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World's Biodiversity Becoming Extinct at Levels Rivalling Earth's Past "Mass Extinctions"

Volume 3 Number 3 - December 1999

Dr Peter Raven

Report of the paper "Plants in Peril: What Should We Do?" given by Dr Peter Raven, Director, Missouri Botanical Garden, St. Louis, U.S.A. and President of the XVI International Botanical Congress at the XVI International Botanical Congress in August, 1999 hosted by the Missouri Botanical Garden.

Over the past several centuries, the documented extinction rates of a wide range of well-known groups of organisms are several times higher than the background rate or rate at which species have been becoming extinct for the past 65 million years, since the major extinction event that closed the Cretaceous Period and the Mesozoic Era, which coincided with the loss of the last surviving dinosaurs. This was the fifth major extinction event in Earth history, a time when two-thirds of all terrestrial organisms that lived at that time disappeared and the character of life changed permanently. The current extinction rate is now approaching 1,000 times the background rate and may climb to 10,000 times the background rate during the next century, if present trends continue. According to the paper, species loss can be estimated even when the members of many groups of organisms are relatively poorly known because of the logarithmic relationship between species number and the area in which they live. On the average, a tenfold increase in area is correlated with a doubling in species number, and a tenfold decrease with a halving of the original number. Given the relationship between species number and area, one can determine the number of species that will survive in a given area. Fragments of a given habitat that have been reduced in size lose half of the species they are going to lose in about 50 years; three-quarters of them in a century.

The paper states that if current trends continue, and we retain just five percent of tropical forests in protected areas, which will be true within 50 years at present rates of destruction (and sooner if these rates are accelerated), then extinction rates will be three or four orders of magnitude higher than those prevailing between mass extinctions. At this rate, one-third to two-thirds of all species of plants, animals, and other organisms would be lost during the second half of the next century, a loss that would easily equal those of past extinctions.

The paper states that vast numbers of unknown plants, animals, and other organisms are currently being lost before they've been recognized. Only about 1.6 million organisms out of a conservative estimate of between seven and ten million have been recognized scientifically. A great majority of these are poorly known, often from a single specimen, a brief description, a locality, nothing more, according to the paper. Some 250,000 of 300,000 species of plants have been identified, leaving some 50,000 completely unknown.

The extreme depletion of genetic variation in individual plant species causes them to become more vulnerable to extinction, according to the paper. Genetically diverse traits in plants can often enable them to grow in harsher environments, for example, or survive the competition with weedy species. About 30 percent of the world's 300,000 plant species are in cultivation now, "which provides a good start for conservation," according to Raven.

The paper outlines a seven-point plan to slow the extinction rates of plants around the world. It suggests that a major United Nations-sponsored conference on this topic could move these steps into country-by-country actions.

"All plants are important in one way or another and this comprehensive plan seeks to save them all - a priceless gift to future generations," said Raven.

1. Establish a new coordinating body - presumably connected with the United Nations directly or through one of its constituent organizations - to monitor the status of plants throughout the world, detect those most in danger, and take steps to conserve them. "There are a number of organizations working effectively in plant conservation now that could benefit greatly from the kind of overall international coordination that such a global body could provide," said Raven. "These organizations include, but are not limited to, Botanic Gardens Conservation International and the Plant Conservation Program of the World Conservation Union's Species Survival Commission."

2. Increase financial support for the study of plants throughout the world both by strengthening the major museums and other institutions that have holdings of specimens and literature on plants and by capacity building in developing countries with scarce resources. Currently, 80 percent of the world's scientists live in industrialized countries, which have about 20 percent of the world's population and only 20 percent of the world's biodiversity.

"Nations will only preserve biodiversity if they have their own institutions and their own scientists to make recommendations about what's best for them," said Raven.

The paper calls for the Convention on Biological Diversity (CBD) and the Global Environment Facility (GEF) to step up their efforts train scientists.

3. Make information on plants - now only available in herbarium, arboreta, seed banks, universities, and botanical gardens - accessible on the Internet to people throughout the world, especially to the poor "who truly need it."

"Although this expenditure may seem high, we are living in an era when our great-grandchildren may live in a world in which more than half of the plant species that exist now will be known only as specimens," said Raven.

4. Place more emphasis on alien-introduced plants and animals as a major cause of biodiversity losses. Studies of aliens and of the ways of controlling them should be taken into account in evaluating the status of species in nature.

5. At the national level in every country around the world, maintain an active census of the condition of the country's plants, so that it will always be obvious which are well protected in nature - or so abundant so as not to cause concern - and those that are rare and endangered.

6. Place special attention on conserving medicinal plants, important for the livelihood of a great majority of the world's population.

7. Internationally fund an ongoing program of research on plant population biology and reproductive characteristics, generally, so that these areas can be understood properly and used as part of the world's overall preservation scheme.

The paper was taken from the Biodiversity Action Network (BIONET) information services. For further information contact Stas Burgiel, Biodiversity Action Network (BIONET), E-mail:, Internet: