Soil organic carbon distribution drives microbial activity and functional diversity in particle and aggregate-size fractions

• Published in: Pedobiologia 2012-03, Vol.55 (2), p.101-110
• Main Authors: Lagomarsino, A., Grego, S., Kandeler, E.
• Format: Article
• Language: English
• Subjects: Aggregates; Carbon; MicroResp-CLPP; Particle size fractions; POM; Soil enzymes
• ISSN: 0031-4056; 1873-1511
• DOI: 10.1016/j.pedobi.2011.12.002

Chemical and functional characterizations of particle-size and aggregate fractions of soils were performed to investigate whether accessibility and decomposability of organic matter regulate functions and diversity of the soil microbial community at the micro-habitat scale. Soils were physically fractionated into particle size fractions, free-particulate organic matter (F-POM), macro-aggregates (250–2000μm) and micro-aggregates (53–250μm). Organic C was enriched in silt and clay, micro-aggregates and F-POM fractions. Enzymes showed the greatest activity in the fine fractions (silt and clay) and F-POM, and were largely influenced by organic C content. MicroResp-CLPP (Community Level Physiological Profile) showed the lowest catabolic responses in the sand and the highest in the fine fraction and micro-aggregates. In general, organic C availability drove soil activity and functional diversity: soils with the higher amount of organic C showed the higher catabolic activity. However, this response was variable within soil fractions, where organic C accessibility, as well as microbial selection and distribution, affected functional diversity.