南亚热带中幼龄针阔混交林碳储量及其分配格局

Carbon storage and their allocation of young-and-middle aged conifer-broadleaf mixed forests in southern subtropical region

以南亚热带中幼龄针阔混交林为研究对象，通过典型样地调查法，对森林生态系统各个层次进行取样调查，采用12个样地实测数据和已有生物量模型相结合的方法计算乔木层生物量，灌木层、草本层和凋落物层采用全部收获法测得其生物量，对土壤层的调查采用剖面法加土钻法，代表性样品碳含量的测定采用重铬酸钾-水合加热法。在此基础上，分析了中幼龄针阔混交林碳储量及其分配格局。结果表明，主要造林树种树根、树杆、树枝和树叶碳含量均值分别为45.07%、46.73%、46.30%和47.72%。植物碳含量表现为乔木〉灌木〉草本。乔木碳储量占植被总碳储量比例介于63.38%-94.08%之间，灌木碳储量所占比例介于3.55%-12.67%之间，而草本碳储量仅介于为1.28%-23.95%之间，不同林龄段乔木和灌木碳储量均值随林龄的增加呈上升趋势，而草本碳储量呈下降趋势。土壤碳储量介于106.73-136.61 t·hm^-2之间，土壤碳储量随林龄的增加呈现出先降低后升高的趋势。针阔混交林总碳储量介于134.79-162.60 t·hm^-2之间，分配格局表现为土壤层〉植被层〉凋落物层。土壤层碳储量所占总碳储量比例范围为78.34%-94.45%，植被层所占比例介于4.84%-20.16%之间，凋落物层仅介于0.71%-1.50%之间，中幼龄针阔混交林碳储量主要以土壤固碳为主。研究结果为树种选择、人工林生态系统固碳潜力以及人工碳汇林的经营管理等研究提供科学参考。

To evaluate the carbon storages and their allocations in young-and-middle aged conifer-broadleaf mixed forests in southern subtropical region of China. 12 plots belonging to different forest ages were selected and plant biomass and soil carbon content were measured. The biomass of tree layer was calculated through analyzing the 12 sampling sites and the existing biomass models by typical plot investigation, while the biomasses of shrub, herb and litter layers were calculated using the full harvest method. The soil layer was investigated using soil profile method in combination with soil drilling method. Carbon content of representative samples was measured using potassium dichromate-external heating method. The average carbon concentration of root, stem, branch and leaf were 45.07%, 46.73%, 46.30% and 47.72%, respectively. The average carbon concentration of plant followed the order： tree〉 shrub〉herb. Carbon storage of tree accounted for 63.38%-94.08% of the plant, carbon storage in shrub accounted for 3.55%-12.67%, while carbon storage in herb accounted for 1.28%-23.95%. The average carbon storage of tree and shrub increased with increasing forest age, on the contrary, average carbon storage of herb decreased with forest age. Carbon storage in soil layer ranged from 106.73 to 136.61 t·hm-2, and that of soil first decreased and then increased with increasing forest age. The total carbon storage of conifer-broadleaf mixed forests with different forest ages ranged from 134.79 to 162.60 t·hm-2, and carbon storage and their allocation were in the order of soil layer〉vegetation layer〉litter layer. Carbon storage of soil, vegetation and litter layers accounted for 78.34%-94.45%, 4.84%-20.16%, and 0.71%-1.50% of total carbon storage of conifer-broadleaf mixed forests, respectively. Soil layer was the dominant bank in young-and-middle aged conifer-broadleaf mixed forest. The study provided insight into the tree species selection, carbon sequestration potential in planted forests and the management of forest carbon sinks plantations.