桂东不同林龄马尾松人工林的生物量及其分配特征

根据5a、15a、21a、32a、60a生的5个不同林龄的15块1 000m2样地(3次重复)调查资料,利用21株不同年龄和径阶的马尾松样木数据,建立以胸径(D)为单变量的生物量回归方程.采用样木回归分析法(乔木层)和样方收获法(灌木层、草本层、地上凋落物)获取不同林龄马尾松人工林的生物量,并分析了其组成、分配特征及不同林龄生物量的变化趋势.结果表明:(1)林分的总生物量随林龄而增加,5a、15a、21a、32a和60a生马尾松人工林生物量分别为15.03、125.93、183.51、191.53、405.31 Mg/hm2,其中活体植物占75.01％～94.19％,地上凋落物占0.86％～24.99％.(2)层次分配方面乔木层占绝对优势,占90.20％～98.35％,且随林龄的增加而增大,其次为地上凋落物,占0.86％～24.99％;草本层和灌木层生物量较小,分别占0.47％～34.85％和0.32％～27.00％,均随林龄的增加呈递减趋势.(3)乔木层器官分配以干所占比例最高,占49.93％～83.10％,且随林龄而增加；根相对比较稳定,占6.97％～12.82％；枝、叶分别占11.75％～14.83％、1.33％～23.65％,均随林龄增大而下降.灌木层器官分配除幼龄林为根＞枝＞叶,其余的均呈枝＞根＞叶的趋势.草本层中龄林和近熟林生物量地下＞地上,其他林龄生物量地上＞地下.(4)各林龄凋落物生物量在3.48～6.68Mg/hm2,规律性不强.(5)马尾松人工林乔木层各器官及林分生物量具有良好的优化增长模型,其32a生林分生物量高于同林龄的楠木人工林,低于热带雨林,是一种速生丰产、固碳潜力大的优良造林树种.

Biomass and Its Allocation in Pinus massoniana Plantation at Different Stand Ages in East Guangxi

Aimed to study the dynamics of the biomass and allocation of the Pinus massoniana plantations with different stand ages (5a,15a,21a,32a,60a) in Guangxi,South of China,we established fifteen plots,each with a size of 20 m×50 m,at different sites.By using the investigation data of 21 Pinus massoniana trees with different ages and diameters at breast height,the regression model of the biomass relating with D (diameter at breast height,1.3 m) was established.And other biomass components were sampled in different quadrates in fifteen 1 000 m² research plots:shrubs (three 4 m² quadrats),herbs (three 1 m² quadrats) and litterfall (three 1 m² quadrates).This method applied to estimate the biomass and allocation characteristics of biomass with stand age.Results showed that:(1)The biomass of the stands increased with stand age,being 15.03 Mg/hm² in 5a stand,125.93 Mg/hm² in 15a stand,183.51 Mg/hm² in 21a stand,191.53 Mg/hm² in 32a stand,405.31 Mg/hm² in 60a stand,and living biomass and litter made up 75.01%~94.19%,0.86%~24.99%,respectively.(2)Most biomass (90.20%~98.35%) of Pinus massoniana plantation was concentrated in the tree layer,and grown with stand age,next was the litter layer,made up 0.86% to 24.99%;Shrub and herb biomass contributed small,made up 0.47% to 34.85%,0.32% to 27.00%,respectively,and decreased with stand age.(3)The biomass of the trunk occupied the greatest proportion of tree layer,made up 49.93% to 83.10%,increased with stand age;Root had a relatively stable biomass,accounted 6.97% to 12.82%;Branches and leaves made up 11.75% to 14.83%,1.33% to 23.65%,decreased with stand age.The biomass allocations of shrub were branch>leave,except root>branch>leaves in young (5a) forest.The above-ground biomass was higher than under-ground biomass in middle-aged (15a) and near mature (21a) forest,but opposite to that of other stands.(4)The litter biomass ranged from 3.48 to 6.68 Mg/hm²,the law was not obvious.(5)Biomass of all tree organs and stand of Pinus massoniana plantation showed a good growth model.Compared with other forest,the total biomass of 32a Pinus massoniana plantation was higher than that of the Phoebe bourmei Plantation,but lower than that of tropical rainforests,and it is the fast growing forest tree species with higher photosynthesis efficiency and potential carbon fixation.