简介:打区域是巴基斯坦的一个生物多样性中心。植物种类,特别树,在Swat,区域从全球气候暴露于扑灭威胁变化。用HADCM3A2a全球气候变化情形,种类分发的最大的熵(MaxEnt)建模在未来分发预言了一个可观的变化受苦pindrow(Royle前D.Don)Royle。AUC(在曲线下面的区域)0.972和0.983珍视目前是重要的,未来分发分别地种类当模特儿。象最温暖的季度(bio_10)和年度温度范围(bio_7)的吝啬的温度那样的有关生物与气候的变量显著地作出贡献到模型并且因此影响种类的预言的分发和密度,是清楚的。未来模型预言到一年,2080人口密度将显著地减少。种类的最高的密度在Sulatanr和Mankial的区域在山谷的东方、西方的边阶被记录。在种类的密度和分发的变化能有可观的影响,不是仅仅在树种类本身上,但是在联系subflora上也。
简介:Theoryandevidenceindicatethattreesandothervegetationinfluencetheatmosphericwater-cycleinvariousways.Theseinfluencesaremoreimportant,morecomplex,andmorepoorlycharacterisedthaniswidelyrealised.Whilethereislittledoubtthatchangesintreecoverwillimpactthewater-cycle,thewiderconsequencesremaindifficulttopredictastheunderlyingrelationshipsandprocessesremainpoorlycharacterised.Nonetheless,asforestsarevulnerabletohumanactivities,theselinkedaspectsofthewater-cyclearealsoatriskandthepotentialconsequencesoflargescaleforestlossaresevere.Here,fornon-specialistreaders,Ireviewourknowledgeofthelinksbetweenvegetation-coverandclimatewithafocusonforestsandrain(precipitation).Ihighlightadvances,uncertaintiesandresearchopportunities.Therearesignificantshortcomingsinourunderstandingoftheatmospherichydrologicalcycleandofitsrepresentationinclimatemodels.Abetterunderstandingoftheroleofvegetationandtree-coverwilreducesomeoftheseshortcomings.Ioutlineandilustratevariousresearchthemeswheretheseadvancesmaybefound.Thesethemesincludethebiologyofevaporation,aerosolsandatmosphericmotion,aswellastheprocessesthatdeterminemonsoonsanddiurnalprecipitationcycles.Anoveltheory-the‘bioticpump’-suggeststhatevaporationandcondensationcanexertamajorinfluenceoveratmosphericdynamics.Thistheoryexplainshowhighrainfallcanbemaintainedwithinthosecontinentalland-massesthataresufficientlyforested.Feedbackswithinmanyoftheseprocessescanresultinnon-linearbehavioursandthepotentialfordramaticchangesasaresultofforestloss(orgain):forexample,switchingfromawettoadrylocalclimate(orvisa-versa).Muchremainsunknownandmultipleresearchdisciplinesareneededtoaddressthis:forestscientistsandotherbiologistshaveamajorroletoplay.Newideas,methodsanddataofferopportunitiestoimproveunderstanding.Expectsurpr
简介:Assessmentofregionalforestcarbonstocksandunderlyingcontrolsiscriticalforguidingforestmanagementinthecontextofcarbonsequestration.Weinvestigatedthevariationsintreebiomasscarbonstocksrelatingtoforesttypes,andestimatedthetotaltreebiomasscarbonstocksandprojectedgainsthroughnaturalstanddevelopmentby2020and2050intheDaqingMountainNatureReservebasedonCategoryIIdataoftheForestInventoryofInnerMongoliafortheperiodending2008.Overatotalareaof388,577ha,thisnaturereservecurrentlystoresanestimated2221GgCintreeabovegroundbiomassalone,withpotentialtogrowbymorethan30%toreach2938GgCby2020andnearlydoubleto4092GgCby2050throughnaturaldevelopmentoftheexistingforeststands.Thetreebiomasscarbondensityandpotentialgainintreebiomasscarbonstocksvarymarkedlyamongforesttypesandwithstanddevelopment.Thevariationsinthepotentialchangeoftreebiomasscarbondensityfortheperiods2008–2020and2008–2050amongforesttypespartlyreflectthevaryingrelationshipsoftreebiomasscarbondensitywithstandagefordifferenttreespecies,andpartlyareattributabletovariationsinthestandagestructureamongdifferentforesttypes.Ofthemajorforesttypes,therankingofprojectedchangesintreebiomasscarbondensityarenotconsistentwithvariationsintherelationshipbetweentreebiomasscarbondensityandstandage,neitheraretheyexplainablebyvariationsinstandagestructures,implyingtheinteractiveeffectbetweenforesttypeandstanddynamicsontemporalchangesintreebiomasscarbondensity.Birchrankhighestforfuturebiomasscarbonsequestrationbecauseofitsdominanceincoverareaandbetteragestructureforpotentialgainintreebiomasscarbonstocks.Poplarandlarchwereout-performerscomparedtootherforesttypesgiventheirgreatercontributiontototaltreebiomasscarbonstocksrelativetotheirdistributionalareas.Findingsinthisstudyillustrateth
简介:S系列多用途青黄贮饲草料收获设备;M系列牧草压扁收获设备;B系列动力旋转耙;2BM-9型免耕播种机;2BP-2型铺膜点播机;4SW-160型马铃薯挖掘机;9QS-1000型青黄贮饲料收获机;
简介:以杭州曲院风荷景点为研究对象,以历史文献为线索,结合山水画、版画、照片、测绘图等图像资料,梳理其景观格局变迁历程,分析演变中景物间的联系,并对各时期园林发展情况进行总结。将其发展历程划分为南宋麯院时期、元代至明代衰落时期、清代更址重建时期及中华人民共和国成立至今的公园化时期。认为清康熙年间曲院的迁址与更名是景点发展的重要转折点,这一举动既使古老的景名得以延续,又使景点有了新的内涵和发展空间。园林建筑与环境的营造围绕"曲"这一主题展开,代表人工的"曲院"与代表自然的"风荷"体现了该景点人工建筑与自然景物并重的审美主旨。通过分析整理历史图像资料对于今人了解古代园林变迁有重要帮助。
简介:农杆菌已广泛应用于单、双子叶植物的遗传转化。T-DNA的传递是农杆菌介导转化的分子基础。T-DNA的传递是一个复杂的过程,与Ti质粒毒性区基因(Vir)、农杆菌染色体上毒性相关基因(chv)有关,另外植物体内部分基因也参与T-DNA的传递。T-DNA传递时在VirD1-VirD2蛋白的作用下形成T链,进一步形成T复合物,经农杆菌四型分泌系统(TypeIVsecretionsystem,T4SS)穿过细菌和植物细胞膜,运输到植物细胞胞质。进入植物细胞的T复合物在植物相关蛋白的作用下经核运输和T链的整合,最终整合到植物基因组。本研究从农杆菌对植物细胞的识别和附着、农杆菌对植物信号的感知和Vir基因的活化、T链的形成、T-复合物的运输、T链进入植物细胞后的核运输和T链的整合机制及相关基因作了详细综述,探讨了农杆菌转化机制研究中的问题,对今后农杆菌转化机制研究做了展望。