广西大青山南亚热带马尾松、杉木混交林生态系统碳素积累和分配特征

Carbon accumulation and distribution in Pinus massoniana and Cunninghamia lanceolata mixed forest ecosystem in Daqingshan, Guangxi of China

选取广西大青山3个13年生马尾松、杉木混交林样区,研究其生态系统的碳素积累和分配特征.结果表明,混交林中两个树种的碳素含量各异.马尾松干、根、枝的碳素含量较高,分别为58.6%、56.3%、51.2%,叶和皮含量较低,变化幅度为46.8%～56.3%.各器官中按碳素含量的高低排列顺序为：干＞根＞枝＞皮＞叶;杉木皮、叶、干的碳素含量较高,分别为52.2%、51.8%、50.2%,碳素含量从高到低依次为：皮＞叶＞干＞根＞枝.从两个树种各器官碳总含量来看,马尾松要高于杉木.灌木层、草本层及地表凋落物层碳素平均含量分别为44.1%、33.0%及48.3%.土壤3个层次（60cm深）碳素含量为1.45%～1.84%,各层次碳素含量分布不均,表层（0～20cm）土壤碳素含量较高.针叶混交林乔木层生物量（t·hm^-2）为85.35～101.35,平均为93.83,且均以马尾松生物量居多（占75.7%～82.6%）.混交林生态系统碳库的空间分布序列为土壤层＞植被层＞凋落物层.植被层的碳贮量平均为51.91t·hm^-2,占整个生态系统碳总贮量的29.03%;乔木层碳贮量占整个生态系统的23.90%,占植被层碳贮量的97.7%.乔木层碳贮量中,马尾松占的比例较大,为65.39%.碳贮量在两个树种各器官中的分配,基本与各自的生物量成正比例关系,树干的碳贮量均最高,马尾松、杉木的树干碳贮量分别占各自碳贮量的53.23%、55.57%,树干的碳总贮量占乔木层碳总贮量的54%.其次,两个树种根也占较大比例,树根碳总贮量占乔木层碳总贮量的19.22%.马尾松、杉木枝、皮在各自碳的贮量中分配不同,马尾松枝占的比例要大于皮,而杉木则相反;凋落物层碳贮量平均为3.25 t·hm^-2,仅占1.82%;林地土壤层（0～60cm）碳贮量是相当可观的,平均为123.43 t·hm^-2,占69.02%.马尾松、杉木混交林年净生产力为11.46t·hm^-2·a^-1,有机碳年净固定量为5.96 t·hm^-2·a^-1,折合成CO2的量为21.88 t·hm^-2·a^-1.

Carbon accumulation and distribution were studied in plantation of Pinus massoniana and Cunninghamia lanceolata mixed forest ecosystem in Daqingshan, Guangxi. The results shew that the mean carbon concentrations of two trees species was different, the total carbon concentrations of Pinus massoniana was much more than that of Cunninghamia lanceolata. The average carbon concentrations in all organs of Pinus massoniana was in the following order： wood（58.6%） 〉 root （56.3%） 〉 branch（51.2% ） 〉 bark（49.8% ） 〉 leaf（46.8% ）, the order of Cunninghamia lanceolata was bark（52.2% ） 〉 leaf （51.8%） 〉 wood（50.2% ） 〉 root（47.5% ） 〉 branch（46.7 % ） .The carbon concentrations of soil （to 60cm） ranged from 1.45% to 1.84 %, with an average of 1.70 %. Carbon concentrations of surface soil（to 20cm） was higher than the other layer. The average carbon concentrations in different layers was in the order as： trees （51.1% ） 〉 standing litters（48.3 % ） 〉 shrub （44.1% ） 〉 herb （33.0%）. The biomass of trees in three plots ranged from 85.35 t·hm^-2 to 101.35 t·hm^-2 ,with average of 93.83 t·hm^-2 ,which was contributed mainly by Pinus massoniana （75.7 % - 82.6 % ）. The biomass of understory plant was 2.10 - 3.95 t· hm^- 2, with an average of 2.72 t · hm^- 2 . Standing stock of ground litter was 5.49 - 7.91 t· hm^- 2, with an average of 6.75 t· hm^- 2. The carbon storage order of mixed forest ecosystem was soil layer 〉 vegetation 〉 standing litter. Of total average carbon, 29.03 % was distributed by vegetation component, 69.02 % by soil （60cm depth）, only 1.82 % by standing ground litter layer. The carbon storage of tree layer occupied 23.90% of total ecosystem and 97.7% of vegetation layer. Of total carbon storage in tree layer,65.39% was distributed by Pinus massoniana. The carbon storage in different organs was positively related to the biomass of corresponding organs. Trunk accumulated the highest carbon storage, comprising 53.23% of carbon storage in overstorey trees of Pinus massoniana, respectively seized 55.57% of Cunninghamia lanceolata. Root made up 19.22% of total tree carbon. The annual net productivity of mixed forest plantation was 11.46 t· hm^-2 · a^-1 , stored carbon up to 5.96 t· hm^-2 · a^-1 , amounted CO2 to 21.88 t· hm-2 ·a^-1 . Forest was a important sink of atmospheric CO2.