25997.青藏高原高寒草甸群落和土壤對(duì)高原鼠兔密度變化的響應(yīng)

1、蘭州大學(xué)碩士學(xué)位論文青藏高原高寒草甸群落和土壤對(duì)高原鼠兔密度變化的響應(yīng)姓名：周雪榮申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：草業(yè)科學(xué)指導(dǎo)教師：郭正剛20100501AbstractAsoneofthekeycomponentsofalpinemeadowecosystem，Ochatonacurzoniaeplaysanimportantroleinthestabilityandhealthofalpinemeadowwhenitspopulationd

2、ensityiSbelowthewarningthresholdvalue，howeverthissmallmammalcausesthegreatdisastertoalpinemeadowwhenitspopulationdensitysurpassthewarningthresholdvalueThereforeitisimportanttodeterminetheresponseofalpinemeadowcommunityan

3、dsoilcharacteristicstochangesofpopulationdensityinOchatonacurzoniaeforquantifyingthewarningthresholdvalueAfieldsurveywasconductedtodisclosetherelationshipbetweensoil，plantcommunitiesandpopulationdensityofOchatonacurzonia

4、ebymeasuringthespeciescompositionofplantcommunitycovetheight，biomasscharacteristics，functionalgroup，soilmoisture，bulkdensit％particlesizecomposition，pH，organicmaRer，N，P，KcontentandorganicmaRer，andMainconclusionsweredrawna

5、sfollowing，F(xiàn)irstlyGeneralheightandcoverofalpinemeadowcommunityfirstlydecreasedandthenincreasedwiththeincreaseofpopulationdensityinOchatonacurzoniae，howeverthebiomassgraduallydecreasedThetypesofnoxiousweedsWasthelowest，an

6、dthetypesofgrassesandtheimportantvalueofsedgesWasbiggestwhentheburrowdensityWas14number／625m2SecondlytherichnessindexofplantcommunityfirstlydecreasedandthenincreasedwiththeincreaseofpopulationdensityinOchatonacurzoniaean

7、dtheevennessindexofplantcommunityfirstlyincreasedandthendecreasedwiththeincreaseofpopulationdensityinOchatonacurzoniaeHowever，thediversityindexofplantcommunityshowedapeakandsmallpeakwhenburrowdensityWas14and54number／625m

8、2，respectivelyThisstudyindicatedthatdiversityindexofplantcommunityWasthebiggestwhenburrowdensityWas14number／625m2andthreeindexeswerethelowestwhenburrowdensityWas34number／625m2ThirdlyTheheightofforagefunctionalgroupsandpo

9、isonousweedsfunctionalgroupswerealldeclinedwiththeincreaseofpopulationdensityinOchatonacurzoniae，andthecoverofforagefunctionalgroupsWaslowestwhenburrowdensityWas34number／625m2，andthecoverofpoisonousforbsfunctionalgroupsW