Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition.
Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition.
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半干旱沙丘草原凋落物分解：供水的中性作用和氮添加的抑制作用
DOI：
10.1371/journal.pone.0162663
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Zhao X
中科院分区：
文献类型：
--
作者：
Li Y;Ning Z;Cui D;Mao W;Bi J;Zhao X
背景干旱生态系统中植物物质的分解被认为在很大程度上受水和氮素有效性的控制。然而，凋落物分解对外界N和水分的反应仍然存在争议，补充N和水分的交互作用也在很大程度上没有得到研究。方法/主要研究结果在内蒙古沙化沙丘草原上，通过为期3.5年的氮素补水田间试验，通过对比底物化学成分(本研究中的氮素浓度、木质素含量)，研究了氮素和水分对3种优势植物(艾蒿、狗尾草和芦荟)叶片和细根中氮素释放和质量损失的影响。处理包括氮素添加、水分添加、氮水结合和不处理对照。叶和根的分解速率与三种树种的初始凋落物N和木质素浓度有关。然而，凋落物质量不能解释本研究中根的质量损失慢于叶的质量损失，因此值得进一步研究。氮素单独或与水分配施显著抑制了3种植物叶和根的干物质损失和氮的释放，而水分输入对叶凋落物和细根的分解影响不大，表明在该系统中，补充氮素和水分对凋落物分解没有交互作用。此外，我们的结果清楚地表明，与低木质素凋落物相比，高木质素凋落物中外源N对干物质损失和氮素释放的抑制作用相对较强。结论/意义这些结果表明，降水增加对生态系统碳周转几乎没有促进作用，但大气氮沉降可以促进中国北部沙化沙丘草原的碳汇和氮素保持。此外，在对该系统的碳循环和养分动态进行建模时，应考虑植物种类的凋落物质量。
Background The decomposition of plant material in arid ecosystems is considered to be substantially controlled by water and N availability. The responses of litter decomposition to external N and water, however, remain controversial, and the interactive effects of supplementary N and water also have been largely unexamined. Methodology/Principal Findings A 3.5-year field experiment with supplementary nitrogen and water was conducted to assess the effects of N and water addition on mass loss and nitrogen release in leaves and fine roots of three dominant plant species (i.e., Artemisia halondendron, Setaria viridis, and Phragmites australis) with contrasting substrate chemistry (e.g. N concentration, lignin content in this study) in a desertified dune grassland of Inner Mongolia, China. The treatments included N addition, water addition, combination of N and water, and an untreated control. The decomposition rate in both leaves and roots was related to the initial litter N and lignin concentrations of the three species. However, litter quality did not explain the slower mass loss in roots than in leaves in the present study, and thus warrant further research. Nitrogen addition, either alone or in combination with water, significantly inhibited dry mass loss and N release in the leaves and roots of the three species, whereas water input had little effect on the decomposition of leaf litter and fine roots, suggesting that there was no interactive effect of supplementary N and water on litter decomposition in this system. Furthermore, our results clearly indicate that the inhibitory effects of external N on dry mass loss and nitrogen release are relatively strong in high-lignin litter compared with low-lignin litter. Conclusion/Significance These findings suggest that increasing precipitation hardly facilitates ecosystem carbon turnover but atmospheric N deposition can enhance carbon sequestration and nitrogen retention in desertified dune grasslands of northern China. Additionally, litter quality of plant species should be considered when modelling the carbon cycle and nutrient dynamics of this system.
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