Abstract
Abstract: Earthworms are often related to fertile soils and are also frequently used as environmental quality indicators. However, to optimize their use as bioindicators, earthworm populations must be evaluated together with the environmental and anthropogenic variables regulating their communities. This review sought to identify the earthworm-sampling, soil chemical and physical, and environmental and anthropogenic attributes evaluated in 124 published studies that quantified earthworm abundance (>7,300 samples) in 765 sites with different types of climate, soils, land use, and management systems in Brazil. Soil chemical and physical attributes (except pH) were less reported (≤50% of studies) than other environmental variables such as sampling date, altitude, temperature, precipitation, climate and soil type, and land use (>50% of studies). Earthworms were rarely identified (24%) and few studies (31%) measured their biomass, although most provided adequate information on sampling protocol. Based on their importance in regulating earthworm populations, a set of variables is proposed to be evaluated when studying earthworm communities and other macrofauna groups. This should help guide future studies on earthworms in Brazil and other countries, optimize data collection and replicability, allow comparisons between different studies, and promote the use of earthworms as soil quality bioindicators.
Highlights
Earthworms are among the most well-known soil animals, being ecosystem engineers (Jones et al, 1994; Lavelle et al, 1997) that actively contribute to many ecosystem services, including carbon sequestration and gaseous exchanges, plant production, and erosion control, as well as soil genesis, decomposition, and nutrient cycling (Stockdale & Watson, 2012; Jouquet et al, 2014; Brown et al, 2015)
The community and abundance of earthworms at a given location are controlled by several biotic and abiotic factors, which act at different spatial scales (Figure 1) and include: climatic conditions, such as climate type, especially precipitation and temperature; soil properties, mainly its type and chemical and physical conditions, among which stand out pH, organic matter, moisture, and texture; vegetation, indicating the type of ecosystem, primarily plant cover; and history of the site, human activities and geological processes (Reynolds & Jordan, 1975; Brown & Domínguez, 2010)
At the lowest spatial scale, i.e., within a soil profile of a particular site, it is mainly the soil physical and chemical characteristics that affect the soil as a habitat for earthworms and the interactions with other organisms that can affect earthworm populations (Brown & Domínguez, 2010)
Summary
How to cite NADOLNY, H.; SANTOS, A.; DEMETRIO, W.; FERREIRA, T.; MAIA, L. dos S.; CONRADO, A.C.; BARTZ, M.; GARRASTAZU, M.; SILVA, E. da; LAVELLE, P.; BARETTA, D.; PASINI, A.; VEZZANI, F.; SOUSA, J.P.; CUNHA, L.; MATHIEU, J.; RÖMBKE, J.; BROWN, G.
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