The Relationship Between Vegetation Characteristics And Soil Properties Of Restoration Preliminary Stage In Wenchuan Earthquake Typical Damaged Area

The devasting Wenchuan Earthquake struck Sichuan Province,Southwestern of China,with a magnitude of 8.0 on May 12,2008.Different from general degradation system,the ecological restoration ecosystem after the earthquake was a complicated ecological system which has unique vegetation and soil conditions.Aiming to comprehensive understanding the dynamic process ecological recovery of vegetation and soil system after the earthquake disaster,we select the Wenchuan earthquake disaster areas including Wenchuan County(Arid-valley climate)and Mianzhu area(Subtropical humid climate)and each typical restoration sample area compared with undamaged area.By using variance analysis,principal component analysis and canonical correlation analysis method,we analyze the different climate zones restoration area and undamaged areas of vegetation recovery,recovery rate and coefficient of variation of soil total nutrient and the distribution of soil available nutrient and microorganisms.Finally,we conclud the main limiting factors of the vegetation-soil system and establish a coupling model of vegetation-soil ecosystem.The studying results are reflected in the following aspect:(1)The vegetation recovery rate in humid subtropical climate zone(67.05%)is higher than arid-valley climate zone(52.79%).The coefficient of variation of the recovery rate in restoration area of arid-valley climate and Subtropical humid climate are 40.44%and 23.06%respectively,higher than the undamaged area which are 14.49%and 8.62%respectively.The result suggests that the vegetation distribution in the recovery procedures show humid subtropical climate zone is more balance than the arid-valley climate zone.However,the restoration area hasn't reached the undamaged level.The different elements content in plant's different organs follow as N>K>Ca>Mg>P>Na.And leaf N:P ratio show restoration area and undamaged area in arid-valley climate zone mainly restricted by phosphorus(P).However,restoration area and undamaged area in Subtropical humid climate are mainly restricted by nitrogen(N).(2)The soil total nutrients in restoration areas are significant lower than undamaged areas in two climate zones.The soil recovery rate show the trend that total nitrogen(TN)and total phosphorus(TP)have higher recovery rate than organic carbon(SOC).And the TN,TP recovery rate in Subtropical humid climate zone is higher than arid-valley climate zone.Due to arid-valley climate zone has a higher coefficient of variation of soil total content than the subtropical humid climate zone,the soil-vegetation system in dry river valley climate will be less stability.Both in two climate zone,the content of available nitrogen,phosphorus,potassium,microbial biomass carbon and microbial biomass nitrogen in restoration areas are higher than undamaged areas.In particularly,the content of MBC and MBN in restoration areas are significant higher than undamaged areas.Three kinds of microbial population in different climate zone are followed the order bacteria>actinomycetes>fungih.The ratio of MBC:MBN show restoration areas and undamaged areas in different climate zone are mainly restricted by carbon(C).(3)The influencing factors of arid-valley climate zone restoration area includes soil SOC,TN,AN,AP and plant C,N,K,Mg.However,the influencing factor of undamaged area mainly consisted of plant C,N,K,Mg.The influencing factors of restoration area and undamaged area of subtropical humid climate are both the same,including plant species richness,biomass and soil TN,AN.In Earthquake disaster area ecosystem,the factors association between vegetation and soil are plant Mg,biomass,C,P and soil SOC,TN,TP,AP,respectively.We set up a model of vegetation and soil in earthquake disaster region.The result shows that arid-valley climate zone restoration area is primary class soil hysteresis model of coordinated development and the subtropical humid climate zone restoration area is primary vegetation soil type synchronous coordination development class.Both the undamaged areas in different climate zone are intermediate vegetation soil type synchronous coordination development class.