全新世中期以来西辽河流域动物地理与环境变迁

nsthatthesteppecouldbeexpanded,andtheforestre2 duced.AndbeforethemidQingDynasty (the18thcenturyAD ),tiger,beerandleopardwere extensivelydistributed.However,afterthemidQingDynasty,especiallyaftertheendofthe 19thcentury,tigerandleopardbecamelessandlessandcouldnotbefoundinanyhistorical documents.Thechangesofanimalgeographybeforethe18thcenturyweretheresultofnatural changes,becausethepopulationwasverysparseduringthisperiodoftime.However,the changesofanimalgeographyafterthe18thcenturywereinducedbyhumanactivities,because theagriculturalpopulationmigratedmassivelyfromtheYellowRiverBasintotheWestLiaohe RiverBasinplusrapidpopulationgrowthafterthemidQingDynasty.Thisresultedinforestre2 ductionandsteppeexpansion. Keywords:middleholocene;Historicalperiod;WestLiaoheRiverBasin;animalgeography 722 地理研究 21卷