct answer is Rainforest. Tropical rainforests exhibit the highest net primary productivity (NPP) among terrestrial ecosystems.
– Net Primary Productivity (NPP) is the rate at which producers (plants) accumulate biomass or store energy, calculated as Gross Primary Productivity (GPP) minus the energy used in respiration.
– Tropical rainforests have ideal conditions for plant growth: high temperatures, abundant rainfall, and high light intensity throughout the year, leading to very high rates of photosynthesis and biomass accumulation.
– Extreme deserts have very low NPP due to limited water availability.
– Lakes and streams (freshwater ecosystems) have moderate NPP, varying greatly depending on factors like nutrient levels and light penetration.
– Mid-latitude grasslands also have moderate NPP, often limited by seasonal rainfall and temperature variations compared to tropical rainforests. Estuaries and coral reefs are aquatic ecosystems with also very high NPP, sometimes comparable to or exceeding rainforests on a per-unit-area basis, but rainforests cover much larger areas globally.