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.
Helmholtz-Centre for Environmental Research - UFZ, Department of Isotope Hydrology, Theodor-Lieser-Str. 4, D-06120 Halle, Germany.
Sci Total Environ. 2016 Mar 1;545-546:30-9. doi: 10.1016/j.scitotenv.2015.12.050. Epub 2015 Dec 30.
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.
研究人员越来越认识到，需要更多关于土壤中 SOC 储量以及控制其稳定性和动态的因素的信息。关于植物群落的变化与地上生产力的变化通过其数量和质量的变化对土壤碳动态的影响之间的相互作用，仍有许多问题尚未得到解答。因此，本研究的主要目的是检验不同生产力的半自然草地的 SOC 积累潜力，并确定 SOM 各组分在不同土壤深度（0-10、10-20、20-30、30-50、50-80 和 80+cm）的分布。SOM 分组被认为是一种相对稳定的措施，用于分离与粘土矿物相关的 SOM 与特定比重小于 2 g cm(-3) 的 SOM（大小密度分组）。分离出两个粘土相关的组分（CF1，<1 μm；和 CF2，1-2 μm）和两个轻组分（LF1，<1.8 g cm(-3)；和 LF2，1.8-2.0 g cm(-3)）。这些组分的稳定性通过其碳热水可提取性（CHWE）和稳定碳同位素组成来表征。在所研究的半自然草地中，大部分 OC 储存在表层 30 cm 内，这里的周转速度很快。只有当考虑到总 SOM 的分数 OC 贡献（CF1 和 LF1）时，低生产力草地的影响才变得明显。在更深的土壤深度，OC 主要归因于低生产力草地的 CF1 组分。我们认为，更深土壤深度间隔中的大多数 OM 是微生物衍生的，这一点可以从 C/N 比和 δ(13)C 值的降低得到证明。这里采用的热水提取和自然 δ(13)C 丰度允许对 SOM 稳定特性进行表征，但是气候变化如何影响不同土壤深度间隔内 OM 的命运仍不清楚。
