Population growth in Central America intensifies competition for available limited resources and forces the poor, who have no access to land, to settle in marginal lands, often along riverbanks and unstable hillsides, in both urban and rural areas. Demographic pressure also induces migration of the rural population to the urban centers, which results in rapid and disorganized urbanization. In urban areas, poorly developed shantytowns in marginal and risky areas are a common phenomenon and the development of urban infrastructure is outpaced by illegal, uncontrolled, and unplanned urbanization. In rural areas, the expansion of the agricultural frontier near water sources is common causing unchecked land degradation and soil erosion, thereby upsetting the balance of ecosystems and creating unstable conditions and hazards. While the relationship between deforestation and environmental disasters is not well documented, it is likely that they are clearly interrelated.
Forests play a critical role in stabilizing soil and storing water.
When forests are cleared, the forest canopy is opened and exposes the forest floor, reducing rainfall interception and infiltration into the soil. This results in an increase in surface run-off when heavy rains occur and induces soil erosion and land degradation. Studies indicate that as much as a 75 per cent increase in run-off is associated with forest clearing, giving rise to excess silting of rivers and reservoirs, and the incidence of downstream flooding can be greatly increased. Soil erosion also causes the loss of soil fertility and productivity and greatly increases the risk of landslides and mudslides on hills and mountainous terrain. The principal causes of deforestation in Central America are the expansion of the agricultural frontier, which can be traced to the pressure of population growth and settlement programs, unequal land distribution, and weak land tenure systems.