Short-term spider community monitoring after cattle removal in grazed grassland

Guilherme Oyarzabal Silva


At the Pampa Biome, grazing, like others disturbances, affects fauna, flora, creating heterogeneity in the environment. Little is known about how the diversity and richness of arthropods change during this impact. To improve the knowledge of how spider diversity is affected by grazing, experiments were realized at Pampa. The hypothesis is that abundance of spider will be different when comparing grazed and ungrazed areas. A paired block, with two areas of one hectare each, was established in three areas in APA do Ibirapuitã. One of these hectares was closed with fences, excluding the catle grazing, in August of 2012. Samplings were realized in November of 2011, 2012 and 2013 using Pitfall traps filled with formol 4% and disposed in an “X” format in each plot. For statistical analyses, T test, ANOSIM, ANOVA and Rarefaction were performed. A total of 1.315 spiders were captured, comprising 77 species and morphospecies of 21 families. The most abundant family was Lycosidae followed by Hahniidae, Linyphiidae and Theridiidae. Linyphiidae was the richest family with 14 species and morphospecies identified. All spiders, adults and juveniles, only adults in species and morphospecies, and most abundant species were used as models for statistics. These models revealed no significant difference between Treatments and Controls after three and 15 months of cattle exclusion.

Iheringia Série Zoologia

Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul

Rua Dr. Salvador França, 1427, 90690-000 Porto Alegre, RS, Brasil