Ábrahám Levente (szerk.): Válogatott tanulmányok VI. - Natura Somogyiensis 19. (Kaposvár, 2010)

HORVÁTH GY., HERCZEG R., TAMÁSI K. & SALI N.: Nestedness of small mammal assemblages and role of indicator species in isolated marshland habitats

HORVÁTH ET AL.: SMALL MAMMALS 287 Rózsa-berek Rózsa-berek is a mosaic-pattern boggy area stretching between Balatonmagyaród and the areas of Stage 1 of the Kis-Balaton Water Protection System, i.e. the expanse between the village and the Hídvégi lake. The low-lying macrohabitat east of the village is typically heterogeneous in its vegetation, due to the presence of sedgy areas and patches of wooded areas, shrubs and forest pathes in a mosaic pattern. The sampling plot is a mosaic area but is dominated by sedgy areas (R_l). This habitat patch is more elevated than the lakeside area of the Hídvégi lake, thus the drastic increase in water levels was not characteristic. Ingói-berek Ingói-berek is a large, homogeneous sedgy area located west of Fenéki-lake. Water levels in Ingói-berek are greatly influenced by water amounts passing in Ingói canal between the sedgy area and the dyke of Fenéki-lake. The sampling area (I_ I

) was laid out near the automatic pumping station of Ingó, in a tussock sedge area under permanent water cover, to the east along the western dyke. Trapping method The method applied in each of the sampling plots was the capture-mark-recapture (CMR) method with the same box-type live-traps (75x95x180 mm). From the number of traps in each of sampling plots and the number of sampling nights in the three monitoring years (2005-2007) we can count the summarized amount of trap occasions, which was as many as 12008 trapping nights for the present study. Captured animals were marked individually and we also recorded the sex (by females: gravidity or lactation too), age and body mass. Ages were determined based on body mass and overall appearance. Statistical methods The nestedness analysis of small mammal assemblages in sampling locations (habitat patches) of various macrohabitats in the Kis-Balaton area was based on presence-absence data of recorded species. The presence-absence matrix is the fundamental unit of analysis in community ecology and biogeography (MCCOY & HECK 1987). In such a matrix, rows are species, columns are sites or samples, and entries are the presence (1) or absence (0) of a species in a site. Few issues in community ecology have been more contentious than the statistical analysis of these data matrices (GOTELLI 2000). Based on presence-absence matrices ATMAR & PATTERSON (1993, 1995) introduced a concept that considers also the placement of a cell in a give matrix. The software published by these authors is the most popular approach for estimating nestedness; based on temperature of the matrix, 7", was the Nestedness Temperature Calculator, (NTC) (ATMAR & PATTERSON 1993). T measures the degree of order in "packed" distribution matrices and takes values from 0 (perfect nestedness) to 100 (maximum disorder). This simple thermodynamic term, T, describes a continuum between the extremes of perfect nestedness (maximally "cold", 0) and hyper-dispersed, checkerboard arrangement (maximally "hot", 100), where matrices that contain both a degree of nested order and randomness will exhibit an intermediate "temperature" (ATMAR & PATTERSON 1993). Nevertheless, several other new softwares have since been released for the analysis of the nestedness of communities (

ULRICH et al. 2009). WINE (Weighted-Interaction Nestedness Estimator) is a new nestedness estimator that takes into account the weight or intensity of each interaction (e.g., in a plant-pollinator network, the number of registered visits of a particular interaction). Thus, instead of using presence-absence matrices,