The body size is one of the main attributes of living organisms. The knowledge of body size patterns of co-occurring species and the related factors can contribute to the understanding of many ecological processes. The aim of the study was the analysis of the distribution of the spider species of different size in heterogeneous forest habitats: ground, herbaceous vegetation, tree trunks and leaves. The research was conducted in deciduous stands of the Białowieża Forest (eastern Poland). Spiders were collected by: a) pitfall traps and sieving the litter through an entomological sieve for the ground layer; b) sweep-netting for herbaceous vegetation; c) bark traps for tree trunks and d) shaking the branches of trees and shrubs for leaves. In total, 247 spider species belonging to 22 families were recorded: 195 species in the ground layer, 122 in herbaceous vegetation, 60 on trunks, and 48 on leaves. The analysis revealed that ground layer was inhabited by the small sized species (mean 5.2 ± 0.11 mm) while larger species inhabited herbaceous vegetation (mean 6.6 ± 0.26 mm), trunks (7.2 ± 0.20 mm) and leaves (6.8 ± 0.41 mm). Moreover, the mean species body size decreased with the increasing number of collected species. Several potential mechanisms are discussed as those determining the preference of various sized spider species in particular habitats like different microclimatic conditions, the nutritional quality of prey and predation. Moreover, the very likely reason of differences in the size of spider species between the ground layer and other habitats is the most complex structure of the former habitat.
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We studied the species richness, diversity, abundance and guild composition of spider assemblages on the hummocks and in the hollows of the alder carr in the Białowieża National Park. We also assessed the effect of vegetation structure and soil humidity on spiders settled in these two microhabitats. The spiders were collected from 10 May until 27 October 2001 by pitfall trapping. The main factor which differed between the hummocks and the hollows was soil humidity. In the case of vegetation cover we found some differences between the microhabitats but it was particularly evident in the case of litter, which was higher on the hummocks. Spider species diversity was significantly higher on the hummocks than in the hollows, but the number of individuals captured in both microhabitats was similar. The collected spiders belonged to six guilds and the proportion of spider individuals in particular guilds was significantly different between the hummocks and the hollows. The most abundant guild in both microhabitats was ‘ground hunters’ and the most numerous species was Piratula hygrophila. Our analyses showed that soil humidity positively affected the number of spider species and the number of individuals. Sampling date strongly influenced the number of collected species and spider individuals. Vegetation and litter cover did not have a significant impact on the spider assemblages. Our findings suggest that research conducted only on hummocks in the alder carr does not reveal the real structure of spider assemblages.
W pracy przeanalizowano różnorodność gatunkową oraz liczebność flory segetalnej i owadów z rzędu prostoskrzydłych, występujących w zbożach ozimych uprawianych w systemie ekologicznym i konwencjonalnym. Badania przeprowadzono w 2012 r., na wybranych gruntach, użytkowanych zgodnie z zasadami rolnictwa ekologicznego oraz na działkach użytkowanych konwencjonalnie, zlokalizowanych na terenie województwa lubelskiego. Nie stwierdzono istotnych różnic w liczbie gatunków chwastów w uprawach ekologicznych i konwencjonalnych, ale zbiorowiska różniły się pod względem jakościowym. Spośród 95 wykazanych gatunków chwastów, 17 wystąpiło tylko w systemie ekologicznym, a 15 – wyłącznie w uprawach konwencjonalnych. Liczebność chwastów w uprawach zbóż ozimych w systemie ekologicznym była istotnie większa (o 45%) niż w uprawach konwencjonalnych. Nie stwierdzono istotnych różnic w bogactwie gatunkowym i liczebności owadów prostoskrzydłych, występujących w uprawach ekologicznych i konwencjonalnych, ale wystąpiły różnice w liczebności poszczególnych rodzin.
EN
The diversity of weed flora and Orthoptera insects in winter cereals cultivated in organic and conventional system was analyzed. The study was carried out in 2012 on selected organic and conventional fields in the Lublin voivodeship. There were no statistical differences in the number of weed species between organic and conventional fields, but there were qualitative differences between weed communities. From among 95 weed species, 17 occurred only on organic fields and 15 were found exclusively on conventional fields. The number of weeds in winter cereals cultivated in organic system was significantly higher (by 45%) than in conventional system. There were no significant differences in species richness and the number of Orthoptera insects between organic and conventional fields, but there were some differences in the number of individuals representing particular families of Orthoptera.
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Species – area (SAR) and species time (STR) relationships describe the increase of species richness with study area and study time and have received much attention among ecologists and are used in different branches of biodiversity research. Unknown sample size effects often hinder a direct comparison of SAR and STR shapes of different taxa and regions. Further, space and time interact during the accumulation of species due to the common sample universe. Here we develop a simple power function scaling model of species richness that integrates space, time, sample size and their interactions. We show that this model is able to precisely describe average species densities and the increase of species richness in a regional metacommunity of a large sample of spiders on Mazurian lake islands (Northern Poland). The model predicts strong area – sample size and time – sample size interactions. Judged from the SAR (z = 0.08) and STR (y = 0.64) slopes it points to only moderate spatial β–diversities but high local temporal species turnover. We suspect that the parameters of many published SARs are strongly influenced by unknown sampling time and sample size effects that make direct comparison difficult.
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