内蒙古不同类型草地土壤氮矿化及其温度敏感性  

Soil nitrogen mineralization and associated temperature sensitivity of different Inner Mongolian grasslands

作　　者：朱剑兴[1,2] 王秋凤[1] 何念鹏[1] 王若梦[1] 代景忠[3] 

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,北京100101 [2]中国科学院大学,北京100049 [3]内蒙古农业大学生态环境学院,呼和浩特010019

出　　处：《生态学报》2013年第19期6320-6327,共8页Acta Ecologica Sinica

基　　金：全国生态环境十年(2000-2010年)变化遥感调查与评估专项(STSN-02-03);国家重点基础研究发展计划项目(2010CB833501)

摘　　要：土壤氮矿化(Nitrogen mineralization)是土壤氮循环的重要环节,对土壤氮素供应以及植物生产力的维持具有十分重要的意义。沿中国东北草地样带(Northeastern China Transect,NECT)分别在典型草地、过渡草地及荒漠草地设置了3个实验样地,利用不同温度(5、10、15、20℃和25℃)和不同水分(30%、60%和90%土壤饱和含水量,Saturated soil moisture,SSM)的室内培养途径,探讨了不同类型草地的土壤氮矿化速率、土壤氮矿化的温度敏感性(Q10)及其主要影响因素。实验结果表明:从典型草地至荒漠草地,土壤全碳、全氮、全磷、微生物生物量碳氮含量均表现为逐渐下降的趋势;类似地,土壤净氮矿化速率、硝化速率也逐渐降低。在20℃和60%SSM时,土壤净氮矿化速率表现为典型草地(0.715 mg N kg-1d-1)>过渡草地(0.507 mg N kg-1d-1)>荒漠草地(0.134 mg N kg-1d-1);相反,温度敏感性却逐渐升高,温度敏感性与基质质量指数呈负相关。草地类型和水分对于土壤净氮矿化速率、硝化速率具有显著影响,且二者间具有显著的交互效应。包含温度和水分的双因素模型可很好地拟合土壤氮矿化速率的变化趋势(P<0.0001),二者可共同解释土壤硝化速率92%—96%的变异。土壤氮矿化沿着草地演替呈现出很好的空间格局、并与温度和水分具有密切关系,为解释内蒙古草地空间分布格局提供了理论基础。Nitrogen （N） mineralization is an important component of the soil N cycle, which is important for supplying the available N in soil to plants in addition to maintaining the plant productivity of terrestrial ecosystems.Especially, when most of grassland ecosystems were confronted with lacking of soil available N, it is more meaningful to focus on the soil N mineralization. In this study, we analyzed 3 different grasslands located along the Northeastern China Transect （NECT）; specifically, a typical grassland, a transitional grassland, and a desert grassland. The soils in the 0-20 cm layer of these grasslands were incubated in the laboratory at different temperature （5, 10, 15, 20 and 25 ℃） and moisture levels （30%, 60%, and 90% saturated soil moisture （SSM）） to evaluate differences in soil N mineralization and temperature sensitivity （Q10）, and to determine the main factors that regulate this process. The results showed that the total carbon, N, and phosphorus, microbial biomass carbon, and microbial biomass N of soils declined with grassland type, from typical grassland, to transitional grassland, to desert grassland. Furthermore, the total carbon, N, phosphorus, microbial biomass carbon, and microbial biomass N in soils were all significantly different among the three different grassland types （P 〈 0.001）.The different soil properties in different grasslands indicated that the quality of the soil substrate tended to decline from typical grassland, to transitional grassland, to desert grassland. In parallel, net soil N mineralization and soil nitrification rates decreased gradually when the soils were incubated at the same temperature and moisture levels. For example, at an incubation temperature of 20 ℃ and moisture level of 60% SSM, the soil net N mineralization rate of the three grasslands was in the following order： typical grassland （0.715 mg N kg-1 d-1） 〉 transitional grassland （0.507 mg N kg-1 d-1） 〉 desert grassland （0.134 mg N kg-1 d-1）. In contrast, th

关 键 词：草地类型 温度 水分 土壤氮矿化速率 温度敏感性（Q10） 

分 类 号：S812[农业科学—草业科学]