川南天然常绿阔叶林人工更新后土壤氮库与微生物的季节变化  

Seasonal variation of soil nitrogen pools and microbes under natural evergreen broadleaved forest and its artificial regeneration forests in Southern Sichuan Province,China

作　　者：龚伟[1] 胡庭兴[1] 王景燕[1] 宫渊波[1] 罗承德[1] 

机构地区：[1]四川农业大学林业生态工程省级重点实验室,雅安625014

出　　处：《生态学报》2011年第7期1763-1771,共9页Acta Ecologica Sinica

基　　金：国家"十五"科技攻关项目(2001BA606A-06;2004BA606A-06);四川省教育厅项目(08zb038);四川农业大学211工程创新团队项目"长江上游植被恢复与重建"资助

摘　　要：对川南天然常绿阔叶林及其人工更新成檫木林、柳杉林和水杉林后土壤不同形态氮素含量、微生物数量和脲酶活性进行研究,并探讨了它们之间的相互关系。结果表明:土壤全氮、微生物量氮、铵态氮和硝态氮含量、细菌、真菌和放线菌数量及脲酶活性,各林分均为秋季>春季>冬季>夏季,各季节均为天然常绿阔叶林>檫木林>水杉林>柳杉林。这说明天然常绿阔叶林人工更新后土壤不同形态氮素含量、微生物数量和脲酶活性下降,土壤保肥和供肥能力降低,而各人工林下降程度不同。土壤不同形态氮素含量与微生物数量和脲酶活性之间呈显著正相关,说明微生物数量及脲酶活性的变化能够表征土壤氮素含量变化。研究结果为保护天然常绿阔叶林、选择适宜的更新树种和天然常绿阔叶林人工更新后林地土壤的科学管理提供依据,也为退耕还林中树种的选择提供参考。Nitrogen（N） along with carbon is the most complex and crucial element essential for life,and plays a critical role in nutrient cycling.In terrestrial ecosystems,N availability is often a limiting factor that controls primary production and C storage.NH＋4-N,NO-3-N and microbial biomass N are different active N pools,and participate in short-term biological cycling within soil.N availability of soils is mostly influenced by these active N pools,which provide the information needed to determine the sustainability of land management.NH＋4-N and NO-3-N are the main soil nitrogen forms that can be directly absorbed and utilized by plants.Microbial biomass plays a critical role in nutrient cycling and is a sensitive indicator of changes in soil quality induced by management practices,and it contains the largest portion of the biologically active N in soil.Soil organic N turns into inorganic nitrogen with the help of soil microorganisms,which have the ability to degrade organic compounds and modify inorganic products,contributing in particular to the mineralization of nutrients.Any changes in the type or amount of organic matter entering the soil could directly affect the structure of the soil microbial community or the functions performed by the various microbial groups in soil.An investigation was carried out to study the differences in soil nitrogen fractions contents,culturable microbial counts and urase activity,and their relationships under natural evergreen broadleaved forest and its artificial regeneration forests of Sassafras tzumu,Cryptomeria fortunei and Metasequoia glyptostroboides in southern Sichuan Province,China.Soil samples were collected from each forest to determine soil nitrogen fractions,microbial counts and enzyme activity.Regression analysis was used to determine the relationship between soil nitrogen fractions,microbial counts and enzyme activity.The results showed that the contents of soil total nitrogen,microbial biomass nitrogen,NH＋4-N and NO-3-N,the counts of culturable bacteria,fungi

关 键 词：天然常绿阔叶林 人工更新 土壤氮库 微生物 土壤肥力 

分 类 号：S714[农业科学—林学]