南京林业大学学报(自然科学版) ›› 2019, Vol. 43 ›› Issue (03): 85-91.doi: 10.3969/j.issn.1000-2006.201805047

• 研究论文 • 上一篇    下一篇

添加无机氮对山西太岳山油松林土壤氮素及温室气体通量的影响

于 辉,陈 燕,张 欢,周志勇*   

  1. 森林资源与生态系统过程北京市重点实验室,北京林业大学林学院,北京 100083
  • 出版日期:2019-05-15 发布日期:2019-05-15
  • 基金资助:
    收稿日期:2018-05-17 修回日期:2018-11-06
    基金项目:国家重点研发计划(2016YFD0600205); 林业科技创新平台运行补助项目(2017,2018-LYPT-DW-153)。
    第一作者:于辉(1003179192@qq.com),ORCID(0000-0002-9196-1880)。*通信作者:周志勇(zhiyong@bjfu.edu.cn),副教授,ORCID(0000-0002-4467-0845)。

The effect of inorganic nitrogen addition on soil nitrogen and greenhouse gas flux for the Pinus tabulaeformis forest in Taiyue Mountain,Shanxi Province

YU Hui, CHEN Yan, ZHANG Huan, ZHOU Zhiyong*   

  1. Beijing Key Laboratory of Forest Resources and Ecosystem Process, College of Forestry, Beijing Forestry University, Beijing 100083, China)
  • Online:2019-05-15 Published:2019-05-15

摘要: 【目的】人类活动频繁引起大气氮沉降加剧,导致陆地生态系统中的氮循环发生了前所未有的变化,进而影响整个陆地生态系统生态环境。笔者通过模拟大气氮沉降,探究森林土壤中氮素含量及温室气体排放速率的响应规律以及氮素对温室气体排放的影响,为提高森林氮素利用率并减缓大气温室效应提供参考。【方法】以山西太岳山暖温带油松林为研究对象,以硝酸铵(NH4NO3)为外源无机氮添加对象,设置对照CK(0 g/m2)、N5(5 g/m2)、N10(10 g/m2)、N20(20 g/m2)、N40(40 g/m2)等5个施氮水平,每个施氮水平设置4个重复,共20块样地。于2017年8月采集土壤样品及温室气体样品(采用静态箱法),测定林地土壤中的全氮(TN)、总可溶性氮(TDN)、可溶性有机氮(DON)、铵态氮(NH+4-N)、硝态氮(NO-3-N))含量及土壤中温室气体N2O、CO2 和CH4的排放量,分析氮添加对土壤氮及温室气体排放的影响。【结果】在N5、N10、N20和N40各施氮水平处理下,油松林0~10 cm土壤中NO-3-N、TDN、DON的含量增加,与CK相比,含量增幅分别为25.04%~246.4%、13.29%~73.82%、4.54%~70.51%,NH+4-N含量随着施氮量水平的增加而增加,但各处理水平对TN含量无影响。在0~10 cm土壤中,与CK相比,NO-3-N和TDN含量在N10、N20、N40处理下显著增加(P <0.05),DON只在N40处理中显著增加(P <0.05),施氮处理对0~10cm土层中的各氮素具有明显的促进作用; 在≥10~20 cm土层中,与CK相比,TN、NH+4-N含量有增长趋势,NO-3-N含量在N10、N20、N40处理下显著增加(P <0.05),分别增加了234%、284%、663%,TDN随着施氮量的增加而增加,而DON则随着处理水平的增加而显著减小(P <0.05)。N2O、CO2的排放量随着施氮量的增加而增加,并且在N20、N40处理下排放量显著增加(P <0.05); 同时氮添加处理对CH4的吸收有明显的抑制现象,使CH4从森林土壤吸收状态转变为排放状态。在相关性分析中,0~10 cm土层及≥10~20 cm土层中NO-3-N和DON、N2O、CO2呈显著相关(P <0.05),而NH+4-N、TDN与N2O、CO2、CH4呈正相关,但无显著性(P >0.05); 在≥10~20 cm土壤中,DON与N2O、CO2、CH4呈负相关。【结论】在无机氮添加试验中,施氮处理明显增加了土壤中有效氮的含量,尤其是在N20和N40处理水平条件下,对油松林土壤中的有效氮素含量及温室气体排放具有明显的调控作用; 同时,有效氮含量的增加对森林土壤中温室气体的排放有明显的促进作用。因此,模拟氮沉降显著促进了森林土壤氮素循环及温室气体的排放,对生态环境的影响及温室效应的变化具有明显作用。

Abstract: 【Objective】Increased atmospheric nitrogen deposition has significantly altered the pathway and quantity of nitrogen input to the terrestrial ecosystems, and consequently influenced the ecosystem function. The atmospheric nitrogen deposition in future was emulated through applying inorganic nitrogen to the forest floor. The effect of nitrogen addition on the soil nitrogen transformation and the greenhouse gas emission was then investigated, the results of which could help evaluated the role of the forest ecosystems in northern China in coping with the global change.【Method】Inorganic nitrogen in the form of ammonium nitrate(NH4NO3), was scattered evenly on the floor of a Pinus tabulaeformis forest under rates of 0, 5, 10, 20 and 40 g/m2 with four replications, for a total of 20 plots. In August 2017, soil cores were sampled for the monitoring of total nitrogen(TN), total soluble nitrogen(TDN), ammonium nitrogen(NH+4-N), and nitrate nitrogen(NO-3-N)contents. Then, soil greenhouse gases(N2O, CO2 and CH4)were collected using the static chamber method to assess the effects of nitrogen addition on soil nitrogen and greenhouse gas emissions.【Result】Inorganic nitrogen addition significantly increased NO-3-N content by 25.04%-246.4%, TDN content by 13.29%-73.82%, and soluble organic nitrogen(DON)content by 4.54%-70.51% in the top 10 cm of the soils. Higher nitrogen treatment gradients significantly increased soil NH+4-N concentrations. No obvious variation was monitored by simulating nitrogen deposition. Nitrate nitrogen and TDN contents were markedly increased in N10, N20 and N40 plots(P < 0.05). DON concentration was significantly increased by N40 treatment. Simulated nitrogen deposition significantly affected soil nitrogen fractions at the soil depth of 0-10 cm. In the ≥10-20 cm soil layer, there was a trend for higher TN and NH+4-N concentrations across nitrogen plots. The content of NO-3-N was significantly increased by 234%, 284% and 663% by N10, N20 and N40 treatments, respectively. The concentration of TDN increased with higher nitrogen treatment levels. However, nitrogen deposition significantly decreased soil DON concentration. The greenhouse gases N2O and CO2 were positively correlated with inorganic nitrogen addition, with significant increases found in the N20 and N40 treatments(P < 0.05). In addition, nitrogen addition significantly decreased soil CH4 assimilation, as more CH4 was emitted at higher levels of nitrogen addition. Correlation analyses suggested that the concentration of NO-3-N was significantly correlated with variation in DON, N2O and CO2 concentrations(P < 0.05). The concentration of DON was negative correlated to N2O, CO2 and CH4. Although positive trends were discovered between NH+4-N and TDN with N2O, CO2 and CH4, these correlations were not significant.【Conclusion】Inorganic nitrogen addition considerably increased the available nitrogen content in the soil and the emission rates of greenhouse gases, especially under N20 and N40 gradients. The increased available nitrogen concentrations in the soil significantly accelerated forest soil greenhouse gas emissions. Overall, simulated atmospheric nitrogen deposition significantly altered forest soil nitrogen transformation and greenhouse gas emissions.

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