Species are less redundant than previously thought for providing ecosystem services, reports this week’s Nature. Scientists from universities throughout North America and Europe, including Wageningen University, part of Wageningen UR, combined data from some of the largest and longest-running biodiversity experiments and found that previous studies have underestimated the importance of biodiversity for maintaining multiple ecosystem services across many years and places.
Biodiversity is rapidly declining worldwide and there is concern that this will lead to declines in the services that ecosystems provide for people, such as food production, carbon storage, and water purification. It remains unclear, though, whether few or many of the species in an ecosystem are needed to provide ecosystem services. Most previous biodiversity studies considered only the number of species needed to provide one service under one set of environmental conditions. These studies found that multiple species were important, but many species appeared redundant. That is, it appeared that the extinction of many species would not affect the functioning of the ecosystem because other species could compensate for their loss.
These investigators found that most of the studied species were important at least once because different sets of species were important: during different years, at different places, for different services, and under different global change (e.g., climate or land-use change) scenarios. Furthermore, the species needed to provide one service during two years were not the same as those needed to provide two services during one year. This means that biodiversity is even more important for maintaining ecosystem services than was previously thought. ‘Our results indicate that many species are needed to maintain ecosystem services at multiple times and places in a changing world’ said Dr. Isbell, ‘and that species are less redundant than was previously thought.’
These scientists also offered recommendations for using these results to prioritize conservation efforts and predict consequences of species extinctions. ‘It is nice to know which groups of species promoted ecosystem functioning under hundreds of sets of environmental conditions,‘ said Isbell, ‘because this will allow us to determine whether some species often provide ecosystem services under environmental conditions that are currently common, or under conditions that will become increasingly common in the future.’ The species that are most important for providing ecosystem services could become priorities for conservation because their extinction could considerably reduce ecosystem services.
Humans derive many benefits from ecosystems, as recently popularized by the Millennium Ecosystem Assessment. These benefits can be described as ‘ecosystem services’. In addition to those listed above, examples of ecosystem services include crop pollination, air purification, and soil formation.
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High plant diversity is needed to maintain ecosystem services, Nature on line edition,10 August 2011.