Epsilon Archive for Student Projects

Abstract

The relative strength of top-down and bottom-up trophic control vary depending on abiotic and biotic conditions. Predators occupying the highest level, such as wolf (Canis lupis) and lynx (Lynx lynx), have the potential to exert a negative impact mesopredators, such as the red fox (Vulpes Vulpes). This study investigates the population development of the fox population at Grimsö Wildlife Research Area in south central Sweden. The analysis was based on a dataset that spans over 50 years including top-down (wolf, lynx and sarcoptic mange), and bottom-up variables (voles (Clethrionomys glareolus and Microtus agrestics), roe deer (Capreolus capreolus) and hares (Lepus europaeus and Lepus timidus)) which have previously been identified to have a significant effect on the population dynamics of the fox. The temporal scope of this dataset includes the time prior to, during and post-reestablishment of wolves and lynx. The presence of sarcoptic mange and wolves had a significant and negative effect on the fox population. A similar result was not found for lynx. Nonetheless, lynx had already established in the area before wolves, which coincided with a decline in the fox population. This indicates that the presence of both apex predators has led to a negative cumulative effect on the fox population. In addition, it was demonstrated that voles continue to be of positive significance for foxes as this relationship remain strong in the absence and presence of apex predators and sarcoptic mange, however with a marked decrease. It is evident that the fox population is limited by both top-down and bottom up forces. This study is of importance in the context of biodiversity as the return of apex predators may result in cascading effects that benefit lower trophic levels and contribute to greater biodiversity.