After Deforestation And The Future

After deforestation, the way the land is managed has important implications toward the land's future health—not only the soil and vegetation but also the life that inhabits the ecosystem. In a tropical rain forest, almost all of the nutrients are located in the plants and trees, not the soil. In the temperate and boreal forests, the opposite is true.

In tropical rain forests, when the trees are cut down in order to convert the land use to agriculture, farmers often burn the tree trunks to release the nutrients from the trees into the soil to grow the crops—a process called "slash and burn" agriculture. Over time, however, rain washes the nutrients from the soil, leaving the land infertile after a few years. At this point, the farmer finds a new plot of land to clear the forest from and starts over, abandoning the prior disturbed area. Unfortunately, rejuvenation of the forest is extremely slow because of the soil's lack of nutrients. It typically takes about 50 years for the forested area to grow back.

According to experts at Michigan State University in their rain forest research program, other types of farming are even worse for forest regrowth. Intensive agricultural systems such as plantations that use a lot of chemicals and fertilizers, kill animals, change the water balance, and weaken entire ecosystems, causing regrowth to take centuries.

Commercial logging is also a problem. Using a method called selective logging, where only selected trees are cut may seem nonintrusive, but because heavy machinery is used, many additional trees are damaged in the process. In a study conducted in Indonesia by Andrew Johns with Michigan State University and the NASA Earth Science Information Partners (ESIP), in an area where only 3 percent of the trees were logged, the logging operation actually damaged 49 percent of the trees in the forest. The positive side of selective logging, however, is that forest regeneration is much more rapid because there are still enough trees left to provide seeds and protect young trees from too much intense sunlight.

Logging using the clear-cutting method is much more damaging because all the trees are cut down, leaving the ground bare. Because even the tree trunks are removed, there are no nutrients left behind. These areas are so infertile, scientists do not know how long it will take for them to regenerate or if they even can. The following table illustrates the various types of tropical deforestation and the regrowth times associated with them.

A positive factor for temperate and boreal forests is that most of them are located in developed countries and are already well managed. One of the future impacts, however, that needs to be considered is the impact to, and adaptation of, wildlife to climate change. According to a study in National Geographic News on April 12, 2006, global warming could threaten up to one-fourth of the Earth's plant and vertebrate animal species with extinction by 2050. The study analyzed 25 biodiversity "hot spots" worldwide, such as the Floristic Region in the South African Cape, the Caribbean Basin, and the tropical regions of the Andes.

Methods of Tropical Deforestation




Slash and Burn Agriculture

Abandoned rapidly

Less than 50 years

Perennial Shade Agriculture

Some trees left

20 years

Intensive Agriculture (Banana Plantation)

Many pesticides, alteration of hydrology

More than 50 years

Cattle Pasture

Degradation of soils

More than 50 years

Selective Logging

Few trees cut

Less than 50 years

Clear-cut Logging

No trees or nutrients

More than 50 years

Source: ESIP

Wildlife habitat will be negatively affected as global warming continues, causing forests to migrate. If species cannot adapt to ecosystem changes, they face extinction. (NPS)

According to the study's lead scientist, Jay Malcolm of the University of Toronto, "These hot spots are the crown jewels of the planet's biodiversity. Unless we get our act together soon, we're looking at committing ourselves to this kind of thing."

The study was based on the assumption that CO2 levels would double (as they are expected to do by 2100) and that temperatures would rise. The study projected that in the 25 hot spot regions, potentially 56,000 plant and 3,700 animal species could become extinct. Another independent study, conducted in 2004 by scientists from Conservation International, obtained similar results. They projected the possibility that more than a million species could be at risk of extinction by 2050.

According to Stuart Pimm, a Duke University expert in biodiversity and extinctions, "Species living in ecological hot spots are at particular risk when their environments change. That's where the most vulnerable species are, because they have the smallest geographical ranges. Species living high on tropical mountainsides, for example, have nowhere to go if temperatures warm their home turf. In South Africa's Cape Floristic

Region, located on the continent's southern tip, species are unable to migrate to lower latitudes to escape the rising temperatures."

Other experts warn that it is not just the "hot spots" that face imminent extinction risk. Terry Root of Stanford University's Center for Environmental Science and Policy says, "Many species are indeed struggling to hold on in locations all over the globe, not just in hot spots. This is not some activity that will be occurring "overseas." The likely extirpations and extinctions will also be occurring within a couple hundred miles of all of our back yards."

Based on a report in LiveScience on June 21, 2005, global warming is already changing animal habitats. According to Terry Root, "As humans argue about thermometer readings, animals are providing evidence that should be figured into scientific and political decisions. Animals are just reacting to what's going on out there. And if their behavior is very similar to what we expect with what's going on with global warming, we can use that information to support what the thermometers are showing."

The future will require solutions that will address multiple issues simultaneously—those involving timber and nontimber forest resources, wildlife, economic issues, human resources and living conditions, water quality, and other environmental concerns.

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