Open oceans have relatively low primary productivity because of low levels of the essential nutrients nitrogen and phosphorus.

Describe the yearly productivity pattern in polar oceans, including the main factor that limits productivity in polar oceans. Availability of solar energy limits photosynthesis productivity.

Why is primary productivity high in the polar oceans? The polar oceans have high productivity because there is little thermocline/pycnocline to prevent nutrient supply from deep waters. Therefore, in sunlit months, polar oceans are extremely productive.

Most areas show an upward trend in NPP. Temperatures appear to decrease across the country during the global warming hiatus (1998–2008), and are accompanied by an increase in precipitation over most regions. The correlation between NPP and annual average temperature is weak.

Deserts are areas of low available water. In extreme desert, be it hot or cold, the absence of water will prevent most plants surviving and, hence, productivity is negligible. Plants may show similar adaptations to conserve water in both environments (xerophytism).

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.

In Tropical Rainforests, water, sunlight, and high temperatures are consistent and a dense concentration of plants is present, causing both the GPP and NPP to be very high. So, high levels of productivity increase biomass.

Along a precipitation gradient, grasslands are located between forests and deserts. Grasslands cover a broad range of environmental conditions with an annual aboveground productivity from 50 to 800 g m −2 that is linearly related to precipitation (Sala et al., 1988).

Across the broad spectrum of the tropical forests studied (dry to wet, lowland to montane, nutrient-rich to nutrient-poor soils), the estimates of total NPP range from 3.4 to 34.4 Mg/ha/yr (lower bounds) and from 6.2 to 63.0 Mg/ha/yr (upper bounds).

A high primary productivity rate in the ecosystems is obtained when the physical factors (for instance: water, nutrients and climate) are favourable. The presence of some forms of secondary energy can also help to increase the primary productivity rate.

Primary productivity is the process by which organisms make their own food from inorganic sources. These organisms are known as autotrophs, since they can use inorganic substrates and solar energy to carry out metabolic processes and build cellular material.

Higher chlorophyll concentrations and in general higher productivity are observed on the equator, along the coasts (especially eastern margins), and in the high latitude ocean (Figure 4a and b).

1. What are the three ways primary productivity can be measured? Primary productivity can be measured by the rate of carbon dioxide utilization, the rate of formation of organic compounds, or the rte of oxygen production.

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.