How is NPP calculated?

Net Primary Productivity (NPP), or the production of plant biomass, is equal to all of the carbon taken up by the vegetation through photosynthesis (called Gross Primary Production or GPP) minus the carbon that is lost to respiration.

What is the NPP?

“Net primary production (NPP) is the difference between total photosynthesis and total respiration in an ecosystem” and is estimated by quantifying the new organic matter formed and retained by living plants in a given time (Clark et al., 2001).

What does high NPP mean?

NPP is the net energy available after respiration. The higher the net primary production, the more animals can be supported per unit area. In most natural ecosystems, high net primary production is generally accompanied by a highly diverse plant and animal community.

Can NPP be negative?

A negative value means decomposition or respiration overpowered carbon absorption; more carbon was released to the atmosphere than the plants took in. In mid-latitudes, productivity is obviously tied to seasonal change, with productivity peaking in each hemisphere’s summer.

What 3 ecosystems have the lowest productivity?

The smallest land areas are occupied by tundra and temperate grassland ecosystems, and the largest land area is occupied by tropical forest. The most productive ecosystems are temperate and tropical forests, and the least productive are deserts and tundras.

What are the units of NPP?

Both gross and net primary production are typically expressed in units of mass per unit area per unit time interval. In terrestrial ecosystems, mass of carbon per unit area per year (g C m⁻² yr⁻¹) is most often used as the unit of measurement.

What is the difference between NPP and GPP?

Gross primary production (GPP) is the total rate at which material is produced and net primary production (NPP) is the rate at which material is accumulated in excess of respiration. In other words, NPP is GPP minus respiration. Net primary production is directly related to ecosystem conditions.

What ecosystems have the highest NPP?

The highest net primary productivity in terrestrial environments occurs in swamps and marshes and tropical rainforests; the lowest occurs in deserts.

What factors affect NPP?

Net primary productivity varies among ecosystems and depends on many factors. These include solar energy input, temperature and moisture levels, carbon dioxide levels, nutrient availability, and community interactions (e.g., grazing by herbivores) 2.

How much NPP do humans use?

Then the researchers used computer models to estimate how much of Earth’s land-based net primary productivity is consumed by humans. They found that humans require 20 percent of the NPP generated on land every year.

Why is NPP more useful than GPP?

Why is net primary production (NPP) a more useful measurement to an ecosystem ecologist than gross primary production (GPP)? NPP can be expressed in terms of carbon fixed by photosynthesis for an entire ecosystem. C) NPP represents the stored chemical energy that is available to consumers in the ecosystem.

What is the gross primary productivity GPP?

Gross primary production (GPP) is the total amount of carbon dioxide “fixed” by land plants per unit time through the photosynthetic reduction of CO₂ into organic compounds.