Gpp and npp relationship

Difference Between NPP and GPP | Difference Between | NPP vs GPP

gpp and npp relationship

In ecology, primary production is the synthesis of organic compounds from atmospheric or NPP = GPP - respiration [by plants]. Net primary production is the. NPP vs GPP. Primary production, in short, is the study of plant growth in ecosystems that forms the base or primary factors in the food web and. Relationship between net and gross primary production in the Sagami Bay, Japan. S. Hashimoto1 of NPP:GPP in order to understand the ecosystem and car-.

Similarly, temperature, while affecting metabolic rates see Q10ranges less widely in the ocean than on land because the heat capacity of seawater buffers temperature changes, and the formation of sea ice insulates it at lower temperatures. However, the availability of light, the source of energy for photosynthesis, and mineral nutrientsthe building blocks for new growth, play crucial roles in regulating primary production in the ocean. This is a relatively thin layer 10— m near the ocean's surface where there is sufficient light for photosynthesis to occur.

Light is attenuated down the water column by its absorption or scattering by the water itself, and by dissolved or particulate material within it including phytoplankton. Net photosynthesis in the water column is determined by the interaction between the photic zone and the mixed layer. Turbulent mixing by wind energy at the ocean's surface homogenises the water column vertically until the turbulence dissipates creating the aforementioned mixed layer.

The deeper the mixed layer, the lower the average amount of light intercepted by phytoplankton within it. The mixed layer can vary from being shallower than the photic zone, to being much deeper than the photic zone. When it is much deeper than the photic zone, this results in phytoplankton spending too much time in the dark for net growth to occur.

The maximum depth of the mixed layer in which net growth can occur is called the critical depth. As long as there are adequate nutrients available, net primary production occurs whenever the mixed layer is shallower than the critical depth. Both the magnitude of wind mixing and the availability of light at the ocean's surface are affected across a range of space- and time-scales.

The most characteristic of these is the seasonal cycle caused by the consequences of the Earth's axial tiltalthough wind magnitudes additionally have strong spatial components. Consequently, primary production in temperate regions such as the North Atlantic is highly seasonal, varying with both incident light at the water's surface reduced in winter and the degree of mixing increased in winter. In tropical regions, such as the gyres in the middle of the major basinslight may only vary slightly across the year, and mixing may only occur episodically, such as during large storms or hurricanes.

Annual mean sea surface nitrate for the World Ocean.

Primary production - Wikipedia

Data from the World Ocean Atlas Mixing also plays an important role in the limitation of primary production by nutrients. Inorganic nutrients, such as nitratephosphate and silicic acid are necessary for phytoplankton to synthesise their cells and cellular machinery. Because of gravitational sinking of particulate material such as planktondead or fecal materialnutrients are constantly lost from the photic zone, and are only replenished by mixing or upwelling of deeper water.

This is exacerbated where summertime solar heating and reduced winds increases vertical stratification and leads to a strong thermoclinesince this makes it more difficult for wind mixing to entrain deeper water. Consequently, between mixing events, primary production and the resulting processes that leads to sinking particulate material constantly acts to consume nutrients in the mixed layer, and in many regions this leads to nutrient exhaustion and decreased mixed layer production in the summer even in the presence of abundant light.

However, as long as the photic zone is deep enough, primary production may continue below the mixed layer where light-limited growth rates mean that nutrients are often more abundant.

Gross Primary Productivity vs. Net Primary Productivity: What's the Difference?

Iron[ edit ] Another factor relatively recently discovered to play a significant role in oceanic primary production is the micronutrient iron. A major source of iron to the oceans is dust from the Earth's desertspicked up and delivered by the wind as aeolian dust. In regions of the ocean that are distant from deserts or that are not reached by dust-carrying winds for example, the Southern and North Pacific oceansthe lack of iron can severely limit the amount of primary production that can occur.

These areas are sometimes known as HNLC High-Nutrient, Low-Chlorophyll regions, because the scarcity of iron both limits phytoplankton growth and leaves a surplus of other nutrients.

gpp and npp relationship

Some scientists have suggested introducing iron to these areas as a means of increasing primary productivity and sequestering carbon dioxide from the atmosphere. Gross production is almost always harder to measure than net, because of respiration, which is a continuous and ongoing process that consumes some of the products of primary production i.

Also, terrestrial ecosystems are generally more difficult because a substantial proportion of total productivity is shunted to below-ground organs and tissues, where it is logistically difficult to measure. Shallow water aquatic systems can also face this problem. Scale also greatly affects measurement techniques. The rate of carbon assimilation in plant tissues, organs, whole plants, or plankton samples can be quantified by biochemically based techniquesbut these techniques are decidedly inappropriate for large scale terrestrial field situations.

There, net primary production is almost always the desired variable, and estimation techniques involve various methods of estimating dry-weight biomass changes over time. Succession see week 24 tends to increase niche diversity and climax communities tend to be more productive than seral stages.

Net primary production also has consequences for global warming, since any reduction in global NPP increases atmospheric CO2.

  • Difference Between NPP and GPP

Net primary production is limited by the same factors as those which limit photosynthesis see week 22plus the nutrient supply. Imagery ATP - the key chemical for storing and releasing energy in cells - is produced in plants via photosynthesis but animals rely on breakdown of glucose sugars to release it.

gpp and npp relationship

This is the basis of aerobic respiration. The agent of respiration is the tiny mitochodrion inside a cell. Mitochondria are found in all animal and plant cells. They have the structures and enzymes required to carry out respiration. The more active the tissue, the more mitochondria will be present.

There are lots in muscle, 30, in a liver cell andin a human egg cell. To measure these factors, gross primary production and net primary production are used.

Gross primary production, or GPP, is the estimation at which the producers in an ecosystem absorb a specific amount of chemical energy as biomass in a given span of time. Biomass is defined as the mass of organisms per unit area and is usually expressed in units of energy or dry organic matter.

Primary production

It is a renewable energy source that can be used for thermal, chemical, and biochemical conversion for useful energy. The measurement is not limited to the partial organisms but also to other ecological units such as population and entire communities. In global terms, patterns of primary production can vary both spatially and temporally depending on the conditions of the ecosystem. Those with lesser productive ecosystems are those with extreme conditions.