不同林龄尾巨桉人工林的生物量分配格局

Biomass allocation pattern of Eucalyptus urophylla×Eucalyptus grandis plantation at different ages

【目的】对雷州半岛5个不同林龄(1,2,3,5,7年生)尾巨桉(E.urophylla×E.grandis)人工林及林下植被的生物量进行研究,分析各林分生物量组成、分配特征及不同林龄间生物量的变化趋势,为分析桉树林碳汇功能随林龄的变化规律提供依据。【方法】采用解析木分析法测定乔木层生物量,利用15株不同年龄和径阶的样木数据,建立以胸径(D)为自变量的叶、枝、干、根、皮等各器官生物量方程,然后估算各林分乔木层及各器官生物量;灌木层、草本层和枯落物层生物量采用样方收集法测定。【结果】尾巨桉林分总生物量随林龄的增加而增大,总生物量变化于15.11~301.80t/hm^2。各林龄中乔木层生物量占总生物量比例均最大,为36.07%~90.49%,且随着林龄的增加而增大;林下灌木层、草本层和枯落物层生物量所占比例基本随林龄增加而减小,分别占4.62%~18.73%,1.55%~24.09%和2.83%~21.11%。乔木层中树干生物量所占比例最大,为24.91%~66.79%,在1~3年生尾巨桉林分中其比例呈增长趋势,在3~5年生林分中呈下降趋势,在5~7年生林分中又逐渐增加;叶、枝、根、皮生物量分别占乔木层总生物量的2.37%~23.63%,8.90%~20.70%,17.34%~30.49%和4.55%~8.08%。【结论】1~7年生的5个林龄尾巨桉林分生物量随林龄的增加表现各异;5~7年生尾巨桉林分生物量较其他树种人工林林分高,是生长较快、碳汇潜力巨大的优良造林树种。

[Objective] This paper measured the biomass in each Eucalyptus urophylla X Eucalyptus grandis plantation at different ages to provide basis for change of carbon sinks in Eucalyptus forests. [Method] The biomasses of plantation and undergrowth vegetation of E. urophylla X E. grandis at five ages （1,2,3,5, and 7 years） in Leizhou Peninsula were investigated, and the composition, distribution pat- tern, and variation trend in each forest were analyzed. Parsing wood analysis was used to determine biomass in arbor layer,and data of 15 sample trees of E. urophylla X E. grandis with different ages and diameters were used to establish biomass equations for leaf, ranch, steam, root and skin using diameter at breast height as independent variable. The biomasses of shrubs, herbs and litter fall layers were determined by quadrat method. [Result] The total forest biomass of E. urophylla X E. grandis plantation increased with stand age and the total biomasses were 15.11-301.80 t/hm2. Arbor layer had the largest contributions of 36.07%-90. 49% and increased with stand age. The ratios of shrub layer,herbs layer and litterfall layer substantially decreased with the increase of stand age and accounted for 4. 62%- 18. 72%, 1. 55%- 24. 09% ,and 2.83%-21.11% respectively. The trunk biomass in the wooden arbor accounted the largest ratio of 24.91%-66.79 %. There was a growing trend in 1--3 years old forests and a declining trend in 3--5 years old. The forest stand gradually increased again in 5--7 years old. The biomasses of leaf,ranch, root and skin contributed 2.37%-23.63%,8.90%-20.70%,17.34%-30.49% and 4.55%-8.08% to the total arbor biomass. [Conclusion] Five E. urophylla×E. grandis plantations with different ages of 1- 7 years showed different trends with the increase of forest age. The biomass of 5-7 years old forests were higher than that of other stands,and it is a good afforestation tree species with fast-growing and carbon se- questration capacity.