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

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