不同密度樟树幼林生物量和碳密度研究

Biomass and Carbon Density of Young Cinnamomum camphora Forest with Different Densities

对不同造林密度(625株/hm^2、1 111株/hm^2、1 667株/hm^2、2 500株/hm^2)下樟树7年生人工幼林生物量和碳密度进行研究,探讨樟树人工林营建适宜造林密度和幼林间伐强度。结果表明:4种不同密度下樟树幼林生物量及主干生物量随造林密度的增大先增加后减小,均在1111株/hm^2密度下最大,分别为24.91t/hm^2和9.24t/hm^2。四种不同密度下樟树幼林各器官生物量分布格局均为树干>树根>树枝>树叶,树干生物量占比在35.43%~45.83%。随着造林密度的增大,乔木层碳密度呈先增大后减小的趋势,造林密度为1111株/hm^2的林分乔木层碳密度最大。不同密度樟树幼林0~100cm层土壤碳密度在65.28~93.94 t/hm^2,林分总碳密度在70.05~101.61t/hm^2,随着林分密度的增大,林分碳密度呈下降趋势,密度为625株/hm^2的林分和1 111株/hm^2的林分碳密度差异较小,但远高于密度为1 667株/hm^2的林分和2 500株/hm^2的林分。综合从生物量积累和碳汇功能来考虑,樟树人工林培育适宜造林密度为1 111株/hm^2,也可在适当密植的林分基础上7年林龄前间伐为1 111株/hm^2左右。

The biomass and carbon density of 7-year-old young plantations of Cinnamomum camphora under different afforestation densities(625 plants per hectare,1 111 plants per hectare,1 667 plants per hectare,2 500 plants per hectare)were studied so as to probe into the suitable density of plantation and the intensity of intermediate cutting of man-made camphor trees.The results showed that the young forest biomass and stem biomass of Cinnamomum camphora increased at first and then decreased with the increase of planting density under four different densities,and they were the highest under the density of 1 111 plants per hectare,which were 24.91 t/hm^2 and 9.24 t/hm^2.The distribution pattern of biomass of various organs of young Cinnamomum camphora plantations under four different densities was in the order of trunk>root>branch>leaf,and the ratio of trunk biomass was between 35.43%to 45.83%.With the increase of afforestation density,the ratio of the biomass of branches and leaves increased first and then decreased.Under the density of 1 111 plants per hectare,the ratio of biomass of the branches and leaves was higher,and the branches and leaves grew vigorously.The carbon contents of different organs of young plantations of Cinnamomum camphora under different densities ranged from 40.53%to 48.26%,and the carbon density in tree layers ranged from 4.77 to 11.22 t/hm^2.With the increase of afforestation density,the carbon density in the tree layers increased first and decreased later,the carbon density of forest stand tree layer with the plantation density of 1 111 t/hm^2 was the largest.The soil carbon density in the 0~100 cm layers of young camphor forests of different densities was between 65.28 and 93.94 t/hm^2,and the soil carbon density mainly accumulated in the 0~30 cm soil layers.The total carbon density of young stands with different densities was between 70.05 and 101.61 t/hm^2.With the increase of stand density,the carbon density of the stand showed a downward trend.The forest stands with a density of 625 t/hm^2 and a density of 1 111 t/hm^2 showed a small difference in carbon density,but was much higher than the forest stands with a density of 1 667 hm^2 and 2 500 hm^2.Considering from biomass accumulation and carbon sequestration functions,the appropriate plantation density for man-made Cinnamomum camphora plantation cultivation is 1 111 t/hm^2,and the intermediate cutting of 7-year forest ages on the basis of properly densely planted forests is about 1 111 t/hm^2.