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 203 proved in either of the pairings (%

2 = 0.008 - 0.506, NS). For September 2004 there was no significant spatial association for the pairs A. agrárius vs. A. flavicollis and A. agrárius vs. С glareolus (%

2 = 0.4 - 0.68, NS), sugesting that the two typical forest dwelling species (A. flavicollis, С glareolus) are spatially separated from the population of the striped field mouse preferring more open areas yet having wide tolerance in terms of habitat. However, in the pairing of A. flavicollis vs. C. glareolus significant spatial association was observed (%

2 = 6.95, p < 0.05). In September, the yellow-necked wood mouse completely moved into the closed forest, and also the bank vole population increased in the area near the closed alder gallery forest. Consequently, the two populations had to share habitats in the protected forest section at a greater degree, the significant spatial association thus being the result of higher spatial overlap in September. For the November capture data, low, non-significant levels of association were obtained again in all three pairings (x

2 = 1.18 -1.84, NS). This result, too, suggests that this month individuals of the various populations were arranged in a way that spatial overlap is minimal, the three populations trying to occupy suitable habitat patches in segregation from each other. The detailed seasonal analysis of population dynamics and spatial organisation of species suggests that by November, after density peaks, the species are already arranged according to their winter survival strategies. Because unexpected results were produced in that month - especially in terms of the spatial distribution of the bank vole - we therefore charted the November capture and location data of the three frequent species together. In that graph capture locations of individuals of the three species, and hexagonal grids corresponding to space coverage. That way, graphics show the areas that are separated with no overlap between populations, as well as those with spatial overlap between two or three populations (Fig. 7.). Based on spatial distributions observed by early November, the area of the closed alder gallery forest was occupied by individuals of the yellow-necked wood mouse and the bank vole populations. In the larger, central part of the 1 hectare forest section only yellow-necked wood mice had their home ranges. In the inner, marginal rows of the grid where higher bank vole capture densities occurred in August and September, the habitat use of the two populations overlapped in November. There were yet another two patches in the closed forest with the space use of the two typically forest-dwelling species overlapping in November, both areas touching the border zone towards Grid B. Based on our November data, the most striking result in Grid В was that bank voles, a species with higher capture frequency, gained space. Thus, it was mostly the striped field mouse and the bank vole that shared among themselves the more open, regrowing forest area. Bank voles were present in higher numbers in the section of Grid В closer to the forestry road, whereas the striped field mouse tended to use the more centrally located areas where in small patches it had habitat overlap with bank voles that had much lower capture frequencies (Fig. 7.). Conclusions Research done both in nearctic and palearctic temperate regions has proved that small mammals are important indicator objects, signifying degradation processes of the areas, as well as the harmful effects of forestry interventions that decrease biological diversity (e.g. MAZURKIEWICZ 1984, STEPHENSON 1993, LINZEY and KESNER 1997, SAITOH and NAKATSU 1997, STEVENS and HUSBAND 1998). Long-term studies have also revealed how drastic changes to ecological background parameters (e.g. droughts that can influence