北京大学环境问题外籍专家讲座PPT――新草场生态学

TheNewRangelandEcology:ABudthatBlossomedtoaFlower新草场生态学：学科发芽的过程LynnHuntsingerUniversityofCalifornia,BerkeleyMainPoints要点•Understandingofthedynamicsofrangelandecosystemshavechanged.•对草场生态的多变性有新的认识•ThemodelsusedintheUnitedStateshavebeenshapedbysocialandeconomicconditionsuniquetoU.S.history.•美国的草场管理模型纳入社会和经济的变量•Understandingrangelandecologicaldynamics,andusingtherightmodel,isessentialforgoodpolicy.•了解草场生态系统的多变性以及使用适合的模型决定着政策的成败Outline汇报内容•Definitions:whatisrangelandecologyandwhymodels?•定义：什么是草场生态学？为什么模型？•LinearSuccessionModelbasedonsuccessiontheory•基于演替的线性演替模式•NewRangelandEcology:StatesandTransitionsModelbasedonnon-equilibriumtheory•新草场生态学：基于非平衡理论的状态-过渡模型•Influencesondevelopmentpolicy•对发展政策产生的影响Rangelands草场•Rangelands:landsthatarenotcultivated,notartificiallyirrigated,nottimberforests.Theyincludegrasslands,deserts,alpineareas,montanemeadows,tundra,woodlands,savanna,shrublands.•草场：没有种植，灌溉和用材木的土地，包括草地，沙地，高寒草原，山地草甸，冻原，林地，热带草原，灌丛带•About2/3ofthelandsurfaceoftheearthCentralquestion:Whatistheimpactofmanagementonrangelands?核心问题：管理对草场带来的影响•Grazing：放牧•NoGrazing：没有放牧•Fire：燃烧•Weather：天气•Seeding,plowing,etc.：种、耕Weusuallymanageatthe“plantcommunity”scale平常在植物群落的尺度上进行管理•The“steppe”vegetationtype：•高寒草原的植被类型•Aneedlegrass(Stipaspp.)grassland：•针茅属为主的草地EcosystemModels:生态系统模型•Showsomeofthemanyinteractionsamongorganismsandenvironment•阐述生物与环境之间的一些关系•Helpusorganizeinformation•整理信息•Canhelppredictmanagementoutcomes•预测管理结果•Shouldhelptoexplainthesystem•说明系统•Shouldhelpusunderstandhowthingswork,whichinteractionsareimportant•了解不同变量之间的关系，提出那些关系相对重要Whydoscientistscreatemodels?科学家为什么建立模型？Whydomanagerswantmodels?管理者为什么需要模型？-organizeinformationandquestions：整理信息和问题-understandhowasystemworks：认识系统的运作-predictoutcomesofmanagement：预测管理的结果-testeffectsofvariables：试验变量的影响Whatcausesvegetationchange?那些因素导致植被的变化？Models,basedontheoriesofwhatdrivesvegetationchange,arecreatedto“explain”whathappensonrangelands,andhowrangelandswillrespondtomanagement.基于导致植被变化的理论，建立模型来解读草场发生了什么？草场对管理的反馈？Whatexplanatorymodel(s)fitsrangelandsbest?那些解释模型最适合草场？ModelsforVegetationChangeatManagementandPlantCommunityScales在植物群落与管理尺度上的植被动态模型SuccessionModel演替模型•Successionisthechangeinanecosystemorcommunityovertime.Thetimescaleisyears.•演替指群落或生态系统在时间尺度上的辩护，其时间尺度指年份•Theclassicalmodeldescribesplantsuccessionas:•古典模型模型解读植被演替：–1)linear线性–2)reversible可逆的–3)predictable能预测的–4)bioticallycontrolled靠生物技术可控制的–5)withastableendpoint.稳定的状态Clements:SpaceforTimeStudyintheTallgrassPrairie克莱门茨：高杆草原在空间上的时间分析10grasslandsneverplowed10个从未种耕的草地10grasslandsplowed20yearsago10个种耕20年的草场地10grasslandsplowedlastyear10个去年种耕的草地10grasslandsPlowed50yearsago10个种耕50年以前的草地Awayofstudyingvegetationchangeovertime在时间尺度上研究植被变化的方法(Clements,1916)Assembleinto“successionalsere”归结到生态演替系列Disturbance:reversestheprogressiontotheendpoint,startstheprocessoveras“secondarysuccession”干扰：逆转演替发展到终点，重新开始次级演替Neverplowed/plowed50yearsagoPlowed10yearsagoFreshlyPlowedPlowed20yearsagoLinear,deterministic(Clementian)successionforaspecificclimate具体气候下的线性的、确定性的演替Succession(plantinteractions,competition)Disturbance(fire,grazing,plowing)Developslikeanorganismtomaturity.Linearsuccessionmodel线性演替模型Seralstage1Seralstage2Seralstage3“Equilibrium”4StableEndPoint“CLIMAX”“MID-SERAL”“PIONEER”TallgrassPrairie(50yearsagoorneverplowed)Taller,perennialgrasses(20yearsago)Earlygrasses(10yearsago)Pioneerspecies(justplowed)Controversialamongscientists,withotherideaspromoted,butnobigchangeuntilthe90s.科学家之间的争议，直到90年代没有变化But,aperfectfittomanagementneedsatthetime.但，很好地适应与当时的管理需求•FitthesocialandecologicalconditionsoftheUnitedStates：适应与当时的美国社会和生态的条件–Mostrangelandsownedandmanagedbythegovernment,neededa“scientific”waytomakedecisions大部分草场都由政府管理拥有和管理，需要“科学性”的决策–Firstgovernmentagencytostartmanagingrangelandsestablishedin1911–Clementspublishedin1916.第一次草场管理机构建立与1911，而克莱门茨出版与1916年–Usescienceasareasonforallocatingresourcesamonglivestockproducers科学作为依据来把资源分配给各畜牧业生产者AdoptedforManagement管理者的采取Increasinggrazingpressure(disturbance)“CLIMAX”“MID-SERAL”“PIONEER”TallgrassPrairieTaller,perennialgrassesEarlygrassesPioneerspecies(justplowed);annuals,weedsCarryingcapacity#animalsallowedUsedfor“RangeCondition”“CLIMAX”“MID-SERAL”“PIONEER”IncreasinggrazingpressureMeasuremanagementoutcomesbymeasuringhowsimilarthespeciescompositionistoclimax.利用与测量管理的影响：测量物种的结构与顶级群落的相似性ExcellentPoorGoodFairCondition“RangelandCondition”草场情况•Linear-successionbasedmethodofassessingrangelandconditionwasusedwidelyinthewestuntilrecently.•基于线性演替模型的方法在西方草场状况研究中常用•Climax=“excellentcondition”•顶级群落：最好的的状态•Earlysuccessionalstage=“poorcondition”•初期延期阶段：不好的状态Managementgoal:Findtherightlevelofgrazingtomaintain“good”orbetterconditionbasedonsuccessiontheory管理目标：基于演替理论，需要合适的放牧程度来保持较好的草场状态•Theclosertoclimax,thebetterthe“condition”•离顶级群落越接近，状态越好•Conditionmeasuredbyspeciescomposition:“climax”speciesvs.“pioneer”species状态评估采取物种结构：顶级物种与初期物种的比较•Establishandregulatefixed“carryingcapacity”:numberofanimals/mufortheyear.•建立与规划承载量：每亩草场能养的牲畜数量Forgovernmentmanagers对于政府的决策者•Awaytocreaterulesforherders,allocateuse：•建立规则和资源分配的方法•Awaytomeasureaffectsofmanage