Ecological Indicators (Jun 2024)
Earthworms’ role in the management and regulation of croplands: Comparative research on field and laboratory studies revealed by bibliometric analysis
Abstract
Environmental changes in croplands pose new threats to earthworms, one of the most well-known soil biota. In this study, we conducted a comparative bibliometric analysis of experimental studies on earthworms in croplands at the field and laboratory scales by identifying the evolution of research topics and knowledge domains over the past 30 years (1992–2022). The results showed that field studies constitute an overwhelming majority of field studies compared to laboratory studies, and a balance has gradually been achieved in the last five years. Representative institutions and authors at the field and laboratory scales were identified. Clustering of the co-citation references indicated that field studies have concentrated on the role of earthworms in crop production in the early stages, such as soil fertility, soil structure, and disease control. Intensive conventional agriculture has caused soil degradation, excessive pollutants, and habit loss, which pose great threats to earthworm biodiversity and other belowground and aboveground organisms preying on earthworms. Earthworms also play an important role as bioindicators in field research, mainly for soil health and ecosystem services. However, the high heterogeneity of field conditions and patchy distribution of earthworms in space and time hinders their use. Earthworms occupy a vital position in laboratory-scale ecotoxicological studies. The use of earthworms to evaluate the ecological and environmental effects of agricultural amendments and toxic substances on agricultural ecosystems is a major concern. Current insights into the DNA molecules and immune systems of earthworms can provide useful biomarkers for field conditions. Multi-contaminations and chronic and intergenerational exposure studies will help bridge this gap in extrapolating laboratory results into the field. In addition, research on the interactions between earthworms and microorganisms regarding the fate, species, and transformation of pollutants is still relatively limited and may provide theoretical support for remediation by earthworms. Overall, this comparative study provides a better understanding of the relationship and applicability of research methods, which could benefit the design of soil management systems that consider the value of earthworms in counteracting threats and challenges in today’s agricultural systems.
