Timber Harvesting

Written by Science Knowledge on 1:40 AM

Tree harvesting in the past meant the removal of all trees of any size and regardless of value. Logging companies clear-cut the landscape, which not only destroys the forest but also eliminates ecosystems. Even animals inhabiting the uncut adjacent forest must contend with the increased activity and noise coming from the clear-cutting zone. Clear-cutting also makes the harvested land vulnerable to soil erosion, floods streams, increases silt levels in streams that harm aquatic life, and makes landslides more likely.

During 2007 in Oregon, storms caused landslides in two clear-cut areas and torrents of mud and debris overwhelmed homes and vehicles and covered a state highway. While no humans were killed, several received injuries, and the damage to wildlife has not been fully resolved. Stephen Hobbs of the Oregon Board of Forestry described the event as a rare quirk of nature. He told the Oregonian, “Mother Nature threw a curveball at us. It was a pretty intense storm event, so you’re going to have unexpected things happen.” Despite these assurances, other people suspect that clear-cutting creates a danger to human and animal life. The University of Washington professor David Montgomery told the Olympian in 2008, “As a geologist, I see no surprises here. When you clear-cut potentially unstable slopes, you increase the risk of landslides up to tenfold.” These differences of opinion on the harm of clear-cutting and other tree harvesting methods continue.

In addition to the harvesting method loggers choose, all harvesting sites require roads built into the forest to give equipment access and allow logging trucks to transport the logs out of the forest. Roads help the overall efficiency of logging, and timber companies cannot do their job without them, but forest roads also harm ecosystems by fragmenting habitat, driving out animal species, and giving access to invasive species.

Once loggers reach the logging site, they can use any of a variety of harvesting methods, described in the table on the next page. Over the long term it is in the best interests of loggers to choose a method that sustains their industry but also conserves forests for future generations.

Logging comprises any of the harvesting methods described in the table below, plus the methods used for felling the trees and the yarding methods for taking the logs out of the forest. Tree cutting can be done in two ways: conventional sawing or mechanical logging. Sawing cuts the full length of trees to the stump close to the ground, while mechanical cutting removes trees using a piece of equipment called a feller (or faller). An operator drives a feller up to the tree to be removed and a blade or saw at the end of the feller’s arm cuts the tree, usually leaving a taller stump than the sawing method.

For centuries, horse-drawn wagons hauled logs out of the forest. This required little road-building and made little noise. In the 1800s horse or oxen teams dragged logs to specialized narrow logging railroads or, in areas where railroads could not reach, to mountain streams where workers transferred the logs to another conveyance, a process called offloading. Gravity simply carried the harvest downstream to a collection point at the bottom of the mountain. Dragging logs downhill to a train or stream soon proved to be inefficient because every forest snag or stump acted as a fishhook and grabbed at each log on the journey. Loggers soon learned that dragging logs uphill by cable to a mountaintop railroad track was the best approach. This so-called uphill logging or skyline logging evolved into the helicopter logging used by many timber operations today in difficult-to-reach terrain. Though horses still haul timber in parts of the world, today most operations use trucks, cables, and helicopters.

Timber harvests consist of whole logs, called roundwood, which means logs denuded of branches and bark. These harvests are of three main types: (1) hardwoods from broadleaf, deciduous trees; (2) softwoods from gymnosperm trees, including pine, spruce, fir, and juniper; or (3) pulpwood, which is any wood harvested for papermaking.

Source of Information : Green Technology Conservation Protecting Our Plant Resources

Old-Growth Forest Ecosystems

Written by Science Knowledge on 1:30 AM

Old-growth forests consist of trees that have never been cut so have never been forced to regrow. These primary forests contain the original growth of a tree population and therefore they contain the oldest and most mature trees found in the forest biome. Old-growth trees arise at the latest stage of forest ecological succession, and because of this they contain a mixture of species and a variety of sizes. They also contain dead trees that have fallen and begun to decay, broken branches, snags, and several canopy layers. All of these things create specialized habitats for a variety of animal life, plants, and fungi. Old-growth forests contain very complex ecosystems with many interrelationships between species, and of course, this enhances biodiversity.

The unique characteristics of old-growth forests sometimes provide habitat for species that cannot live anywhere else. Some of these specialized habitats include hollowed trees, tree cavities, decaying logs, the canopy, the understory, moist soil, and bark. In dense old-growth forests, the top of the canopy receives direct sunlight for the life in that habitat, while creatures near the forest floor live in dark, shaded surroundings. Animal diversity in old-growth forests includes moose, bear, weasel, lynx, fox, wolf, deer, bobcat, mountain lion, chipmunks, squirrels, shrews, bats, woodpeckers, owls, and hawks. This represents only a partial list and does not account for the microbes, insects, invertebrates, amphibians, reptiles, songbirds, and aquatic species that also live in old-growth forests. Vines, ferns, shrubs, mosses, lichens, and some grasses dominate the plant diversity. A typical old-growth forest in the Pacific Northwest contains giant redwoods, Douglas fir, spruce, and possibly hemlock and cedar. Each 2.5 acres (0.01 km) contain about 20 large trees at least 300 years old, many measuring over three feet (1 m) in diameter.

