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

192 NATURA SOMOGYIENSIS ious fragments are optimal or suboptimal for survival of the given population, and how the migration pattern between them influence the seasonal pattern of density. This relationship, however, works on the other way round too: density increase in a particular patch can force certain individuals of the population to migrate between habitats or microhabitats. Various population dynamic data and information on movements of small mammals in mosaic landscapes with variable vegetation are important for the understanding of casual interrelationships that determine the stability of landscapes in an ecological sense (SZACKI and LIRO 1991). Focusing primarily on Europe, several publications have dealt with the study of structure and ecology of small mammal populations in various forest types (JENSEN 1975, SMAL and FAIRLEY 1982, JUCHIEWICZ et al. 1986; HESKE and STEEN 1990). Changes in the small mammal fauna were investigated in habitats of intact areas and in those under forestry management (HANSSON 1978). In several species, the number of captures as a function of plant cover was also analysed (JENSEN 1984, MAZURKIEWICZ 1994). The live trapping study of small mammals in a strictly protected alder gallery forest (Lankóci-erdö) was launched in autumn 2000, in the upper Drava reach. In addition to the closed forest section, we also started trapping in plot that was clear-cut in 2000 and is now gradually regrowing beside the closed forest, thus in 2003-2004 the populationand community-level monitoring of small mammals was performed together in the two plots. One of our objectives has been to find out about the small mammal community and about the changes in its composition, in the alder bog-forest, a type of floodland forests. The 1-ha felled plot besides the strictly protected area is in a state of gradual spontaneous reforestation, thus our other objective has been to investigate the ecological question of how the two areas are used by small mammals, and whether there is migration between the old, closed alder gallery forest and the area which was felled some years ago but is now regrowing. The present study investigates (i) to what extent the composition of the communities in the two sample areas differ from each other, (ii) how dense the populations of characteristic species can grow in the different habitats, and (iii) what kind of spatial pattern these populations will have using the two different areas. Material and method Study area The live-trapping monitoring of small mammals was done in two neighbouring habitats of Lankóci-forest in 2003-2004. One is a strictly protected lowland alder gallery forest {Paridi quadrifoliae-Alnetum), bordered by an edge zone abounding in shrubs. The other area is located beside the first one: it is an approximately 1 hectare forest section, in the state of gradual spontaneous reforestation following clear-felling. Since the area was clear-cut, plant cover has increased in the regrowing area, making the plot increasingly suitable for small mammals. In the studied alder forest, a highly variable plant association has formed, as a result of high levels of precipitation, with a number of larger, sedge-covered patches. Due to the wet period in late winter and spring, these patches turn into areas with stagnant water. In addition to the variable vegetation, the mosscovered stumps and fallen trunks provide excellent shelter for small mammals, and also serve as suitable trap stations. There is one forestry road north of the two selected forest sections and another one between the two, both of which, have played an important role in making the once continuous forest become fragmented.