ENHS Nature Trails Mar 99 Article 2

Natural History and You - The President's Forum
by Nathan Tublitz

Global Biodiversity: Much ado about nothing or for whom the bell tolls?

"If a species goes extinct every 23 seconds, certainly a new species must evolve every 23 seconds" (Lynn Snodgrass, Speaker of the House, Oregon House of Representatives)

My 10 year old son's 5th grade class put on an "ecological conference" last week. At the "conference" students played the roles of fishermen (wore plastic bibs and rain coats), city dwellers (ties and jackets or dresses), scientists (white beards and white lab coats), and construction workers (jeans and work shirts). The goal of the "conference" was to debate the effect of humans on other species, focusing on the pacific salmon. These 5th graders easily grasped the concept of a biological species, a population of organisms that look alike and that produce offspring that are like themselves, and moved on to discussing weightier issues. The debate quickly focused on one issue: the fact that number of species on earth are diminishing and how to stop that decline.

Lynn Snodgrass aside, there is no doubt that the number of species worldwide are decreasing. The current debate both in political and biological circles revolves around the number of species alive on our precious Earth and the rate of their decline. To date about 1.5 million living species have been identified. Of these, approximately 2.5% (41,000 species) are vertebrates, 55% (800,000) are insects, and 17% (250,000) are plants (vascular plants and bryophytes). The rest are an incredible assemblage of various invertebrates, microorganisms, fungi and algae. But how many living species are not yet identified?

An accurate estimate of number of species on earth continues to be frustratingly elusive to those few biologists who have tried to tackle this problem. It isn't like counting the pennies in your pocket since we don't have any idea many there are. Biologists have therefore had to estimate species numbers based on various measurement schemes. But what to measure? One biological tenet is that the absolute number of species per unit area (hectare, acre, square kilometer, etc) increases as one approaches the equator. The best known example of species diversity in an ecosystem is that of tropical rain forests. As a result, most studies have focused on counting tropical species. However that is clearly problematic since it is humanly impossible to count all species in any tropical ecosystem since most are present in relatively low numbers and many occur only seasonally. Moreover some species are localized to only a subarea of an ecosystem, for example some birds and mammals are only found in the upper canopy of the rainforest. Even if a reasonable estimate of the number of species in the tropical rainforest was possible, it would be near impossible to use that number as a basis for estimating species numbers in other poorly explored habitats such as coral reefs, the floor of the deep ocean, the soil of tropical forests, deserts, and tropical savannahs. It is truly a daunting task.

Despite these impediments, some biologists have taken up this gauntlet and have generated estimates of world wide species numbers ranging from 5 million to over 30 million! Assuming an intermediate figure of 15 million species, we have only identified a measly 16% of the species on our planet. Unfortunately we had better work fast since, based on the quote by House Speaker Snodgrass, we are losing over 1 million species a year! Even if that is an overestimate, it is probably not off by more than a factor of 10 and that number is still grossly unacceptable. Sadly, much more lip service than research money is going towards this issue.

Although the evidence is fairly overwhelming, politicians seem to think that the world wide species decline, like global warming, is still debatable and thus not worthy of any effort. The parallels between this and the smoking-causes-cancer debate are striking in both the one-sidedness of the data (all pointing to a decline in worldwide species number) and the unwillingness of politicians to find solutions to the problem. What are we to do?

Well, perhaps politicians are just too old and can't adjust to new situations. Maybe we need younger politicians with a fresh new viewpoint. After all, the students in my son's 5th grade class found two solutions within 5 minutes of discussing this in their conference: don't build in ecologically sensitive areas and reduce human population growth. Too bad 5th graders can't run for political office. Or that their elders won't listen to them. We'd be much better off either way.

N.B. This month's speaker, Dr. P.J. DeVries, is one of the world's true authorities on species numbers in the tropics. And a great lecturer to boot. Don't miss this if you are interested in this subject.

Nathan Tublitz

[ Back ]

Page last modified: 28 March 1999
Location: http://biology.uoregon.edu/enhs/archive/mar99/mar992.html
E-mail the WebSpinner: aloysius@gladstone.uoregon.edu