Impacts of anthropogenic N additions on nitrogen mineralization from plant litter in exotic annual grasslands
Impacts of anthropogenic N additions on nitrogen mineralization from plant litter in exotic annual grasslands
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DOI：
10.1016/j.soilbio.2006.04.048
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发表时间：
2007
影响因子：
9.7
通讯作者：
Abby G. Sirulnik;E. Allen;T. Meixner;M. Allen
中科院分区：
文献类型：
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作者：
Abby G. Sirulnik;E. Allen;T. Meixner;M. Allen
加州南部城市地区从氮沉降中吸收的氮高达45公斤。利用15 N标记的一年生杂草二雄雀麦（Bromus diandrus）凋落物进行了田间分解研究，以确定土壤氮素的升高是否严格来自氮沉降，或者凋落物的氮矿化速率是否也在氮沉降下增加。组织N和木质素的浓度，这是负相关的领域网站与高和低N沉积，确定N从植物凋落物移动到土壤中，并成为植物可用的速率。通过在高氮和低氮土壤上分别放置枯落物和土壤氮两个水平的析因试验，研究了土壤氮对枯落物氮素向土壤迁移的影响。凋落物质量的变化与N沉降导致更快的N循环从凋落物到土壤。高N/低木质素凋落物中的全N、NH 4+、NO3-、微生物N和有机N含量均高于低N/高木质素凋落物。高氮土壤凋落物对土壤NH 4+和微生物氮的贡献大于低氮土壤。研究结束时，高氮土壤上高氮凋落物中矿化的氮占土壤NH 4+的46%和土壤NO3−的11%，而低氮土壤上低氮凋落物中矿化的氮占土壤NH 4+的35%和土壤NO3−的6%。研究表明，在高氮沉降地区，在夏季氮沉降季节结束时，土壤无机氮浓度升高是植物凋落物氮矿化和氮沉降的结果。
Urban regions of southern California receive up to 45kg Nha–1y–1from nitrogen (N) deposition. A field decomposition study was done using15N-labelled litter of the widespread exotic annual grass Bromus diandrus to determine whether elevated soil N is strictly from N deposition or whether N mineralization rates from litter are also increased under N deposition. Tissue N and lignin concentrations, which are inversely related in field sites with high and low N deposition, determine the rate at which N moves from plant litter to soil and becomes available to plants. The effect of soil N on N movement from litter to soil was tested by placing litter on high and low N soil in a factorial experiment with two levels of litter N and two levels of soil N. The litter quality changes associated with N deposition resulted in faster rates of N cycling from litter to soil. Concentrations of litter-derived N in total N, NH4+, NO3−, microbial N and organic N were all higher from high N/low lignin litter than from low N/high lignin litter. Litter contributed more N to soil NH4+and microbial N in high N than low N soil. At the end of the study, N mineralized from high N litter on high N soil accounted for 46% of soil NH4+and 11% of soil NO3−, compared to 35% of soil NH4+and 6% of soil NO3−from low N litter on low N soil. The study showed that in high N deposition areas, elevated inorganic soil N concentrations at the end of the summer N deposition season are a result of N mineralized from plant litter as well as from N deposition.