Friday, September 12, 2008

A Student Guide To Tropical Forest Conservation-2

DEFORESTATION
Before the dawn of agriculture approximately 10,000 years ago, forests and open woodland covered about 15.3 billion acres (6.2 billion ha) of the globe. Over the centuries, however, about one-third of these natural forests has been destroyed. According to a 1982 study by FAO, about 27.9 million acres (11.3 million ha) of tropical forests are cut each year-an area about the size of the States of Ohio or Virginia. Between 1985 and 1990, an estimated 210 million acres (85 million ha) of tropical forests were cut or cleared. In India, Malaysia, and the Philippines, the best commercial forests are gone, and cutting is increasing in South America. If deforestation is not stopped soon, the world will lose most of its tropical forests in the next several decades.
Reasons for Deforestation
Several factors are responsible for deforestation in the Tropics: clearing for agriculture, fuelwood cutting, and harvesting of wood products. By far the most important of these is clearing for agriculture. In the Tropics, the age-old practice of shifting, sometimes called "slash-and-burn," agriculture has been used for centuries. In this primitive system, local people cut a small patch of forest to make way for subsistence farming. After a few years, soil fertility declines and people move on, usually to cut another patch of trees and begin another garden.
In the abandoned garden plot, the degraded soil at first supports only weeds and shrubby trees. Later, soil fertility and trees return, but that may take decades. As population pressure increases, the fallow (rest) period between cycles of gardening is shortened, agricultural yields decrease, and the forest region is further degraded to small trees, brush, or eroded savanna.
Conversion to sedentary agriculture is an even greater threat to tropical forests. Vast areas that once supported tropical forests are now permanently occupied by subsistence farmers and ranchers and by commercial farmers who produce sugar, cocoa, palm oil, and other products.
In many tropical countries there is a critical shortage of firewood. For millions of rural poor, survival depends on finding enough wood to cook the evening meal. Every year more of the forest is destroyed, and the distance from home to the forest increases. Not only do people suffer by having to spend much of their time in the search for wood, but so does the land. Damage is greatest in dry tropical forests where firewood cutting converts forests to savannas and grasslands.
The global demand for tropical hardwoods, an $8-billion-a-year industry, also contributes to forest loss. Tropical forests are usually selectively logged rather than clear-cut. Selective logging leaves the forest cover intact but usually reduces its commercial value because the biggest and best trees are removed. Selective logging also damages remaining trees and soil, increases the likelihood of fire, and degrades the habitat for wildlife species that require large, old trees-the ones usually cut. In addition, logging roads open up the forests to shifting cultivation and permanent settlement.
In the past, logging was done primarily by primitive means-trees were cut with axes and logs were moved with animals such as oxen. Today the use of modern machinery--chain saws, tractors, and trucks -makes logging easier, faster, and potentially more destructive.
Endangered Wildlife
Forests are biological communities-complex associations of trees with other plants and animals that have evolved together over millions of years. Because of the worldwide loss of tropical forests, thousands of species of birds and animals are threatened with extinction. The list includes many unique and fascinating animals, among them the orangutan, mountain gorilla, manatee, jaguar, and Puerto Rican parrot. Although diverse and widely separated around the globe, these specles have one important thing in common. They, along with many other endangered species, rely on tropical forests for all or part of their habitat.
Orangutans (Pongo pygmaeus) are totally dependent on small and isolated patches of tropical forests remaining in Borneo and Sumatra, Indonesia. Orangutans spend most of their time in the forest canopy where they feed on leaves, figs and other fruit, bark, nuts, and insects. Large trees of the old-growth forests support woody vines that serve as aerial ladders, enabling the animals to move about, build their nests, and forage for food. When the old forests are cut, orangutans disappear.
The largest of all primates, the gorilla, is one of man's closest relatives in the animal kingdom. Too large and clumsy to move about in the forest canopy, the gorilla lives on the forest floor where it forages for a variety of plant materials. Loss of tropical forests in central and west Africa is a major reason for the decreasing numbers of mountain gorillas (Gorilla gorilla). Some habitat has been secured, but the future of this gentle giant is in grave danger as a result of habitat loss and poaching.
The jaguar (Leo onca), a resident of the Southwestern United States and Central and South America, is closely associated with forests. Its endangered status is the result of hunting and habitat loss.
The Puerto Rican parrot (Amazona vittata), a medium-sized, green bird with blue wing feathers, once inhabited the entire island of Puerto Rico and the neighboring islands of Mona and Culebra. Forest destruction is the principal reason for the decline of this species. Hunting also contributed. Today, only a few Puerto Rican parrots remain in the wild and their survival may depend on the success of a captive breeding program).
In addition to species that reside in tropical forests year round, others depend on such forests for part of the year. Many species of migrant birds journey 1,000 miles or more between their summer breeding grounds in the north and their tropical wintering grounds. These birds are also threatened by tropical forest destruction.
THE PRACTICE OF FORESTRY
Forestry-loosely defined as the systematic management and use of forests and their natural resources for human benefit-has been practiced for centuries. Most often, forestry efforts have been initiated in response to indiscriminate timber cutting that denuded the land and caused erosion, floods, or a shortage of wood products.
Ancient Forestry Practices
In ancient Persia (now Iran), forest protection and nature conservation laws were in effect as early as 1,700 B.C. Two thousand years ago the Chinese practiced what they called "four sides" forestry-trees were planted on house side, village side, road side, and water side. More than 1,000 years ago, Javanese maharajahs brought in teak and began to cultivate it. In the African Tropics, agroforestry (growing of food crops in association with trees) has been practiced for hundreds of years.
In the Yucatan Peninsula of southern Mexico, the ancient Mayas cultivated fruit and nut trees along with such staples as corn, beans, and squash. Bark, fibers, and resin were obtained from plants grown in fields, kitchen gardens, and orchards. Early in their civilization, the Mayas practiced slash-and-burn agriculture. As their population grew, they found more efficient methods of growing crops. They terraced hillsides, learned how to decrease the time between "rotations" of agricultural land with native forests, dug drainage channels and canals to move water to and from cultivated areas, and filled in swampland to plant crops.
