Biodiversity, But Not Community Composition, Surprisingly Stable Over Time

A major turnover of species in habitats around the globe is underway, resulting in the creation of novel biological communities, but overall species diversity is much more stable than scientists had believed, according to a new report in the journal Science.

In a survey of 100 long-term biodiversity monitoring projects in a variety of habitats around the world, the authors found that the majority of those studies (59 percent) documented increasing species richness. Biodiversity declined in 41 percent of the studies, but, in all cases the overall change in biodiversity was modest, the researchers said.

Biodiversity-studies-800Researchers examined 6.1 million records covering 35,613 species — from Arctic tundra to the South Seas, including mammals, birds, fish, invertebrates and plants. This map shows the locations of the biodiversity sudies they analyzed. Data sets are color-coded to reflect their climatic region: pink, global; royal blue, polar; turquoise, polar-temperate; green, temperate; gold, temperate-tropical; red, tropical. (Image credit: Dornelas, et al., Science, 2014)

When looking at changes in the species constituting those communities, however, the researchers found a surprisingly high rate of change — an average of about 10 percent change per decade. “A main policy application of this work is that we’re going to need to focus as much on the identity of species as on the number of species,” researcher Nick Gotelli of the University of Vermont said. “The number of species in a place may not be our best scorecard for environmental change.”

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