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 297 The IndVal analysis of 2007 suggested that whenever the root vole appears in a given macrohabitat, it can be characterized as a significant character species in the comparing studies of community ecology. Its typical indicator feature appears even if its individuals cannot be detected in a high proportion - this could be seen by the appearance of the species in the Halász-rét in 2005 as a good example. The eurasian pygmy shrew (S . minutus) - a typical species of marshy-moorish habitats - was a significant character species of two macrohabitat patches on the third level of the habitat hierarchy. The significant maximum character value of the wood mouse (A. sylvaticus) was typical in the Halász-rét in this quantitative data based analysis (Fig. 5). Discussion Nestedness pattern is most often used to explore the structure of communities (ATMAR & PATTERSON 1993, PATTERSON & ATMAR 2000, GANZHORN & EISENBEISS 2001), which has a great importance by the protection of meta-communities, where species loss decrease immediately the predictability of species composition (PATTERSON 1987, CUTLER 1991, BÁLDI 2003b). By analyzing mammal communities there were several case studies which described the nestedness, for instance islands within an archipelago (KRISTUFEK & KLETECKI 2007), isolated peaks along a mountain range (MCDONALD & BROWN 1992, HADLEY & MAURER 2001), habitat fragments within a landscape (PATTERSON & ATMAR 2000) and by the approach describing spatial distribution of species and interspecific interactions (BAKER & PATTERSON 2011). These studies have a great importance regarding both biogeographical, community ecological and environmental protection view points, and some of the previous works (e.g.: MCDONALD & BROWN 1992) draw the attention to the problems of using nestedness approach ( BÁLDI 2003a). Nestedness pattern can originate from many different factors such as extinction, colonization, disturbance, spatial distribution of habitats and hierarchical niche associations (PATTERSON & ATMAR 2000, BÁLDI 2003a). These processes have big significance related with the fragmented refuge relict wetlands, primarily by those habitat patches which are isolated on different levels and can be typified by different land-use intensity and the negative effects of considerable human disturbances prevail - these are important questions concerning several animal assemblages of the Kis-Balaton Landscape Protection Area in terms of environment protection and management activities. Because of the relict characteristic of Kis-Balaton marshlands the water-reserve system maintaining human interventions affect appreciably the biodiversity, thus the hypothesis-testing control of these effects are highlighted projects in the Hungarian Biodiversity Monitoring System (HBMS). Small mammal species abundances or community compositions - as disturbance indicators - have potential to be important tools for land- and conservation management to evaluate effects of disturbance (LEIS et al. 2008), therefore small mammals are important objects by the conservational monitoring of Kis-Balaton marshland area. In case there are relict, habitat specialist species in a fragmented, refuge community, then the latter effects can cause local extinctions, species turnovers and they may induce the alteration of the community structure. One goal of nestedness analysis has always been to identify such 'deviating' species and to infer the causes of idiosyncrasy ( ULRICH et al. 2009). ATMAR & PATTERSON (1993) explained the existence of idiosyncratic species by post-isolation immigration, geographic barriers and competitive exclusion. Because the base of the nestedness analysis
