Home >> Science & Nature >> Nature

What Kinds of Ecosystems Exist in the Nitrogen Cycle?

The Nitrogen Cycle is a key geochemical process that allows an ecosystem to function. Nitrogen is used by biological organisms to build amino acids, nucleic acids and proteins. As a pure element, nitrogen is inert, and must be fixed into organic molecules, such as ammonia and nitrates. This is accomplished by bacteria and fungi. Nitrogen is then passed through the food chain and back into the soil by the decomposition of organic matter. The nitrogen cycle is a crucial component in the functioning of ecosystems because it is intrinsic to the functioning of a food pyramid.

Rain Forest
- Rain forests have a large variety of primary producers (as vegetation) and consumers occupying the various levels of its food chain. The nitrogen cycle is incorporated into the rain forest ecosystem by the nitrogen-fixing bacteria creating organic molecules in the soil. This takes the form of bacteria dwelling in root nodules, fixing nitrogen into molecules that can sustain plant life. Bacteria also convert decaying biomass in the soil into nitrates for plant growth. The nitrogen is then passed up the food chain through a large number of primary producers and consumers. It is eventually returned to the soil either as animal waste or decomposition. Nitrates are also conveyed by rivers into the oceans, where they are recycled into the atmosphere.
Deserts
- The nitrogen cycle in a desert begins with the uptake of nitrates by desert plants. These are then consumed by insects and reptiles. These creatures are, in turn, eaten by secondary consumers such as small carnivores and snakes. The nitrogen-bearing compounds in these animals are passed further up the food chain to larger carnivores such as coyotes and birds of prey. These creatures occupy the tertiary level of the desert food pyramid. Their waste products and dead bodies return nitrogen back into the soil, where bacteria and fungi mineralize them for plant growth.
African Savanna
- Savanna ecosystems have specialized food chains; this is reflected in the ratio of producers to consumers. Unlike desert ecosystems, savannas are characterized by continuous grasslands and other perennial vegetation. This contributes to a diversity of primary herbivore consumers. Above these animals are secondary consumers and a distinct group of scavengers. However, the nitrogen cycle remains the same, as characterized by the movement of nitrogenous compounds from the soil to vegetation, and up through the various levels of this ecosystem's food pyramid. Ultimately the cycle begins again with organic decomposition of all the consumers by denitrifying bacteria and fungi.

Nature