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首页> 中文期刊> 《土壤》 >戴云山自然保护区森林土壤氮转化特点研究

戴云山自然保护区森林土壤氮转化特点研究

         
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摘要

利用15N稳定同位素成对标记法并结合MCMC数值模型,研究了戴云山国家级自然保护区天然毛竹林(BF)及其邻近黄山松–杉木林(NF)土壤氮素初级转化速率,以评估该地区森林生态系统土壤氮状态,并分析其保氮机制.结果表明:BF土壤NH4+-N的总产生速率(以N量计,13.16μg/(g·d))是NF土壤的2倍(6.25μg/(g·d)),其中黏土矿物对NH4+-N的解吸作用是BF产生NH4+-N的主要过程(55%),而NF主要以有机氮的矿化作用为主(56%).BF土壤氮素初级矿化速率为5.56μg/(g·d),显著高于NF的3.40μg/(g·d).土壤氮素初级矿化速率与土壤全氮含量显著正相关(P<0.05),而与C/N比表现显著负相关(P<0.05).BF与NF土壤NH4+-N总产生量的90%均被土壤微生物的同化作用以及黏土矿物的吸附作用所消耗.两种土壤的硝化作用微弱,BF土壤总硝化速率(以N量计,0.23μg/(g·d))与NF土壤(0.26μg/(g·d))相差不大.两种林地土壤硝化作用均以有机氮的异养硝化为主,自养硝化过程可忽略不计.BF与NF土壤中NO3–-N消耗速率均超过了产生速率,表明BF与NF土壤均能有效降低NO3–-N的潜在淋失风险,其中BF土壤中NO3–-N的消耗以微生物的同化作用为主(58%),而NF土壤以NO3–-N异化还原为NH4+-N过程为主(68%).戴云山国家级自然保护区两种亚热带森林土壤的氮转化过程均以NH4+-N转化为主,产生的绝大多数NH4+-N会迅速通过微生物对NH4+-N的同化作用以及黏土矿物对NH4+-N的吸附作用固持到有机氮库中;自养硝化过程微弱,使得无机氮主要以NH4+-N的形式保存于土壤中,同时酸性土壤环境有效削弱了NH4+-N的挥发损失.此外,相对较高的NO3–-N微生物同化速率以及异化还原为NH4+-N速率,进一步有效降低了NO3–-N的淋溶损失以及反硝化作用的气态损失风险,使该地区森林土壤能够在多雨的条件下有效保持氮素,满足植物的生长需求.%A 15N tracing study was carried out to identify the potential gross nitrogen transformations of natural Moso Bamboo forest (BF) soil and adjacent native forest of Huangshan pine (NF) soil in Daiyun Mountain National Nature Reserve of Fujian Province. The results showed that total NH4+-N production (N13.16 μg/(g·d)) was twice higher in BF soil than that in NF soil (6.25 μg/(g·d)) soil with amounted to 55% of total NH4+-N production came from release of adsorbed NH4+ in BF soil while equal to 56% in NF soil was mineralization of soil labile and recalcitrant organic matter. Gross mineralization rate was significantly faster in BF soil (5.56 μg/(g·d)) compared to NF soil (3.40 μg/(g·d)) and gross mineralization rate was found positive correlated with TN and negative correlated with C/N ratio. Approximately 90% of total NH4+-N production was consumed by immobilization of NH4+ and adsorption of NH4+ on cation exchange sites in the two soils. Total NO3–-N production in BF soil (0.23 μg/(g·d)) was almost the same with NF soil (0.26 μg/(g·d)), of which approximately 90% were came from heterotrophic nitrification and oxidation of NH4+ were negligible compared to ONrec in the two soils. Total NO3–-N consumption exceeded total NO3–-N production in both soils, which may reduce the risk of potential for N losses. INO3 amounted to 58% of total NO3–-N consumption in BF soil while DNO3 responsible for 68% of total consumption of NO3– in NF soil. The N transformation processes in the two soils were dominant by NH4+-N dynamics and most of total NH4+-N production was immediately counterbalanced by NH4+ immobilization and adsorption of NH4+ on cation exchange sites. Soil inorganic nitrogen was mainly in form of NH4+-N as oxidation of NH4+-N was insignificant in combination with acidic soil environment inhibited ammonium volatilization. Moreover, higher INO3 and DNO3 can significantly reduce potential NO3–-N leaching or gaseous losses under this high temperature and rainfall condition and retain abundant available N in soil to maintain plant growth.

著录项

  • 来源
    《土壤》 |2017年第2期|240-247|共8页
  • 作者

    袁磊; 李文周; 陈文伟; 张金波; 蔡祖聪;

  • 作者单位

    南京师范大学地理科学学院,南京 210023;

    戴云山国家级自然保护区管理局,福建德化 362500;

    戴云山国家级自然保护区管理局,福建德化 362500;

    南京师范大学地理科学学院,南京 210023;

    江苏省地理环境演化国家重点实验室培育建设点,南京 210023;

    江苏省地理信息资源开发与利用协同创新中心,南京 210023;

    南京师范大学虚拟地理环境教育部重点实验室,南京 210023;

    南京师范大学地理科学学院,南京 210023;

    江苏省地理环境演化国家重点实验室培育建设点,南京 210023;

    江苏省地理信息资源开发与利用协同创新中心,南京 210023;

    南京师范大学虚拟地理环境教育部重点实验室,南京 210023;

  • 原文格式 PDF
  • 正文语种 chi
  • 中图分类 土壤肥力与植物;
  • 关键词

    15N成对标记; MCMC数值优化模型; 氮初级转化速率; 保氮机制;

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