Deforestation is the permanent destruction of indigenous forests and woodlands. The term does not include the removal of industrial forests such as plantations of gums or pines. Deforestation has resulted in the reduction of indigenous for­ests to four-fifths of their pre-agricultural area.

Indigenous forests now cover 21% of the earth’s land surface. The World Resources Institute regards defor­estation as one of the world’s most pressing land-use problems. The difference between forests and woodlands is that whereas in a forest the crowns of individual trees touch to form a single canopy, in woodland, trees STOW far apart, so that the canopy is open.

Of great concern is the rate at which deforestation is occurring. Currently, 12 million hectares of forests are cleared annually. Almost all of this deforestation occurs in the moist forests and open woodlands of the tropics.

At this rate all moist tropical forest could be lost by the year 2050, except for isolated areas in -Amazonia, the Zaire basin, as well as a few protected areas within reserves and parks. Some countries such as Ivory Coast, Nigeria, Costa Rica, and Sri Lanka are likely to lose all their tropical forests by the year 2010 if no conservation steps are taken.

The destruction of forests due to unscrupulous and indiscriminate felling of trees has lead to an overall deterioration of our environment and is posing a serious threat to the quality of “life in future. Forest area in world has dwindled from 7,000 million hectares (year 1900) to 2S90 million hectares (year 1975). It is expected to further reduce to 2300 mil­lion hectares by year 2010 AD if the present trend of deforestation is not re­versed.

Causes of Deforestation:

(1) Population Explosion:

Population explosion poses a grave threat to the environment. Vast areas of forest land are cleared of trees to reclaim land for human settlements (factories, agriculture, housing, roads, railway tracks etc.) growth of population increases the demand for forest products like timber, firewood, paper and other valuable products of industrial importance, all necessitating felling of trees.

(2) Forest Fires:

Fires in the forests may be due to natural calamities or human activities:

(a) Smoldering of the humus and organic matter forming a thick cover over the forest floor (i.e. ground fires).

(b) Dried twigs and leaves may catch fire (i.e. surface fires).

(c) In densely populated forests, tree tops may catch fire by heat produced by constant rubbing against each other (i.e. crown fires).

(d) Human activities like clearing forest for habitation, agriculture, firewood, construction of roads, railway tracks and carelessness (throwing burning cigarette stubbs on dried foliage).

Fire destroys fully grown trees, results in killing and scorching of the seeds, humus, ground flora and animal life.

(3) Grazing Animals:

Trampling of the forest soil in the course of overgrazing by livestock has four reaching effects such as loss of porosity of soil, soil erosion and desertification of the previously fertile forest area.

(4) Pest Attack:

Forest pests like insects etc. destroy trees by eating up the leaves, boring into shoots and by spreading diseases.

(5) Natural Forces:

Floods, storms, snow, lightening etc. are the natural forces which damage for­ests.

Effects of Deforestation:

Forests are closely related with climatic change, biological diversity, wild ani­mals, crops, medicinal plants etc.

Large scale deforestation has many far-reaching consequences:

(a) Habitat destruction of wild animals (tree-using animals are deprived of food and shelter.)

(b) Increased soil erosion due to reduction of vegetation cover.

(c) Reduction in the oxygen liberated by plants through photosynthesis.

(d) Increase in pollution due to burning of wood and due to reduction in Car- bon-dioxide fixation by plants.

(e) Decrease in availability of forest products.

(f) Loss of cultural diversity

(g) Loss of Biodiversity

(h) Scarcity of fuel wood and deterioration in economy and quality of life of peo­ple residing near forests.

(i) Lowering of the water table due to more run-off and thereby increased use of the underground water increases the frequency of droughts.

(j) Rise in Carbon dioxide level has resulted in increased thermal level of earth which in turn results in melting of ice caps and glaciers and consequent flooding of coastal areas.