Degradation of natural resources can occur, not just by the action of pollutants but also by improper resource utilisation practices.
1. Soil Erosion and Desertification:
Topsoil is the most fertile soil and it takes centuries to build. Improper human activities can remove it, resulting in arid patches of land. Natural resources get degraded not only by pollutants, but also by improper practices of their utilisation and maintenance.
Soil erosion is caused by human activities like over-cultivation, unrestricted grazing, deforestation and poor irrigation. All these practices lead to the removal of top soil. Desertification is also a major problem these days, that occurs mainly due to urbanisation.
2. Water-Lodging and Soil Salinity:
Irrigation without proper drainage of water leads to water-lodging in the soil. It draws salt to the surface of the soil. Deposited salt starts collecting at the roots of the plants and affect the plant growth and productivity. It is extremely damaging to the agriculture. Water-lodging and soil salinity are some of the problems that have come in the wake of the Green Revolution.
3. Deforestation:
It is the conversion of forested areas to non-forested area. Almost 40% forests have been lost in the tropics, compared to only 1% in the temperate region. In India, at the beginning of the 20th century, forest covered area was about 30% of land, whereas by the end of the century, it reduced to 19.4%. The National Forest Policy (1988) has recommended 33% forest cover for the plains and 67% for the hills.
Reasons of Deforestation:
(a) Urbanisation
(b) Overgrazing by animals
(c) Forest fires
(d) Demand of wood and other forest products.
Effects of Deforestation:
(i) Increased levels of CO2 concentration in atmosphere.
(ii) Loss of diversity due to habitat destruction.
(iii) Disturbs hydrologic cycle.
(iv) Leads to soil erosion.
(v) Desertification also occurs in extreme cases.
4. Slash and Burn/Jhum Cultivation:
It is practiced in the North-Eastern states of the India. In this method, the farmers cut down the trees of the forest and burn the plant remains. The ash is used as a fertiliser and the land is then used for farming or cattle grazing.
After cultivation, the area is left for several years so as to allow its recovery. This same process is repeated at some other area. In initial days, there was ample recovery time, but now-a-days with increasing population and repeated cultivation, this recovery phase is done away with, resulting in deforestation.