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SoilmoistureconditionandsoilnitrogendynamicsinapureAlnusjaponicaforestinKorea韩国赤杨纯林中土壤湿度状况对土壤氮素动态的影响LANDSCAPEANDECOLOGICALENGINEERING卷:7期:1页:93-99出版年:JAN2011赤杨（中国树木分类学）又名日本桤木，桦木科桤木属AbstractThisstudywasconductedtoexaminetheinfluencesofsoil-moistureconditionsonsoilnitrogen(N)dynamics,includinginsitusoilNmineralization,Navailability,anddenitrificationinapureAlnusjaponicaforestlocatedinSeoul,centralKorea.ThesoilNmineralization,Navailability,anddenitrificationweredeterminedusingtheburiedbagincubationmethod,ionexchangeresinbagmethod,andacetyleneblockmethod,respectively.TheannualnetNmineralizationrate(kgNha−1year−1)andannualNavailability(mgNbag−1)were40.26and80.65intherelativelydrysite,−5.43and45.39inthemoistsite,and7.09and39.17inthewetsite,respectively.TheannualnetNmineralizationrateandannualNavailabilityinthedrysiteweresignificantlyhigherthanthoseinthemoistandwetsites,whereastherewasnosignificantdifferencebetweenthemoistandwetsites.Theannualmeandenitrificationrate(kgNha−1year−1)inthedry,moist,andwetsiteswas2.37,2.76,and1.59,respectively.However,therewasnosignificantdifferenceamongsitesduetothehighspatialandtemporalvariations.Ourresultsindicatethatsoil-moistureconditioninfluencedtheinsituNmineralizationandresinbagNavailabilityinanA.japonicaforest,andtreatmentsofproperdrainageforpoorlydrainedsiteswouldincreasesoilNmineralizationandNavailabilityandconsequentlybeusefultoconserveandmanagetheA.japonicaforest.这项研究是探讨位于韩国首都首尔附近的赤杨纯林中土壤水分条件对土壤氮（N）动态的影响，包括原位土壤中N的矿化，有效性以及反硝化作用。分别采用埋袋培育法，离子交换树脂袋法，乙炔阻塞法来测定土壤氮的矿化、有效性和反硝化作用。在相对干燥的地方，每年N净矿化速率为40.26kgNha−1year−1，有效N含量为80.65mgNbag−1，在潮湿的地区，每年N净矿化速率和有效N含量分别为-5.43kgNha−1year−1和45.39mgNbag−1，在湿润地区，每年N净矿化速率和有效N含量分别为7.09kgNha−1year−1和39.17mgNbag−1。干燥地方，每年的净氮矿化速率和有效氮含量明显比潮湿和湿润地区高，而在潮湿地方和湿润地区没有显著差异。年平均反硝化速率在干燥，潮湿，湿润地区分别为2.37kgNha−1year−1，2.76kgNha−1year−1，1.59kgNha−1year−1。然而，在各个地区并没有因为极度的时空变化出现显着性差异。我们的研究结果表明，赤杨纯林中，土壤水分条件影响着原位氮矿化和树脂袋中有效性氮的含量，在排水不良的地区，适当排水会提高土壤氮素矿化速率和增加有效N含量，因此可以用来保护和管理赤杨林。Introduction引言Alnusspp.playanimportantroleinthesoilnitrogen(N)cycle.ItcanconvertgaseousN2intheatmosphereintoammoniainthesoilthroughN-fixationforsymbiosiswithFrankia.Therefore,Alnusspp.canincreasenotonlythesoilNcontentbutalsotherateofthesoilNcycle(Binkleyetal.1992b).Inparticular,Alnusspp.acceleratesthesoilNturnoverrateandincreasestheNavailability(Binkleyetal.1992a,b;Hartetal.1997).Alnusjaponica(Thunb.)SteudisdistributedwidelyintemperateAsiaandisnativetoChina,Japan,andKorea.ItisknownthatthetypicalhabitatsofA.japonicaareswampsandconstantlyorperiodicallyfloodedareaswithpoorlydrainedsoils(IwanagaandYamamoto2007).InKorea,A.japonicaoccursasasingletreeinthewetlandsalongriversandstreams(Kimetal.2005),butthespeciesisrarelyfoundasaforest.