The health of an old-growth forest depends on fires caused by natural circumstances, such as lightning strikes. Frequent, short-lived ground fires reduce competing vegetation and degrade dead wood, which hastens the return of nutrients to the soil. Fires also thin out the densest growth and open more space for sunlight to reach places that had been cut off from light. Though fires may temporarily destroy some wildlife habitat, fires also create new habitat. For instance, some small mammals may prefer the plants and grasses that first break through the earth after a fire, and only ground fires afford this opportunity.

Old-growth forests and their ecosystems have remained largely a mystery despite the studies that have been conducted in them. They have outlived generations of humans, and they surely contain undiscovered species as well as ecosystems that have not been fully identified. These forests survived from a time when humans did not affect seemingly every corner of the Earth. For that reason alone, they deserve respect within the world of living things.

Source of Information : Green Technology Conservation Protecting Our Plant Resources

Tempe rate and Boreal Forest Loss

Written by Science Knowledge on 1:24 AM

Forest evaluation takes place by two main methods: aerial surveys and satellite imagery and on-the-ground field studies. Aerial surveys gather information on forested regions such as the Blue Ridge Mountains. Satellite images help scientists view much larger expanses such as the total area forests occupy on a continent. Scientists who conduct field surveys gather detailed information by observing forest ecosystems up close. Field surveys typically collect data on the following topics in assessing forest health:

» grass and wildflower ground cover
» wildlife diversity
» densities of small, stunted trees
» numbers of large, old-growth trees
» increased old-growth mortality rates due to thickets of small trees
» large-scale insect or other parasite infestation
» pathogens in rain runoff
» shift from low-intensity ground/grass fires to fast and large canopy fires, called crown fires

The FAO report states that the net rate of global forest destruction has slowed in some places, which is an encouraging sign, but overall the world continues to lose forests. For instance, aerial and satellite studies have revealed that forest area has increased a small amount (less than 0.1 percent) in Europe and parts of Asia in the past 15 to 20 years. During the same period, the total area of North American forests did not increase, but their destruction was greatly diminished. Both of these trends suggest that Europe and most of North America have put significant effort into forest conservation. Only Mexico, which loses about 0.5 percent of its trees annually, and select parts of Asia have continued losing temperate forests with no sign of slowing.

The United States destroyed most of its old-growth forests by 1920, especially in the East and Midwest, where secondary forests have now replaced them. Sections of the West and Alaska still experience large losses, however, to the point where plant and animal diversity now differs from the diversity that sustained Native Americans before European settlers arrived. Between 1600 and 1800, eastern settlements began removing trees for lumber, and the need for wood grew as the settlements became cities. When settlers migrated west, more trees came down for building houses, barns, and fencing. In the 1800s railroads crisscrossed the continent, and the new tracks demanded a constant supply of wood for railroad ties. Today lumber and paper make up the main uses of the country’s timber harvest, but trees supply other non wood products.

How has Europe managed to increase the amount of its forested land, especially in one of the most densely populated parts of the world? European countries have taken the lead in exploring sustainable methods in forest management. For example, in Europe tree plantations that restore destroyed forests tend to contain plantings of native trees interspersed with monoculture. This mixture of natural and artificial conditions allows a secondary forest to grow quickly, yet it retains some of the biodiversity of the original forest. Primary forest makes up only 4 percent of Europe’s forest area, so these secondary forests represent the continent’s best hope of reversing decades of deforestation. In North America primary forests account for almost 45 percent of total forests, mostly in Canada, and 12 percent of those primary forests have now been entered into conservation programs. The goal is to emulate Europe and begin rebuilding forested area.

Alaska has presented the American public with a unique situation regarding deforestation. Alaska’s large expanses of forest have been tempting the timber industry for many years, and the state now supports an active logging industry; about 5 percent of Alaskans are employed by the timber industry. But increased logging and further destruction of forest tracts due to new oil exploration have drawn increasingly heated debate. Laurie Cooper of the Alaska Wilderness League told the Los Angeles Times in 2008, “We’re at a crucial time right now to make sure we’re looking at a future that retains some of this landscape and some of this way of life for future generations.”

Alaska contains two principal types of forests: coastal rain forest and interior boreal forest. Most of the timber activity takes place in the coastal regions, and of the total forests available for logging, the federal government owns 51 percent, the state and local governments own 25 percent, and private owners hold about 24 percent. Alaska Native corporations make up 99 percent of all private forest landowners. Alaska also contains the nation’s largest and second-largest national forests: the Tongass National Forest, containing 16.8 million acres (68,000 km2), and the Chugach National Forest, with 5.9 million acres (24,000 km2). Logging presently occurs in a small portion of each of these forests, but Tongass has of late become a focal point in a debate on the possible expansion of Alaska’s logging.

