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SPATIAL DISTRIBUTION OF SMALL MAMMAL POPULATIONS IN DRAVA FLOODPLAIN FOREST PROSTORNA DISTRIBUCIJA POPULACIJA SITNIH SISAVACA U POPLAVNOJ UMI UZ DRAVU Győző F. Horváth1, Dávid Schäffer1, Ákos Pogány2, Dániel Tóth1 Summary In the present study we examined the spatial distribution of the small mammals of a floodplain forest by River Drava based on a three-year live trapping (capture-mark-recapture). We registered the presence of 5 shrew and 5 rodent species between 2001 and 2003. Of them Apodemus agrarius, A. flavicollis, Myodes glareolus and Sorex araneus were generally typical in the region. In our examination striped field mouse was the most frequently recorded species. The habitat use of the Apodemus species was equal, however the habitat use of bank vole was the opposite, preferring the area between the river and the dirt road. This indicates the spatial segregation of the bank vole and the two mouse species. Striped field mice travelled greater distances than bank voles did. Yellow-necked mouse individuals covered significantly greater movement distances than striped field mice. As suggested by our study, the dirt road as a dividing line of the trapped forests had no barrier effect on the movements of individuals of the three rodent populations. Key words: floodplain forest, small mammals, capture-mark-recapture, spatial association Introduction Uvod There are several environmental factors, which affect the spatial pattern of populations and influence the formation of unique motion patterns, for instance the availability of resources, the risk of predation and other abiotic environmental factors. These factors have mostly heterogeneous spatial distribution, therefore show mosaic-like pattern (Ims 1995). Understanding the temporal and spatial scales at which organisms perceive and respond to their environment is a central issue in ecology (Wiens 1989), although there has been a tendency by ecologists to study many phenomena within a narrow range of scales (Morris 1987a, 1987b, Bowman et al. 2000). Floodplain and riparian areas are valuable ecosystems on every forest landscapes because of their high productivity and their inherent connection with the rest of the watershed. Riparian areas within forests are generally cooler, moister, and structurally more complex and more productive than the upland areas, so they afford home to distinct communities of plants and animals very often (McComb et al. 1993, Kelsey & West 1998). Small mammals play important roles in the riparian forest (Cockle & Richardson 2003), because they are the primary prey of many predators (Kelsey & West 1998, Hanski et al. 2001), some of them affect plant species composition and soil fertility through selective herbivory and seed dispersal (Sirotnak 2000) and finally because of their feeding and burrowing activities and their role in food webs (Wijnhoven et al. 2005, 2006). Small rodents are also an important factor in the regeneration of forest stands (Heroldová 2007, 2008, Suchomel 2008). Periodic floods are important extrinsic environmental factors in riverine ecosystems. Flooding has a considerably negative impact on small mammal populations resulting in high mortality, and restricting their presence to refuges on elevated terrains after inundation (Pachinger & Haferkorn 1998, Andersen et al. 2000, Wijnhoven et al. 2005). Riverine landscapes are 1University of Pécs, Institute of Biology, Department of Animal Ecology, H-7624 Pécs, Ifjúság u. 6., Hungary, e-mail: hgypte@gamma.ttk.pte.hu 2Eötvös Lóránd University, Institute of Biology, Department of Ethology, H-1117 Budapest, Pázmány Péter sétány 1/C., Hungary |