IL CAMBIAMENTO CLIMATICO HA CONSEGUENZE SULLE SPECIE ARTICO-ALPINE? IL CASO-STUDIO DELL’ARVICOLA DELLE NEVI, CHIONOMYS NIVALIS, NELLE ALPI CENTRO-ORIENTALI (RODENTIA: CRICETIDAE)

Has the climate change consequences for arctic-alpine species? The case study of the snow vole Chionomys nivalis in the central-eastern Alps (Rodentia: Cricetidae). The monitoring of small mammals, which are excellent bioindicators of terrestrial biocenosis, can provide important indications on the effect of environmental change on local ecosystems, especially in the Alps, which are particularly sensitive to these fast-occurring modifications. In this context, in summer/autumn 2016 we performed a pilot study in the Central Italian Alps, based on the capture-mark-recapture method. Specifically, we aimed to compare the small mammals assemblages in three close-by open sites above tree line, set at the same elevation but characterized by different habitats: scree, grassland and mixed area (shrubs). We identified the individuals by fur-clipping and morphometric measures, and we modelled the temporal trend of the recorded demographic parameters (sex, reproductive status, age, body mass and morphometric measures) over time. We applied Redundancy Detrended Analysis (RDA) to compare the results with an analogous study realized in 1997, conducted in the same study area, in the same habitat typologies and applying the same capture procedure. We found that in both surveys the small mammals assemblages were represented especially by bank vole Myodes glareolus and snow vole Chionomys nivalis. While in 1997 the two species were sympatric in the three sites, in 2016 they were associated together only in the scree habitat. These results suggest an altitudinal shift of bank vole from forest habitat to alpine highlands, which may have caused a modification of snow vole distribution in response to the plausible insurgence of interspecific competition, with snow vole isolating itself in the most suitable habitat, i.e. the scree. We conclude that these considerations should be supported by a long-term project, aiming at disentangling climate change driven effects from those caused by stochastic demographic fluctuations that typically characterize the population dynamic of these small mammal species.