Which type of ecosystem has the highest mean net primary productivity (dry gram/m2/year).

Correct option is B

Boreal forests, also known as taiga, have the highest mean net primary productivity (NPP) among the ecosystems listed, particularly in colder regions. Although the growing season is short and temperatures are lower compared to tropical regions, boreal forests compensate by supporting vast areas of coniferous trees, which contribute to high biomass accumulation. This ecosystem stores significant amounts of carbon in both the trees and soil, contributing to a high NPP over time.
Information Booster:
· Net Primary Productivity (NPP) is the rate at which plants in an ecosystem produce net useful chemical energy. It is calculated as the total amount of biomass produced through photosynthesis minus the energy plants use during respiration.
· Boreal forests have a significant role in the global carbon cycle, storing large amounts of carbon in the form of biomass and soil. The slow decomposition rate in these cold regions further enhances carbon accumulation.
Additional Knowledge:
  Lake and stream: These ecosystems generally have lower NPP compared to terrestrial ecosystems due to limited light penetration, nutrient availability, and smaller biomass production.
Tropical Savanna: Tropical savannas have moderate NPP, mainly due to seasonal variations in rainfall, but they do not match the biomass and productivity levels of boreal forests.
Agricultural Land: While agriculture can be productive, its NPP is typically lower than that of natural ecosystems like forests, which have larger biomass and higher long-term productivity.