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Lecture VIII Rainforest
Rainforest • Nobody is sure how intensive tropical rainforest once were. One of the widely accepted estimates is that they covered 25 million square kilometers, or 16% of the land surface of the earth. Today, they cover around ten million kilometers. Half of the loss has been attributed to permanent farms conversion; a quarter to the development of pasteurland, livestock and ranches; and another quarter to shifting cultivations.
Rainforest preserve life-giving species and protect millions of living creatures, and regulate the flow of water on earth. Like a gigantic sponge, they soak up water from heavy tropical rainfalls, then release it slowly and steadily, providing a constant supply for people and farmers living hundreds or even thousands of miles away. • Tropical forest also play a crucial role in the global recycling of carbon. • The rainforest are disappearing because people are poor and greedy, and not because they are ignorant or stupid. Most attempts to grow plants and animals in the tropics have been geared to producing food for substinence and commodities for cash.
Causes of Destruction of Rainforests • 1. Poverty drives people into the woods for fuel, food and work. • 2. Word’s growing demand for wood products (timber) encourages the continued rape of rainforests. • 3. Poor government policies.
4. Global increase in the demand for forest products for building constructions, furniture, plywood, firewood, weaving materials, gums, resins, oils, charcoals, even chopsticks for japanese restaurants. • 5. Government’s opening of the forest frontiers as a way to bolster the economy, and to relocate people in various settlement programs. • 6. Ever-increasing and growing number of people who live and continue to establish residence in the rainforest.
Effects of Rainforest Destruction • 1. If nothing is done to check global population growth, and to control tropical deforestation, there may be only 20,000 square miles of rainforest left in te world by the year 2050, and nothing by 2100. • 2. The practice of slash-and-burn affects the uncut area, and the remaining trees suffer. • 3. In steep areas, logging does not only destroy the forest, but also erodes bare grounds.
4. Many valuable chemical compounds are sourced from the jungles. Unfortunately, as the forest are cut, many of these potentially life-saving tropical plants disappear forever. • 5. More than 1,000 tribes of indegenous people are close to extinction. The enroachment has led to repeated violence and lost lives, mostly among native rubber trappers and settlers. • 6. Deforestation releases more than a billion tons of carbon into the air annually contributing immensely to the greenhouse effect.
Forest Management (Multiple-Use Management System) • Multiple-use sustained management of forest primarily aims to make the greatest number of forest resources available to the greatest number of people. A forest cannot be all things to all people. Sound multiple-use management must weigh the needs of many people and those needs vary according to their values of top priority.
1. Forest as Wildlife Habitat National forest as well as private woodlands offer excellent wildlife habitat. 2.Forest as Wilderness, Recreational and Scientific Areas The wilderness is an area where the earth and its community of life are untrammelled by man, where man himself is a visitor and does not remain. These areas have to be conserved and preserved for recreational activities and scientific activities.
3. Forest as Source of Fuel An alternative source of energy is the biomass of trees, which is renewable. Wood and wood products provide 1.5% of the energy consumed globally. 4. Forest as Source of Wood Production Philippine forest and wood industry contributed significantly to our Gross Domestic Product (GDP) and export earnings. However, primary and secondary wood-based activities accounted for only 2.5% of the national output in 1988 as compared to 9.8% in 1970. the country even became a net importer for its wood requirments in the early ‘90s to date.
Reforestration • Whenever timber is removed, either by clearcutting or by selective cutting, the denuded area must be reforested to ensure a sustained yield. Undesirable cutting practices are expected to increase treefold by the year 2020, especially farmer-owned woodlots. Reforestration--efforts to replant the forest– may be done by either natural or artificial methods.
1. Natural Reseeding After claercutting, a few mature, wild-firm tulls may be left intact as a seed source within the otherwise logged off-site. Seeds are scattered by the wind, birds, rodents, and runoff water. The seeds are eventually dispersed throughout denuded area. This is natural reseeding process. • 2. Seeding by Foresters Aerial seeding using planes flying slowly just above the treetops is employed in rugged terrains. In a logged-off site that is flat, power-driven seeding machine is used. These machines plant up to 3.3 hectares per day, and simultaneously fertilize the soil and apply herbicide to prevent weed enroachment.
3. Planting • Actual planting of young trees from plantation stock is a better and more successful means of reforestation. On flat lands. Three workers, a tractor, and a planting machine can set 1,000 to 2,000 trees per hour.
Causes of Deforestation • Human have already cut down 40% of the world’s closed canopy tropical rainforest. About 105,000 square kilometer are destroyed annually. By estimates, present rates of removal will leave only scattered remnants of tropical rainforest by the year 2025. • 1.Slash-and-Burn Agriculture Much forest destruction can be blamed on slash-and –burn or shifting agriculture. This is done by farmers cutting the trees, tilling the land for few years then abandoning or leving it fallow – for up to 7 years. Devastating effects are high in too large clearcut areas. The fallow period is often too short for soil fertility to be restored.
2. Fire • Fire is used as a tool in slash-and-burn farming(kaingin system) to dispose of fallen trees and to prevent the invasion of weeds and shrubs in the crop area. Large forest areas have been destroyed when such fire have raged out of control. • 3. Cattle Ranching • Large areas of tropical forest are being cleared away for cattle ranching. Hamburger, hotdog, and luncheon meat productions demand the conversion of forest to ranches and gracing lands at the rate of 21,500 square kilometres per year.
4. Gathering Fuel Wood • More than one billion cibicmters of wood are harvested for fuel in the tropics. The wood is either used for firewood or is converted to charcoal. • 5. Industrial Logging • Commercial logging in tropical regions is frequently wasteful and inefficient. Most clearcut areas do not become reforested by natural means. The land-starved squatters move in to eke out their livelihood through slash-and-burn agriculture.
Effects of Deforestation • 1. Firewood Scarcity • 2. Climatic Changes • 3. Loss of Genetic “Pools” • 4.Extinction of Species To Save The Tropical Forest 1. Forest industries reseed or replant areas that they have harvested.
2. Villagers reforest areas from where they have removed trees for use as fuels. Plant fast-growing trees which attain a height of 6 meters (20 feet) in four to five years. • 3. Countries with rainforest provide financial grants to support research and education on the ecology and management of tropical forest. • 4. Countries with rainforest convert 15% of their forest to national parks and preserves. • 5. Provide funding for this project.
