L. Forró szerk.: Miscellanea Zoologica Hungarica 12. 1998 (Budapest, 1998)

Horváth, Gy.: Population dynamics and trappability of four rodent species in a forest habitat

also applied by Krebs & Boonstra (1984), and they also assessed the Jolly-trappability and the maximum trappability index defined by Hilborn et al. (1976). Small mammal population studies relying on trapping were started in Hungary in the 1960s (Palotás 1968, 1970). Several research studies were launched in the 1970-80s out of which some focused on small mammal population size estimations (Demeter 1979, 1981), while others intended to analyse correlations between small mammal communities and vegetation cover (Csizmazia 1980, Palotás 1986, Németh 1993). As part of the "SíkfóTcut Project", movements of individuals, activity centers and home range sizes were also studied in addition to population dynamics and trophic ecology (Némeczki 1984). Despite the research activity referred to above, Hungarian information on long-term spatial and temporal patterns of small mammals is very scarce. Consequently, monitoring of small mammals in Hungary at the population dynamics level is justified, and it requires multiannual data collection i. e. live trapping in designated sample plots. At the Department of Ecology and Zoogeography in Janus Pannonius University, small mammal live trappings were started in 1994 in a hornbeam-oak forest sample plot in the Dráva Lowlands. In the present study the results from 15 months of four-night trap sampling of four rodent populations and from 10 months of five-night trappings are presented, with focus on population dynamics, capture data and trappability. Material and methods Study area The sampling quadrat is located between the villages of Vajszló and Páprád (N 45 51', E 18 00') in Baranya county, in the Dráva Lowlands. The 1-hectare plot which covers a hornbeam-oak (Querco robori-Carpinetum) forest section, is part of the recently designated Bükkhát Forest forest reserve. Four levels of the vegetation can be differentiated in the grid area. The height of the upper canopy is around 25 m, with a cover of 50-70 %. Characteristic species are Quercus robur, Fraximus angustifolia and Robinia pseudoacacia. The lower canopy layer is 4—10 m high with 20-95 % cover with the following characteristic species: Carpinus betulus, Ulmus minor, Fraximus angustifolia and Robinia pseudoacacia. The shrub layer of 1-4 m height and 25-90 % cover consists of young individuals of Cornus sanguinea, Ligustrum vulgare, Crategus monogyna, Sambucus nigra and Robinia pseudoacacia. Characteristic species of the high herb layer with 90-100 % cover are Corydalis cava, Anemone nemoralis, Stellaria holostea, Galium aparine, Veronica hederifolia, Lamium purpureum, Alliaria petiolata, Urtica dioica. In a smaller spot the herb layer is shorter and not very dense (40-70 % cover), and a thick litter of fallen leaves is present. Dominant species are: Dentaria bulbifera shoots, Ficaria verna, Hedera helix, Asperula odorata, Ajuga reptans, Stellaria holostea, Rubus sp. In patches where the undergrowth is scarce (0-30 % cover) and small, leaf cover is dominant or the surface is bare, with scattered specimens of Circaea lutetiana, Hedera helix, Pulmonaria officinalis, Asperula odorata. Since no forestry activity has been carried out in the area for three years, the extent of the latter has decreased parallel with the regeneration of the vegetation. Trapping methods In 1995-1996 a 1-ha grid containing 9 by 9 live traps at an equal distance of 12.5 m from each other was used for trapping in the sampling area. Wooden and plastic traps were positioned in the grid points alternately (Horváth et al. 1996). Sampling was done in 15 four-night trapping periods from June to October 1995 and from February to November 1996, making up 4860 trap nights. In 1997 the number of nights was raised from 4 to 5, and the grid covering the same 1 ha area contained 121 stations in 11 rows, with traps positioned 10 meters apart. These five-night sampling periods were repeated