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Keywords:

  • floodplain meadows;
  • grasslands;
  • myrmecophily;
  • natural catastrophes;
  • population dynamics

Abstract

Historically, fires were frequent events in many grassland habitats and important factors shaping their biodiversity. Nowadays, although mostly prevented, they still happen occasionally. Using the occasion of an extensive fire that occurred at the floodplain meadow complex in the Vistula river valley, southern Poland, in March 2012, we investigated its impact on one of the largest European metapopulations of endangered Maculinea teleius and Maculinea nausithous butterflies. Maculinea are regarded as flagships of grassland conservation and useful indicators of insect species richness. Over 50 local populations of both butterflies, intensively monitored with catch-per-time-unit method, proved to act as independent demographic units, and no spatial autocorrelation in their year-to-year trends was detected. The changes in butterfly abundances between summer season of 2011 and 2012 indicated absolutely no impact of fire. Although about one fifth of area was burnt, the entire metapopulations remained unaffected. The changes of 14 local populations inhabiting burnt meadows were not significantly different from those at meadows spared by the fire. Moreover, population changes in the former group were independent of the proportion of burnt area. The impact of fire was obviously minimized by its early spring timing, but in this part of Europe, grassland fires prevail in this period because of a combination of ecological and climatic factors. Together with the lack of a negative effect of flood documented in an earlier study, our findings indicate strong resilience to natural catastrophes in the investigated butterfly species. Copyright © 2014 John Wiley & Sons, Ltd.