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Abstract:
There is much interest in the identification of the main drivers controlling changes in the microbialcommunity that may be related to sustainable land use. We examined the influence of soil proper-ties and land-use intensity (N fertilization, mowing, grazing) on total phospholipid fatty acid (PLFA)biomass, microbial community composition (PLFA profiles) and activities of enzymes involved in the C,N, and P cycle. These relationships were examined in the topsoil of grasslands from three German regions(Schorfheide-Chorin (SCH), Hainich-Dün (HAI), Schwäbische Alb (ALB)) with different parent material.Differences in soil properties explained 60% of variation in PLFA data and 81% of variation in enzyme activ-ities across regions and land-use intensities. Degraded peat soils in the lowland areas of the SCH withhigh organic carbon (OC) concentrations and sand content contained lower PLFA biomass, lower concen-trations of bacterial, fungal, and arbuscular mycorrhizal PLFAs, but greater enzyme activities, and specificenzyme activities (per unit microbial biomass) than mineral soils in the upland areas of the HAI and ALB,which are finer textured, drier, and have smaller OC concentrations. After extraction of variation thatoriginated from large-scale differences among regions and differences in land-use intensities betweenplots, soil properties still explained a significant amount of variation in PLFA data (34%) and enzymeactivities (60%). Total PLFA biomass and all enzyme activities were mainly related to OC concentration,while relative abundance of fungi and fungal to bacterial ratio were mainly related to soil moisture.Land-use intensity (LUI) significantly decreased the soil C:N ratio. There was no direct effect of LUI ontotal PLFA biomass, microbial community composition, N and P cycling enzyme activities independentof study region and soil properties. In contrast, the activities and specific activities of enzymes involvedin the C cycle increased significantly with LUI independent of study region and soil properties, which canhave impact on soil organic matter decomposition and nutrient cycling. Our findings demonstrate thatmicrobial biomass and community composition as well as enzyme activities are more controlled by soilproperties than by grassland management at the regional scale.
