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 295 Apodemusflavicollis * Xaonxs ano malus * Micromys mtnutus * Apodemus agrárius • * Microtia agrestis ' • Arvtcola terrestris • Mus spicilegus * Fig. 4: Dendrogram of the habitats in 2006 (Bray-Curtis-index, UPGMA). Species possessing significant maximum indicator values are marked (*: P< 0.05, **: P< 0.01) The mound-building mouse (M spicilegus ) appeared in the same habitat patch of the Keleti-berek (K.E2) as a colouring element of the small mammal assemblage in 2006, and its maximum indicator value can be considered to be significant based on the statistical calculations of IndVal program (Fig. 4). This result can be regarded as an opposite result in relation to the character values of field vole and european water vole. The appearance of mound-building mouse was due to the environmental background variables of autumn 2006 and the presence of plough-lands beside the sampled patch. This allowed this mouse species which uses mostly agricultural areas to ensconce more often to the sedgy marshes from the fields. Mound-building mouse was typical for one habitat patch from the 6 sampled areas, therefore its significant indicator value was caused by its rareness and we could characterise it as an absolute asymmetrical indicator species. On the basis of 2007 trapping we computed the input matrices of IndVal analysis based on trapping data of 3 macro-habitats and 5 habitat patches. We recorded 12 small mammal species and 6 of them received significant maximum indicator value. It was a very important result of this year that we indicated the recolonised individuals of root vole in many habitat patches of Keleti-berek. Through the analysis we received greater than 80 % indicator values for the common shrew (S . araneus) and the striped field mouse (A. agrarius), therefore these two species can be considered as symmetrical indicator species of more habitat patches. We received lower than 55 % values for every other species and those which were characterized by significant maximum Indval values appeared as asymmetrical character species of certain habitat patches (Table 5). Based on the quantitative data the root vole appeared in this study with significant maximum indicator value in the regenerated sedgy area of Balatoni-berek following the mowings. Then the rediscovered root vole was a typical indicator species in the Balatoniberek in an enclosed, treatment-free, regenerated sedgy habitat which is beyond the pale of the national park. The same habitat patch and the regenerated habitat quality were characterized by the appearance of european water vole individuals as well (Fig. 5).
