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At the end of 1996 the IUCN announced that 33,730 species of plant are threatened with extinction. Should we care?

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Introduction

At the end of 1996 the IUCN announced that 33,730 species of plant are threatened with extinction. Should we care? "In one of our religious books it is written that the tree is like ten sons. It gives ten valuable things: oxygen, water, energy, food, clothes, timber, medicinal herbs, fodder flowers and shade." (Chipko leader, Sunderlal Bahaguna) Plants are essential to life on earth. They have the unique ability to fix carbon and synthesise all the primary metabolites essential for biosynthesis; for example, the 20 amino acids necessary for life. About 4 million species on earth rely upon the 380,000 species of plant (consisting of 250,000 higher plants) for survival (Green Inheritance, 1984). This number is not certain - estimates have been as low as 345,000 for species already named and described (Cronquist, 1981) and as high as 630,000 for species described plus an estimate of still unnamed and undescribed species (Schultes, 1972; Tippo and Stern, 1977). As described by Bahaguna, plants provide for us in many ways. On 8th April 1998 a major twenty-year study by botanists and conservationists was made public: on a worldwide scale one in every 8 plant species is presently facing extinction. The United States is the statistical leader among nations that harbours whole strains of soon-to-be-obliterated plants. According to the World Conservation Union's Red List, nearly one in 3 plant species in the USA will soon no longer exist (of 16,108 species described). However, Dr. Pimm said he thought that the plight of plant life in the U.S. seems more grim than in other nations because those surveys made for the report were better conducted on American soil than elsewhere. Causes of extinction: There are several causes of extinction: loss of habitat; change in habitat quality; habitat fragmentation; persecution and exploitation of populations; and changes in the biotic environment (Global Biodiversity Assessment, 1995). Any loss of habit increases the risk of extinction of some species, so the loss of biodiversity cannot be minimised by a careful consideration of single species. ...read more.

Middle

Phytophora infestans was able to infect all potatoes, leading to the death of over one million people. Species in the wild have been used many times before, crossed with a domestic variety to produce an improved plant. The tomato plant of today (Lycopersicon esculentum) is a compilation of many plants: resistance to the fungus Fusarium oxysporum was obtained from L. pimpinellifolium; the genes used to adapt the fruit stalk for mechanical harvesting from L. cheesmanii; a more intense colour from L. chmielewskii; and finally increased beta carotene and vitamin C content (from L. hirsutum and L. peruvianum respectively). A wild species on the Galapagos islands can be crossed with a domestic tomato plant to convey salt resistance too (Green Inheritance, 1984). These modifications improve not only the aesthetic properties for the consumer, but also the nutritional value and even enabling plants to be grown in previously inhospitable soils. Since Haber designed the aptly named 'Haber process' to produce ammonia, fertilizer has been applied to crops to increase the yield. The unfortunate consequence of excessive application is eutrophication (once the fertilizer is washed into streams). There is a species of South American grass that can form a symbiotic relationship with nitrogen-fixing bacteria; if this property could be introduced into wheat, then fertilizer application would be reduced and the wheat could be grown on poorer soils (Plant Extinction, 1990). There are more than just those improvements mentioned above too. Some wild plants produce insecticides - these are secondary products which reduce a plant's palatability - approximately 400,000 plants produce them. The accumulation of alkaloids or saponins produces a repellant bitter taste; cyanogens are toxic, and neem oil affects the hormonal balance and life cycle of the attacking insect. Pyrethrin, extracted from Chrysanthemum cinerariifolium, is an especially effective insecticide. It is a member of the pyrethroids that is broken down by sunlight; it has a very specialised mechanism that penetrates the cell membrane of the insect, blocking open the sodium channels, which disrupts the nervous system - it is dependent on the principle that pyrethroids are more soluble in fats than water. ...read more.

Conclusion

states that "triage is both unworkable and misleading in its apparent common sense". It is obvious that the rate of extinction is hundreds of times higher than the natural background rate that prevailed, before the beginning of rapid human population growth (a few thousand years ago). This is the real reason why there are so many plants nearing extinction: due to pressure by population expansion on the land. If the population growth rate can be reduced, then maybe some plant preservation could take place. Many people see the expenditure of vast amounts of money on nature reserves to be inappropriate, especially when one considers that up to 95% of all plants are not near extinction. In addition, when there are so many famine related problems in the world, surely the most important task is to produce as much food as possible, and if a few plants become extinct along the way then it is an unfortunate consequence. The plants of the world are also extremely important to many countries' economies. The exportation of mahogany from Brazil is the second biggest industry in the country (mining being the first) - if the mahogany trees are not cut down to be sold then an economy crashes (but the eventual problem still remains that at the rate the trees are cut down, this is a finite source of income). Summary: As can be seen by my proportionately biased argument, there are many reasons why we "should care". "It is within the power of people, as intelligent beings, to modify their ways to avoid the unnecessary destruction of variety" - so much of the extinction of plant species is due to man, and his impact on nature. Mass extinction has occurred in the past of different species (eg the death of the dinosaurs), but this is situation is different: we have a choice about whether or not to save our 'green heritage' - the public needs to be made aware of the possibility that by 2050 up to 60,000 species may be extinct (IUCN, 1980)... "nothing stimulates interest and concern like scarcity. ...read more.

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