Gunung Leuser Rain Forest on the Indonesian island of Sumatra. Rainforests are the most biodiverse ecosystems in the world. Photo by: Rhett A. Butler.
A new study finds that diversity of plant species matters—big time. Analyzing nearly 600 research studies, the meta-study in the American Journal of Botany found that productivity in biodiverse plant ecosystems was 1.5 times higher than in monocultures. In other words, a prairie is more productive than a cornfield and forest more productive than a rubber plantation. The researchers warn that eroding plant diversity threatens essential ecosystems services such as food, water purification, oxygen production, carbon sequestration, and the availability of raw materials.
“The idea that declining diversity compromises the functioning of ecosystems was controversial for many years,” says marine ecologist, Emmett Duffy of the Virginia Institute of Marine Science. “This paper should be the final nail in the coffin of that controversy. It’s the most rigorous and comprehensive analysis yet, and it clearly shows that extinction of plant species compromises the productivity that supports Earth’s ecosystems.”
In addition to diverse ecosystems increasing productivity, the scientists found that such ecosystems more efficiently capture light and nutrients. Laboratory studies have also shown that diverse algae communities sequester carbon and produce oxygen twice as quickly as a single-species algae community.
According to researchers, the importance of plant diversity was consistent across the planet, spanning terrestrial, freshwater and saltwater ecosystems.
Even so the researchers admit that scientists may still be underestimating the overall importance of biodiversity. Most studies are currently done over small periods of time and in small spaces, but “data are generally consistent with the idea that the strength of diversity effects are stronger in experiments that run longer, and in experiments performed at larger spatial scales,” the scientists write.
However, as researchers discover how important diverse ecosystems much more work needs to be done.
Lead author Brad Cardinale of the University of Michigan says that future studies in plant diversity and biodiversity will help researchers “calculate the number of species needed to support the variety of processes required to sustain life in real ecosystems.”
“We don’t mean ‘need’ in an ethical or an aesthetic way. We mean an actual concrete number of species required to sustain basic life-support processes,” Cardinale clarifies.
Plants, along with many animal species, are currently threatened by a wide-variety of factors with some of the largest including deforestation, habitat loss, invasive species, pollution, and climate change.
CITATION: Cardinale, Bradley J., Kristin L. Matulich, David U. Hooper, Jarrett E. Byrnes, Emmett Duffy, Lars Gamfeldt, Patricia Balvanera, Mary I. O’Connor, and Andrew Gonzalez (2011). The functional role of producer diversity in ecosystems. American Journal of Botany 98(3): 572-592. DOI: 10.3732/ajb.1000364
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