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华西雨屏区苦竹林土壤呼吸对模拟氮沉降的响应
引用本文:涂利华,胡庭兴,黄立华,李仁洪,戴洪忠,雒守华,向元彬.华西雨屏区苦竹林土壤呼吸对模拟氮沉降的响应[J].植物生态学报,2009,33(4):728-738.
作者姓名:涂利华  胡庭兴  黄立华  李仁洪  戴洪忠  雒守华  向元彬
作者单位:(四川农业大学林学院四川省林业生态工程省级重点实验室,四川雅安 625014)
基金项目:国家科技支撑计划子专题,四川省重点学科建设项目 
摘    要: 2007年11月至2008年11月, 对华西雨屏区苦竹(Pleioblastus amarus)人工林进行了模拟氮沉降试验, 氮沉降水平分别为对照(CK, 0 g N·m–2·a–1)、低氮(5 g N·m–2·a–1)、中氮(15 g N·m–2·a–1)和高氮(30 g N·m–2·a–1)。每月下旬, 采用红外CO2分析法测定土壤呼吸速率, 并定量地对各处理施氮(NH4NO3)。结果表明: 2008年试验地氮湿沉降量为8.241 g·m–2, 超出该地区氮沉降临界负荷。在生长季节, 苦竹林根呼吸占总土壤呼吸的60%左右。模拟氮沉降促进了苦竹林土壤呼吸速率, 使苦竹林土壤每年向大气释放的CO2增加了9.4%~28.6%。在大时间尺度上(如1 a), 土壤呼吸主要受温度的影响。2008年6~10月, 土壤呼吸速率24 h平均值均表现为: 对照<低氮<中氮<高氮。氮沉降处理1 a后, 土壤微生物呼吸速率和土壤微生物生物量碳、氮增加, 并且均与氮沉降量具有相同趋势。各处理土壤呼吸速率与10 cm土壤温度、月平均气温呈极显著指数正相关关系, 利用温度单因素模型可以解释土壤呼吸速率的大部分。模拟氮沉降使得土壤呼吸Q10值增大, 表明氮沉降可能增强了土壤呼吸的温度敏感性。在氮沉降持续增加和全球气候变暖的背景下, 氮沉降和温度的共同作用可能使得苦竹林向大气中排放的CO2增加。

关 键 词:氮沉降  土壤呼吸  根呼吸  微生物呼吸  温度敏感性  苦竹林  华西雨屏区

RESPONSE OF SOIL RESPIRATION TO SIMULATED NITROGEN DEPOSITION IN PLEIOBLASTUS AMARUS FOREST,RAINY AREA OF WEST CHINA
TU Li-Hua,HU Ting-Xing,HUANG Li-Hua,LI Ren-Hong,DAI Hong-Zhong,LUO Shou-Hua,XIANG Yuan-Bin.RESPONSE OF SOIL RESPIRATION TO SIMULATED NITROGEN DEPOSITION IN PLEIOBLASTUS AMARUS FOREST,RAINY AREA OF WEST CHINA[J].Acta Phytoecologica Sinica,2009,33(4):728-738.
Authors:TU Li-Hua  HU Ting-Xing  HUANG Li-Hua  LI Ren-Hong  DAI Hong-Zhong  LUO Shou-Hua  XIANG Yuan-Bin
Institution:Key Laboratory of Ecological Forestry Engineering of Sichuan Province, College of Forestry, Sichuan Agricultural University, Ya’an, Sichuan 625014, China
Abstract:Aims Our objectives were to determine the effect of increased nitrogen deposition on total soil respiration and microbial respiration of Pleioblastus amarus forest, and whether increased nitrogen deposition alters the temperature sensitivity of soil respiration. Methods For one year starting November 2007, we conducted a simulated nitrogen deposition field experiment in P. amarus forest, Rainy Area of West China. The levels of nitrogen deposition were control (CK, 0 g N·m–2·a–1), low nitrogen (5 g N·m–2·a–1), medium nitrogen (15 g N·m–2·a–1) and high nitrogen (30 g N·m–2·a–1). At the end of each month, soil respiration was measured by infrared gas analyzer, and NH4NO3 was added to N-treated plots. Natural wet nitrogen deposition was measured in 2008, and 0–20 cm horizon soil was collected for soil respiration sampling in November 2008. These soil samples were maintained in the laboratory at 20 ℃, and we measured soil microbial respiration (by infrared gas analyzer) and microbial biomass carbon and nitrogen. Important findings The wet nitrogen deposition of Liujiang, Hongya County is 8.241 g·m–2; it exceeds the local nitrogen deposition critical loads. Root respiration accounts for about 60% of the total soil respiration of P. amarus forest from April to October. Nitrogen deposition promotes soil respiration of P. amarus forest, and CO2 release from forest soil is increased by 9.4%–28.6%. Microbial respiration, microbial biomass carbon and nitrogen were stimulated by nitrogen deposition, and respiration rate rises with increased nitrogen deposition. The soil respiration rate exhibited positive exponential relationships with air temperature and soil temperature at 10 cm depth. Exponential relationships between temperature and soil respiration were highly significant in all plots. Nitrogen deposition may increase temperature sensitivity of soil respiration. With increasing rates of anthropogenic N deposition and global warming, nitrogen combined with temperature may increase the release of CO2 from P. amarus forest soil.
Keywords:nitrogen deposition  soil respiration  root respiration  microbial respiration  temperature sensitivity  Pleioblastus amarus forest  Rainy Area of West China
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