氮添加对内蒙古温带典型草原土壤的酸化效应及水分的影响  

Soil acidification induced by nitrogen addition and its responses to water addition in Inner Mongolia Temperate Steppe, China

作　　者：郭群[1,2] GUO Qun(Key Laboratory of Ecosystem Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100190,China) .)

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室 [2]中国科学院大学资源与环境学院

出　　处：《应用生态学报》2019年第10期3285-3291,共7页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(31570437);美丽中国生态文明建设科技工程专项(XDA23060205);国家重点研发计划项目(2017YFA0604801)资助~~

摘　　要：氮(N)沉降增加带来的土壤酸化问题已经得到广泛的关注,然而土壤酸化是否受到未来降水格局改变的影响研究相对匮乏.本研究基于内蒙古温带典型草原5年(2013—2017年)的N添加(10和40 g N·m^-2·a^-1)和增雨(增雨量80 mm,分2 mm×40次、5 mm×16次、10 mm×8次、20 mm×4次、40 mm×2次5种处理)控制试验分析了水分对N添加后土壤酸化的影响.结果表明:40 g N·m^-2·a^-1 N添加在土壤酸化出现的时间、酸化程度以及酸化随时间的变化速率上均大于10 g N·m^-2·a^(-1)N添加.40 g N·m^-2·a^-1 N添加一年后即在各层土壤中观测到了显著的土壤pH降低,而10 g N·m^-2·a^-1 N添加只有土壤表层(0~5 cm)在N添加一年后出现显著的土壤pH降低,5~10和10~20 cm土层显著的土壤pH降低分别出现在氮添加4年和5年后.氮添加后土壤pH的降低幅度随氮添加年限的延长而增加,40 g N·m^-2·a^(-1)N添加土壤pH随时间的降低速率大于10 g N·m^-2·a^-1N添加.增雨不改变氮添加后土壤pH降低的结果,但中小强度增雨方式(2~20 mm)在干旱年份有缓解10 g N·m^-2·a^-1 N添加处理土壤酸化的趋势,而所有增雨方式在湿润年份均有加剧氮添加(10和40 g N·m^-2·a^-1)后土壤酸化的趋势,尤其是表层土壤,但缓解和加剧的程度均不显著.高强度增雨方式后(10~40 mm)土壤无机氮的淋溶可能是增雨加剧氮添加后土壤酸化的一个重要原因.本研究将为预测草原生态系统对未来氮沉降和降水格局改变的响应提供科学依据.Soil acidification due to exogenous nitrogen(N)deposition has been received sufficient attention in the past several decades.Whether the N-induced soil acidification is modulated by the altering precipitation regimes remains unclear.In this study,based on a five-year(2013-2017)manipulative field experiment with factorial N addition(10 and 40 g N·m^-2·a^-1)and water addition(a total amount of 80 mm·a^-1 was added in terms of five intensities,i.e.,2 mm×40 times,5 mm×16 times,10 mm×8 times,20 mm×4 times,and 40 mm×2 times)in a typical steppe in Inner Mongolia,I analyzed the effects of water addition on soil acidification induced by N addition.I found that soil acidification induced by 40 g N m^-2·a^-1 N addition occurred earlier,more significant,and with a greater year by year changed rate than that of 10 g N·m^-2·a^-1 N addition.After one year treatment,I observed significant soil acidification at soil profiles of 0-5,5-10,and 10-20 cm in the treatment of 40 g N·m^-2·a^-1 N addition,while significant soil acidification in 10 g N·m^-2·a^-1 N addition was observed after 1,4,and 5 year since N was added for the three layers,respectively.In general,the magnitude of soil acidification induced by N addition increased with the increasing period after N addition,and the slope of the regression line was steeper in the relatively higher dose of N addition(40 g N·m^-2·a^-1).Soil acidification induced by N addition could not be reversed by water addition,but water addition in terms of relatively lower intensities(i.e.,all the treatments except 40 mm×2 times)could relieve the N-induced soil acidification to a certain extent in the treatment with lower dose of N addition(10 g N·m^-2·a^-1)in dry years.In wet years,however,water addition exacerbated soil acidification after N was added,especially in the topsoil.The leaching of soil inorganic N after higher intensity of water addition(10-40 mm)could explain the deteriorated N-induced soil acidification when water was added.There was no significance for the relief

关 键 词：氮沉降 土壤酸化 降水格局 增雨 

分 类 号：S812.2[农业科学—草业科学]