短期氮沉降对纳帕海高寒退化疏花早熟禾草甸土壤呼吸干湿季变化的影响  

Effect of short⁃term nitrogen deposition on dry⁃wet seasonal variation of soil respiration in degraded Poa pratensis alpine meadow of the Napahai,Yunnan,China

作　　者：孙官发 陆梅[1] 闪昇阳 赵定蓉 孙煜佳 刘国庆 赵旭燕 冯峻 SUN Guanfa;LU Mei;SHAN Shengyang;ZHAO Dingrong;SUN Yujia;LIU Guoqing;ZHAO Xuyan;FENG Jun(College of Ecology and Environment,Southwest Forestry University,Kunming 650024,China;Napahai Provincial Nature Reserve Management and Protection Bureau,Diqing 674400,Yunnan,China;Forest Seed and Seedling Station of Yunnan Province,Kunming 650215,China)

机构地区：[1]西南林业大学生态与环境学院,昆明650024 [2]纳帕海省级自然保护区管护局,云南迪庆674400 [3]云南省林木种苗工作站,昆明650215

出　　处：《应用生态学报》2024年第2期390-398,共9页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金地区科学基金项目(42067011);云南省应用基础研究面上项目(202001AT070113);云南省中青年学术技术带头人后备人才项目(202205AC160047);西南林业大学博士启动基金项目(111901);云南省一流学科建设项目(云教发[2022]73号)资助。

摘　　要：为探究氮沉降增加背景下高寒草甸土壤呼吸干湿季变化及其与环境因子的耦合关系,选择纳帕海典型退化草甸疏花早熟禾群落,设置对照(0 g·m^(-2)·a^(-1))、低氮(5 g·m^(-2)·a^(-1))、中氮(10 g·m^(-2)·a^(-1))和高氮(15 g·m^(-2)·a^(-1))4个水平的氮沉降模拟试验,分析氮沉降引起的地上生物量、植物多样性及土壤理化性质变化对土壤呼吸的影响。结果表明:不同氮沉降处理均显著促进草甸土壤呼吸,干季和湿季土壤呼吸速率相较于对照分别增加了21.9%~53.9%和27.3%~51.2%,且在中氮处理下增幅最大。氮沉降显著提升草甸地上生物量(增幅达52.2%~66.4%);植物多样性随氮添加总体呈降低趋势,湿季最大降幅(13.5%~24.2%)出现在高氮处理。氮沉降显著增加土壤铵态氮、有机质、微生物生物量碳氮、温度和含水率(增幅为14.3%~333.5%),氮沉降显著降低土壤pH(减幅达9.0%~34.6%)。结构方程表明,植物生物量及Shannon多样性、微生物生物量和温湿度对土壤呼吸具有显著促进作用,土壤容重则表现为抑制效应;氮库和pH对土壤呼吸变化的解释率分别为55.7%和45.1%,是影响土壤CO_(2)排放的主导因素。短期大气氮沉降主要通过改变土壤pH及氮库组成而促进高寒退化草甸土壤呼吸。To explore the coupling of dry⁃wet seasonal variations of soil respiration with their environmental factors in the alpine meadow under the background of increasing nitrogen(N)deposition,we conducted an experiment in the typical degraded Poa pratensis meadow in the Napahai,Yunnan.There were four treatments,i.e.,control(0 g·m^(-2)·a^(-1)),low(5 g·m^(-2)·a^(-1)),medium(10 g·m^(-2)·a^(-1)),and high(15 g·m^(-2)·a^(-1))levels.We examined the effects of aboveground biomass,plant diversity,and soil physicochemical properties on soil respiration.The results showed that N deposition significantly promoted soil respiration.Compared with that in the control,soil respiration rates increased by 21.9%-53.9%and 27.3%-51.2%in dry and wet seasons,respectively.The maxi⁃mum value of soil respiration rate was recorded in the medium N treatment.N deposition dramatically elevated aboveground biomass(52.2%-66.4%).Plant diversity declined with increasing N addition levels,with the maxi⁃mum value(13.5%-24.2%)being recorded in high treatment in wet season.The values of ammonium nitrogen,organic matter,microbial biomass carbon and nitrogen,temperature and moisture in the three N treatments were elevated by 14.3%-333.5%compared with the control,while those of soil pH were decreased by 9.0%-34.6%.Results of the structural equation modelling showed that plant biomass,Shannon diversity,microbial biomass,soil temperature,and moisture showed a positive effect on soil respiration,while bulk density had a negative effect.Soil nitrogen pool and pH were main factors driving soil CO_(2)emissions,accounting for 55.7%and 45.1%of the varia⁃tions,respectively.Therefore,short⁃term atmospheric N deposition stimulated soil respiration primarily via altering soil pH and nitrogen pool components in the degraded alpine meadow.

关 键 词：氮沉降 高寒草甸 土壤呼吸 碳库 氮库 纳帕海 

分 类 号：S812.2[农业科学—草业科学]