Stoichiometric imbalance and microbial community regulate microbial elements use efficiencies under nitrogen addition
Stoichiometric imbalance and microbial community regulate microbial elements use efficiencies under nitrogen addition
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DOI：
10.1016/j.soilbio.2021.108207
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发表时间：
2021-03-12
影响因子：
9.7
通讯作者：
Wang, Chao
中科院分区：
文献类型：
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作者：
Li, Jing;Sang, Changpeng;Wang, Chao
微生物元素利用效率是调控土壤碳、氮矿化过程的重要参数。微生物碳利用效率（CUE）描述了用于生长的碳相对于总有机碳吸收的比例。因此，高CUE值意味着相对较少的CO2排放和更多的微生物生物质中的C保留。同样，较高的微生物氮利用效率（NUE）表明有效的生物量氮螯合和较少的氮矿化。然而，很少有人知道如何微生物的CUE和NUE的森林土壤中的N富集的影响。本文采用O-18-水示踪法，在长期的氮素添加试验中，同时研究了土壤微生物CUE和NUE的变化（大气氮沉降，2.7 g N m（-2）yr（-1）），低氮添加（大气氮沉降+2.5gNm（-2）yr（-1））和高氮添加（大气氮沉降+7.5gNm（-2）yr（-1））的温带森林。我们发现微生物CUE对氮添加的反应依赖于氮添加速率和土壤层位。在有机质土壤中，低氮处理显著提高了微生物CUE，提高幅度为45.12%，而高氮处理显著降低了微生物CUE，降低幅度为27.84%。此外，矿质土壤微生物CUE在低N添加下没有变化，但在高N添加下显著增加了133.18%。有机质土壤微生物氮素利用效率随施氮量的增加而降低，而矿质土壤微生物氮素利用效率随施氮量的增加而降低。微生物生物量和资源之间与磷相关的化学计量不平衡以及氮添加下微生物群落的变化与微生物CUE和NUE相关。此外，氮添加降低了有机土壤中的微生物生物量周转，但加速了它在矿质土壤。总之，我们的研究结果表明，氮添加可以控制土壤C和N循环过程中，通过影响微生物元素的利用效率（即CUE和NUE），从而可能会影响C和N在这个温带森林土壤中的固定。
Microbial elements use efficiencies are the important parameters in regulating soil carbon (C) and nitrogen (N) mineralization processes. Microbial C use efficiency (CUE) describes the proportion of C used for growth relative to the total organic C uptake. As such, high CUE values mean relatively less CO2 emission and more C retention in microbial biomass. Similarly, a higher microbial N use efficiency (NUE) indicates efficient biomass N sequestration and less N mineralization. However, very little is known how the microbial CUE and NUE are affected by N enrichment in forest soils. Here, we studied soil microbial CUE and NUE simultaneously using O-18-water tracer approach in a long-term N addition experiment comprising control (atmospheric N deposition, 2.7 g N m(-2) yr(-1)), low N addition (atmospheric N deposition + 2.5 g N m(-2) yr(-1)) and high N addition (atmospheric N deposition + 7.5 g N m(-2) yr(-1)) in a temperate forest. We found microbial CUE responses to N addition were dependent on N addition rates and soil horizons. Specifically, low N addition significantly increased the microbial CUE by 45.12% while high N addition significantly reduced it by 27.84% in organic soil. Further, mineral soil microbial CUE did not change under low N addition but significantly increased by 133.18% under high N addition. We also found microbial NUE decreased with increasing N addition rate in organic soil but showed an opposite pattern in mineral soil. The stoichiometric imbalances associated with phosphorus between microbial biomass and resources and the microbial community changes under N addition were correlated with microbial CUE and NUE. Further, N addition decreased microbial biomass turnover in organic soil but accelerated it in mineral soil. Altogether, our results indicated that N addition could control soil C and N cycling processes by affecting microbial elements use efficiencies (i.e. CUE and NUE), which may consequently impact C and N sequestration in this temperate forest soil.