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氮沉降和土壤线虫对落叶松人工林土壤有机碳矿化的影响

刘静1,2,孙涛1,程云云1,2,王清奎1,3*#br#   

  1. (1中国科学院森林生态与管理重点实验室(沈阳应用生态研究所), 沈阳 110016; 2中国科学院大学, 北京 100049; 3中国科学院会同森林生态实验站, 湖南会同 418307)
  • 出版日期:2017-08-10 发布日期:2017-08-10

Effect of nitrogen deposition and soil nematode on soil organic carbon mineralization in a Larix gmelinii plantation.

LIU Jing1,2, SUN Tao1, CHENG Yun-yun1,2, WANG Qing-kui1,3*#br#   

  1. (1CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang 110016, China; 2University of Chinese Academy of Sciences, Beijing 100049, China; 3Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Huitong 418307, Hunan, China).
  • Online:2017-08-10 Published:2017-08-10

摘要:

大气氮沉降不仅含有无机态氮,还含有大量有机态氮,然而目前大部分研究主要关注无机态氮沉降对土壤有机碳(SOC)矿化的影响,对于有机态氮沉降的影响关注甚少。为更全面地了解大气氮沉降对SOC矿化的影响,我们在温带落叶松(Larix gmelinii)人工林长期氮沉降试验样地中采集了对照(CK)、无机氮(IN)、有机氮(ON)及无机氮有机氮混施(IN∶ON=7∶3;MN)4种不同氮沉降处理的表层土壤(0~10 cm),然后进行室内恒温(25 ℃)培养62 d,测定SOC矿化速率。同时,为了研究氮沉降背景下土壤线虫在SOC矿化中的作用,我们将每个氮沉降处理的土壤分为2组,分别添加或不添加线虫抑制剂。结果显示:与CK处理相比,IN、ON及MN处理均显著降低了SOC矿化速率,其SOC累积矿化量分别降低了15.7%、23.9%和34.3%,表明无机有机氮混施处理对SOC矿化的抑制作用大于无机氮沉降和有机氮沉降。因此,单一形态的氮沉降模拟研究可能低估了大气氮沉降对SOC矿化的抑制作用。另外,添加线虫抑制剂促进了SOC矿化,且添加线虫抑制剂在IN、ON和MN处理中对SOC累积矿化量影响的效应值较CK处理分别增加了0.08%、42.40%和29.0%,该结果表明,土壤线虫对SOC矿化的影响与氮沉降形态有关。相关性分析结果显示,SOC累积矿化量与土壤C∶N、有效磷含量及真菌∶细菌呈显著正相关,与土壤硝态氮含量和革兰氏阳性细菌∶革兰氏阴性细菌比呈显著负相关。因此,在全球变化背景下,氮沉降的增加有利于降低温带森林生态系统土壤碳释放。
 

关键词: 景观偏好, 农业景观, 利益相关者, 照片引导访谈

Abstract: Atmospheric nitrogen deposition contains both inorganic and organic nitrogen. How-ever, most of the previous studies focused on the effect of inorganic nitrogen deposition on soil organic carbon (SOC) mineralization; little information on how organic nitrogen deposition affects SOC mineralization is available. In this experiment, surface soils (0-10 cm) were collected in a longterm experiment of simulating nitrogen deposition that included the control (CK), inorganic nitrogen (IN), organic nitrogen (ON), and inorganic + organic nitrogen (IN∶ON=7∶3; MN) treatments in a larch (Larix gmelinii) plantation. These soil samples were divided into two groups with or without nematocide to investigate the role of soil nematode on SOC mineralization under the background of nitrogen deposition. All soils were incubated at 25 ℃ for 62 days, and the rate of SOC mineralization was measured. The results showed that the SOC mineralization was significantly suppressed by nitrogen deposition, and it was reduced by 15.7%, 23.9%, and 34.3% in IN, ON and MN treatments compared to CK treatment, respectively. This suggested that the suppression of mixed nitrogen deposition on SOC mineralization was higher than that of inorganic or organic nitrogen deposition alone. Thus, the suppression of atmospheric nitrogen deposition on SOC mineralization might be underestimated by using a single type of inorganic or organic nitrogen deposition. The rate of SOC mineralization increased when nematocide was added to soils. The effect value of nematocide increased by 0.08%, 42.40% and 29.0% in IN, ON and MN treatments compared with the CK treatment, respectively. The result indicated that the effect of soil nematode on SOC mineralization depended on the form of nitrogen deposition. Furthermore, cumulative amount of SOC mineralization was significantly positively related to C∶N ratio, available phosphorus concentration and the ratio of fungi to bacteria, but was significantly negatively correlated with NO3--N concentration and the ratio of grampositive bacteria to gramnegative bacteria. So, nitrogen deposition was helpful to decrease CO2 emission from soil in temperate forest ecosystems under the background of global change.

Key words: landscape preference, stakeholders, agricultural landscape, photo elicitation interview