Type of fixative solution in pitfall traps as a decisive factor affecting community parameters of Collembola (Hexapoda) inhabiting superficial subterranean habitats

Abstract

Vertical distribution of collembolan communities along a depth gradient was studied at three forested karst scree slopes in the Western Carpathians, differing in topography, microclimate, soil-chemical parameters, and forest associations. Two different fixative solutions were used in subterranean pitfall traps. The activity and species richness of Collembola in the vertical scree profiles were significantly higher in traps filled with ethylene glycol than in those filled with formaldehyde at all three sites. Using traps filled with formaldehyde, both Collembola species numbers and activity positively correlated with the soil moisture and carbon content, while for ethylene glycol traps this relation was the same only for species numbers and carbon content. Ecological groups of Collembola showed a different response, distinguished by the level of association to subterranean habitats, to environmental factors and to the fixation liquid used in the subterranean traps. Eutroglophiles, the forms relatively well-adapted to subterranean habitats, were associated with depth exclusively when using ethylene glycol traps. This implies that ethylene glycol is a more suitable preservative in terms of species richness and activity of Collembola in deeper scree layers compared to traditionally used formaldehyde. Thus, the effect of environmental factors on diversity and vertical distribution of Collembola in scree habitats may be substantially superimposed by the type of fixation used in subterranean traps.