Navegando por Assunto "Aracnofauna"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Inventário da araneofauna (Arachnida, Araneae) de serapilheria na Estação Científica Ferreira Penna, Pará, Brasil
(Universidade Federal do Pará, 2004-03-02) BARREIROS, José Augusto Pereira; BONALDO, Alexandre Bragio; http://lattes.cnpq.br/8721994758453503
The Ferreira Penna Scientific Station (ECFP), with near 33.000 ha, is located at Caxiuanã National Forest, Pará state, Brazil. A structured protocol of ground litter spiders sampling resulted in 400 samples of 1m² concentrated litter, from both rainy and dry seasons. The spiders were sorted by a combination of manual sorting and Winkler device techniques. These samples were obtained in five plots, three located in Terra Firme (dryland) forest (LBA-EXP, LBA-CON and TF-IMC) and two in igapó (wetland) forest (IG-N and IG-S). One of the Terra Firme plots (LBA-EXP) is under hidric stress and it was used plastic panels and gutters to exclude most of the rainfall. A total of 2230 individuals (mean: 5,6 individuals / m²), beionging to 34 families, were collected. Seven families were represented only by juveniles: Nesticidae, Pisauridae, Gnaphosidae, Mimetidae, Deinopidae, Oxiopidae, Uloboridae. The most abundant families were Salticidae, Theridiidae, Ctenidae, Oonopidae and Linyphiidae. 876 adults, beionging to 120 species or morphospecies in 27 families were sampled. The most abundant species were Styposis sp.3 (Theridiidae), with 16,55% of all adults, Anapisona sp.1 (Anapidae), with 6,96%, Meioneta sp.1 (Linyphiidae), with 6,39%, Oonopidae sp.1, with 5,59% and Salticidae sp.1, with 4,56%. In order to implement the majority of the analysis, 15 occasional species were excluded. The observed species accumulation curves for all samples and for the samples from each plot didn't reach the asymptote in the end of samples addition. The patterns of abundance and incidence of these species suggest the existence of total species richness from 123 to 184 species. The largest species richness estimates were from plot LBA-EXP (75 - 110 species). The smallest ones were observed at plot IG-N (25 - 59 species). Despite the species richness and the abundance of spiders had reached the largest values at plot LBA-EXP, the overall diversity was larger at plots LBA-CON and TF-IMC. The Igapó overall diversity was lower than in Terra Firme. The species composition was different in Terra Firme and Igapó habitats, as demonstrated by similarity indexes and percentage complementarity. The abundance and species richness of litter spiders increased in dry period and decreased with the raising of soil residual humidity.
Acesso aberto (Open Access)
Inventário de aranhas (Arachnida, Araneae) em quatro fitofisionomias da serra do cachimbo, Novo Progresso, Pará, Brasil
(Universidade Federal do Pará, 2005-03-04) RICETTI, Janael; BONALDO, Alexandre Bragio; http://lattes.cnpq.br/8721994758453503
A inventory of the spider fauna was carried out at Serra do Cachimbo, inside the "Campo de Provas Brigadeiro Velloso", Novo Progresso municipality, Pará state, Brasil. Two expeditions were made, during both dry (August and September, 2003) and wet (March and April, 2004) seasons. Three collectors participated in each expedition. The sampling effort, represented by 240 samples, was divided through the following methods: beating tray and sweeping net (96 samples); nocturnal hand search (96 samples) and concentrated litter sorted by a combination of hand search and Winkler extractors (48 samples). The spiders assemblages from four vegetation types (open rainforest, Formiga river's riparian forest, arboreal savanna and white sand vegetation) were compared. A total of 4964 spiders were obtained, from which 2724 adults, resulting in 397 recognized morpho-species in 37 families. The most abundant families were Theridiidae, Salticidae and Araneidae and the ones with more species were Salticidae, Araneidae e Theridiidae. The singletons represented 40% of the total species richness and only two species presented more than 100 individuals. The estimated richness species curves reached from 473 (bootstrap) to 674 (jackknife2) species. The higher alpha-diversity (Shannon-Wiener index) was observed in open rainforest, followed by Formiga river's riparian forest, white sand vegetation and arboreal savanna. the higher beta-diversity (Jaccard and Morisita-Horn indexes) was observed between Open rainforest and white sand vegetation and the lowest one was between open rainforest, arboreal savanna and Formiga river's riparian forest. The dry season presented more species than the wet season. However, no such difference was detected in white sand vegetation. A principal component analysis revealed that some species are linked to arboreal vegetations and others are linked to the open vegetation in white sand. Those differences in diversity and taxonomic composition between the various vegetations can be explained by drifts in availability of food items (preys), space resources (refugees and substratum to web attachment), as well as micro-climatic factors (temperature and moisture) of a given vegetation type. The most experienced conectar sampled more species than any other collector and all less experienced collectors sampled similar number of species. The differences in abundance among samples obtained by each conectar were not significant. The night hand sampling was the most efficient technique regarding the detection of differences in species richness among vegetation types. The methods beating tray/sweep net and litter sampling do not showed any significant difference in relation to species richness.