GEOGRAPHY
A
High-resolution global satellite photographs taken during a 5-year period beginning in 2000 have given researchers a comprehensive picture of how much forest cover is left on earth and exactly where this forest cover is located. In 2005, forest cover comprised about a third of total land although this figure was down by 20 percent of the original cover that existed some decades ago. Britain has only 13 percent wood cover, one of the lowest in Europe, which, along with the rest of the world, averages about 37 percent. Given the world’s insatiable need for wood, these numbers are not surprising. However, the truly significant discovery that the images afford is that the trees aren’t where they used to be. Millions of individual trees are scattered on lowland terrain, but very little continuous forest cover exists in lowland areas in developed countries and more recently in developing countries. The images show that over the years forest cover has gradually been pushed up steeply sloping terrain. How did this happen?
B
When a population grows, human activity increases. To accommodate the needs of a burgeoning populace, land must be made available for agriculture, manufacturing, infrastructure such as bridges and highways, and buildings for residential and public use. Since ancient times, people have been chopping down trees and stripping the land of other vegetation to free up needed space. Today, deforestation is especially evident in developed areas—countries with strong economies divest land of its forest cover with greater ease because they possess the technology and know-how to clear land effectively and quickly. But even in developing areas, large areas of forests have been cut down, such as the Amazon Jungle, where a whopping 90 percent of the forest cover has been cleared for crops, pasturage and urban development. Moreover, the Industrial Age triggered an exodus of people living on mountainsides to large cities for factory work. The sloping areas left behind permitted trees that once forested the terrain to grow back. Only in areas where the population is scant do researchers find a continuous spread of virtually untouched forest.
C
Continuous or intact forest is defined as an unbroken expanse of forest ecosystem, with little or no sign of human activity, and as such, is capable of supporting a broad range of animal and plant species. In other words, intact forest means intact native biodiversity. Only 23.5 percent of existing forest on earth is intact; this is a mere 8.8 percent of total land area. In places where human activity has escalated, the result has been greatly reduced intact forest in lowlands and greater forest cover on mountains and other steep terrain. In lowland areas where forests still stand, much of the cover is characterized by discontinuity. This is because only isolated sections remain when trees are cleared for other purposes. In-between these scattered patches of forest is land devoted to agricultural and urban growth. The phenomenon reflects human thinking on land use. Forest is relegated to land that is less usable; wood may be valuable, but lowland is much more valuable. Sloping land has low utility even if wood and its products are in demand. Since trees can grow on both lowland and sloping terrain, it makes sense for human beings to use less valuable land for trees.
D
Forest fragmentation has a cascade effect on an environment. Deforested land consists of existing patches that are small and isolated; what was once inner forest becomes bounded by a completely different habitat such as grassland. Inner forest habitat is necessary for bird species and other animal organisms to survive, but when trees are chopped down, inner forest becomes exposed to the elements. Forest floor and canopy are laid bare to sunlight, resulting in higher temperatures. Wind disturbs the canopy that animals use for habitat and protection. Larger predatory animals need more extensive forest areas to hunt for food and to hide from humans hunting them. These species begin to disappear.
E
In one example, researchers observing native species on a forest island in Thailand where a hydroelectric reservoir was constructed became eyewitnesses of the almost total extinction of these species. At the same time, the Malayan field rat—a species of a bordering habitat—began invading the existing forest cover. This served to further decimate the native species of the forest. It can thus be seen that fragmented forests experience both a drastic reduction in native biodiversity and a modification in the forest’s ecosystem that changes its overall biodiversity.
F
At present, studies on forest defragmentation focus on space patterns of existing forest cover, how these patterns have been changing and what effect these patterns have on the biodiversity of the forest ecosystem. However, experts in geography recommend an analysis of the underlying causes of fragmentation. Only by determining what drives fragmentation can world governments put into place policies that address the need for sustainable land use and the protection of forest ecosystems around the world. |