Earth in middle of sixth mass extinction, half of its species could be wiped out by 2100

November 14th, 2007 - 8:33 am ICT by admin  
Many scientists now argue that the Earth is in the middle of the sixth mass extinction in the history of life. Some estimates suggest that as much as 50 percent of all known species could be extinct by the end of this century.

According to an international team of scientists, new analysis shows plant communities as being composed of both stars and supporting players.

Some plants are so productive that they dominate the productivity of natural habitats. Supporting species complement key players and enhance the productivity of plant communities even further.

Lead authors of the study - Michel Loreau of McGill University in Montreal and Andy Hector, an assistant professor at the University of Zurich - further go on to say that species extinction is one of the most pronounced environmental changes of our time.

“Our analyses provide the most comprehensive evidence yet that natural habitats with a greater variety of plant species are more productive. Our analyses show that diverse communities are more productive because plants are ‘complementary’ in how they use biological resources. In other words, different plant species play unique roles in the environment,” said Loreau.

Assistant Professor Hector said: “The results of our analyses suggest that plant communities operate much like a soccer team. Teams are composed of both star players and supporting players. You probably can’t win many games if you lose your top striker because she or he is the most productive player and can dominate a game. But strikers cannot win games by themselves. They need great passes from supporting players and solid goal-tending if the team is going to be successful as a whole.”

“The process by which plants grow and produce more plant biomass is one of the most fundamental biological processes on the planet,” added Bradley Cardinale, assistant professor of biology at the University of California, Santa Barbara.

Plant productivity regulates the ability of nature to take greenhouse gases like carbon dioxide out of the atmosphere, as well as the ability of habitats to produce oxygen, food, fibre, and bio-fuels, according to the authors of the study.

“Therefore, species extinctions could compromise the benefits that nature provides to society,” said Cardinale.

The study summarized the results of 44 experiments from around the world that simulated plant species extinction and showed that ecosystems with fewer species produce up to 50 percent less plant biomass than those with more “natural” levels of diversity.

The article is to appear in the online issue of the Proceedings of the National Academy of Sciences. (ANI)

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