Journal of Resources and Ecology ›› 2017, Vol. 8 ›› Issue (3): 258-267.DOI: 10.5814/j.issn.1674-764x.2017.03.006

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Enzyme Activities and Microbial Communities in Subtropical Forest Soil Aggregates to Ammonium and Nitrate-Nitrogen Additions

WEI Yan1, WANG Zhongqiang1, ZHANG Xinyu2,3,*, YANG Hao2, LIU Xiyu1, LIU Wenjing1   

  1. 1. Northeast Normal University, College of Geographic Science, Changchun 130024, China;
    2. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
    3. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2017-02-02 Revised:2017-03-28 Online:2017-05-20 Published:2017-05-20
  • Contact: ZHANG Xinyu, E-mail: zhangxy@igsnrr.ac.cn.
  • Supported by:
    National Natural Science Foundation of China (41571251, 41571130043); Technology Innovation Program of Chinese Academy of Sciences (201604).

Abstract: A laboratory incubation experiment was established to examine the impacts of nitrate and ammonium nitrogen additions on soil microbial attributes of a subtropical Pinus elliottii forest ecosystem in southern China. Soils were subjected to three different treatments: the control with no nitrogen addition (CK), the ammonium nitrogen addition (NH4+-N), and the nitrate nitrogen addition (NO3--N). Samples from bulk and two different size fractions (macroaggregate (>250 μm) and microaggregate (53-250 μm)) were analyzed for soil properties, enzyme activities and microbial communities on day 7 and 15 of the incubation. Our study demonstrated that NH4+-N had a greater influence on soil microbial activities than NO3--N. NH4+-N additions resulted in significant increases in β-1,4-glucosidase (βG) and β-1,4-N-acetyl glucosaminidase (NAG) enzyme activities in bulk, macroaggregate and microaggregate soils after 7 and 15 days incubation. NO3--N additions only significantly increased in βG and NAG enzyme activities in bulk, macroaggregate soils after 7 and 15 days incubation, but not in microaggregate. All NH4+-N and NO3--N additions resulted in significant increases in gram-positive bacterial PLFAs in microaggregates. Only a significant correlation between soil nutrient contents and enzyme activities in macroaggregates was founded, which suggests that the soil aggregation structure played an important role in the determining enzyme activities.

Key words: ammonium nitrogen, enzyme activity, phosphor-lipid fatty acid (PLFA)., soil aggregate, nitrate nitrogen