1. Seasonal dynamics and depth distribution of belowground biomass carbon and nitrogen of extensive grassland and a Miscanthus plantation.
- Author
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Poeplau, Christopher, Germer, Kai, and Schwarz, Kai-Uwe
- Subjects
NITROGEN in soils ,MISCANTHUS ,GRASSLANDS ,SANDY soils ,DRILL core analysis ,GRASSLAND soils - Abstract
Background and aims: Belowground carbon (C) inputs are a major source of soil organic carbon (SOC) in terrestrial ecosystems, and substrate C:N ratios drive SOC stabilisation. In perennial systems, quantitative information on seasonal dynamics of belowground biomass is scarce, but necessary, e.g. to improve SOC modelling and representative sampling. Methods: Seasonal dynamics and depth distribution of belowground biomass C and N of extensive grassland and Miscanthus on sandy soil were estimated. Core samples (1 m depth) were taken six times in 1 year. Miscanthus-derived SOC was quantified using
13 C natural abundance. Results: Grassland and Miscanthus differed strongly in belowground biomass C (2.5 ± 0.3 vs. 7.3 ± 1.1 Mg ha−1 ) and C:N ratios (28.6 ± 0.5 vs. 60 ± 3.3). Peak grassland belowground biomass C and N stocks occurred in summer, while those of rhizomatous Miscanthus were in winter due to different strategies of resource allocation. Grassland roots showed a strong seasonal pattern of C:N ratios, indicating N remobilisation. Miscanthus-derived topsoil SOC was low relative to the high belowground biomass, indicating a slow transfer of rhizome carbon to bulk SOC. Conclusions: Representative belowground biomass sampling of perennials should take seasonal dynamics into account, especially in system comparisons. Furthermore, C inputs from rhizome and roots should be estimated separately owing to likely differences in turnover times. [ABSTRACT FROM AUTHOR]- Published
- 2019
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