Diversidade de aranhas (Arachnida: Araneae) edáficas em áreas cultivadas sob sistema plantio direto com e sem terraceamento e fragmento de floresta nativa

Abstract

Land use and management can significantly impact the conservation of edaphic spider biodiversity, which are of great ecological importance. Therefore, this study aimed to evaluate the structure of the Araneae assemblage in areas subjected to a no-till system with and without terracing and an area of native forest fragment. The study was carried out at the Federal Technological University of Paraná, on the Dois Vizinhos campus, in three different areas: a no-till system with terracing (SPDT), a no-till system without terracing (SPDS) and a native forest fragment (FN). Sampling took place once a year in October, from 2020 to 2023, with the installation of 32 pitfall traps in each area, which remained in the field for seven days, with subsequent classification of the order Araneae at the taxonomic level of family. A total of 1.836 spiders were identified, 600 in 2020, 718 in 2021, 303 in 2022 and 215 in 2023, distributed in 21 families and 13 guilds. In 2020 and 2021, the SPDT and SPDS areas did not differ statistically in abundance and richness, only when compared to the FN. The same occurs for the Simpson index (1-D). In 2022, there was only a significant difference in abundance between SPDS and FN. However, there were no significant differences between the areas for richness and Simpson index (1-D). In 2023, there was no statistical difference in any areas for abundance, richness or Simpson index (1-D). The permutational multivariate analysis of variance and the non-metric scaling analysis indicated similarity in the composition of the edaphic spider assembly between the SPDT and SPDS areas, attributing dissimilarity only when compared to the FN. Principal component analysis (PCA) in 2020 explained 26.86% of the total variability of the data, showing a greater association between the families Linyphiidae and Theridiidae with the SPDT area, Salticidae with SPDS and Zodariidae and Dipluridae with FN. In 2021, the analysis explained 33.9% of the total variability; the families Linyphiidae and Theridiidae showed the most significant association with the SPDT area, Salticidae with SPDS and Zodariidae, Dipluridae and Gnaphosidae with the NF area. Although in 2022, the PCA explained 44.2% of the total variability, there was no clear differentiation between the agricultural areas. However, the families Zodariidae, Dipluridae, Gnaphosidae and Amaurobiidae were associated with the FN area. In 2023, the analysis explained 31.7% of the total variability of the data, indicating a greater association between the Lycosidae families and the SPDT area, as well as Zodariidae, Oonopidae, and Caponiidae with SPDS, and Linyphiidae with FN. The results suggest that no-till farming has influenced the similarity in the diversity of the spider assemblage between the agricultural areas over the years, despite the adoption of terracing in the SPDT. However, the FN area had a family distribution strongly associated with the quality and structural complexity of the vegetation.