The agricultural sophistication of the Mayas enabled their civilization to grow and flourish. What brought about their decline about A.D. 820 is not fully known, but some believe that as their society developed, the Mayas made unsustainable demands on their environment.
Relatively little is known about tropical forestry before the mid1800's in most places. At that time, the European colonial empiresnotably the Dutch, English, and Spanish-brought modern forest management practices to Indonesia, India, Africa, and the Caribbean. Centers for forestry and forestry research were established, and more careful records were kept.
Sustainable Forestry
Modern forestry has its basis in 18th-century Germany. Like the Chinese and the Mayan forest practices, German forestry is essentially agricultural. Trees are managed as a crop. Two concepts are important: renewability and sustainability. Renewability means that trees can be replanted and seeded and harvested over and over again on the same tract of land in what are known as crop "rotations." Sustainability means that forest harvest can be sustained over the long term. How far into the future were foresters expected to plan? As long as there were vast acres of virgin (original) forests remaining, this question was somewhat academic. Today, however, sustainability is a vital issue in forestry. Most of the world's virgin forests are gone, and people must rely more and more on second- growth or managed forests. Perhaps we now face, as never before, the limits to long-term productivity.
In the German forest model, forestry is viewed as a continual process of harvest and regeneration. Harvest of wood products is a goal, but a forester's principal tasks are to assure long-term productivity. That is achieved by cutting the older, mature, and slow-growing timber to make way for a new crop of young, fast-growing trees.
Harvest-Regeneration Methods
Three examples of timber harvest-regeneration methods (silvicultural systems) illustrate how foresters manage stands to produce timber on a sustained basis.
Selection
Individual trees or small groups of trees are harvested as they become mature. Numerous small openings in the forest are created in which saplings or new seedlings can grow. The resulting forest has a continuous forest canopy and trees of all ages. Such systems favor slow-growing species that are shade tolerant.
Clearcutting
In clearcutting, an entire stand of trees is removed in one operation. From the forester's point of view, clearcutting is the easiest way to manage a forest-and the most economical. Regeneration may come from sprouts on stumps, from seedlings that survive the logging operation, or from seeds that germinate after the harvest. If natural regeneration is delayed longer than desired, the area is planted or seeded.
Clearcutting systems are often used to manage fast-growing species that require a lot of light. Resulting stands are even aged because all the trees in an area are cut-and regenerated-at the same time. Clearcutting has become controversial in recent years because it has the potential to damage watersheds and because it tends to eliminate species of wildlife dependent on old growth trees. If clearcuts are kept small and the cutting interval is long enough, however, biological diversity may not be impaired.
Shelterwood
In shelterwood systems, the forest canopy is removed over a period of years, usually in two cuttings. After the first harvest, natural regeneration begins in the understory. By the time the second harvest is made, enough young trees have grown to assure adequate regeneration. Shelterwood systems favor species that are intermediate in tolerance to shade. Such systems are difficult to use successfully and are the least used of the three silvicultural methods described.
Multiple-Use Forestry
Gifford Pinchot, the first Chief of the U.S. Forest Service, was also this country's first professional forester. Pinchot advocated the use of forest resources-all resources, not just timber-for human benefit. Pinchot was a strong and charismatic leader, and his ideas helped shape the course of forestry in the United States.
Pinchot had a vocal opponent in John Muir, a young naturalist from California who believed that public lands should be preserved rather than used. Eventually Muir and Pinchot became rivals for public approval. Oddly enough, there was no
loser in this early conservation battle. Muir's preservation ethic became embodied in the philosophy of the National Parks, and Pinchot's concept of wise use became the guiding principle of the National Forests.
National Forests are still managed under the concepts of multiple use and sustained yield. The dominant uses of National Forests are considered to be wood, water, wildlife, forage (for domestic cattle and wildlife), and recreation. Extraction of minerals and other valuable products is also considered a legitimate use of National Forests. Because Pinchot's philosophy left room for the "highest and best use" of a given area, the U.S. National Forests now include a wilderness system of more than 32 million acres (13 million ha) in which timber harvest is not allowed.
Today it is generally recognized that most, if not all, nondestructive uses of forest are valid. Some areas may be set aside as parks; others for wildlife habitat or as wilderness. Still others will be managed for timber harvest or multiple benefits. Today, conflicts arise primarily over where these different uses will be dominant. In the National Forests, such decisions are made through a land-use planning process in which the public has ample opportunities for input and involvement.
FORESTRY RESEARCH
At the turn of the century, very little was known about the world's native forests or how to manage them. In the United States, foresters were quick to recognize the value of information about forests and a branch of research was established in the Forest Service in 1915. Early research was done primarily in support of reforestation efforts, but, as forestry grew in size and complexity, so did the research.
Today, the USDA Forest Service has six regional experiment stations located in important forest regions. Each experiment station has several field laboratories generally with specialized assignments for a geographic region or a specific subject area, and numerous sites for field research. In addition, the Forest Products Laboratory in Madison, WI, serves as a nationwide center for research and development of new technology relating to wood , including tropical woods. Two laboratories are dedicated exclusively to tropical forest research: the International Institute of Tropical Forestry in Puerto Rico and the Institute of Pacific Islands Forestry in Hawaii.
Research is vital for modern forest management, which is information intensive. Today's foresters require vast quantities of data and a knowledge of ecology: they must understand not only the parts of ecosystems but how different parts of the environment interact. Scientific investigations are conducted in support of all kinds of forestry activities: silviculture, forest insect and disease control, wildlife habitat management, fire prevention and control, range and watershed management, forest products utilization, forest survey, reforestation, ecology, and economics.

