Study: Almost half the world’s plants close to extinction
Australian Broadcasting Corporation
Researchers say the percentage of the world’s plants threatened with extinction is much larger than commonly believed and could be as high as 47 per cent if tropical species are included.
The study, published in the November issue of Science, challenges earlier research that estimated the number of species in danger of extinction was about 13 per cent.
Previous studies of extinct plants underestimated the numbers because they failed to include many plants growing in tropical countries such as Ecuador and Colombia.
Plants are becoming extinct for many reasons, including global warming and human encroachment into area habitats, a researcher at the US Missouri Botanical Gardens, Peter Jorgensen said, who co-authored the new study.
For example, scientists discovered a single collection of the passion flower, a light purple flower found only in southern Ecuador, during the 1970s, Mr Jorgensen said.
But recent trips to the region have found the species has since disappeared.
Mr Jorgensen reviewed data from 189 countries and territories and determined between 310,000 and 422,000 plants, or 22 to 47 per cent, could be threatened.
In previous studies “if you can’t evaluate a species you basically don’t include it,” Mr Jorgensen said.
“Still, we don’t know enough … to go out and do something active on the ground to save them.
“Just because there are more of them doesn’t mean it’s easier.”
Identifying threatened species is a crucial step toward developing better management plans to protect them, but Mr Jorgensen conceded it will take a large amount of money to develop such projects.
Maintaining a global database of threatened plants would cost an estimated $US12.1 million annually, the researchers said.
The vast majority of plants that are threatened in tropical areas are those located with a wide variety of plant life or where habitat loss is rapidly occurring.
As a model for their research, Mr Jorgensen and his co-author, Nigel Pitman from US Duke University, analysed more than 4,000 species native to Ecuador.
After sifting through data and determining those that could be on the verge of extinction, such as plants with small populations or which are located only in a small geographical area, they determined that 83 per cent of all plants in the country are threatened.
Mr Jorgensen said the findings for Ecuador are important because the country has one of the most complete databases of plant species.
Such results also can be applied to neighboring countries such as Peru and Colombia where data are scarce.
“We know so little about plants in tropical regions and what really bothers me is we have to guess so much because we don’t have enough manpower to go through all the countries,” Mr Jorgensen said.
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Posted by: Paul on October 31, 2002 at 19:42:17