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 Vanishing SpeciesEarth's Worth: Page 3 The gross national product of a country is considered the major yardstick by which economic success is measured, and the natural world is traditionally valued in terms of the revenues it produces when exploited. This rigid and limited evaluation was recently examined and found lacking by a team of 13 ecologists, economists and geographers, who analyzed the monetary value of ecological systems to human society. They sought to place specific values on 17 types of environmental services that 11 ecosystems provide to humans each year (Stevens 1997b). Among these ecosystems were open oceans, estuaries, seagrass and algae beds, coral reefs, tropical and temperate forests, grasslands and rangelands, tidal marshes and mangroves, wetlands, lakes and rivers (Stevens 1997b).
In a report published in the scientific journal Nature, these specialists estimated the total global value of these ecosystems and their production at $16 trillion to $54 trillion per year, with $33 trillion the most likely figure; by contrast, the gross national product (all the goods and services produced by the world's peoples each year) was estimated at a mere $18 trillion (Stevens 1997b). They rated the value of nature's climate regulation at $684 billion, natural raw materials at $721 billion, pollination by natural pollinators at $117 billion, recreation and ecotourism provided by nature at $815 billion, soil retention and formation at $53 billion, water supply at $1.7 trillion, and food production at $1.4 trillion. Thus, ecosystems such as forests, which provide several of these ecological services, such as climate regulation, ecotourism, soil retention and water supply, are worth far more left standing than cut as lumber for short-term profit. Wildlife performs services as well, including natural pollination, attraction of ecotourism and recreation such as bird-watching, and others such as seed dispersal and soil enrichment. The linkages between particular ecosystems and local economies were systematically analyzed in this study; for example, the Louisiana shrimp catch depends on wetlands as nurseries, and these wetlands also provide flood control and other services in their overall value (Stevens 1997b).
If the costs of destroying these ecosystems were computed when development was considered, such as the loss in flood control and water pollution filtration by wetlands, the researchers concluded that society would be more likely to protect them from destruction. They pointed out that when a wetland is filled in for a shopping center, the dollar value of that habitat in preventing floods and cleansing water is not figured in, resulting in a gradual erosion of natural wealth (Stevens 1997b). The heavy rains that ravaged many parts of the world in 1997 and 1998, caused by El Nino's effect on the weather, produced floods and mudslides in areas where forests had been cut and wetlands filled. Hundreds of lives were lost, and property damage totaled billions of dollars. Areas with forest and extensive wetlands were hardly damaged. Some wetlands are being restored in the United States--river courses returned to natural curves, and flood plains protected from building, in the realization that the lost income from not developing these areas is more than compensated for by the protection from natural disaster they provide, which creates economic stability in developed areas located far from wetlands.
However important such economic analyses are in re-evaluating our destruction of ecosystems, preserving nature cannot be reduced to economic calculations. If this is the sole basis of conservation, it could lead to destructive manipulations in the environment designed to accommodate complex economic theories. The major lesson to be learned from these new ways of looking at Earth's use to humans is that we have grossly underestimated life-giving ecosystems and their wild fauna and flora. They have evolved over a period of millions of years, and we must respect and preserve them in as natural a state as possible.
Although people in the United States are far more aware of the ecological value of wetlands and forests, this seems to have had little effect on preserving such valuable ecosystems. Trees are still cleared on steep slopes and other fragile areas, for example. This causes landslides and mudslides and floods, resulting in destruction of homes, roads, farmland and other valuable assets, as well as siltation and pollution of waterways. Yet there is little thought given to banning this practice by law. 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 examined in this study resulted in a 25 to 30 percent reduction in potential economic growth (Stevens 1997b).
A 1997 collection of articles, Nature's Services: Societal Dependence on Natural Ecosystems (Island Press), edited by Dr. Gretchen C. Daily, a biologist at Stanford University, concludes that many ecosystems, once destroyed, are either irreplaceable or take thousands of years to replenish, such as ancient aquifers or old-growth forests. Daily concluded that we cannot afford to wait to act until we have disrupted the planet's life-support system beyond repair (Stevens 1997b). Some 20 scientists contributed to this book, including Dr. Norman Myers, author of many books on the value of wild plants to medicine and agriculture. He documented the multibillion-dollar insurance value that wild grains provide in disease resistance (Daily 1997). Katherine Ewel of the Forest Service discussed the lower cost of treating sewage in constructed wetlands, as compared to treatment plants, and Gary Nabhan and Stephen Buchmann found that wild pollinators save American farmers $1.6 billion annually (Daily 1997). This book's experts make a strong case for protecting environments in a natural state and provide evidence that we are only beginning to appreciate the complexity of these ecosystems. This can apply, for example, to commonly accepted mitigation rules used in US wetland-filling cases, in which a wetland is created for one that is destroyed. Ecologists consider that the natural wetland is far more complex and irreplaceable than the man-made one, and they should not be considered equal under the law.
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