Species Turnover Slows One‑Third 1970s, Study Finds
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- Queen Mary University of London researchers (Emmanuel Nwankwo and Axel Rossberg) found that species turnover across global ecosystems has declined by roughly one‑third since the mid‑1970s when measured over five‑year periods.
- BioTIME database, covering more than half a million locations over the past 150 years and including birds, plants, freshwater and marine species, provided the data for the analysis.
- Christopher Terry (University of Oxford) reported a short‑term turnover decline in North American birds in human‑modified habitats, supporting the slowdown result.
- Maria Dornelas (BioTIME leadership council) highlighted that two long‑term studies—the North Sea International Bottom Trawl Survey and the North American Breeding Bird Survey—show an increase in turnover in recent decades, a trend she finds hard to reconcile with the new findings.
- Jacob O’Sullivan (Forest Research) explained that turnover estimates vary with the length of the observation window but concluded that the slowdown interpretation best fits the current results.
- Ryan Chisholm (National University of Singapore) said the results look convincing, echoing concerns that a slowdown in intrinsic turnover could limit ecosystems’ ability to “repair” under climate change.
- Landscape fragmentation reduces regional species pools, which the authors argue slows the replacement of disappearing species and hampers ecosystems’ long‑term survival.
Why it matters: Conservationists and policymakers lose a key indicator of ecosystem resilience, as the slowdown implies fewer species can replace those lost, while fragmented landscapes and reduced regional species pools exacerbate the problem, limiting nature’s ability to adapt to climate change. This undermines agricultural productivity and human wellbeing that depend on stable ecosystem services.
