不同林龄尾巨桉人工林碳储量及分配格局

Carbon Storage and Its Distribution in Eucalyptus urophylla× E.grandis Plantations at Different Stand Ages

利用桂东南桉树（Eucalyptus spp.）主产区5个不同林龄（1a、2a、3a、5a和8a）15个样点45个样地调查数据,分析桂东南尾巨桉（Eucalyptus urophylla×E.grandis）人工林的碳格局及其动态变化特征。结果表明：（1）尾巨桉人工林生态系统总碳储量表现为3a林龄（195.25t·hm-2）〉5a林龄（169.57t·hm-2）〉8a林龄（166.70t·hm-2）〉2a林龄（165.00t·hm-2）〉1a林龄（111.84t·hm-2）;不同林龄碳储量分布格局均为土壤层〉植被层〉凋落物层,地下部分〉地上部分;其中植被层为4.87－80.54t·hm-2,占总碳储量的4.36%－48.31%,随林龄的增加而增加;凋落物层为0.92－3.25t·hm-2,占0.82%－1.91%,随林龄增加呈递减趋势;土壤层为3a林龄（162.53t·hm-2,83.24%）〉2a林龄（141.55t·hm-2,85.79%）〉5a林龄（112.26t·hm-2,60.22%）〉1a林龄（106.05t·hm-2,94.82%）〉8a林龄（84.50t·hm-2,50.69%）。（2）植被层碳储量以乔木层最大（3.10－78.97t·hm-2）,占63.64%－99.25%,其中乔木层各器官碳储量以树干最大（1.58－68.84t·hm-2）,占乔木层碳储量的50.90%－87.18%,随林龄的增加而增加,枝、叶、根分别占4.97%－12.17%、1.97%－22.36%和5.87%－14.57%,均随林龄而下降。（3）桂东南尾巨桉人工林生态系统年净固碳量平均为11.73t·hm-2·a-1,2a林龄（16.03t·hm-2·a-1）最大,3a林龄的固碳能力也很高,8a林龄年净固碳量与5a林龄持平,高达11.96t·hm-2·a-1,是较好的碳汇林业树种。提高桉树林的生态服务功能、降低其负面效应将有利于桉树人工林生产的发展。

Based on the data of 45 plantation stand plots（1 000m2）with five different stand ages（1a,2a,3a,5a,and 8a）collected from 50 sample sites in the main eucalyptus production areas in Guangxi,southwest in China,we studied the carbon storage and its characteristics of dynamic change.The result showed that：（1）The total carbon storage of Eucalyptus urophylla×E.grandis plantation ecosystem in the order of 3a（195.25t·hm-2）〉5a（169.57t·hm-2）〉8a（166.70t·hm-2）〉2a（165.00t·hm-2）〉1a（111.84t·hm-2）,respectively;Carbon storage of different ages in different layers appeared：soil layer〉vegetable layer〉litter layer,underground〉aboveground;Carbon storage of vegetable layer is 4.87-80.54t·hm-2,contributed 4.36%-48.31%to the total carbon storage of the ecosystems,and grew with ages;The carbon storage of litter layer is 0.92-3.25t·hm-2,only contributed 0.82%-1.91%to the total carbon storage,appears descend trend with ages;The order of carbon storage of soil layer is 3a（162.53t·hm-2,83.24%）〉2a（141.55t·hm-2,85.79%）〉5a（112.26t·hm-2,60.22%）〉1a（106.05t·hm-2,94.82%）〉8a（84.50t·hm-2,50.69%）.（2）Tree layer stored the highest carbon storage（3.10-78.96t·hm-2）and comprised 63.64%-99.25%of carbon storage in vegetable layer.The carbon storage of tree layer in different organs was positively different,stem stored the highest carbon storage（1.58-68.84t·hm-2）,and accounted to 50.90%-87.18%,which also increased with ages,the other organs distributing sequence of the carbon storage in tree layer is branch（4.97%-12.17%）,leaf（1.97%-22.36%）,root（5.87%-14.57%）,all decreased with ages.（3）The average annual net carbon fixation of Eucalyptus urophylla×E.grandis plantation is 11.73t·hm-2·a-1,where 2a（16.03t·hm-2·a-1）forest stored the highest,respectively,3aforest is a better species of carbon sequestration forestry with high capability of carbon deposition,8aannual net carbon fixation up to 11.96t·hm-2·a-1,and flat with 5a.Therefore,to improve the eucalyptus forest ecological service function and reduce its negative effect will be conducive to the development and growth of eucalyptus plants.