Environmental Engineering Reference
In-Depth Information
HUMAN IMPACT ON THE FOREST
Although forests do provide food, it was only through agriculture and crop production
that food supplies became sufficient to sustain a settled and concentrated population in
villages, towns and eventually cities. As populations have expanded so there has always
been pressure on forest reserves to increase the area of agricultural land. The European
deciduous forests were decimated in the last millennium; North American forests
suffered similarly though not on such a vast scale. Even the boreal forests of Canada,
Scandinavia and the former Soviet Union are
Figure 28.7
Relation between tropical
rain forest formation and
environmental conditions.
Source: Based on Collinson (1977).
being utilized, though in this instance for paper and timber products rather than replacing
them with agriculture. It is not surprising therefore that the tropical rain forests have
begun to suffer severe depredation. The scale of damage varies. In the small, fragmented
states of West Africa each country has used its timber resources as a source of foreign
exchange without being able to preserve large areas. For example, Ivory Coast produced
5·5 million m
3
of industrial roundwood in the late 1970s. By 1999 the figure had fallen
below 2·5 million m
3
. In the same time the population grew from about 6 million to
almost 14 million and plantation crops increased in area under government incentives.
Privatization of the forestry industry has meant that control of timber resources has
become more difficult. In Brazil pressure on land has, until recently, been much less and
so vast areas of rain forest remained undisturbed, but there is still a considerable annual
loss (see, p. 573). In Borneo drought induced by the major El Niño of 1997/8 assisted
forest clearance during the short dry season. Smoke from the forest became so severe that
aircraft movement in Indonesia and Singapore was disrupted and air pollution was a
