| Stellera chamaejasme L.is a kind of intrusive,perennial weed and primary companion species in the alpine meadow ecosystem,with its root of high lignification.It is one of the very serious intrusive weeds in pasture and harms about 1.33 million hectares in China.As the result of overgrazing,Stellera chamaejasme L.extends continuously in the Qinghai-Tibet plateau where the alpine meadow ecosystem stored a large amount of carbon.So far few studies on the effect of plant multiplication on carbon storage of ecosystem in the alpine meadow have been reported,and the research on the changes in ecosystem carbon storage resulted from multiplication of Stellera chamaejasme L.are less.The study includes all the levels of ecosystem carbon stock,i.e.carbon quantity,carbon concentration and carbon allocation for the sake of exploring the effect of Stellera chamaejasme L.multiplication on carbon stock and the mechanism of the changes in carbon storage caused by the carbon input and output ways of ecosystem and soil ecosystem.Simultaneously,the study further contributed to understand the effects of plant species on carbon cycl es,and help to know the procession of plant-soil carbon cycles.For exploring carbon stock changed by Stellera chamaejasme L.multiplication,the three kinds of block the different age Stellera chamaejasme L.(old,young,non-exsited)was found to construct plot in the alpine meadow of Tangke township,Zoige county in Sichuan province(E:102.61,N:33.17).In July,2013,the ecosystem carbon stock was measured,including bulk density,soil moisture,the aboveground and blowground biomass of plant community as well as carbon concentration of plant community and soil.The research on mechanism of carbon storage changed by Stellera chamaejasme L.multiplication was tested in the same area from May to October 2013,including the net carbon flux,leaf area index,the turnover rate of radicula nutrients flow rate.The results show that:1.Carbon stock changed significantly resulted from the multiplication of Stellera chamaejasme L..Old stellerae block stored 346.34 kg·103·hm-2 carbon,and it increased 14.27%and 19.62%compared with young stellerae and non-exsited stellerae block,respectively.2.Accompanied with the multiplication of Stellera chamaejasme L.,the increase in ecosystem carbon stock was mainly caused by the increase in the underground biomass,the extension of its root distribution and increase in soil carbon concentration.The distribution of thick root(>2mm)was multiply increased from layer 0-50cm to 0-100cm in the alpine meadow ecosystem.In the topsoil(0-15cm),thick biomass is 216.93 g/m2 in old stellerae block,it was more 152.76 g/m2 than in the non-existed stellerae block and the proportion of increase was 239.25%.It was found that soil carbon concentration increased significantly(P<0.05)in the soil layer distributed the main apical of Stellera chamaejasme L.The soil carbon concentration was higher significantly in the young stellerea block than old and non-exsited stellerea block in the upper soil(0-30cm),respectively(P<0.05),but soil carbon concentration was highest in the old stellerea block in the middle layer(30-70cm)(P<0.05).3.During the growing season,the increase in net photosynthetic rate led to the increase in ecosystem carbon input results from the multiplication of Stellera chamaejasme L.,and meanwhile ecosystem carbon output decreased caused by reducing the net flux ecosystem respiration.Therefore,the increase in carbon accumulation was promoted during the growth process through the above-mentioned two ways.In the early of growing season,Stellera chamaejasme L.prepared for nutritional reserves for itself recovery at the following growing season by the backflow.4.The soil carbon storage increased resulted from the increase in turnover rate of radicula in the rhizosphere soil.From August to September,radicula turnover reached as 0.20 per month,and increased significantly(P<0.05),and it was positive correlation with the soil carbon concentration significantly(r=0.604,P=0,002). |
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