高中英语模二U2背景材料The-Disappearing-RainforestsVIP专享VIP免费

TheDisappearingRainforestsWearelosingEarth'sgreatestbiologicaltreasuresjustaswearebeginningtoappreciatetheirtruevalue.Rainforestsoncecovered14%oftheearth'slandsurface;nowtheycoveramere6%andexpertsestimatethatthelastremainingrainforestscouldbeconsumedinlessthan40years.Oneandone-halfacresofrainforestarelosteverysecondwithtragicconsequencesforbothdevelopingandindustrialcountries.Rainforestsarebeingdestroyedbecausethevalueofrainforestlandisperceivedasonlythevalueofitstimberbyshort-sightedgovernments,multi-nationalloggingcompanies,andlandowners.Nearlyhalfoftheworld'sspeciesofplants,animalsandmicroorganismswillbedestroyedorseverelythreatenedoverthenextquartercenturyduetorainforestdeforestation.Expertsestimatesthatwearelosing137plant,animalandinsectspecieseverysingledayduetorainforestdeforestation.Thatequatesto50,000speciesayear.Astherainforestspeciesdisappear,sodomanypossiblecuresforlife-threateningdiseases.Currently,121prescriptiondrugssoldworldwidecomefromplant-derivedsources.While25%ofWesternpharmaceuticalsarederivedfromrainforestingredients,lessthat1%ofthesetropicaltreesandplantshavebeentestedbyscientists.Mostrainforestsareclearedbychainsaws,bulldozersandfiresforitstimbervalueandthenarefollowedbyfarmingandranchingoperations,evenbyworldgiantslikeMitsubishiCorporation,GeorgiaPacific,TexacoandUnocal.TherewereanestimatedtenmillionIndianslivingintheAmazonianRainforestfivecenturiesago.Todaytherearelessthan200,000.InBrazilalone,Europeancolonistshavedestroyedmorethan90indigenoustribessincethe1900's,withthemhavegonecenturiesofaccumulatedknowledgeofthemedicinalvalueofrainforestspecies.Astheirhomelandscontinuetobedestroyedbydeforestation,rainforestpeoplesarealsodisappearing.MostmedicinemenandshamansremainingintheRainforeststodayare70yearsoldormore.Eachtimearainforestmedicinemandies,itisasifalibraryhasburneddown.Whenamedicinemandieswithoutpassinghisartsontothenextgeneration,thetribeandtheworldlosesthousandsofyearsofirreplaceableknowledgeaboutmedicinalplants.