Explain the function of ‘reservoir’ in a nutrient cycle. List the two types of nutrient cycles in nature.

OR

Explain with the help of two examples, how the pyramid of numbers and the pyramid of biomass can look inverted.

The function of the 'reservoir' is to meet the deficit which occurs due to an imbalance in the rate of influx and efflux.

The movement of nutrient elements through the various components of an ecosystem is called nutrient cycling.

There are two types of nutrient cycles in nature –

i. Gaseous – reservoir exists in atmosphere

ii. Sedimentary – reservoir exists in the Earth’s crust

OR

In most ecosystems, all the pyramids of number are upright.
For example, the producers are more in number than the herbivores and herbivores are more in number than the carnivores.

But the pyramids of number can be inverted too. For example, there are number of insects feeding on one big tree.

The pyramid of biomass represents the total amount of living matter present at each trophic level of an ecosystem. This pyramid can be both upright and inverted. In grassland ecosystem, the pyramid of biomass is upright. The number of biomass present at tertiary level is less than the secondary level and the producer level. In pond ecosystem, the pyramid of biomass is inverted because the biomass of fishes exceeds that of zooplanktons.