The Characteritics Of Soil Organic Carbon Pool Of Invasive Species (Spartina Alterniflora) And Indigenous Species (Phragmites Australis) Wetlands In Shanyutan Of The Minjiang River Estury

Shanyutan Wetland is the largest estuarine wetland in the Minjiang River estrary area. To reveal the effects of invasive plant on underground soil organic crabon cycle process in wetland system, Soil samples at a depth of 0-60cm under invasive Spartina alterniflora and indigenous Phragmites australis in the Shanyutan Wetland were collected to compare the Organic Carbon,Ease of oxidation of carbon,Light fraction organic carbon,Microbial biomass carbon and Dissolved organic carbon. The results indicated:(1) The soil organic carbon(SOC),light fraction organic carbon(LFOC),microbial biomass carbon(MBC) and dissolved organic carbon(DOC) content of Spartina alterniflora were at range from 19.32～31.45 g/kg,1.29～3.14 g/kg,116.97～555.14 mg/kg,22.89～71.34 mg/kg, the average content were 23.41 g/kg,1.81 g/kg,292.93 mg/kg, 46.23 mg/kg respectively, they were highter than that of Phragmites australis(SOC,LFOC,MBC and DOC content were at range from 20.32～24.57 g/kg,1.26～2.63 g/kg, 176.68～423.30 mg/kg,20.71～45.11 mg/kg, the average content were 22.59 g/kg,1.73 g/kg,272.47 mg/kg,29.88 mg/kg). However, the Ease of oxidation of carbon(EOC) content of Spartina alterniflora(at range from 4.95～7.83 g/kg, the average content were 5.87 g/kg) were lower than that of Phragmites australis(at range from 5.11～7.78 g/kg, the average content were 6.02 g/kg), and the vertical distribution of soil active organic carbon under two plants have obvious variability.(2) EOC/SOC of soil under Spartina alterniflora and Phragmites australis were 25.23% and 26.43%,,LFOC/SOC were 7.73% and 7.64%,MBC/SOC were 1.26% and 1.22%, DOC/SOC were 0.19% and 0.13% respectively. The effects of invasive Spartina alterniflora on the active organic carbon proportion of indigenous Phragmites australis wetland were not obvious(P>0.05).(3) Effect of root system characteristics and physiochemical porperties of soils on different active organic carbon and the relation between different active organic carbon were different; effect of root system characteristics and physiochemical porperties of soils on same active organic carbon were different too.(4) SOC density under Spartina alterniflora were 14.36～17.86 kg/m3, the average value (16.03 kg/m3) were higher than that under Phragmites australis(11.21～14.46 kg/m3, the average value were 13.19 kg/m3); SOC storages in siol at a depth of 0-60cm under Spartina alterniflora(96.16 t/hm2) were higher than that under Phragmites australis; the SOC density and SOC storages of indigenous wetland were significantly increased after Spartina alterniflora invaded(P<0.01).