Extinctions could cut plant productivity in half
Friday, November 9, 2007 | 09:52 AM ET
by Eve Savory, CBCNews.ca
In a study that has startled even its authors, scientists have concluded that the extinction of plant species can reduce an ecosystem’s ability to support life by up to fifty percent.
It’s called "productivity" and what a plant produces is essential to life on earth: oxygen. That’s not all. Plants produce food in crops, fibre in trees, clean water, and biofuels. And they suck the greenhouse gas carbon dioxide out of the atmosphere.
"Nature does things that support humanity that allow us to exist", says Bradley Cardinale, the lead author. "The erosion of all those services is going to come back to bite us."
In the study, published this week in the Proceedings of the National Academy of Sciences, the international group of researchers looked at 44 studies that had simulated species extinction in grasslands, estuaries and the tundra. What they found was that even if the dominant species survived, the ecosystem as a whole did its’ job less efficiently.
Michel Loreau of McGill University said "diverse communities are more productive because plants are ‘complementary’ in how they use biological resources. In other words, different plant species play unique roles." The scientists say it’s like soccer. To succeed, the star needs her supporting players. Translate that into an ecosystem, and it means the plant species that survive produce less biomass, or plant matter.
"We’re talking about looking out into a forest or a grassland or any sort of natural habitat and there being fifty percent less plant matter - you know, half. Half of all the plant life." says Cardinale, a biologist at the University of California at San Diego.
The unhappy equation: Fewer distinct species = Less biomass = Less oxygen, fibre, and food. And less carbon dioxide being scoured from the atmosphere.
The rate of extinction is so fast, researchers estimate half of all species will be gone by the end of this century. But until now many scientists, including Cardinale, have argued that as long as the dominant species – the great fish, the Douglas fir – can be managed, the ecosystems would thrive and be productive. Oxygen would not decline, and there would be no increase in carbon dioxide in the atmosphere.
No longer. What’s more, the group is convinced a fifty percent loss of productivity is not a threshold. "It’s going to prove much, much greater than that when we let these studies run out their full course", says Cardinale. While a few years is fine to understand a grassland, it could take a century to see the full impact of species loss in a forest.
He believes the findings represent a general rule: that as the supporting species in any ecosystem from ocean to forest decline, so will the productivity of the planet. "This can’t be ignored", he says. "We are in a period of catastrophic change. Whether or not that matters for humanity, I think is still a question. Our study is suggesting that maybe it does."
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Comments
D. Shyry
AB
And Canadians have elected a shrub (little bush) who sees slashing funding for environmental groups and objectives as his dictatorial prime directive. Unless citizens get serious about the environment, and elect representatives that ACTIVELY support conservation, instead of contributing to increased CO2 in the atmosphere by POSTURING conservation, there will be no hope for the next generations. Collectively we need a swift crack to the head to shake us out of our comfortable delirium.
Posted November 12, 2007 08:43 AM
Bill Royds
Ottawa
What this report should do is wake up legislators about the real monetary losses from loss of natural areas.
The cost to a developer of clearing vegated land should be hundreds of thousands of dollars a hectare, rather than being tax supported(new infrastructure for sprawl is provided by taxes), as it is now.
Too often, destruction of greenspace is allowed because one can "mitigate" the loss of one or two species. This report show that mitigation is wrong. Preservation is the only real solution.
Posted November 12, 2007 10:38 AM
Jamie Laidlaw
Ottawa
A masterful article that tells us that mutuality and common objectives serve individual interests the best. Let us concentrate on moving these essential insights up the system to our own decision makers and insist on implementation with care.
Posted November 12, 2007 11:07 AM
Violet Caibaiosai
Burlington
In that Indigenous Peoples in Canada have lived within this environment since their beginning, and been speaking out about these environmental issues for years, it would be great if their Indigenous knowledge could be used toward the care and rejuvenation of these, our non-human relatives.
Posted November 12, 2007 08:39 PM
Garet
Winnipeg
There is a glaring problem with this, being that we have more trees in north america than ever in almost 100 years.
I wonder how much this guy was paid to "scientifically" prove that we need air to live, and less air is bad.
Posted November 13, 2007 09:06 AM
Margaret Johnson
Chesterville
I think new products must be more careful. In great ignorance we sprayed our apple trees with D.D.T. My blood sample shows chemicals and I have breathing problems. I know that we lost all our BLue Birds after the first year of spraying.
Posted November 13, 2007 05:55 PM
Garet
Winnipeg
We go with what science we have, Margaret. Not even 30 years ago, scientists were convinced that emissions from cars was causing global COOLING. Even now, everyone with an agenda is making global warming out to be the end of the world.
Posted November 14, 2007 02:16 PM