Unit4Globalwarming课时作业Ⅰ
阅读理解(2019·浙江高考)Californiahaslosthalfitsbigtreessincethe1930s,accordingtoastudytobepublishedTuesdayandclimatechangeseemstobeamajorfactor(因素).Thenumberoftreeslargerthantwofeetacrosshasdeclinedby50percentonmorethan46,000squaremilesofCaliforniaforests,thenewstudyfinds
Noareawassparedorunaffected,fromthefoggynortherncoasttotheSierraNevadaMountainstotheSanGabrielsaboveLosAngeles
IntheSierrahighcountry,thenumberofbigtreeshasfallenbymorethan55percent;inpartsofsouthernCaliforniathedeclinewasnearly75percent
Manyfactorscontributedtothedecline,saidPatrickMcIntyre,anecologistwhowastheleadauthorofthestudy
Woodcutterstargetedbigtrees
Housingdevelopmentpushedintothewoods
AggressivewildfirecontrolhasleftCaliforniaforestscrowdedwithsmalltreesthatcompetewithbigtreesforresources(资源).Bu