Annual dynamics of the earthworm Hormogaster elisae (Oligochaeta, Hormogastridae) in central Spain

A population of an endogeic earthworm Hormogaster elisae (Oligochaeta, Hormogastridae) from the area known as El Molar (Madrid, Spain) was studied by sampling over 12 months. Annual rainfall in the area is low, amounting only to 411 mm. Rainfall is distributed irregularly with two rainy periods alternating with two dry ones. The H. elisae population varies according to rainfall and increases during wet periods. Individuals of all developmental stages are present throughout the year and two recruitment periods can be distinguished during the rainy periods. The presence of mature individuals of H. elisae is high throughout most of the year. This fact together with other characteristics of the species suggests that H. elisae portrays a K type reproductive strategy. H. elisae population moves within the soil profile according to its humidity contents, with the population present near surface soil during humid months and in deeper soil during dry months.