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Download fileEstimates of local biodiversity change over time stand up to scrutiny
journal contribution
posted on 2016-11-25, 14:36 authored by Mark Vellend, Maria Dornelas, Lander Baeten, Robin Beausejour, Carissa D. Brown, Pieter De Frenne, Sarah C. Elmendorf, Nicholas J. Gotelli, Faye Moyes, Isla H. Myers-Smith, Anne E. Magurran, Brian McGill, Hideyasu ShimadzuHideyasu Shimadzu, Caya SieversWe present new data and analyses revealing fundamental flaws in a critique of two
recent meta-analyses of local-scale temporal biodiversity change. First, the conclusion that short-term time series lead to biased estimates of long-term change was based on two errors in the simulations used to support it. Second, the conclusion of negative relationships between temporal biodiversity change and study duration was entirely dependent on unrealistic model
assumptions, the use of a subset of data, and inclusion of one outlier data point in one study. Third, the finding of a decline in local biodiversity, after eliminating post-disturbance studies, is not robust to alternative analyses on the original dataset, and is absent in a larger, updated
dataset. Finally, the undebatable point – noted in both original papers – that studies in the ecological literature are geographically biased, was used to cast doubt on the conclusion that, outside of areas converted to croplands or asphalt, the distribution of biodiversity trends is
centered approximately on zero. Future studies may modify conclusions, but at present, alternative conclusions based on the geographic-bias argument rely on speculation. In sum, the critique raises points of uncertainty typical of all ecological studies, but does not provide an
evidence-based alternative interpretation.
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