不同林龄尾细桉人工林的生物量和能量分配

Biomass-and energy allocation in Eucalyptus urophylla×Eucalyptus tereticornis plantations at different stand ages

对广东省遂溪县北坡林场1～4年生尾细桉人工林的生物量和能量进行研究.结果表明:林龄对林分现存生物量影响极显著(P<0.01),1～4年生林分生物量在10.61～147.28t.hm-2,随林龄增加,各组分和林分的生物量均增加,叶片、枝、树皮生物量占林分总生物量的比例逐年减小,而树干则呈逐年升高趋势.4个林龄阶段各组分生物量的分布规律,1～2年生为树干>枝>树皮>根>叶片,3～4年生为树干>根>枝>树皮>叶片.不同林龄各组分的平均灰分含量在0.47%～5.91%,以树皮的灰分含量最高、树干最低.各组分的平均干质量热值和去灰分热值分别为17.33～20.60kJ.g-1和18.42～21.59kJ.g-1,均以叶片数值最高、树皮最低.林龄对枝、树干、树皮的干质量热值及对叶片、树干、树皮的去灰分热值有显著影响(P<0.05),对叶片和根的干质量热值、枝和根的去灰分热值及植物体热值的影响不显著(P>0.05).1～4年生尾细桉的林分能量现存量在199.98～2837.20GJ.hm-2,林龄对其的影响达极显著水平(P<0.01),随林龄增长,各组分和林分能量现存量增加,且各组分能量分配比例的变化趋势与生物量相同.

An investigation was made on the biomass-and energy allocation in 1-4-year-old Eucalyptus urophylla×Eucalyptus tereticornis plantations at Beipo Forest Farm of Suixi County in Guangdong Province.Stand age had significant effects on the retained biomass of the plantations （P〈0.01）.The biomass was in the range of 10.61-147.28 t·hm^-2.Both the total biomass and the biomass of above-and belowground components increased with increasing stand age.The proportions of leaf-,branch-and bark biomass to total biomass decreased with year,while that of stem biomass was in reverse.The biomass allocation of the components in 1-and 2-year-old plantations decreased in order of stem〉branch〉bark〉root〉leaf,and that in 3-and 4-year-old plantations was in order of stem〉root〉branch〉bark〉leaf.The mean ash content （AC） of the five components at different stand ages ranged from 0.47% to 5.91%,being the highest in bark and the lowest in stem.The mean gross caloric value （GCV） and ash free caloric value （AFCV） of different components ranged from 17.33 to 20.60 kJ·g^-1 and from 18.42 to 21.59 kJ·g^-1 respectively.Of all the components,leaf had the highest GVC and AFCV,while bark had the lowest ones.Stand age had significant effects on the GVC of branch,stem,and bark,and on the AFCV of leaf,stem,and bark （P〈0.05）,but the effects on the GVC of leaf and root,the AFCV of branch and root,and the GVC and AFCV of individual trees were not significant （P〉0.05）.The retained energy of 1-4-year-old plantations ranged from 199.98 to 2837.20 GJ·hm^-2,with significant differences among the stand ages （P〈0.01）.The retained energy of various components and plantations increased with stand age,and the energy allocation of various components had the same trend as biomass allocation.