Recommendations for assessing earthworm populations in Brazilian ecosystems

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.

摘要：蚯蚓通常与肥沃土壤密切相关，同时也常被用作环境质量指示物。然而，若要优化其作为生物指示物的应用价值，必须结合调控蚯蚓群落的环境与人为变量，对蚯蚓种群开展评估。本综述旨在梳理124项已发表研究中的评估内容，涵盖蚯蚓采样方法、土壤理化属性及环境与人为特征；这些研究在巴西765个涵盖不同气候、土壤类型、土地利用与管理模式的样点中，量化了蚯蚓的种群丰度，累计样本量超7300份。相较于采样日期、海拔、气温、降水量、气候与土壤类型、土地利用等环境变量（报道率≥50%），除pH外的土壤理化属性的报道率较低，仅≤50%的研究涉及该类内容。蚯蚓的物种鉴定率极低，仅为24%；且仅有31%的研究测定了其生物量，尽管多数研究提供了较为完整的采样方案信息。基于调控蚯蚓种群的关键变量的重要性，本研究提出了一套在研究蚯蚓群落及其他大型土壤动物类群时应纳入评估的变量体系。该体系将有助于指导巴西及其他国家未来的蚯蚓相关研究，优化数据收集流程与研究可重复性，推动不同研究间的横向对比，并促进蚯蚓作为土壤质量生物指示物的应用推广。