© Senckenberg Museum of Natural History Görlitz · 2015 ISSN 1864-6417 pp. 85–89 SHORT COMMUNICATION Short note on enchytraeid occurrence in deep layers of urban soils Jiří Schlaghamerský Masaryk University, Faculty of Science, Department of Botany and Zoology, Kotlářská 2, 611 37 Brno, Czech Republic E-mail: jiris@sci.muni.cz Received 27 February 2015 | Accepted 10 June 2015 Published online at www.soil-organisms.de 1 August 2015 | Printed version 15 August 2015 87 (2) · August 2015 1. Introduction Most soil organisms require aerobic conditions and access to carbon as a source of energy and building material for their bodies. Therefore, in soils of most terrestrial ecosystems animals are concentrated in the upper 10–15 cm layer and few individuals of few species occur below 50 cm depth. Where plant roots or earthworm tunnels reach further down, also other soil organisms follow along these rather thin structures, i. e. the rhizo- and drilosphere (Lavelle & Spain 2005). Exceptions where a more general colonization of soil into greater depth occurs are dry grasslands and arable fields. Ploughing relocates substantial amounts of dead organic matter into greater depth whereas the upper soil is more exposed to desiccation and freezing, resulting in a more even distribution of soil organisms along the vertical profile and their penetration in considerable numbers at least down to the plough pan. Also buried soil horizons with adequate dead organic matter content might host soil organisms as long as some exchange of soil air provides enough oxygen (Gurwick et al. 2008). Such buried horizons are typical of alluvial soils. Buried soil horizons or buried layers or pockets of humus-rich soil or of other organic materials can also be found in urban soils as a consequence of land reclamation, landscaping, construction activities, dumping of waste etc. However, most samplings for soil fauna have been limited to the upper soil layer of some 8 to 15 cm based on the general experience that further down numbers of soil fauna are negligible (and also due to the fact that extracting soil cores reaching further down can get difficult even in deeply weathered soils). This all applies also to the vertical distribution of potworms or enchytraeids (Annelida: Clitellata: Enchytraeidae), that are a numerically and functionally important part of soil mesofauna. Very few data are available about the occurrence of enchytraeids below 20 cm soil depth (see Discussion). Although enchytraeids reach only low densities in deep soil and their occurrence is clustered based on the availability of sources of organic matter (Dózsa-Farkas 1992), their occurrence still shows that they find food and participate in decomposition processes at substantial depth. Deeper layers might also host specialized species hitherto unknown to science (Dózsa-Farkas 1991). As part of an environmental assessment project, samples of anthroposols were taken from several sites in the Swedish city of Malmö at three different depths down to 2 m below ground. Soil samples were examined to find out if they contained enchytraeids and if so what species and in what numbers were present. Unfortunately, only little information about the project and sampling sites was available to the author; presented background data are mostly based on Törneman (2014). Nevertheless this was a rare opportunity to investigate the possibility of soil animal live in urban soils at substantial depth. 2. Material and methods In October 2012, five sites in the city of Malmö in southern Sweden were sampled, covering reclaimed land areas at the sea front as well as old industrial and residential land, currently used as urban greens of various types and sizes (Tab. 1). At each site one pit was dug and soil was sampled from layers defined by three depth ranges: 0.1–0.5 m, 0.6–1.0 m and 1.6–2.0 m (for the exact ranges actually sampled at the individual sites see Tab. 1). The individual samples were put into plastic