Response of microbial community composition and activity in agricultural and grassland soils after a simulated rainfall

摘要: Rainfall in Mediterranean climates may affect soil microbial processes and communities differently agricultural vs. grassland soils. We explored the hypothesis that land use intensification decreases resistance of community composition activity to perturbation. Soil carbon (C) nitrogen (N) dynamics responses a simulated Spring rainfall were measured ecosystems. The California ecosystems consisted two paired sets: annual vegetable crops Salinas Valley, perennial grass agriculture native Carmel Valley. types respective ecosystem pairs derived from granitic parent material had sandy loam textures. Intact cores (30 cm deep) collected March 1999. After equilibration, dry (approx. K 1t oK2 MPa) exposed 2.4 cm, then at 0, 6, 24, 120 h after rewetting. Microbial biomass C (MBC) inorganic N did not respond N2O CO2 efflux respiration increased rewetting all soils, with larger than Phospholipid fatty acid (PLFA) profiles indicated changes most pronounced intensive production, followed by relict grassland. Changes specific PLFA markers consistent across sites. There more similarities among groups associated Differences be related different plant species grasslands. Agricultural appeared decrease diversity, as estimated numbers individual identified for each ecosystem, reduce change In systems, reductions both measures diversity perturbation lower function, i.e. moisture availability. q 2005 Elsevier Ltd. All rights reserved.