Evaluation of sampling techniques and influence of environmental variables on ants in forest fragments in an oil extraction area in the Amazon

Abstract

Around the world, urban landscapes are environments modified by man, generally related to low diversity. The efficiency of a biodiversity inventory is linked to the choice of the sampling technique since the taxonomic and ecological responses of the taxons vary between methods. Here we investigate differences in the ant’s composition sampled using three different techniques in two fragments of the urban forest in the Brazilian Amazon. We also assessed whether the different techniques maintained the same ecological responses. We sampled 12 collection points at each fragment, at vegetation, and manual collection and Winkler extractor on the ground. At the same points, soil samples were collected to determine their granulometry, pH, and concentrations of organic matter, sodium, phosphorus, and potassium. We collected 115 taxa and 4720 ants. The Cururu was the richest site with more species in general, as well as in the techniques of manual collection and Winkler. We detected a complementary effect on sampling techniques, which collected different ants’ assemblages. The potassium concentration positively influenced the assemblage’s composition, but its effect varies according to the sampling techniques used. The studied fragments revealed diversity very similar to those registered in continuous Amazonian forests. The use of sampling techniques together improves the representation of the diversity of ants in the studied fragments. Edaphic environmental variables seem to have a predominant effect on ants, affecting their distribution in the landscape even in urban fragments. This highlights the importance of urban forest fragments and their inherent ecological processes.

Gamma, alpha, and beta diversity of ant assemblages response to a gradient of forest cover in human‐modified landscape in Brazilian Amazon

“…The difference between estimated and observed number of species (57%‐170%) and sampling completeness were moderate (36.07%‐63.36%). However, these patterns of species accumulated curve and sampling completeness are recurrent fact in ant assemblages diversity studies (Leal et al, 2012; Souza & Araújo, 2020). Although there is overlap among the species accumulation curves, this mainly happen among sampling areas with similar forest cover (e.g., 96.55 – 100%), which markedly accumulated more ant species than those with lower forest cover (e.g., sampling areas 10 and 11, respectively, with 13.31 and 24.58%) (see Figure S1).…”

Sampling techniques and environmental variables influence the distribution of pseudoscorpions in urban forest fragments in the central Amazon

“…We also collected environmental variables related to soil (clay content, pH, organic matter, sodium, phosphorus, and potassium concentration) due to their influence on invertebrates in previous studies in the Amazon region (Aguiar et al 2006;Tarli et al 2014;Dambros et al 2017;Souza and Araújo 2020;Torres et al 2020). In each fragment, 12 soil samples were collected along the aforementioned transects (same points as for Berlese and Winkler samples) using an auger.…”

“…Soil characteristics and vegetation structure are the most frequently tested predictors in distribution models of edaphic organisms (Costa et al 2015;Dambros et al 2020). Environmental factors such as soil texture and chemistry generate microhabitat variability that can affect the spatial distribution pattern of invertebrates at local scales (Mezger and Pfeiffer 2011), as has been determined in the Amazon for oribatid mites (Moraes et al 2011), cockroaches (Tarli et al 2014), termites (Dambros et al 2017), and ants (Souza and Araújo 2020;Torres et al 2020).…”

Community structure of ants (Hymenoptera: Formicidae) in an open habitat: the importance of environmental heterogeneity and interspecific interactions

“…The collection of ants from the plants was performed using the beating technique with capture in entomological umbrella. Thus, 3 branches of similar size and shape of each plant were beaten 10 times and the dislodged insects were collected in the entomological umbrella (Kuchenbecker & Fagundes, 2018;Souza & Araújo, 2020). This was done in the morning from 8 to 11 h. All insects sampled from each plant were properly conditioned in individual plastic containers and transported to the Laboratory of Conservation Biology of the State University of Montes Claros, where they were screened.…”

“…Vegetation traits, such as plant size, canopy cover and abundance and richness of plant species have been used as environmental heterogeneity measures to explain ant diversity (Fonseca & Benson, 2003;Queiroz et al, 2017;Silva et al, 2017). In general, more heterogeneous habitats have greater diversity of ants because they have more microhabitats for nesting and greater availability of food resources (Davidson et al, 2003;Fonseca & Benson, 2003;Souza & Araújo, 2020). Positive relationship between ant species diversity and habitat heterogeneity seems to be a common phenomenon, but some studies also have shown negative or absence of a relationship between habitat heterogeneity and ant species diversity (Lassau & Hochuli, 2004;Ribbons, 2014).…”