Carbon input belowground is the major C flux contributing to leaf litter mass loss: Evidences from a 13C labelled-leaf litter experiment
Carbon input belowground is the major C flux contributing to leaf litter mass loss: Evidences from a 13C labelled-leaf litter experiment
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DOI：
10.1016/j.soilbio.2010.02.018
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发表时间：
2010-07-01
影响因子：
9.7
通讯作者：
Cotrufo, M. F.
中科院分区：
文献类型：
--
作者：
Rubino, M.;Dungait, J. A. J.;Cotrufo, M. F.
为了更深入地了解凋落叶-土壤生物地球化学连续体，将凋落叶通过分解而损失的碳分成(i)向大气排放的二氧化碳和（ii）向土壤有机质（SOM）输入的碳是至关重要的。然而，这是一项具有挑战性的任务，因为发生了许多不同的过程，导致凋落物生物量损失。为了定量测定凋落叶分解的不同碳流通量，在意大利中部一个短轮作的胡杨林进行了田间试验。将富含C-13 （δ C-13近似于+160‰）的黑杨叶凋落物放置在项圈内，与土壤直接接触分解（δ C-13近似于-26‰）11个月。从项圈内流出的二氧化碳及其同位素组成每隔一个月测定一次。11个月后，对剩余凋落物和土壤剖面（0-20 cm）取样并分析其总C和C-13含量。采用气相色谱（GC）、气相色谱-质谱（MS）和气相色谱-燃烧-同位素比值（GC/C/IRMS）对土壤样品中提取的磷脂脂肪酸（PLFA）进行分析，确定土壤微生物中含有凋落物衍生碳的类群，并确定土壤微生物生物量（SMB）中含有碳的数量。实验结束时，幼崽的体重下降了约80%。研究发现，作为输入到土壤中的凋落物c损失的比例（占总碳损失的67 +/- 12%）是作为二氧化碳释放到大气中的比例（30 +/- 3%）的两倍，从而证明了在凋落物分解研究中，量化过滤器衍生的碳输入到土壤的重要性。土壤中plfa的平均δ C-13值（δ C-13 = -12.5‰）表明，一年后，凋落物来源的C持续结合（占总PLFA-C的7.8 +/- 1.6%）。因此，通过应用稳定的C-13同位素分析，我们在宏观和微观水平上量化了促进凋落物分解的两种主要C通量。(C) 2010 Elsevier Ltd.版权所有。
Partitioning of the quantities of C lost by leaf litter through decomposition into (i) CO2 efflux to the atmosphere and (ii) C input to soil organic matter (SOM) is essential in order to develop a deeper understanding of the litter-soil biogeochemical continuum. However, this is a challenging task due to the occurrence of many different processes contributing to litter biomass loss. With the aim of quantifying different fluxes of C lost by leaf litter decomposition, a field experiment was performed at a short rotation coppice poplar plantation in central Italy. Populus nigra leaf litter, enriched in C-13 (delta C-13 similar to +160 parts per thousand) was placed within collars to decompose in direct contact with the soil (delta C-13 similar to -26 parts per thousand) for 11 months. CO2 efflux from within the collars and its isotopic composition were determined at monthly intervals. After 11 months, remaining litter and soil profiles (0-20 cm) were sampled and analysed for their total C and C-13 content. Gas chromatography (GC), GC-mass spectrometry (MS) and GC-combustion-isotope ratio (GC/C/IRMS) were used to analyse phospholipid fatty acids (PLFA) extracted from soil samples to identify the groups of soil micro-organisms that had incorporated litter-derived C and to determine the quantity of C incorporated by the soil microbial biomass (SMB). By the end of the experiment, the litter had lost about 80% of its original weight. The fraction of litter c lost as an input into the soil (67 +/- 12% of the total C loss) was found to be twice as much as the fraction released as CO2 to the atmosphere (30 +/- 3%), thus demonstrating the importance of quantifying fitter-derived C input to soils, in litter decomposition studies. The mean delta C-13 values of PLFAs in soil (delta C-13 = -12.5 parts per thousand) showed sustained incorporation of litter-derived C after one year (7.8 +/- 1.6% of total PLFA-C). Thus, through the application of stable C-13 isotope analyses, we have quantified two major C fluxes contributing to litter decomposition, at macroscopic and microscopic levels. (C) 2010 Elsevier Ltd. All rights reserved.