MICROHABITAT REQUIREMENTS OF FIVE RARE VERTIGINID SPECIES (GASTROPODA, PULMONATA: VERTIGINIDAE) IN WETLANDS OF WESTERN POLAND

摘要

Microhabitat requirements of five vertiginid species - Vertigo angustior, V. moulinsiana, V. pygmaea, V. substriata and Columella edentula - were studied in two wetland areas of western Poland; two of the species, V. angustior and V. moulinsiana, are respectively listed as "near threatened" and "vulnerable" according to the IUCN red list. Data on the species and their habitats were collected biweekly during spring and summer months in 2008 and 2009 along four permanent transects at each site. Factors influencing the distribution of vertiginids were examined using Canonical Correspondence Analysis and Canonical Varieties Analysis. A variance partitioning approach was used to determine the influence of groups of factors. The small-scale distribution of the vertiginids was strongly influenced by specific environmental conditions. Both abiotic microhabitat characteristics and vegetation structure significantly influenced the composition of the studied malacocenoses. The most important factors were: litter moisture, shading, ground water level and the abundance of the following plants species: Carex acutiformis, Thelypteris palustris, Lysimachia vulgaris and Urtica dioica. Within the habitats covered by the study, abiotic factors were more important than vegetation composition, although the influence of two groups of variables was partially overlapping.