Investigating the Impacts of Agricultural Land Use on Soil Earthworm Communities: A Case Study of Northern Zagros

Abstract

The earthworm is an essential part of the soil's invertebrate community, as they contribute to the total belowground biomass and the biogeochemical cycle of the soil. Recent studies indicate the adverse effects of environmental stresses, including human activities and land-use change on the abundance and diversity of earthworms. The land-use type has a significant impact on earthworm abundance and composition in agricultural ecosystems. In this study, we investigated the impact of agricultural land use and pastures on the genetic diversity of earthworms in the Northern Zagros Mountains by using COI molecular marker and DNA barcoding as well as Multiple Factor analysis methods. We sampled six pasture and four farmland sites. We assessed the abundance and OTU composition of earthworm communities across pastures and farmlands by quadrats. In addition, we compared two types of land uses. For recognizing the OTUs, we used the barcoding method. Our results indicated 13 OTUs among captured earthworms. According to our findings, the number of total OTUs, density, and earthworm communities have changed between the two land uses. Overall, this study showed the benefit of using barcoding to recognize earthworms. The species of earthworms were sensitive to the cropping system. The endogenous and smaller species from the Lumbricidae family were dominant in the farming system. In cultivation systems, chemical inputs and organic materials from plant residues, cover crops, manure applications or organic fertilizers determine the population of invasive species of earthworms. More research on the effect of cultivation methods, crop rotation, and crop residue management on the diversity and population of earthworms is necessary.

Keywords: Oligochaeta, Biodiversity, OUT, Barcoding, Land-use