Effects of animal manure application on springtails (Collembola) in perennial ley

The density and diversity of springtails (Collembola) in the upper soil layer (0-3.8 cm) were studied in a perennial grass-clover ley in NW Norway during April-June 2012. The study was part of a field experiment comparing yields and soil characteristics after application of non-digested slurry (NS) versus anaerobically digested slurry (DS) from dairy cows. In total for three sampling dates, 39 species of springtails were identified. In the Control plots receiving no manure, the density level was around 30 000 individuals (ind.) m (2) throughout the whole season. Three days after slurry application (40 t ha (1)), the density of springtails had dropped significantly; from 55 214 to 7410 ind. m (2) in the NS treatment and from 41 914 to 10 260 ind. m (2) in the DS treatment. After 7 weeks the densities had increased again to 54% and 38% of the initial levels in NS and DS treatments, respectively. The springtails were divided into two ecological groups based on morphology and colour. The epigeic group comprised surface-dwelling species with eye organs and pigmentation. The endogeic group comprised soil-dwelling species lacking eye organs and pigmentation, and generally with shorter extremities than those found in the epigeic group. The negative effect of manure application on density was more severe and long-lasting in the epigeic than in the endogeic group. This effect was similar for both manure types. One species (Parisotoma notabilis) comprised 50% of the epigeic population, while three Mesaphorura spp. and Stanaphorura lubbocki comprised half the endogeic population. In general, the community structure, described by the relative abundance of each species, was more affected by manure application in the epigeic than in the endogeic group. Hence, slurry application seemed to affect surface-dwelling species more negatively than soil-dwelling species, even within the small sampling depth used here. The density of endogeic species seemed to recover faster than the density of the epigeic species. A simplified classification of epigeic and endogeic springtails, based on the presence or absence of pigmentation and eyes, may be useful in studies of soil springtails where identification of the actual species is not the primary purpose. (C) 2016 Elsevier B.V. All rights reserved.