Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Horváth, Gy., Molnár, Dániel - Csonka, Gergely: Population dynamics and spatial pattern of small mammals in protected forest and reforested area - Kisemlősök populációdinamikája és térbeli mintázata védett erdei és újraerdősödő területen

HORVÁTH ET AL.: POPULATION DYNAMICS AND SPATIAL PATTERN 205 forests in the Carpathians, revealing 6 species in both habitat types, but with no considerable difference in diversities (although data were not analysed statistically). In two out of three study years, the small mammal community turned out to be more diverse in the pine forest. During the studies in 2003-2004 analysed in the present paper, the number of species recorded decreased because of the unfavourable survival conditions in 2003, despite that the regrowing forest area neighbouring the strictly protected forest section was also introduced to the investigations. Changes in environmental conditions had the greatest influence on the bank vole population which had twice or three times higher densities in earlier years than had the Apodemus species that were characteristic species in the present study period as well. Due to more favourable survival conditions, capture parameters improved in 2004, based on which it was possible to analyse the space use and spatial overlap of the three most frequent species, as well as we could determine any spatial association between their populations. We clearly showed a shift in area and habitat use by the two Apodemus populations in autumn, and the higher bank vole capture frequency in the regrowing area around November was explained by emigration starting from the closed forest as abundance grew. However, due to the low rate of recaptured individuals we could not directly confirm the assumed directions of migration. In the case of striped field mouse, the preference of the edge zone of forest habitats could be demonstrated here in Lankóci forest too, as well as the fact that in this habitat individuals of the population dispersed in the regrowing area instead of the closed forest. Looking at the edge zone - closed forest gradient, it was the A. agrárius population that was present with higher abundance in the edge zones than in the central and inner patches of the studied forest section. This phenomenon has been noted earlier for this species in papers produced at our department (HORVÁTH et al. 1996, HORVÁTH et al. 2001). The considerable degree of dispersion by A. agrárius in the regrowing area of Lankóci forest is primarily the result of habitat selection, and is caused also by competition between populations of the the three dominant species {A. agrárius, A. flavicollis, С glareolus) (ZEJDA 1967, GLIWICZ 1984, CHELKOWSKA et al. 1985). In the case of the bank vole, the pure faunal evaluation of capture data, the statistical analysis of relative proportions, and results from the investigation of space use by the population all suggest that it was a pronounced surge of emigration that caused the observed spatial pattern between the closed alder gallery forest and the regrowing area, possibly enhanced by competition with the yellow-necked wood mouse showing similar densities (GLIWICZ 1981, 1984). Of course this cannot be proved during a single trapping period, but the distribution of individuals does follow the arrangement of resources (shelter, food), which is probably entirely different in respect of the two areas in November than in the summer months. With a view to the results having gained we believe that continuing monitoring is important; the synchronous monitoring of the two habitats with different vegetation structure has yielded many information about small mammal ecology, despite the fact that the year 2003 had low density values. Based on longer term studies it will be possible to seek answer to such actual questions about the upper Drava reach like how drastic changes in the water regimes of floodland forests influence the spatial patterns and demographic fluctuations of settling and dispersing small mammals. Acknowledgement Monitoring activities were supported by the Duna-Drava National Park Directorate.