Land-use Systems Impact on the Diversity and Abundance of Pheretima Group (Clitellata: Megascolecidae)

Abstract

Earthworms are widely distributed in Indonesia, especially in Sulawesi, which has high biodiversity and endemicity. The soil’s physical and chemical properties greatly influence the presence of earthworms. However, land conversion from natural habitats can potentially reduce the diversity of earthworm species. Until now, there has been no report on diversity of earthworms in Sulawesi. This study aims to provide baseline data on the diversity of earthworm and their relationship with soil properties in several habitats in the enclave Lindu, Sulawesi. This study was conducted in five habitats in the enclave Lindu, including primary forest, secondary forest, grassland, cacao plantation, and rural area. Samples were collected using digging and hand-sorting method and preserved in 4% formaldehyde for identification. Soil samples were collected using compositing method and analyzed in the laboratory. Species diversity was displayed through rarefaction and extrapolation curves, while the effect of soil properties on earthworm abundance was analyzed using Canonical Correspondence Analysis (CCA). The results showed that there were 269 individuals of earthworms belonging to 16 species from three genera, with four of them being endemic species. The distribution varied greatly between habitats, with primary forest having the highest species richness and diversity, while rural area recorded the lowest value. This variation indicates an influence of the soil properties on the abundance and distribution of earthworms. These finding reinforce that converting natural land to anthropogenic land reduces the diversity of earthworms, presumably due to changes in environmental conditions. Nevertheless, this study successfully identified several morphospecies that can become new species, indicating that Sulawesi still has excellent potential for discovering new taxa.