Gross Primary Productivity

It is the rate at which organic matter is synthesised by producers per unit area and time that are known as gross primary productivity (GPP). The amount of carbon fixed during photosynthesis by all producers in an ecosystem is referred to as gross primary productivity. However, the metabolic processes of the producers consume a significant portion of the energy that has been captured (respiration). Known as net primary productivity, it is the amount of fixed carbon that is not consumed by plants, and it is this remaining fixed carbon that is made available to various consumers in the ecosystem, such as herbivores, decomposers, and carnivores. To be sure, there is no accumulation or reduction in the total amount of organic matter present in any stable ecosystem, resulting in an overall balance between gross primary productivity and total consumption in any stable ecosystem. The biomass of a system is defined as the total mass of all the organisms present at any given time, divided by the total amount of organic matter in the system.

In comparison to other types of vegetation, the biomass of tropical rainforests is significantly greater. Obtaining accurate estimates of the mass of other organisms in an ecosystem, such as animals, requires destructive sampling of all of the plants in an area (including their underground parts), as well as estimates of the mass of other organisms in the ecosystem, such as insects. Tropical rainforests typically have biomass values in the range of 400 to 700 metric tonnes per hectare, which is significantly higher than the biomass values of most temperate forests and significantly higher than the biomass values of other vegetation with fewer or no trees, according to measurements. It was discovered that the biomass of a tropical deciduous forest in Thailand was approximately 340 kilograms per hectare when it was measured.

Example of gross primary productivity:

As an example, research conducted on an oak-pine forest in New York discovered that the total amount of solar energy fixed by vegetation (ie., the gross primary productivity) was approximately 48.1 thousand kilojoules per hectare per year. This fixation rate corresponded to less than 0.01 percent of the total solar radiation that was absorbed by the forest canopy.

GPP of the temperate forest:

The gross primary productivity (the total biomass fixed by the vegetation in a unit area within a unit time) of temperate forests has been estimated to be between 16 and 50 metric tonnes per hectare per year on average. In young forests where the trees are rapidly growing toward full size, net primary productivity (gross primary productivity minus the amount of energy used by plants in respiration) is approximately 10 metric tonnes per hectare per year; it is greatest in young forests where the trees are rapidly growing toward full size, and it decreases in old forests. In contrast to tropical rainforests, the gross primary productivity of temperate forests is significantly lower than that of tropical rainforests, but the net primary productivity is not significantly different, indicating that the consumer component of the temperate forest ecosystem has less diversity and complexity than the consumer component of tropical rainforests.

Temperate forests have proven to be beneficial to human populations in a variety of ways. Even though they have been largely replaced by more straightforward agricultural systems in most places, large areas of them still exist, particularly on poorer soils, and are important sources of timber. Timber yield and quality are maximised by maintaining forests in a state of maximum net primary productivity—that is, by harvesting trees before they reach the point at which their growth rate begins to decline. Even though old-growth forests produce a lot of biomass and have a lot of conservation value, they are not very efficient in terms of total sustained timber yield.

Conclusion:

It is the total amount of carbon fixed during photosynthesis by all producers in an ecosystem that is known as gross primary productivity. It is the rate at which organic matter is synthesised by producers per unit area and time that are known as gross primary productivity (GPP).

The biomass of a system is defined as the total mass of all the organisms present at any given time, divided by the total amount of organic matter in the system.

Tropical rainforests typically have biomass values in the range of 400 to 700 metric tonnes per hectare, which is significantly higher than the biomass values of most temperate forests and significantly higher than the biomass values of other vegetation with fewer or no trees, according to measurements.

The gross primary productivity (the total biomass fixed by the vegetation in a unit area within a unit time) of temperate forests has been estimated to be between 16 and 50 metric tonnes per hectare per year on average.