Plant More, Plant Different Species

Landscape designers like to plant masses of one perennial, one tree or one shrub to "make a statement," but perhaps everyone ought to re-think the issue.  A major new study published in this week's issue of the journal Nature  concludes that ecosystems with many different plant species are less vulnerable to disease and pests, are more productive, and recover more easily from extreme variations in climate.

Over a 12-year period, scientists at the University of Minnesota and the University of Nebraska conducted experiments to determine if plant diversity affects the stability of ecosystems. The experiments took place at the National Science Foundation's Cedar Creek Natural History Area.  According to Martin Caldwell, program director of the NSF's Division of Environmental Biology, "This study clearly demonstrates that stability of a plant community through time increases as species richness goes up."  The scientists found that plant communities with the greatest biodiversity also produced the greatest plant growth and were far more likely to hang onto essential soil nutrients.

(photo: David Tilman, UMN)

Over 100 years ago, Charles Darwin first theorized that the more diverse the species, the more productive the ecosystem.  Until recently, however, his idea never underwent rigorous scientific testing.

The new study is the first on this issue that has gathered data in a controlled environment over a long enough period to determine whether biodiversity can stabilize an ecosystem. David Tilman, an ecologist at the University of Minnesota, said biodiversity has decreased in global ecosystems as forests and prairies have been cleared to make way for roads, buildings, and agricultural fields. Researchers now believe that species are dying out at the rate of one a day -- and that's a very conservative estimate.

At Cedar Creek, Tilman's team constructed 147 miniature prairies and planted them with one to 24 species.  Then they waited to see which plots did best.

Tilman and his colleagues now believe that biodiversity in plant species could be a key factor in in restoring global ecosystems and meeting global energy needs. "Diverse prairie grasslands are 240 percent more productive than grasslands with a single prairie species," he said. "That's a huge advantage.  Biomass from diverse prairies can, for example, be used to make biofuels without the need for annual tilling, fertilizers, and pesticides, which require energy and pollute the environment.  Because they are perennials you can plant a prairie once and mow it for biomass every fall, essentially forever."

Sounds like this research may have come just at the appropriate time!

Comments

[panasianbiz]

Your discussion was very thought provoking and should remind every gardener that, not only are gardens places of refuge and beauty, but they hold a place in the ecosystem as well.