| With the decreasing natural plantation resources,the areas of plantation increased continuously.The Chinese fir(Cunninghamia lanceolata(Lamb.)Hook.)plantation play an important role in forest ecosystems,which is a major forest types in southern collective forest area. The statistics from the 6th National Forest Resources Inventory showed that the total area of Chinese fir plantation have reached 921.5 million hm2,accounting for 29%of those of plantation in the whole nation.At present,the studying on carbon storage and the carbon cycle in Chinese fir plantation became a hot topic.Object of this article mainly focused on carbon storage in Chinese fir ecosystem with different site management treatments at 1st to 10th years after a rotation,which was on the basis of Fan Shaohui research.The results were showed as follows:1.There were differences among carbon content in overstory layer,shrub layer,herb layer, litter layer;soil layer and logging slash of second-rotation Chinese fir plantation in different ages. Carbon content of different components in overstory layer at 1 st to 10th years after treatments were:living branches ranged from 42.71%to 45.71%,dead branches ranged from 45.42%to 46.67%,living leaves ranged from 45.84%to 50.73%,dead leaves ranged from 45.59%to 50.44%, stems ranged from 46.04%to 47.83%,barks ranged from 45.31%to 51.36%,roots ranged from 43.66%to 49.44%,and those carbon content increased with time.Carbon couteut of different roots ranged from 43.66%to 51.75%,and increased with the increasing diameter class.2.Carbon content changed in different components in shrubs layer at 1st to 10th years after treatments,and the values ranged form 41.15%to 43.78%in branches,ranged form 38.10%to 44.35%in leaves,ranged form 37.00%to 47.82%in roots.Carbon content changed in different components of herb layers,and the values ranged form 37.19%to 45.78%in above-ground parts, ranged form 35.89%to 47.82%in underground parts.The carbon content decreased with the increasing stand ages.Carbon content in different components ranged form 42.57%to 53.78%in Chinese fir litter at 6th to 9th years after treatments,but little annual variation.3.Carbon content at 0-10 cm and 10-20 cm soil depth with treatment 3(stem and bark harvest treatment)and treatment 4(double slash treatment)were slightly higher at 3rd,6th,9th,and 10th years after treatments,and were lower with treatment 5(slash burring treatment)and treatment 1 (no slash treatment),but no significant difference of soil carbon content in plantation with different treatments(P＞0.05).4.Carbon content in different soil depths with different treatments at 10th year ranged form 2.65%to 3.21%at 0-10 cm layer,ranged form 2.02%to 2.33%at 10-20 cm layer,ranged form 1.46%to 1.65%at 20-40 cm layer,respectively.The difference among different treatments mainly found at 0-10 cm and 10-20 cm soil depth,and the difference decreased with the increasing soil depth.5.There were no significant difference among carbon storage of overstory layer among Chinese fir plantations with different treatments at 1st to 7th years after treatments,carbon storage of overstory layer in Chinese fir plantations by treatment 4 was 42.95 t·hm-2,and significantly higher than in treatments 1 and 5.Carbon storage of overstory by treatments 3 and 4 at 9th year after treatments were significantly higher than those with treatments 1 and 5,respectively.Carbon storage of overstory in Chinese fir plantations with treatment 4 at 10 year after treatments was 66.37 t·hm-2,which were significantly higher than those with treatments 1(51.74 t·hm-2)and 5 (55.87 t·hm-2)(P＜0.05),carbon storage of overstory layer with treatments 2,3 and 5 were 64.65 t·hm-2,64.04 t·hm-2and 55.87 t·hm-2,respectively,which were significantly higher than that with treatment 1(51.74 t·hm-2)(P＜0.05).6.Carbon storage of shrub and herb layer in Chinese fir plantations with treatments 1 and 2 at 1st to 10th years after treatments were relatively higher,and those with treatments 3 and 4 were relatively lower.Carbon storage of shrub and herb layers of the plantations with different treatments gradually reduced with the increasing stand age.7.Mean annual carbon return in Chinese fir litter at 6th to 10th yeats after treatments were 147.16kg·hm-2,201.15kg·hm-2,204.95kg·hm-2,205.40kg·hm-2and 237.05kg·hm-2,respectively, mean annual carbon return was 199.14 kg·hm-2.Mean annual carbon return in Chinese fir litter increased with the increasing stand age.Mean annual carbon return in Chinese fir litter with treatment 3 at 6th year after treatments was 152.55 kg·hm-2,and was significantly higher than that with treatment 5(63.84 kg·hm-2) (P＜0.05).But annual carbon return had no significant difference among different treatments in Chinese fir litter at 7th to 10th years after treatments(P＞0.05).8.In different years(3rd,6th,9th,and 10th years after treatments),carbon content at 0-10cm, 10-20 cm and 20-40 cm soil depth with treatments 4 and 3 relatively higher,and treatments 1 and 5 were relatively lower,but no significant difference was found among different treatments (P＞0.05).Total carbon storage at 0-100 cm soil depth in plantations with different treatments at 3rd years after treatments were in the order:treatment 5＞treatment 4＞treatment 1＞treatment 3＞treatment 2,and at 6th,9th and 10th years were treatment 4＞treatment 3＞treatment 5＞treatment 2＞treatment 1,but no significant difference was found in different treatments(P＞0.05).9.At 1st to 10th years after treatments,carbon storage in Chinese fir ecosystem with treatments 4 and 3 were relatively higher,but treatments 5,1 and 2 were relatively lower. Although there was no significant impact on ecosystem carbon storage with different treatments at 1st to 10th years after treatments(P＞0.05),preserving logging slash was beneficial to remain and improve the productivity of ecosystem in a second-rotation Chinese fir plantations,and increased carbon storage of ecosystem.10.Over the 5-years period at 6th to 10th years after treatments,about 1967.96 kg·hm-2of litter production returned to the plantation soil,production of annual litter was 393.59 kg·hm-2, annual total litter production gradually increased with the increasing stand age,but little annual variation. |
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