title: Carbon storage potential in size-density fractions from semi-natural grassland ecosystems with different productivities over varying soil depths.
abstract: Researchers have increasingly recognised a profound need for more information on SOC stocks in the soil and the factors governing their stability and dynamics. Many questions still remain unanswered about the interplay between changes in plant communities and the extent to which changes in aboveground productivity affect the carbon dynamics in soils through changes in its quantity and quality. Therefore, the main aim of this research was to examine the SOC accumulation potential of semi-natural grasslands of different productivities and determine the distribution of SOM fractions over varying soil depth intervals (0-10, 10-20, 20-30 30-50 50-80 and 80+cm). SOM fractionation was considered as a relative measure of stability to separate SOM associated with clay minerals from SOM of specific light densities less than 2 g cm(-3) (size-density fractionation). Two clay-associated fractions (CF1, <1 μm; and CF2, 1-2 μm) and two light fractions (LF1, <1.8 g cm(-3); and LF2, 1.8-2.0 g cm(-3)) were separated. The stability of these fractions was characterised by their carbon hot water extractability (CHWE) and stable carbon isotope composition. In the semi-natural grasslands studied, most OC was stored in the top 30 cm, where turnover is rapid. Effects of low productivity grasslands became only significantly apparent when fractional OC contributions of total SOM was considered (CF1 and LF1). In deeper soil depths OC was largely attributed to the CF1 fraction of low productivity grasslands. We suggest that the majority of OM in deeper soil depth intervals is microbially-derived, as evidenced by decreasing C/N ratios and decreasing δ(13)C values. The hot water extraction and natural δ(13)C abundance, employed here allowed the characterisation of SOM stabilisation properties, however how climatic changes affect the fate of OM within different soil depth intervals is still unknown.
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Soil Ecology, Theodor-Lieser-Str. 4, 06120 Halle, Germany; Helmholtz-Centre for Environmental Research - UFZ, Environmental and Biotechnology Centre (UBZ), Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Breulmann
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Isotope Hydrology, Theodor-Lieser-Str. 4, D-06120 Halle, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Boettger
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Soil Ecology, Theodor-Lieser-Str. 4, 06120 Halle, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.
authors.forename: François
authors.initials: F
authors.lastname: Buscot
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department, Department of Soil Physics, Theodor-Lieser-Str. 4, D-06120 Halle, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Gruendling
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Soil Ecology, Theodor-Lieser-Str. 4, 06120 Halle, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Schulz
mesh_terms: D057965:Carbon Sequestration; D004784:Environmental Monitoring; D065948:Grassland; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil
keywords: Carbon cycling; Semi-natural grasslands; Size–density fractionation; Soil organic carbon stocks; Soil organic matter; Stable isotope