If we want to keep the benefits we get from the world’s plants — oxygen, food and fiber, for instance — we might consider seriously stepping up the conservation efforts, according to a new study. An analysis conducted by an international team of scientists found that as plant species continue to go extinct, total plant productivity in those areas decreases.
“It’s really about the number of species,” said Bradley Cardinale, assistant professor of biology at UCSB and lead author of the paper, which appeared last week in the online issue of the Proceedings of the National Academy of Sciences.
By studying the results of 44 experiments from around the world which simulated plant species extinction the researchers found that ecosystems with decreased biodiversity produced up to 50 percent less plant biomass than ecosystems with more natural levels of diversity.
Not only would more diverse plants communities be more likely to have highly productive species, but more importantly, the researchers say, the more diverse communities have species that complement each other in the way they behave in their environment.
It helps to think about it the way co-author Andy Hector from the University of Zurich sees it: “The results of our analyses suggest that plant communities operate much like a soccer team,” he said. “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 David Beckhams of our local plant community would probably be trees and plants like the Scrub Oak and the Manzanita, according to Cardinale.
“There are, however, hundreds of plant species that comprise the chaparral,” he said. Loss of these less dominant species could decrease plant productivity by more than the loss of each of the biggest plants alone.
It’s a finding that might cause some conservationists to rethink their methods. Cardinale was one of them.
“There’s been this question of how much species extinction matters,” he said “I have to admit, I was on the side of the debate that focused on conserving the dominant species.” The paper, he said, convinced him that bigger isn’t necessarily better.
“The big guys are important but not enough.” And because experiments to date have only been funded to run over a few years, it’s likely the impacts of species diversity has been understated, Cardinale said.
The solution isn’t going to be an easy one. In order to keep varieties of species, entire habitats would need to be preserved, not just single species, according to Cardinale. It’s a tall order for a growing human population, he said.
“But if we want to preserve the basic oxygen/carbon dioxide process, we should conserve more species of plants,” he said.