Plant Extinctions Reduce Ecosystem Productivity

As plant species go extinct, natural habitats will have less greenery overall, a new study suggests, which could allow more heat-trapping carbon-dioxide to remain in the atmosphere.

The study, detailed in the Nov. 5 online issue of the journal Proceedings of the National Academy of Sciences, summarized the results of 44 experiments from around the world that simulated plant species extinction in ecosystems. The results showed that ecosystems with fewer plant species produced up to 50 percent less plant biomass than those with more natural levels of plant diversity.

You might think extinctions would just mean other plants would take over and fill in the gaps, but that is not the case, the scientists found.

"Our analyses provide the most comprehensive evidence yet that natural habitats with a greater variety of plant species are more productive," said study co-author Michel Loreau of McGill University in Montreal. "This occurs partly because diverse communities are more likely to contain highly productive species. But even more important, 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"

Some species act as the major producers of the ecosystem, the researchers say, but others play supporting roles that are key to the productivity of the plant community as a whole.

Loss of plant species also can have an impact outside an ecosystem, as photosynthesis is a key method for sopping up extra carbon dioxide in the atmosphere. If plant productivity decreases, that also means that less oxygen, food, fiber and biofuels will be naturally produced, the authors say.

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