The soil food webs in this collection represent a total of 32 belowground communities studied by Neutel et al. (2007), from two natural successions in sandy dune soils: one on the Waddensea Island of Schiermonnikoog in the north of the Netherlands and the other at Hulshorsterzand, on the Veluwe, in the central Netherlands. The study sites, which constitute the two gradients, represent four consecutive stages in chronosequences of early primary vegetation succession, increasing in aboveground and below-ground productivity. The Jacobians of the 32 food webs (two series, four stages with four replicates per stage) were calculated by Neutel et al. (2007) from observed average biomass data of the respective systems, and inferring steady-state biomass flow data using a procedure described by Hunt et al. (1987). The Jacobians represent the interaction strengths of the species in the two food webs, evaluated at equilibrium.

The Antarctic food webs represent two entire above-belowground communities from Signy Island Reference Sites on Signy Island, one of the South Orkney Islands in the Maritime Antarctic. The two communities are a dry moss community (Antarctic dry tundra) and a wet moss community (Antarctic wet tundra). These two communities were the focus of intensive biological study by personnel from the British Antarctic Survey over the course of a decade in the 1970''s, of which the results were finally compiled into a meta-analysis by Davis (1981). The Jacobians of the dry and wet tundra were calculated by Neutel and Thorne (2014) using the empirical biomass and flow data of the respective systems from Davis'' analysis. The Jacobians represent the interaction strengths of the species in the two food webs, evaluated at equilibrium.

The soil food webs in this collection represent seven belowground communities from native and agricultural soils. The seven communities are from experimental research sites in the USA, Sweden and the Netherlands. The Jacobians of the seven food webs were calculated by de Ruiter et al. (1995) using the empirical biomass data of the respective systems, and inferring steady-state biomass flow data using a procedure described by Hunt et al. (1987), see further references below. The Jacobians represent the interaction strengths of the species in the two food webs, evaluated at equilibrium.