氮添加对亚热带山地杜鹃灌丛土壤呼吸的影响  

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

作　　者：张蔷[1,2] 李家湘[3] 谢宗强[1] 

机构地区：[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

出　　处：《植物生态学报》2017年第1期95-104,共10页Chinese Journal of Plant Ecology

基　　金：中国科学院战略性先导科技专项(XDA-05050302)

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CO_2量分别为2.37、2.79、2.26和2.30 kgCO_2·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1.66μmol CO_2·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(Q_(10))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。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%, respectiv

关 键 词：土壤呼吸的温度敏感性 土壤温度 土壤含水量 根系生物量 凋落物生物量 

分 类 号：Q948[生物学—植物学]