Biodiversity


Biodiversity is measured by the number of species present in a system [1]. It is not accurately quantified because we have discovered only 1.5-1.8 million species, less than half of the total estimated amount of between 3.6-100 million ([1], p. 14). Most of the undiscovered species are small in size, but even rare large mammals are still occasionally discovered in remote localities. The factors that cause loss of biodiversity (extinction of species) are summarized by the acronym HIPPO (p. 50): Habitat destruction, Invasive species, Pollution, Population, and Overharvesting. The driving force for most modern extinctions is human population growth, which directly leads to the leading cause of extinction, habitat destruction. The near extinction of the Vancouver Island marmot is a result of clear cutting of forest to harvest timber; humans either wipe out species’ habitats during the process of extraction of natural resources (in this case, timber) or occupy the land, killing or displacing species from their ecosystem.

Arguments supporting conservation of biodiversity:

· Ecosystems become less robust as component species become extinct, and therefore less effective at cleaning our air and water and enriching our soil.

· The current extinction rate is 100 to 1000 times higher than before man. Previous mass extinctions show that evolution requires ~10 million years to restore diversity to predisaster levels. Thus, our descendants will suffer.

· Once a species goes extinct, it is lost forever. With each lost species, we lose valuable scientific information and potential products including life-saving pharmaceuticals.

We can preserve a small number of species in zoos, but we cannot preserve most small species that are vital parts of ecosystems. Moreover, like species, once an ecosystem is gone, it is lost forever (even if we develop the technology to replicate entire ecosystems far in the future, the space will not be available).

I have personally witnessed the frailty of ecosystems, and the devastating feeling of loss at their passing. When I was a child, my family would vacation on the east coast of southern Florida, in West Palm Beach. Up until the early 1970’s there was a beautiful coral reef in Phipps Park. We would return each year to skin dive, and the incredible diversity of marine life fascinated me. Those experiences convinced me at an early age to become a scientist. However, the last year we went to Phipps Beach, about 1973, the entire reef was dead. All of the fish, eels, and urchins were gone, and the sand on the beachfront had washed away, exposing the dead reef. The reef was subareal in places, which I had never seen before. I couldn’t believe how one year could change paradise into a wasteland. I questioned people on the beach, and learned that during the previous year the anglers had started to catch parrotfish because they found them to be tasty. My theory was that overfishing removed one of the critical components of the reef ecosystem. Parrotfish graze on coral reefs, nibbling the reef down to keep it below the waterline, passing the hard parts through their digestive systems, and then excreting sand-sized particles. Without the parrotfish, the reef grew above the waterline and died, and without a living reef the entire ecosystem collapsed. This type of “domino effect” has been observed in many ecosystems, although in general ecosystems are more robust, and can survive the loss of multiple species or experience multiple forms of degradation before the completely collapse.

In his book “The Future of Life”, E.O. Wilson is most interested in small species including insects and microorganisms (his research specialty is ants). In terms of number of individuals, number of species, and even biomass, these are the dominant animal groups on earth; large mammals are relatively insignificant. Each species is a product of billions of years of evolution, and microorganisms hold a wealth of genetic information, yet we are unaware of the existence of most species. “Among the multicellular organisms of Earth in all environments, the smallest species are also the least known” ([1], p. 15). Many may prove to be invaluable as sources of medicines or for bioengineering, but only if we discover and study them before they go extinct. Some have unique properties that enable them to live in extreme environments of high or low temperature, pressure, and salinity. These organisms are being intensively studied because they may yield insights into the origin of life on earth and possibly other planets. Small organisms lie at or near the base of the food chain, and if enough of them go extinct the entire ecosystem could crumble, and biodiversity would plummet. Also, since life regulates the environment to keep it livable (the concept of Gaia) then extinction of these species may make the earth uninhabitable for us.

Wilson views human beings as a part of nature; we cannot be separated from it because it is part of us. Our ancestors evolved in the environment over millions of years; we are happiest when we are in the same environment occupied by our ancestors (e.g., in a savannah). Because of our brains and the energy we obtain from fossil fuels, we have the power to destroy nature; we have already destroyed a large percentage of natural habitats and caused the extinctions of many species. However our brains also give us the ability to consider our choices, and we could choose to dedicate some of our resources to preserving ecosystems. We have the power to save nature because we know what factors cause species to become extinct (HIPPO) and we have a plan to reduce or eliminate those factors at a relatively low economic cost ([1], Chpt. 7). However, if we don’t take action soon, we may pass the “point of no return” and become unable to save nature. This may make life difficult or impossible for us, as nature is our “life support system”.

Wilson advocates the purchase by non-Governmental Organizations (NGO’s) of large undeveloped contiguous tracts of land in areas that have high biodiversity and set them aside as reserves in an effort to preserve as many species as possible. The global “hotspots” that are a high priority to purchase are at risk and have high concentrations of species ([1], p. 160). Scientific considerations dictate that each reserve should be large in area because the number of species a reserve can support is roughly proportional to the fourth root of its area ([1], p. 58); also, large size makes them less vulnerable to human activities and invasion of alien species ([1], pg. 177). The reserves should be implemented in three steps to maximize their effectiveness ([1], pp. 177-8): 1) creation of reserves, 2) restoration by reclaiming developed land to enlarge reserves, and 3) connect reserves using large natural corridors. Other elements of the plan ([1], pp. 161-4) include preserving existing frontier forests, ceasing all logging of old-growth forests, protecting freshwater and marine ecosystems, continuing scientific and mapping studies of species and ecosystems, using biodiversity to improve health and make money, and supporting population planning to reduce the rate of increase of human population. Together these changes will help reduce the negative impacts represented by the letters in “HIPPO”. The plan is economically feasible because the total cost of $30 billion is only 1/1000 of the current annual world domestic product. It is politically feasible because it relies on NGO’s and private donations.

One of the arguments against Wilson’s plan is that it is just another example of wealthy developed countries using their money to steal land from poor countries. How can Wilson’s plan be made attractive to the governments and citizens of developing countries, and how could it actually benefit them? To understand how people in developing countries will react to conservation proposals proposed by citizens of developed countries, we have to put ourselves in their position. They will ask “why should we agree to the demands of the U.S. to limit our economic activities and preserve our natural areas for the global good when the U.S. has already become rich by plundering their own?” The U.S. must accept that other countries will not agree to make sacrifices if the U.S. does not make some of its own.

In general, people in developing countries want to raise their standard of living, and land is usually essential to accomplish that goal. They will resent the purchase of land in their countries by foreign concerns unless they actually profit, not just in the short term by a lump sum payment, but in the long term. Conservation must be made profitable for native peoples, perhaps by promoting ecotourism or by identifying or growing plants for pharmaceuticals. Once the native people recognize that the preserved land is a long-term source of income, they will be motivated to protect the land. Involving natives in the process of making decisions that affect the reserve, and guaranteeing that the reserve will be a source of jobs and income, gives natives a stake in conservation.

1. Wilson, E.O., The Future of Life. 2002: Knopf.

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About johncayers

John C. Ayers is a Professor of Earth and Environmental Sciences at Vanderbilt University. As a geochemist he specializes in sustainability and also the chemistry of natural waters. He has been PI on 5 and co-Pi on 2 grants from the National Science Foundation, and has a publication h-index of 14. He has been Associate editor of American Mineralogist and Geochemical Transactions of the American Chemical Society, and does GIS consulting for the ERS group. He is currently writing a book titled " Sustainability: The Problems of Peak Oil, Global Climate Change, and Environmental Degradation."
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