Explain How do nitrogen cycles through a tropical rain forest?

Answer 1

The nitrogen in a tropical rain forest goes through the normal nitrogen cycle steps and also gains nitrogen directly from lightning activity.

Basic Nitrogen cycle steps:

1. Nitrogen-fixation: nitrogen gas (N2) in the atmosphere is changed into ammonia (NH3) by special nitrogen-fixing bacteria in the soil.

2. Nitrification: the conversion of ammonia (NH3) to nitrate (NO3-), done in two steps by bacteria. In the first step NH3 is converted to nitrite (NO2-). The second step is for NO2- to be converted into NO3-.

3. Assimilation: NH3 and NO3- compounds are taken into plants' biological tissues. Nitrogen is needed for the building of proteins and nucleic acids (DNA and RNA). Plants can use NO3- and NH3, animals obtain nitrogen by eating plants or other animals.

4. Ammonification: the conversion of organic nitrogen into ammonia (NH3); acomplished by the decomposition of organisms or waste products (urine and feces).

5. Denitrification: the process of changing NO3- to N2 gas. This is done by bacteria where there is little or no oxygen. This returns nitrogen to the atmosphere.

Role of lightning:Lightning produces NH3, NO2-, and NO3- compounds fromN2 gas in the atmosphere so nitrogen can be incorperated into the stages of the cycle without nitrogen-fixing bacteria.

Lightning is an important part of the nitrogen cycle, especially in the rain forest since the soils are heavily leached. Much of the nitrogen in the soil is washed away by the rain. The lightning replenishes the soil and leaves some of nitrogen compounds in the air. Plant leaves can readily take up NO3- from the air and some plants depend on it (such as epiphytes whose roots do not reach the soil).

Estimates of how much nitrogen forests take in varies widely, but some have speculated that in a year a rainforest could take in as much as 50 pounds of nitrogen per acre.