Gross Primary Productivity (GPP) is focused on which part of the plant?

Gross Primary Productivity (GPP) refers to the total amount of organic matter or energy that is produced by photosynthesis in an ecosystem over a specific time period. It primarily focuses on the aboveground parts of the plant, especially leaves and stems, where most photosynthesis occurs.

Leaves contain chlorophyll and are equipped to capture sunlight, converting carbon dioxide and water into glucose and oxygen through the photosynthetic process. This is the main contribution to GPP, as it represents the total energy captured from sunlight before any of it is used by the plant for respiration or lost as heat.

Although roots play crucial roles in nutrient and water uptake, they are not directly involved in the photosynthetic process that contributes to GPP. Hence, GPP is not concerned with the belowground components or the photosynthetic activities of the roots, which are minimal. In conclusion, the focus on the aboveground parts aligns with our understanding of where the primary productivity initiated by photosynthesis is most prominent in plant systems.