赤杨在土壤的N循环中起着重要的作用。在土壤中，赤杨在与弗兰克氏菌共生情况下发生固氮效应，将大气中的气态氮转化成氨态。因此赤杨不仅增加了土壤氮含量，还提高了土壤氮循环的速率。特别的是，赤杨增加了氮的周转率和可利用率。赤杨广泛分布在亚洲温带地区，是中日韩的乡土种。据了解，赤杨的典型生境为沼泽和土壤排水性差、时常遭遇洪水的地区。在韩国，赤杨独棵地出现在在河畔溪边的湿地，而罕见以森林形式呈现。ApureA.japonicaforestinKoreaisdesignatedasEcologicalLandscapePreservationArea,andalong-termmonitoringprogramisbeingconductedintheforest.However,studiesonecologicalcharacteristicsofA.japonicaarenecessarytoprepareforestmanagementplansforprotectingtheforest.Interestingly,soil-moistureconditionsintheA.japonicaforestaredifferentfromthoseofcommonforests,anditisspeculatedthatsoil-moistureinfluencesnutrientdistributionandcyclingintheforest.Therefore,itisimportanttoexaminetherelationshipbetweensoil-moistureconditionsandNdynamics,includingNmineralization,Navailability,anddenitrificationinthealderforestandtoproposemanagementpracticesfortheforest.一片赤杨纯林在韩国被定为生态景观保护区，林区里会实行长期的观测方案。为了给森林保护的管理计划做准备，对于赤杨的生态特征的研究是必须的。有趣的是，赤杨林中的土壤湿度情况同那些常见的森林不同。据推测，土壤湿度影响林内的养分分配和循环。因此，找出土壤湿度情况与氮动态（包括氮的矿化作用，氮的可利用率和反硝化作用）之间的关系的是很重要的，可以为森林的水肥管理提供参考。TherearenumerousstudiesontheNcycleofAlnusspp.(Binkleyetal.1992a,b;Hartetal.1997;VermesandMyrold1992).However,informationontheseasonalchangesinsoilNcyclesinAlnusspp.isverylimited(StruweandKjøller1990).Also,onlyafewstudiesfocusontherelationshipbetweensoil-moistureconditionsandsoilNdynamicsinAlnusspp.(Sexstoneetal.1988;StruweandKjøller1990).WehypothesizedthattherewouldbesignificanttemporalvariationsinNmineralization,Navailability,anddenitrification,andwehypothesizedthatsoil-moistureconditionwouldincreasethesesoilNdynamicsinapureA.japonicaforest.Theobjectivesofthestudywereto:(1)examinetheseasonalpatternofNmineralization,Navailability,anddenitrification,(2)investigaterelationshipsbetweensoilmoistureandNdynamics,and(3)suggestmanagementapproachesforthelong-termecologicalconservationofapureA.JaponicaforestlocatedinHeonilleung,Seoul,Korea.关于赤杨的研究有很多，但关于赤杨种土壤氮循环季节变换的信息却很有限。而且，很少有着重于赤杨土壤湿度情况和土壤氮动态之间关系的研究。我们假设在氮的矿化作用、可利用率和反硝化作用有了显著的时空变化，也可以假设在赤杨林中，土壤湿度情况能提高这些土壤氮动态。这项研究的目标如下：1.寻找氮的矿化作用、可利用率和反硝化作用的季节性变化模式。2.调查土壤湿度和氮动态之间的关系。3.为韩国首尔献仁陵地区的赤杨纯林的长期生态保护提出管理方法。MaterialsandmethodsStudysiteThestudywasconductedinapureA.japonicaforestatHeonilleunginSeoul,centralKorea(372705200N,1270405300E).TheHeonilleungistheroyaltomboftheJoseonDynastylocatedwithintheadministrativedistrictofSeoulCity.Thealderforesthasbe