Soil Fauna-Indicators of Ungrazed Versus Grazed Grassland Ecosystems in Romania

In order to establish the influence of grazing regime on soil fauna communities, a complex study was conducted on eight mountain grasslands in Romania. The grassland sites were grouped by management regime: ungrazed or intensely grazed by sheep. Eight environmental factors were measured, both abiotic (soil acidity, soil resistance at penetration, soil and air humidity, soil and air temperature, and soil electrical conductivity) and biotic (vegetation coverage). There was significant variability in the average values of these factors at the microhabitat level (between all grasslands investigated). Analysis of eighty soil samples allowed for the identification of sixteen soil fauna taxa, which constituted the database for statistical processing. The community status of these soil invertebrate faunas was mainly evaluated using three parameters: numerical abundance, taxa richness, and Shannon–Wiener index of diversity. Collembola and Oribatida were the most dominant taxa. The numerical abundance and taxa diversity recorded high values in ungrazed grasslands. Soil resistance at penetration, vegetation coverage, and soil pH influenced the numerical abundance of soil fauna communities significantly. Grassland management influenced the composition of soil invertebrates in both regimes, with Chilopoda, Staphylinidae, Diplopoda, and Enchytraeidae clearly preferring ungrazed ecosystems, whilst Mesostigmata was much commoner in grazed sites. The study revealed that correlations between the species composition of soil communities and environmental parameters under differing management regimes (ungrazed vs. grazed), demonstrated that these invertebrates can be used as bioindicators in such terrestrial ecosystems.