Natural Hazards: Causes and Effects - Disaster Management Center ...

present state and would be better off as forest. Therefore, it is necessary to gather information
on overall forest trends.
In much of the world this data on forest trends has generally been unreliable or altogether
lacking. But recently a large number of surveys have been initiated, many of them making use
of satellite photography, and the quality of forest data is improving fast.
Discussions of forest trends are plagued by definitional problems. How many trees, how close
together, make a forest? At what point does selective logging become deforestation? If the
clearing of a slash-and-burn farmer will be left for natural regrowth, has deforestation occurred?
Even statistics on tree planting can be confusing. A eucalyptus plantation established on former
cropland should not be lumped together with a restored hillside forest of mixed native species.
And “reforestation” often means clearing standing forests to make room for tree plantations.
Impact on Built and Natural Environments
Impact on Buildings
Deforestation and timber scarcity have an especially harmful impact on housing in poor
countries. Even if Third World governments were to make a serious effort to meet the housing
problem, adequate wood supplies would not be available in many cases. For example, in the
late 1970s the Indian state of Gujarat conceived of an ambitious plan to construct huts for
landless laborers. The plan was derailed by the lack of raw materials. The program called for
25 million wood poles, but only 400,000 of these became available each year; and only four
million bamboo stalks were produced a year although 765 million were needed.
Impact on Agriculture and Ecology
Deforestation’s impact on food supply follows this chain of events:
1. deforestation
2. erosion
3. collapse of hillsides
4. loss of topsoil and agricultural land.
Deforestation also unbalances the water supply by contributing to drought and flood.
Impact on Economy
What are the economic consequences of uncontrolled deforestation and forest-product scarcity?
One outcome of a nation’s forestry shortcomings can be a rising dependence on imported forest
products. Already most Third World countries are net importers of forest products, particularly
paper (the production of which requires both wood-fiber and manufacturing plants).
Trade-deficit figures do not come close to capturing the negative impacts of tree scarcity, some
of which are acutely felt by low-income citizens even in timber-exporting countries. For one
thing the major forest products used by most Third World residents never enter the market
economy; when fruits or firewood become scarce, people either do without or switch to
noncommercial alternatives rather than to imported goods. In addition, foreign exchange
shortages and high prices can hold a nation’s wood and paper consumption well below the
levels at which basic needs are satisfied.
Acute scarcities of firewood and timber plague wide areas of Africa, Asia, and Latin America.
But a continuation of the last quarter-century’s trends of deforestation, inadequate forest
renewal, and growth in wood demand would have worldwide repercussions. The amount of