In the period 1997-1998, the Flemish Forest Service funded a study (B&G/29/98) that initiated a region-wide soil fauna survey by a consortium of three Universities (RuG, KuL and UA; now University of Ghent, KU Leuven and University of Antwerp) and two Research Institutes (IBW and RBINS; now INBO and RBINS ) . The survey was conducted on 56 well selected forest plots representative for all forest- and soil types in Flanders Region. The goals of the study were (1) to assess the diversity of soil dwelling organisms (soil fauna) across Flanders’ forests; (2) to look for bioindicators for forest soil quality and (3) to explore if a biological forest soil classification system based on soil fauna composition could be designed. Recognizing the critical role of soil organisms in ecosystem functioning (e.g. nutrient cycling), the study sought to establish a link between soil biodiversity and soil condition. Here we publish the Collembola data sampled in this initial project, as a T0. Over time, other organism ...