植物生态学报 ›› 2017, Vol. 41 ›› Issue (1): 95-104.DOI: 10.17521/cjpe.2015.0302

所属专题: 中国灌丛生态系统碳储量的研究 碳水能量通量

• 研究论文 • 上一篇    下一篇

氮添加对亚热带山地杜鹃灌丛土壤呼吸的影响

张蔷1,2, 李家湘3, 谢宗强1,*()   

  1. 1中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093
    2中国科学院大学, 北京 100049
    3中南林业科技大学林学院, 长沙 410004
  • 收稿日期:2015-08-17 接受日期:2016-01-17 出版日期:2017-01-10 发布日期:2017-01-23
  • 通讯作者: 谢宗强
  • 作者简介:* 通信作者Author for correspondence (E-mail:sunzhiqiang1956@sina.com)
  • 基金资助:
    中国科学院战略性先导科技专项(XDA- 05050302)

Effects of nitrogen addition on soil respiration of Rhododendron simsii shrubland in the subtropical mountainous areas of China

Qiang ZHANG1,2, Jia-Xiang LI3, Zong-Qiang XIE1,*()   

  1. 1State Key Laboratory of Vegetation and Environment Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

    2University of Chinese Academy of Sciences, Beijing 100049, China
    and
    3Faculty of Forestry, Central South University of Forestry and Technology, Changsha 410004, China
  • Received:2015-08-17 Accepted:2016-01-17 Online:2017-01-10 Published:2017-01-23
  • Contact: Zong-Qiang XIE
  • About author:KANG Jing-yao(1991-), E-mail: kangjingyao_nj@163.com

摘要:

为探究灌丛生态系统对大气氮沉降的响应, 2013年1月至2014年9月, 对湖南大围山杜鹃(Rhododendron simsii)灌丛群落进行了短期模拟氮沉降试验, 施氮浓度分别为0 (CK)、2 (LN)、5 (MN)和10 (HN) g·m-2·a-1。利用LI-8100土壤碳通量测量系统测定土壤呼吸速率, 并测定不同氮处理下根系生物量增量和凋落物量。结果表明: 该地区土壤呼吸呈现明显的季节动态, 夏季土壤呼吸最强, 冬季最弱。CK、LN、MN和HN处理样地每年通过土壤呼吸释放的CO2量分别为2.37、2.79、2.26和2.30 kg CO2·m-2。CK、LN、MN和HN处理下, 年平均土壤呼吸速率分别为1.71、2.01、1.63和1.66 μmol CO2·m-2·s-1, LN处理样地的年均土壤呼吸速率与对照样地相比增加了17.25%, MN和HN处理则比对照样地稍低。施氮增加了根系生物量增量和凋落物量, 但没有达到显著水平。土壤呼吸速率与5 cm土壤温度呈显著指数相关关系, 与5 cm土壤的含水量呈显著线性相关关系。CK、LN、MN和HN处理下, 土壤呼吸的温度敏感性(Q10)值分别为3.96、3.60、3.71和3.51, 表明施氮降低了温度敏感性。氮添加导致的根系生物量增加是引起该区域土壤呼吸速率变化的一个重要原因。

关键词: 土壤呼吸的温度敏感性(Q10), 土壤温度, 土壤含水量, 根系生物量, 凋落物生物量

Abstract:

Aims As the second largest C flux between the atmosphere and terrestrial ecosystems, soil respiration plays a vital role in regulating atmosphere CO2 concentration. Therefore, understanding the response of soil respiration to the increasing nitrogen deposition is urgently needed for prediction of future climate change. However, it is still unclear how nitrogen deposition influences soil respiration of shrubland in subtropical China. Our objectives were to explore the effects of different levels of nitrogen fertilization on soil respiration, root biomass increment, and litter biomass, and to analyze the relationships between soil respiration and soil temperature and moisture.
Methods From January 2013 to September 2014, we conducted a short-term simulated nitrogen deposition experiment in the Rhododendron simsii shrubland of Dawei Mountain, located in Hunan Province, southern China. Four levels of nitrogen addition treatments (each level with three replicates) were established: control (CK, no nitrogen addition), low nitrogen addition (LN, 2 g·m-2·a-1), medium nitrogen addition (MN, 5 g·m-2·a-1) and high nitrogen addition (HN, 10 g·m-2·a-1). Soil respiration was measured by LI-8100 soil CO2 efflux system. At the same time, we measured root biomass increment and litter biomass in each plot.
Important findings Soil respiration exhibited a strong seasonal pattern, with the highest rates found in summer and the lowest rates in winter. Annual accumulative soil respiration rate in the CK, LN, MN and HN was (2.37 ± 0.39), (2.79 ± 0.42), (2.26 ± 0.38) and (2.30 ± 0.36) kg CO2·m-2, respectively. Annual mean soil respiration rate in the CK, LN, MN and HN was (1.71 ± 0.28), (2.01 ± 0.30), (1.63 ± 0.27) and (1.66 ± 0.26) μmol CO2·m-2·s-1, respectively, and it was 17.25% higher in the LN treatment compared with CK (p = 0.06). The root biomass increment was increased by LN, MN, and HN treatments by 18.36%, 36.49% and 61.63%, respectively, compared to CK. The litter biomass was increased by LN, MN, and HN treatments by 35.87%, 22.17% and 15.35%, respectively, compared with CK. Soil respiration exhibited a significant exponential relationship with soil temperature (p < 0.01, R2 is 0.77 to 0.82) and a significant linear relationship with soil moisture at the depth of 5 cm (p < 0.05, R2 is 0.10 to 0.15). The temperature sensitivity (Q10) value of CK, LN, MN and HN plots was 3.96, 3.60, 3.71 and 3.51, respectively. These results suggested that nitrogen addition promoted plant growth and decreased the temperature sensitivity of soil respiration. The increase of root biomass under N addition may be an important reason for the change of soil respiration in the study area.

Key words: temperature sensitivity (Q10), soil temperature, soil moisture, root biomass, litter biomass