Species Richness and Density of Earthworms in Relation to Soil Factors in Olive Orchard Production Systems in Central Greece

Abstract

Earthworms can be used as bioindicators of soil management as they are easy to classify and very sensitive to changes of both physical and chemical soil parameters. The aim of this work was to study relations between earthworm species (richness and density) and the physicochemical soil properties such as pH, organic matter, soil moisture, and texture (percentages of sand, silt, and clay) under different farming practices (organic and conventional) in olive groves in central Greece. The data revealed significantly greater values of earthworm species richness, density, soil organic matter, and moisture in the organic olive groves than in the conventional ones. Furthermore, total earthworm density was positively correlated to earthworm Shannon diversity index, soil moisture, organic matter, nitrogen, phosphorus, and potassium in organic olive groves. However, total earthworm density was negatively correlated to soil pH and silt in conventional olive groves. It can be concluded that species richness and density of earthworms in olive groves can be considered as sensitive indicators of management practices.