Spiders (Arachnida: Araneae) in Agricultural Land Use Systems in Subtropical Environments

Abstract

Changes in land use management in agricultural areas can affect the biodiversity of spider families. This study aimed to evaluate spider diversity in different land use systems with capture by two sampling methods, and to identify soil properties that can modulate the occurrence of spiders. Five land use systems, representative of traditional agricultural areas, were evaluated in the west of Santa Catarina, Brazil, to establish a scale of land use intensity: native forest, eucalyptus reforestation areas, pastures, crop-livestock integration areas, and annual crops under no-tillage. The collection methods were manual from soil monoliths and soil traps. Altogether 479 individuals were captured, which were distributed among 20 families, 40 genera, and 8 species. Principal component analysis separated the land use systems and showed an association of spider families with land use in the two sampling methods. There was reduction in spider diversity as the intensity of land use increased. The manual collection method was more efficient for families of soil spiders, whereas traps were more efficient for epigeic spiders. The Lycosidae family was more resistant to environmental pressures, while Oonopidae and Amaurobiidae were more sensitive to environmental modifications. The differences in the spider communities were explained by the following soil properties: organic matter, mean weight-diameter of soil aggregates, and resistance to penetration, which were associated with the degree of anthropic intervention in the land use systems.

Soil spiders (Arachnida: Araneae) in native and reforested Araucaria forests

“…Since there are no historical records for these forests in relation to the true local diversity, these families can serve as indicators for discriminating environments (Figure 3 and Table 2) (Jung et al, 2008a, b). The band of families found with the highest frequency in this study is also among the most abundant group of spiders in most Brazilian soil ecosystems, thus corroborating their representativeness (Benati et al, 2005;Brescovit et al, 2004;Rosa et al, 2018a).…”

“…Organic matter is very important to the biological complexity in various ecological niches. The favoring of accumulation of surface litter in quantity and quality maintains the microclimate and moisture, as well as the diversity of microhabitats at this site and this is favorable to various soil organisms that are attracted by the diversity of plant residues, becoming potential prey for spiders (Malumbres-Olarte et al, 2013;Rosa et al, 2018a). Thus, the C-Lt, C-org and other parameter linkage to organic matter, become an indirect conditioner for the abundance of spider families.…”

“…Other factors can be influencing the composition of soil spider families, such as climatic condition (Mantyka-Pringle et al, 2015), floristic composition and diversity in the area (Jung et al, 2008b;Sabais et al, 2011), as well as the soil community as a whole, and are directly related to the spiders, either through the presence of food (such as springtails, mites and dipterans, which are important prey) (Gravesen, 2008;Pommeresche et al, 2013), or by the absence or presence of predators (Rosa et al, 2018a).…”

“…Only C-Lt had influence on the composition of the families associated with the NF for the winter. Therefore, Corinnidae was described as a family established in forests where temporal stability (over the periods) is greater (Rosa et al, 2018a) under different soil use systems. Here these spiders were found in the forest due to their habit of actively searching for prey (Lo-Man-Hung et al, 2011).…”

Collembola community structure under different land management in subtropical Brazil

“…Sampling was carried out in the winter (May 2013). The sampling took place at that time based on studies of the diversity of the edaphic fauna when, mainly, the richness of many arthropods show differences across land use systems (Machado, Oliveira Filho, Santos, Paulino, & Baretta, 2019; Ortiz et al, 2019; Pompeo et al, 2017; Rosa et al, 2015; Rosa, Santos, Brescovit, Mafra, & Baretta, 2018a, 2018b; Santos et al, 2018). In each system, using the three municipalities as true replicates (n = 3), nine points (central point) in a sampling grid (centered in a 1 ha plot) were georeferenced, distanced 30 m from each other and 20 m of border.…”