Population pressure and deforestation
A growing population needs more food, water, land and energy, so forests are cleared. Deforestation causes soil erosion, less rain and more CO₂; reforestation and afforestation repair the damage.
How a large population strains the environment
- More people need more water, food, space, energy, land and fuel.
- More land goes under crops, more water to irrigation, and more fertilisers and pesticides enter the environment.
- Forests are cleared for houses, roads, schools and colleges, and industries.
- Resources are used faster than nature can replace them, and careless use makes it worse.
- Results: deforestation, pollution of air, water and land, using up of fossil fuels, biomagnification of pesticides, ozone depletion and global warming, and unhygienic living from more waste.
Effects of deforestation
| Effect | Why it happens |
|---|---|
| Loss of biodiversity | Wild plants and animals lose their homes, and many species disappear |
| Less rainfall | Fewer trees give out less water vapour to the air |
| Lower water table and a drier climate | Less water soaks into the ground, which upsets the water cycle |
| Soil erosion and desertification | With no roots to hold it, soil is washed or blown away; land loses fertility and can turn to desert |
| More CO₂ and global warming | Fewer trees take in carbon dioxide by photosynthesis |
Reforestation vs afforestation
Silviculture is the growing and care of forest trees; it supplies wood to industry and also adds to forest cover.
Ways to protect and rebuild forests
- Enforce strict laws against felling trees, since forests take a long time to grow back.
- Plant more trees for every tree that is cut.
- Join Van Mahotsav, the festival of mass tree planting in the first week of July.
- Practise silviculture and social forestry.
- Learn from the Chipko movement: women in the sub-Himalayan region hugged trees to stop them being cut.
The Chipko movement began when village women in the hills hugged trees to save them from felling. Planting a sapling during Van Mahotsav and using both sides of paper are small ways you can protect forests.
1 marks: “What is afforestation?” Growing a new forest where there was no forest before.
2 marks: “Give two ways in which deforestation affects the water cycle and the climate.” Less rainfall; lower water table and a drier climate (also more CO₂ and global warming).
3 marks: “Hill villages that lost their forests now face poorer soil and drying springs. Explain three such effects of cutting forests on a large scale, and two ways to rebuild the forest cover.” Effects: loss of habitat and biodiversity; soil erosion and desertification; less rain and lower water table; more CO₂. Rebuild: reforestation, afforestation (social forestry, Van Mahotsav), silviculture, strict laws.
Re = again, Af = new. Reforest where it was; afforest where it never was.