NCERT Solutions: Class 7 Science Chapter 12 - Forests: Our Lifeline

Animals help forests grow by dispersing seeds through their droppings, fur or movement. Insects, birds and other animals help in pollination. Animal wastes also enrich the soil after decomposition.

Forest vegetation slows down rainwater flow and allows more water to seep into the ground. Roots hold the soil and reduce runoff. This reduces sudden flow of water into rivers and helps prevent floods.

Decomposers are organisms that break down dead plants, dead animals and wastes into simpler substances. Bacteria and fungi are decomposers. In forests they convert dead matter into humus and recycle nutrients into the soil.

Green plants in forests take in carbon dioxide and release oxygen during photosynthesis. Animals and plants use oxygen for respiration and release carbon dioxide. Forests therefore help maintain the balance of oxygen and carbon dioxide in the atmosphere.

There is no waste in a forest because dead plants, animals and droppings are decomposed by microorganisms into humus. Nutrients return to the soil and are reused by plants.

Five forest products are wood, gum, medicinal plants, fruits and honey. Forests also provide bamboo, fibres, resins and fodder.

(a) pollination
(b) air and water
(c) lowest
(d) soil

Forests affect the whole environment by maintaining oxygen and carbon dioxide balance, rainfall, climate, soil and water resources. Loss or damage to distant forests can therefore affect air, water cycle, biodiversity and human life everywhere.

A variety of plants and animals makes a forest stable. Different organisms depend on one another for food, pollination, seed dispersal, shelter and nutrient recycling. If one kind is lost, many others may be affected.

(iv) Kerosene

(iii) Forests have no influence on climate.

decomposers