4 comments:

redapes said...

Great post. Would it be okay to use it on my non-profit's website? Our readers could learn a lot from it..

I can link back to you.

Richard Zimmerman
Director, Orangutan Outreach
http://redapes.org
Reach out and save the orangutans!

shzainzy said...

hi there!

i've added this blog to my other blogs as well.. please link back.. ^_^

http://shzainzy.blogspot.com
http://shzainzy2.blogspot.com
http://shzainzy3.blogspot.com
http://shzainzy4.blogspot.com

thanks :)

ed said...

一夜情聊天室,一夜情,情色聊天室,情色,美女交友,交友,AIO交友愛情館,AIO,成人交友,愛情公寓,做愛影片,做愛,性愛,微風成人區,微風成人,嘟嘟成人網,成人影片,成人,成人貼圖,18成人,成人圖片區,成人圖片,成人影城,成人小說,成人文章,成人網站,成人論壇,情色貼圖,色情貼圖,色情A片,A片,色情小說,情色小說,情色文學,寄情築園小遊戲, 情色A片,色情影片,AV女優,AV,A漫,免費A片,A片下載

情色,A片,AIO,AV,日本AV,色情A片,AV女優,A漫,免費A片,A片下載,情色A片,哈啦聊天室,UT聊天室,聊天室,豆豆聊天室,色情聊天室,尋夢園聊天室,080視訊聊天室,080聊天室,080苗栗人聊天室,免費視訊聊天,上班族聊天室,080中部人聊天室,視訊聊天室,視訊聊天,成人聊天室,一夜情聊天室,辣妹視訊,情色視訊,成人,成人影片,成人光碟,成人影城,自拍

A片,AIO,AV,日本AV,色情A片,AV女優,A漫,AIO交友愛情館,線上A片,免費A片,A片下載,情色A片,微風成人,嘟嘟成人網,成人,成人影片,成人光碟,成人影城,成人交友,愛情公寓,色情聊天室,情色貼圖,色情,色情影片,做愛,情色,哈啦聊天室,聊天室,UT聊天室,豆豆聊天室,尋夢園聊天室,080視訊聊天室,080聊天室,080苗栗人聊天室,自拍,性愛

情趣用品,情趣用品,情趣,情趣,A片,A片,情色,A片,A片,情色,情趣用品,情趣用品,A片,A片,情色,情色

情色視訊,美女視訊,辣妹視訊,視訊聊天室,視訊交友網,免費視訊聊天,視訊交友90739,視訊,免費視訊,情人視訊網,視訊辣妹,影音視訊聊天室,視訊交友,視訊聊天,免費視訊聊天室,成人視訊,UT聊天室,聊天室,豆豆聊天室,色情聊天室,尋夢園聊天室,聊天室尋夢園,080聊天室,080苗栗人聊天室,上班族聊天室,小高聊天室

宮保雞丁Alex said...

徵信社,尋人,偵探,偵探社,徵才,私家偵探,徵信,徵信社,徵信公司,抓猴,出軌,背叛,婚姻,劈腿,感情,第三者,婚外情,一夜情,小老婆,外遇,商標,市場調查,公平交易法,抓姦,債務,債務協商,應收帳款,詐欺,離婚,監護權,法律諮詢,法律常識,離婚諮詢,找人,追蹤器,GPS,徵信,徵信公司,尋人,抓姦,外遇,徵信,徵信社,徵信公司,尋人,抓姦,外遇,徵信,徵信社,徵信公司,尋人,抓姦,外遇,徵信,徵信社,徵信公司,尋人,抓姦,外遇,徵信社