1 / 13

DO ROADS HARM TOADS?

DO ROADS HARM TOADS?. A stochastic simulation model of the spadefoot toad ( Pelobates fuscus ) in a Danish pond system Tove Hels, Centre of Forest and Landscape Gösta Nachman, University of Copenhagen. The problem was approached in two ways:. Experimentally:

roza
Télécharger la présentation

DO ROADS HARM TOADS?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DO ROADSHARM TOADS? A stochastic simulation model of the spadefoot toad (Pelobates fuscus) in a Danish pond system Tove Hels, Centre of Forest and Landscape Gösta Nachman, University of Copenhagen

  2. The problem was approached in two ways: Experimentally: • Data were collected from five adjacent ponds in Jutland • All individuals arriving and leaving the ponds were caught and marked individually to provide information about age specific survival and reproduction rates • Reproduction was estimated from the weight loss of the females during their stay in the ponds Theoretically: • A general stochastic simulation model of a spatially divided population (metapopulation) was developed • The model includes demographic and environmental stochasticity • Data from the field system were used to estimate the relevant parameters • The model predicts the number of males and females in each age class and in each pond

  3. MetaFusc: A stochastic simulation model of Pelobates fuscus

  4. Conclusions: • The ponds constitute a core-satellite (or source-sink) metapopulation system • Stochastic processes make local (and to some extent regional) dynamics unpredictable • Inverse density-dependent mortality on eggs and tadpoles imposes a threshold effect that impedes colonization of empty ponds and leads to sudden extinctions • Environmental stochasticity has a negative effect on regional persistence but may be beneficial to the satellite subpopulations • Lower dispersal rates decrease the proportion of occupied ponds • A road has a negative effect on the isolated pond but not on the remaining metapopulation • Efforts to increase juvenile survival will be more beneficial than efforts that only increase adult survival and reproduction

  5. Thank you for your attention

More Related