Carbon Density And Its Distribution Characteristics Of The Main Vegetation Ecosystem In The Northern Of Shaanxi

The northern of Shaanxi on the loess hilly and gully region is key area of ecosystemrestoration and “Grain for Green” in China. To meet the reguiremen of rehanbilitation benefitassessment, this research taking north shaaxi as case area, six main vegetation ecosystemswere studied inclouding vegetation, soil and carbon density, by analyzing the distributioncharacteristics of carbon density in each of the components, combined with statisticsestimated carbon sequestration. The mian results are as follows:(1) There was significant difference in the pattern of biomass accumulation and partitioningfor all there trees. And the ranking of contribution of biomass in shrubs was branch> root>leaf, while in the alfalfa plantation，it was root> leaf.Each organ carbon contentt rate for six plant types was lower than the national average andthe mean carbon content rates among different species was tree> shrub> herb. The differenceof organ carbon content rate did not exist in the same species，but was significant differentamong plant species，remarkably for the same organ.The carbon density of plant was between3.8871t/hm2and11.5116t/hm2，and it wasbiggest in oriental arborvitae，following with sibirica，caragana，acaciat，sea-buckthorn andalfalfa. There was significant difference in Carbon density of the organ of different species，while the largest carbon density of organ is stem in tree, respectively，branch in shrub，root inalfalfa.(2) The mean carbon content rate of soil was between2.24and14.83g C/kg in sevenecosystem types，while the biggest in sea-buckthorn，following by acacia，alfalfa，agricultural，sibirica，oriental arborvitae，and the smallest in caragana. The contribution ofsoil organic carbon content was mainly distributed in the soil surface and it decreasedfollowing the soil depth increased. The mean soil carbon density in different ecosystem wasbetween35.15t C/hm2and93.43t C/hm2and it was biggest in sea-buckthorn，following by，acacia，alfalfa，agricultural，sibirica land，oriental arborvitae，and caragana land.(3) The carbon density of6ecosystem types was between48.50t C/hm2and104.22tC/hm2, while soil layers accounted for between61.69%and95.77%, highlighting the mostcontribution of carbon accumulation in the plantation ecosystem. Besides，the ratio of carbondensity of the soil and plant was between22.64and3.24. (4) The total carbon storage of “grain for green” project in Northern Shaanxi was98.4303million t C, respectively，77.372million t C in tree, accounting for78.61%in project,15.2087million t C in shrub, accounting for15.45%in project, and5.8496million t C in herb,accounting for5.94%in project. Besides，the contribution of carbon storage was90.0912million t C in soil and8.339million t C in plant. The carbon stock was dramatically greater insoil than in plant, but its increment was lower in soil than in plant. For all the differentecosystem types，the carbon stock increased with increasing time after grain for green.