L. Forró szerk.: Miscellanea Zoologica Hungarica 13. 2000 (Budapest, 2000)

Horváth, Gy.; Pintér, V.: Small mammal fauna of two abandoned field habitats, and a spatio-temporal analysis of four rodent populations

Agricultural cultivation in the area near the village Nagycsány was discontinued in 1995. Its most elevated point is near the road connecting Vajszló and Sellye, from where, gently sloping towards the south-southwest, its vegetation gradually transforms into a marshy association with Calamagrostis epigeios dominance. The vegetation does not form zones along the 100 meter long water-cover gradient. It is in the early stage of secondary succession, with a high degree of heterogeneity which is caused mainly by the random settling of colonising species. Environmental pressure and regulating mechanisms still have secondary importance in the formation of the patterns of the community. The patchiness of the patterns can be observed only at a small scale (1 m

2

). Patches are generally monotypic, with shape and size variance originating from differences in the growth strategies of the plant species. Based on its physiognomy, the area can be divided into two parts, out of which the first is a double-level ruderal association. In its lower herb layer perennial weed-type dicotyledons are found forming a low (5-10 cm) and dense (80-100%) cover, with some of the generalists of the original marsh vegatation having grown to exist in masses. The most frequent species are Trifolium pratense, Ambrosia elatior, Potentilla reptans, Stenactis annua, Stellaria media, Euphorbia cyparissias, Setaria viridis, Matricaria maritima, Consolida regalis, Anthémis arvensis. Its upper layer consists of high weeds (60-100 cm high, 30—40% cover), with some marshland species having become dominant. The most characteristic frequent species are Solidago gigantea, Cirsium arvense, Erigeon canadensis, Artemisia vulgaris, Daucus carota, Stenactis annua, Calamagrostis epigeios, Agrostis stolonifera. The physiognomically different, other part of the area is a double-level association near the road, with a shrub layer just establishing itself. From the Robinia pseudo-acacia stand north of the road, seedlings have colonised and constitute a loose third layer (of 2-3 m heigth, 20-30% cover) on top of the twolevel association. B - 5-year old abandoned field with ruderal weed association The sampling grid here was placed in an area where cultivation had been stopped four years before. It is in the surroundings of the village Páprád, and is mainly a double-level weed association with haymeadow and marshland species, with no physiognomical patchiness. The lower herb layer is low (5-20 cm), with high degree of cover (150%), consisting mostly of dicotyledons, though at places monocotyledons also reach a considerable degree of cover. Its dominant species are: Potentilla reptans, Veronica chamaedrys, Daucus carota, Plantago lanceolata, Trifolium pratense. Ranunculus acris, Centaurea jacea, Stenactis annua, Ranunculus repens, Agrostis stolonifera, Achillea millefolium. The upper herb layer is a 70-100 cm high weed association with 50-70% cover. Its dominant species are: Daucus carota, Cirsium arvense, Erigeon canadensis, Crepis tectorum, Calamagrostis epigeios, Artemisia vulgaris, Solidago gigantea, Valeriana officinalis, Urtica dioica, Centaurea jacea. The shallow depressions found along the northern and western edges of the grid were covered with water after showers in the summer. Characteristic species are as follows: Erigeon canadensis, Sambucus ebulus, Sambucus nigra, Lolium perenne, Daucus carota, Stellaria media, Dactylis glomerata, Chenopodium album, Cichorium intybus, Convolvulus arvensis, Setaria viridis. Trapping methods For capturing small mammals, we used box-type live-traps. In both areas a 1 hectare grid of 11 stations by 11 stations (with traps positioned 10 m apart) was applied. Traps were baited with bacon and a grain mixture scented with vegetable oil and aniseed-extract. Except for the hot summer months (June, July and August), traps were operated throughout the day, and, accordingly, were checked twice daily (7.00 CET, 20.00 CET), totaling 9 consecutive checkings in each monthly session. In the summer period we checked the traps only once a day (in the morning), since during the daytime traps were left closed and were re-opened only at around 18.00-19.00, so as to protect the animals from being killed in the overheating compartments. For the individual identification of the captured animals we applied the removal of the terminal knuckle of toes (Begon 1979), and we recorded the sex (also gravidity or lactation in females), age and weight of the animals. In the area situated near the village Nagycsány, which had been abandoned for a year at the beginning of our investigations (area A), traps were operated from March through October both in 1997 and