Soil microbial indicators across land use types in the river oasis Bulgan sum center, Western Mongolia

Rapid land use modifications affect the scarce agroecological resources of the river oasis Bulgan sum center in the Altay Mountains, Western Mongolia. In our study we hypothesize that soil microbial indicators are sensitive to current management effects and allow to identify different land use types. To test this hypothesis we analyzed the topsoil of six typical land use types (pediment rangeland, degraded cropland, floodplain rangeland, irrigated horticulture, irrigated seabuckthorn (Hippophae rhamnoides L) plantations, irrigated meadows) for soil biological and physico-chemical properties. Microbial biomass carbon (C) showed a maximum of 816 mu gg(-1) soil at the floodplain rangeland sites and was with 228 mu gg(-1) soil lowest at seabuckthorn and pediment sites. At the pediment sites, however, microbial biomass C as % of soil organic C (SOC) was highest with 9.5% while only 2.1% were measured at the irrigated seabuckthorn and meadow sites. At the latter sites, the highest contribution of 0.45% ergosterol to microbial biomass C was found whereas only 0.02% was measured at the pediment sites. The metabolic quotient qCO(2) formed two groups; one varied around 49 mg CO2-C g(-1) microbial biomass C d(-1) at the seabuckthorn and meadow sites and one around 16 at the other four sites. In conclusion, cultivated and irrigated sites, especially the seabuckthorn sites, had less microbial biomass and substrate use efficiency but more saprotrophic fungi than non-cultivated sites. (C) 2017 Elsevier Ltd. All rights reserved.