The initial lignin:nitrogen ratio of litter from above and below ground sources strongly and negatively influenced decay rates of slowly decomposing litter carbon pools
The initial lignin:nitrogen ratio of litter from above and below ground sources strongly and negatively influenced decay rates of slowly decomposing litter carbon pools
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DOI：
10.1016/j.soilbio.2014.06.013
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发表时间：
2014-10
影响因子：
9.7
通讯作者：
C. Walela;H. Daniel;B. Wilson;P. Lockwood;A. Cowie;S. Harden
中科院分区：
文献类型：
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作者：
C. Walela;H. Daniel;B. Wilson;P. Lockwood;A. Cowie;S. Harden
了解植物凋落物的初始生化组成和随后的分解之间的相互作用，将提高我们的理解，其对微生物基质的使用，以解释土壤碳库之间的有机质流动的影响。我们确定了土地利用（耕地/原生林地/原生牧场），凋落物类型（地上和地下）和它们的相互作用的影响，对初始生化组成（碳，氮，水溶性碳，木质素，单宁和纤维素）和分解的凋落物。凋落物分解的C矿化的微生物呼吸和测定的CO2-C生产在105天的实验室培养与土壤中进行了研究。两池模型被用来量化C矿化动力学。对于所有凋落物类型，活性碳库的衰减速率常数范围为0.072 d− 1至0.805 d− 1，代表相对较短的半衰期，介于1至10天之间，这意味着该库含有在孵化初始阶段被微生物快速矿化的化合物。相反，慢碳库的衰减速率常数在土地利用内部和土地利用之间的凋落物类型之间变化很大，范围从0.002 d-1到0.019 d-1，代表半衰期在37到446天之间。在所有的凋落物类型中，初始木质素：N的比例强烈和负面的影响，这意味着这两个凋落物质量变量之间的相互作用有重要的控制凋落物慢C库的分解的衰减速率。我们解释我们的研究结果表明，在流动的C从活跃的池到缓慢的池主要是由土壤中的微生物活性驱动，C的转移率将在很大程度上由不同的土地利用系统下的凋落物的质量，特别是初始的木质素：N比的凋落物。与天然牧场和耕作相比，天然林地地上和地下凋落物的特点是较高的木质素：N比和更慢的分解缓慢的C库，这意味着凋落物可能会持续存在于土壤中，然而，根据本研究中土壤的桑迪性质，它可能缺乏长期免受微生物降解的保护。
Understanding the interactions between the initial biochemical composition and subsequent decomposition of plant litter will improve our understanding of its influence on microbial substrate use to explain the flow of organic matter between soil carbon pools. We determined the effects of land use (cultivation/native woodland/native pasture), litter type (above and below ground) and their interaction on the initial biochemical composition (carbon, nitrogen, water soluble carbon, lignin, tannin and cellulose) and decomposition of litter. Litter decomposition was studied as the mineralization of C from litter by microbial respiration and was measured as CO2–C production during 105 d of laboratory incubation with soil. A two-pool model was used to quantify C mineralization kinetics. For all litter types, the active C pool decay rate constants ranged from 0.072 d−1to 0.805 d−1which represented relatively short half-lives of between 1 and 10 days, implying that this pool contained compounds that were rapidly mineralized by microbes during the initial stages of incubation. Conversely, the decay rate constants for the slow C pool varied widely between litter types within and among land uses ranging from 0.002 d−1and 0.019 d−1representing half-lives of between 37 and 446 days. In all litter types, the initial lignin:N ratio strongly and negatively influenced the decay rate of the slow C pool which implied that the interaction between these two litter quality variables had important controls over the decomposition of the litter slow C pool. We interpret our results to suggest that where the flow of C from the active pool to the slow pool is largely driven by microbial activity in soil, the rate of transfer of C will be largely controlled by the quality of litter under different land-use systems and particularly the initial lignin:N ratio of the litter. Compared with native pastures and cultivation, above and below ground litter from native woodland was characterized by higher lignin:N ratio and more slowly decomposing slow C pools which implies that litter is likely to persist in soils, however based on the sandy nature of the soils in this study, it is likely to lack protection from microbial degradation in the long term.