Endangered Species Handbook

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Benefits of Forests

     The great beauty and inspirational qualities of forests belie their important biological tasks.  By producing vast amounts of oxygen and water vapor, and absorbing carbon dioxide, they help support all life on Earth.  A single mature oak tree produces enough oxygen to keep eight people alive for a year.  In 1995, an international team of ecologists working in Brazil documented that each hectare (2.47 acres) of undisturbed tropical rainforests absorbs 1 ton of carbon dioxide per year.  The world's rainforests are thus absorbing a billion tons of carbon dioxide a year, one-sixth the amount produced by burning fossil fuels such as oil and coal, according to the National Oceanic and Atmospheric Administration (NOAA).  Cutting and burning of forests around the world releases carbon dioxide into the air.  The high levels of carbon dioxide in the world's atmosphere have caused increases in average global temperatures.  The value of tropical forests in trapping carbon dioxide is so significant that four US utility companies have sponsored a pilot program in Belize to protect large areas of forest and plant trees; energy companies will contribute $2.6 million to a 120,000-acre reserve that will absorb 5.2 million tons of carbon dioxide gas over 40 years (Geatz 1996).  The Clean Air Act allows such "pollution credits" to compensate for pollution released elsewhere.  In 2000, the US government proposed a massive program of tree planting and protection of forests to compensate for the effects of global warming caused by the release of carbon dioxide and other pollutants. 
     The cooling effect of forests results from leaf transpiration generating moisture that rises to the atmosphere, forming clouds which release water as rain or other precipitation.  When forests are cut, the climate dries as rainfall decreases and soils lose moisture.  Tree roots absorb about one‑half of the rain that falls, releasing the water gradually during the year (Schreiber et al. 1989).  In countries with wet and dry seasons, water retention by trees makes the difference between deadly floods that kill thousands of people and sweep away their homes and precious topsoil, and river levels that remain stable, preserving soil and the environment.  Forests stabilize the soil, preventing erosion and landslides and allowing streams and rivers to flow clear.
     The leaves, bark and wood of trees have been found to contain hundreds of compounds valuable to medicine and industry.  Forests produce a wealth of useful species:  oils, gums, resins, tannins, waxes, edible oils, dyes, cosmetics, spices, fruits, nuts and life‑saving compounds used in medicine.  Spices alone are worth more than $1 billion per year (Schreiber et al. 1989).  Medications derived from wild plants are worth $40 billion annually (Lean and Hinrichsen 1994).  Painkillers, birth‑control agents and malaria drugs, as well as quinine, digitalis and morphine, are all derived from tropical forest plants.  According to one study, more than 40 percent of all prescriptions in the United States still depend on natural plant sources (Swaminathan 1990).  Only a small percentage of wild plants have been tested for medicinal value.  In some cases, plants that might have disappeared altogether were found to be medical treasures.  The Madagascar periwinkle, native to an island which has lost 80 percent of its forests to deforestation, has been the source of two potent compounds that have proven effective in the treatment of Hodgkin's disease and produce a 99 percent remission in patients with acute lymphocytic leukemia (Myers 1983).  Global sales of these two drugs now exceed $180 million a year (Wilson 1992).  Taxol, a compound from the Pacific Yew found in the last of North America's old-growth forests, has proven effective against ovarian and other cancers.
     In the long run, forests left standing are of greater benefit than those cut and destroyed.  The dollar value of natural ecological systems, of which forests make up a large part, in performing services for human society has been estimated at as much as $54 trillion, as seen in Chapter 1 ("Earth's Worth" section).  Along with their role in flood prevention and climate regulation, forests provide fruits and flowers to be pollinated by wild insects and birds, and clear rivers as habitat for valuable salmon and trout fisheries (Stevens 1997b).  The World Resources Institute in Washington, DC, has calculated that the loss of value from deforestation is four times as high as the value of the timber extracted and the depletion of soils, forests and fisheries amounted to an average reduction of 25 to 30 percent in potential economic growth (Stevens 1997b).
     The ways in which forests function are only beginning to be understood.  Great fig trees are dependent on tiny wasps to complete their reproduction, and fungi in the roots of trees play intrinsic roles in their survival.  Pollinators are key to the health of forests, but for many species of trees and plants, only fragmentary information has been acquired about how they are pollinated and the conservation status of these pollinators.  Understanding the interrelationships of plants and animals within these ecosystems is key to their preservation, yet forest ecology is in its infancy.  
     While logic would seem to mandate that such awesome and useful ecosystems be accorded great respect and legal protection, the opposite is true.  They are being destroyed so rapidly by logging, dams, climatic changes caused by human activity, and pollution that the last pristine forests may soon be gone.  Even minor alterations in their environments have interfered with their healthy functioning.
     Cutting forests for financial gain or to resettle people from overpopulated cities provides developing countries with short-term solutions to problems and one-time profits.  Neither the extremely important ecological roles that forests play, nor their value as species storehouses, are appreciated by the majority of the world's nations.  The recent spate of massive landslides and floods after periods of heavy rains in countries around the world has, in most cases, been traced to logging that left hillsides and entire regions open to erosion.  Millions of people have been left homeless around the world in recent years, and thousands have lost their lives to such floods.  These floods may be only a prelude to far more serious and long-lasting consequences of forest destruction.  Global warming will increase as forests vanish, especially with the cutting of old-growth trees, which have immense canopies for absorbing carbon dioxide and cooling the atmosphere.  Higher temperatures have already brought droughts, increased desertification and caused rivers and streams to lose volume and even dry up.  The loss of potential disease cures is another byproduct of destroying forests, and the destruction of these beautiful environments, with their multitude of life forms, may result in collapsed ecosystems that cannot be restored.

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