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Small-scale distribution of wintering terrestrial snails in forest site : relation to habitat conditions

Szybiak K., Błoszyk J., Koralewska-Batura E., Gołdyn B.

Polish Journal of Ecology

2009

Vol. 57, nr 3

525-535

The aim of our study was to assess the small scale distribution (up to several m[^2]) of hibernating forest-dwelling snails in relation to small-scale environmental factors, like litter composition, soil temperature and humidity or vegetation cover. The study was conducted in the "Dębno nad Wartą" (local name) natural reserve, western Poland, in December 2006. A novel, cartographic method was applied for analysing and illustrating the small-scale distribution and habitat preferences of the snails. Four permanent study plots (15 m[^2]) were established in 50 m intervals. Each plot was divided in fifteen 1m[^2] squares, and from each square a litter sample was taken and analysed (60 samples in total). 17 snail species were recorded (6.13 species per plot; 0.8 per square). The distribution of particular species was clustered as its coefficients of variation were high (CV%> 150) as well as was the small-scale distribution of the total abundance of all the species (CV% = 122). The most uniformly distributed and frequent (C% of all samples) species were Trichia hispida (Linnaeus) (CV%= 153; C% = 45), Cochlodina laminata (Montagu) (206; 30) and Perforatella incarnata (O.F. Muller)(152; 37). Among frequent species the greatest value of CV% (425) and therefore the most patchy distribution was recorded for Ruthenica filograna (Rossmassler). According to the results of CCA, this species, together with Vitrina pellucida (O.F. Muller) (CV% = 296), and Clausilia bidentata (Strom) (CV% = 291), were the most stenotopic, wintering in specific microhabitats with low herb layer coverage, elm leaves prevailing in the litter and high percentages of hornbeam, ash, birch and alder leaves. In turn, for Perforatella rubiginosa (A. Shmidt) (CV% = 440) and Perforatella bidentata (Gmelin)(CV% = 440), also the species with patchy distribution - optimal wintering conditions were found in places with a higher soil temperature and the litter consisting mainly of oak leaves. The remaining snail species seem to be more eurytopic and winter in microhabitats with intermediate conditions. The results of the present study show that for the distribution of majority of species studied the most important factor is the proportion between the coverage of litter and herbaceous vegetation cover. The species richness of the malacocenoses studied strongly depends on the diversity of litter, since particular species prefer leaves of different trees.

Abundance and diversity of soil microarthropod communities related to different land use regime in a traditional farm in Western Norway

Gulvik M., Błoszyk J., Austad I., Bajaczyk R., Piwczyński D.

Polish Journal of Ecology

2008

Vol. 56, nr 2

273-288

Acari and Collembola are the dominant groups within the mycophagous arthropods linked to fungal-based food webs in undisturbed soils. Studies on soil microarthropod communities in old, traditional, multifunctional farmland, and studies on secondary succession following marginalization and abandonment of traditional farmland are lacking in Europe. Thus, we studied patterns of microarthropod communities related to different land use regimes in a traditional farm in Western Norway. Soil mesofauna communities were analysed at four sites: site OM - old, herb rich, open hay meadow in traditional use; site F1 - abandoned hay meadow with pollarded trees (first fallow); site F2 - deciduous woodland (abandoned hay meadow with old pollards, heavily overgrown, second fallow); and site RM - restored hay meadow with scattered, newly pollarded trees. The abundance of the taxa varied considerably between habitats (for instance: total microarthropods - from 112.4 [plus or minus] 11.4 to 29.2 [plus or minus] 3.4, Acari - from 83.9[plus or minus] 10.2 to 15.6[plus or minus] 1.8 and Oribatida - from 68.6[plus or minus] 9.5 to 8.2[plus or minus] 1.3 x 10[^3] m[^-2], for OM and RM sites respectively). The abundance of total Acari, total Oribatida, Oribatida adults and juveniles differed significantly between OM-F1, OM-RM, OM-F2 and RM-F2 sites and it was significantly correlated with continuity of land use and/or tree cover. Oribatida was the group with the highest densities and percentage dominance (except RM site). The percent contribution of total Oribatida in Acari abundance was negatively correlated with the percentage of Actinedida. Nine Ptyctimina species, six Nothroidea species and four Uropodina species were detected, but most of them occurred as single individuals. Abundance of three Ptyctimina [Atropacarus (Atropacarus) striculus (C.L. Koch), Phthiracarus ferrugineus (C.L. Koch), P. globosus (C.L. Koch)], and two Uropodina [Trachytes pauperior Berlese and Dinychus perforatus Kramer] species differed significantly between some sites. The percentage similarity (Renkonen index) has a high indicative value for measuring the distance between ecosystems with apparently similar communities of Uropodina. The OM and RM sites differed most and site pairs - F1-F2 and F1-RM were the most similar. The densities of some taxa were about two- or three-fold greater for the F1site than the RM site. Ratios of Acari to Collembola, total Oribatida to Collembola and total Oribatida to Actinedida were highest on OM site (3.2, 2.6, 11.8 respectively) and decreased in the following order: F2>F1>RM (as an example, total Oribatida to Actinedida ratios were 9.8 on F2 site, 6.2 on F1 and 3.1 on RM). These ratios differed significantly between the OM and RM sites. The lowest ratios on RM site are probably an effect of recent disturbance (change of land use) of this site. Our results suggest that soil in OM site, despite constant disturbance during long time (scything, hay raking and sheep grazing), has probably a stable mesofauna community with the highest abundance of Oribatida. Our results have provided new knowledge about ecosystems in traditional farmland and can be used in monitoring programmes of post-arable land.