A Single Extinction Affects Many

When plant species become extinct, other plants in the same ecosystem also suffer and become less productive, according to new research announced by the University of California, Santa Barbara.

The research, conducted by an international team of scientists, finds that natural systems that lose plants to extinction can end up producing up to 50 percent less overall plant life and biomass. Those findings have serious implications for humans as well, because people depend on plants for food, fiber, biofuels, oxygen and carbon dioxide absorption.

The researchers reached their conclusions after analyzing the results of 44 experiments around the world that simulated the effects of plant species extinction. Their study is published in this week's online issue of the Proceedings of the National Academy of Sciences.

"The results of our analyses suggest that plant communities operate much like a soccer team," said Andy Hector, a co-author of the study and an assistant professor at the University of Zurich. "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."

Many scientists have already expressed concern that our planet is in the midst of its sixth mass extinction, and some warn that up to half of all known species could be extinct by the end of the 21st Century. As troubling as such reports might be, the impact of today's plant extinctions on human life might be even greater than experiments have so far indicated.

"We found that as experiments were run longer, they detected increasingly strong impacts of species diversity on plant productivity," said Bradley Cardinale, the study's lead author and an assistant professor of biology at UC Santa Barbara. "Unfortunately, because most experiments have only been funded to run for a few years at a time, they have probably underestimated the impacts of extinction on natural habitats."

Other researchers who contributed to the study include Michel Loreau of McGill University in Montreal; Marc W. Cadotte, Ian T. Carroll and Jerome J. Weis of UC Santa Barbara; Justin P. Wright of Duke University; and Diane S. Srivastava of the University of British Columbia.

University of California, Santa Barbara, "Scientists Warn That Species Extinction Could Reduce Productivity of Plants on Earth by as Much as Half." URL: (http://www.ia.ucsb.edu/pa/display.aspx?pkey=1682)