Chapter 14: Ecosystem

Ans: The biogeochemical cycle, often known as nutrient cycling, is the exchange of nutrients between ecosystem elements. Nutrient cycle guarantees that nutrients in the ecosystem are never wasted. They are continually renewed in ecosystem reservoirs.

Reservoir Function: A nutrient could become inadequate when the outflow and influx of that nutrient are out of balance. By supplying nitrogen, the reservoir balances for the nitrogen deficiency.

Phosphorus Cycle: The phosphorus reservoir is found in the earth's crust. A sedimentary cycle is exemplified by the phosphorus cycle. Phosphorus is naturally stored in rocks. Phosphorus is found in the form of phosphates in rocks. During the rock weathering, low concentrations of phosphates mix in the soil solution. Plant roots absorb phosphorus from the soil solution. Phosphates are supplied by plants to both primary and secondary users.

Ans: A community's P/R ratio is the proportion of gross output to communal respiration. This could be one, a number less than one, or a number more than one.

In a pioneer town, the P/R ratio can be less than or more than one.

A climax community's P/R ratio, on the other hand, is 1.

There are two possible scenarios in a pioneer village.

(a) Respiratory loss is minimised when gross output is higher and there are fewer consumers. As a consequence, the P/R ratio will be greater than 1.

(b) When decomposition rates are higher due to a significant decomposer population, gross productivity is poorer than respiratory losses.

The P/R ratio is smaller than one in this scenario.

In the case of the climax community, the P/R ratio is one. As a consequence of the community's stability, this happens. The P/R ratio is depicted in the graph below at various stages of community succession. The primary community is at the top of the diagram, whereas the climax community is at the base.

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