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

Loess plateau is the most fragile region in ecological environment, wherethe original vegetation was destructed, the terrain were broken, and the soil andwater was lost. Forest ecosystem not only has an important effect on soil andwater conservation, but also play a pivotal role in forest carbon cycle. So theafforestation in the loess plateau could restore the ecological environment, andat the same time, the increase of the area of artificial ecological forest couldremit global climate change effectively. By studying the carbon storage of forestecosystem in different vegetation, exploring the carbon storage of plantation andits potential would support us to evaluate the carbon storage ability of plantationand its function in area carbon balance, meanwhile providing a basis for themodels of the loess plateau vegetation afforestation.In this study, the mingled forest consisted by young plantation ofPlatycladus orientalis and Populus simonii, which planted in loess plateau, wasset as the research objects, we also set the adjacent barren land as the control plot and searched the carbon density and its character of distribution in space indifferent layer of ecosystem by using the method of sample plot survey, the finalconclusions are as follows:（1）The carbon density of plantation in different vegetation layers were:arbor layer was11.539t·hm^-2, accounting for94.33%of total OCD in forestecological system, shrub and herbage layers were0.113t·hm^-2、0.580t·hm^-2respectively, however, the carbon density of litter was only0.142t·hm^-2. For thetwo arbor plants, the carbon storage of Platycladus orientalis was3.597kg perplant, while Populus simonii is1.877kg, according to those dates, we concludedthat the potential of storage carbon in Platycladus orientalis was higher thanPopulus simonii.（2） Mean carbon content of arbor tissue, shrub layer, herbage layer andlitter layer were50.70%、50.35%、46.88%、48.44%、35.6%respectively.Apparently, carbon content in litter layer is lower, other layers had no obviousdifference, biomass is the primary affecting factor to carbon storage.（3）The soil carbon density was53.172t·hm^-2 in0-80cm in mingledforest of Platycladus orientalis and Populus simonii. It declined5.15%compared with barren land. The soil carbon density reduced gradually with theincreasing of the soil depth in forest land and barren land, but the soil carbondensity in the surface layer（0¹0cm） accounted for17.22%and17.26%of the total soil storage of forest land and barren land respectively, which wassignificantly higher than other soil layers （P<0.05）.（4）The carbon density was65.546t·hm^-2in the young plantation ecosystemof mingled forest （Platycladus orientalis and Populus simonii）, compared withthe adjacent barren land, it increased10.54%, which suggested that afforestationcould increase the ecosystem carbon storage. In different layer of artificial forestecosystem, the order of carbon density from large to small was: soil layer>arborlayer>litter layer>herbage layer>shrub layer. The soil carbon density was themain contributor for the young plantation ecosystem.