Question

Give reasons why:

1. The forest ecosystem is more stable than a cropland ecosystem.
2. Available energy goes on decreasing at each trophic level in a food chain.

Answer 1

Forest ecosystem:

1. It is a functional unit consisting of soil, plants, insects, animals, birds, and man at its trophic levels.

Cropland ecosystem:

1. This ecosystem consists of soil, crops, and man as its units.

Explanation:

1. In a forest ecosystem, more variety of organisms are present at different trophic levels and in a cropland ecosystem, the variety of organisms is less. The greater variety at each trophic level makes the ecosystem more stable. Thus, the forest ecosystem is more stable than the cropland ecosystem.
2. According to the second law of thermodynamics at each level of energy transfer majority of the energy is lost as unavailable heat. Only 10% of the energy is transferred to the next level in a food chain. This is why the energy goes on decreasing at each trophic level.