In January 2008, President George W. Bush approved a plan to open an additional 3 million acres (12,140 km2) of Tongass National Forest to the timber industry. Though the decision sought to relieve financial stress in Alaska’s economy, environmentalists pointed out that logging may not help the economy much. Tom Waldo, attorney for the environmental group Earthjustice, warned in a New York Times article that logging may harm Alaska more than help it: “It leaves 2.4 million acres [9,712 km] of wild, roadless backcountry areas open to clear-cutting and new logging roads.” Meanwhile, the logging industry contributes only about 1 percent of Alaska’s economy.

The Pacific Northwest has had similar questions on the extent with which logging should take place, especially when local mill towns depend on timber for their income. One question that turned into a serious argument between the timber industry and environmentalists came in 1986, when the northern spotted owl was placed on the endangered species list. Spotted owls prefer habitat of old-growth forests like the kind that stretch from northern California to Canada. Listing the owl as threatened pitted conservationists against people whose livelihoods depended on logging. Many of these forests now receive federal protection as habitat for the owl, and the mill towns have slowly found income in nonforest pursuits, including tourism.

Temperate forests have not had the controversies that characterize the forests in Alaska or the Pacific Northwest, so the public has perhaps overlooked the dire condition of these forests. Part of this complacency comes from the fact that forests are a renewable resource: The trees grow back after they have been cut. But the time required to replace a forest is hundreds of years, depending on the type of trees growing there. Julia Bonds of the Coal River Mountain Watch in Appalachia said in a 2003 interview on mining and logging in the area of West Virginia where she grew up, “It’s [mountaintop mining] not only turning the mountaintops into wastelands, but the valleys as well. The wonderful and valuable hardwood forests are being destroyed, and they will not return for over 600 years, if ever. Our beautiful mountain streams have been devastated.” The temperate forested land in the United States has now stabilized, but that may be little comfort to people who remember when these forests stretched for hundreds of miles. The worth of forests is explored further in the sidebar “Old-Growth Forest Ecosystems.”

The United States has been able to stabilize its forested land area by reversing its commerce in wood products. The United States exported lumber for decades until the start of the 1990s, when imports began to outweigh exports. Today the value of U.S. wood product imports is double the value of its exports. In other words, the United States spares its forests by relying on wood products from other countries. In addition to primary wood products (raw lumber), the United States imports a large quantity of its secondary wood products, such as furniture.

Source of Information : Green Technology Conservation Protecting Our Plant Resources

Temperate and Boreal Forest Preservation

Written by Science Knowledge on 2:18 AM

Temperate and boreal forests differ from tropical forests in that they grow at latitudes of cool to cold winters and live in places that receive seasonal variation. Like tropical forests, temperate and boreal forests have been greatly reduced from their original area on Earth. While tropical forests have lost an estimated 50 percent of their area, a very small percentage of temperate forests and boreal forests remain from their original population.

The temperate forests that remain in eastern North America, northeastern Asia, and Europe share the following characteristics: varied temperature from below zero to 85°F (30°C); even precipitation throughout the year; moderately dense canopy with partial light penetration; fertile soil; and seven to 10 tree species per square mile (three to four species per km).

Temperate forests contain plant, tree, and animal diversity, and they occupy moderate climates with a long growing season. These factors have made temperate forests attractive to generations of people for timber and hunting. Due to their location in temperate climates, cities and towns have grown up near temperate forests, so the trees have been accessible for logging. As towns expanded, the forests became fragmented, which worsened the conditions for the forest ecosystem.

Boreal forests, also called taiga, occupy the largest biome on the Earth's land surface and grow in the northern parts of North America, Europe, and Asia. These forests contain the following characteristics: cold climates with precipitation mainly as snow; sparse canopy that permits moderate light penetration; nutrient-poor soil; trees that are mainly cold-tolerant evergreen conifers; and animal diversity that may be greater than plant diversity. Though boreal forests occupy places remote from many urban centers, they have been severely reduced by centuries of logging and are in jeopardy of disappearing within a few generations.

Globalization of economic markets combined with population growth has put pressure on all the world's forests, but these things occur unevenly across the face of the globe. Because temperate forests occur near population centers, throughout history they have been cut down at a faster rate than the remote boreal forests. Regardless of how these forests have been accessed and harvested, temperate and boreal forests require the same dedicated protection as forests in the Tropics. Though local efforts can protect some tropical forests, temperate and boreal forests will likely need the oversight of governments and international organizations. These forests lie in industrialized countries where big businesses and government have often worked in close association. The international Food and Agriculture Organization of the United Nations (FAO) stated in its recent report State of the World's Forests 2007, 「 『What happens to forests' will be largely determined by 『what happens outside forests'.」 In other words, small local communities may no longer have the power to protect the remaining forests and the success or failure of conservation will rest with strong leadership.

Source of Information : Green Technology Conservation Protecting Our Plant Resources


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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