By Alex Varga
It is well known that biological diversity underpins the functioning of ecosystems and the services that they provide. However, in a new study, researchers at the University of California-Santa Cruz demonstrate that higher levels of biodiversity are required in order to maintain multiple ecosystem functions simultaneously, over time.
Erica Zavaleta, UCSC associate professor of environmental studies and co-author of the study, describes this higher order biodiversity as a “quilt” where each patch represents a diverse species assemblage and ecosystem. The study shows that landscapes with a higher diversity of patches can provide more benefits than a homogeneous landscape.
“A mix of meadows, young forest, old forest and shrub lands, for example, might provide more benefits than a landscape of continuous young forest, even if that young forest itself has high biodiversity,” Zavaleta said.
To test this idea, Zavaleta and colleagues took advantage of a long-term experiment run by Professor of Ecology David Tilman at the University of Minnesota. Tilman’s experiment analyzes the health of 168 plots containing randomized combinations of grassland species to determine the impact of different species combinations.
Using Tilman’s data, gathered since 1997, the team conducted 7,512 computer simulations to assess the level of ecosystem functioning across the landscape. Specifically, they analyzed how species diversity impacted the grassland’s ability to provide up to eight different ecosystem functions simultaneously. Over time and all combinations of ecosystem functions, increased species diversity was required to match increases in ecosystem functioning.
As conversation efforts often are directed toward single species or a maximizing a single ecosystem function, the findings of this research show the importance of protecting higher levels of biodiversity to support sustained multi-functionality of ecosystems in the long term.
These findings were published this week in the article “Several scales of biodiversity affect ecosystem multifunctionality” in the Proceedings of the National Academy of Sciences.
Alex Varga is deputy director of the Earth Institute Center for Environmental Sustainability.