Vole outbreaks in a landscape context:: evidence from a six year study of Microtus arvalis

Analysis of population variations in space and time suggests that landscape may act as a substrate for several kinds of interactions: neighborhood effects, edge effects, prey-predator and parasite-host relationships, etc. Here we discuss how landscape structure and physiognomy affect vole population dynamics. We present the results of a six-year survey of vole populations in the Jura mountains of eastern France (700-900 m elev.) which was conducted to determine whether patch array (i.e. spatial arrangement of different habitat patches) and vole demography are interconnected? The population kinetics of M. arvalis has been monitored in different habitats characterized by extensive homogenous and heterogeneous landscapes. We compare results from different parts of these landscapes to test the neighborhood effects of hedgerow networks, wood mosaics, forests, and villages. Analysis suggests that (1) refuge habitats for specialist predators act as destabilizing factors increasing both the amplitude of fluctuations and the duration of the high density phase, (2) refuge habitats for generalist predators act as regulating factors, dampening vole population kinetics and shortening the phase of peak numbers, (3) sink effects occur at forest edges and in the vicinity of villages, and (4) barrier effects are detected in grassland surrounded by forest. Such descriptive studies have implications for pest control strategies and provide a framework for further demographic field studies and natural experiments.