Study On Carbon Density Of Populus Tomentosa Plantations At Different Ages On Loess Plateau

In recent years,due to irrational development and utilization of the Loess Plateau with serious damage to vegetation,natural disasters frequently occurred and directly impacted on people's production and life.At the national attention and strong support,the ecological restoration on the Loess Plateau has made some progress.Populus tomentosa plantation as one of the main tree species on the Loess Plateau,its ecological aspects of carbon storage was not enough.Therefore,this article relied on environmental monitoring project of afforestation in Shaanxi Province(funded by the Yen loans),studied Populus tomentosa plantations at different ages using field investigations and the measured carbon content of research methods, investigated sample sites 11 and obtained 389 samples.Using Excel and SPSS 17.0 softwares for data processing to analyze each component carbon density of Populus tomentosa plantations ecosystems at different ages and its spatial distribution,reaching the following results:1.Different ages of the Populus tomentosa plantations ecosystems,the total carbon density were significantly different:45 years old Populus tomentosa plantation ecosystem,the total carbon density (17.081 kg·m^-2) >25 years old Populus tomentosa plantation ecosystem,the total carbon density (14.674 kg·m^-2) >10 years old Populus tomentosa plantation ecosystem,the total carbon density (9.728 kg·m^-2),45 years old Populus tomentosa plantation ecosystem organic carbon density compared with wasteland,10 years old Populus tomentosa plantation and 25 years old Populus tomentosa plantation,respectively,increased 8.573 kg·m^-2,7.353 kg·m^-2 and 2.407 kg·m^-2,increased 100.764%,75.586% and 16.403%.2.The carbon density of the spatial distribution of Populus tomentosa plantations ecosystems at different ages was significant: the organic carbon density of soil layer of 10 years old,25 years old and 45 years old Populus tomentosa plantations ecosystems was more than other layers.The proportion of organic carbon density of the trunk on the organic carbon density of aboveground of tree layers of 10 years old,25 years old and 45 year-old Populus tomentosa plantations ecosystems was largest.The organic carbon density of the root(root diameter > 10mm) occupied the largest proportion in the organic carbon density of underground roots of 10 years old,25 years old and 45 year-old Populus tomentosa plantations ecosystems.3. The soil layer carbon densities in the 0-80cm depth of Populus tomentosa plantations ecosystems at different ages were significant differences and had significantly vertical distribution:soil organic carbon density of 10 years old,25 years old and 45 years old Populus tomentosa plantation respectively compared with the adjacent wildland at the same soil depth:10 years old Populus tomentosa plantation, the total average soil organic carbon density reduced 0.784 kg·m^-2 and decreased 9.495%;25 years old Populus tomentosa plantation,the total average soil organic carbon density increased 2.798 kg?m^-2 and increased 33.886%;45-year-old Populus tomentosa plantation,the total average soil organic carbon density increased by 3.569 kg·m^-2,increasing 43.224%.And in 0-80cm soil depth the soil organic carbon densities of the 10-year-old,25 years old and 45 years old Populus tomentosa plantation had significantly vertical distribution:increasing with soil depth,soil organic carbon density declined.0-20cm soil organic carbon density was significantly higher than other soil organic carbon density (P<0.05);20-80cm of soil organic carbon density difference was not significant (P>0.05).