Paysage et pullulation animale : les facteurs paysagers de la vitesse de propagation des vagues de pullulations du campagnol terrestre

Abstract

The spreading of fossorial water vole outbreaks in the grasslands of the massif of Jura (France) is a periodic phenomenon which poses many problems to agriculture (pest control) and public health (disease transmission). In this context, researchers try to understand the role of landscape structures. More precisely, the aim of the present study is to analyze the role of certain landscape features in relation to the velocity of the travelling wave spreading. The study site is the plateau of Nozeroy (region of Franche-Comté, France), where animal density estimates were obtained for several dates. The computation of “velocity vectors” allowed to link the density evolution and the landscape data stemmed from a multispectral satellite image. Statistical relationships were computed between the velocity and many local factors (accessibility to the grassland, proximity of hedgerows and forests) for several neighborhood sizes. The results show that the bocage is the most important factor which slows down the spreading. Accessibility to the resources is less important and plays a part in the velocity only for high density spreading. Lastly, the forests slow down the spread locally and only for low density populations. These results are interpreted in the light of dispersal modalities in the water voles, and of the regulatory role of predators linked to wooded structures.

Keywords

• accessibility
• potential model
• spread
• landscape constraint
• travelling wave