作 者 ：田大伦*,尹刚强,方晰,项文化,闫文德
期 刊 ：生态学报 2010年 30卷 22期 页码：6297~6308
Keywords:Huitong County of Hunan Province, ‘Grain for Green’ program, Carbon density, Carbon storage,
摘 要 ：对湖南会同5种退耕还林模式初期森林生态系统碳密度、碳贮量及其空间分布特征进行了研究。结果表明：主要造林树种马尾松、樟树、杜英、乐昌含笑、红花木莲不同器官的平均碳密度分别为：05296、05188、05178、05376、05355 gC/g，树种间同一器官的平均碳密度排序为：树干＞树根＞树叶＞树枝＞树皮；5种退耕还林模式中活地被物层、死地被物层碳密度分别介于04380—05380gC/g、05060—05200gC/g之间，土壤层（0-60 cm，下同）平均有机碳密度介于000786—001485 gC/g之间；退耕还林3a后，乐昌含笑×红花木莲混交林、杜英×乐昌含笑混交林、杜英×樟树混交林、樟树林土壤层有机碳密度比原坡耕地分别提高了53.57%、39.19%、38.57%、24.82%，而马尾松林地下降了18.72%。林木不同器官中的碳贮量基本上与各器官的生物量成正比例，同一造林时间的4种模式中，以杜英×樟树混交林各器官的碳贮量最大，为1.219 tC/hm2，杜英×乐昌含笑混交林最小，仅为0199 tC/hm2，均以干根碳贮量为最大，占其各器官碳贮量的57.50%以上。5种退耕还林模式恢复初期的生态系统中，土壤层碳贮量最大，为74.518—119.312 tC/hm2，占96.180%以上，植被层为其次，在0633—2.960tC/hm2之间，仅占0642%—3.820%，死地被物层为最小。退耕后，樟树林、杜英×樟树混交林、乐昌含笑×红花木莲混交林、杜英×乐昌含笑混交林生态系统碳贮量分别增加了19.477、27.722、41.643、26.821 tC/hm2，马尾松林下降了1.675 tC/hm2。
Abstract:Carbon density, storage and spatial distribution in young stands within five afforestation patterns following the ‘Grain for Green’ program (GGP, i.e., conversion of farmland to florets) were investigated in Huitong County, Hunan Province. The five afforestation patterns included Pinus massoniana pure forests, Cinnamomum camphora pure forests, Michelia chapensis and Manglietia insignis mixed forests, Elaeocarpus sylvestris and Michelia chapensis mixed forests, and Elaeocarpus sylvestris and Cinnamomum camphora mixed forests. The results showed that the mean carbon densities of all organs were 05296, 05188, 05178, 05376, and 05355 gC/g for the tree species Pinus massoniana, Cinnamomum camphora, Elaeocarpus sylvestris, Michelia chapensis, and Manglietia insignis, respectively. The average carbon densities in different organs of the five tree species ranked in the order as: trunk>root>leaf >branch>bark. Carbon densities ranged from 04380 to 05380gC/g, 05060 to05200gC/g and 000786 to 001485 gC/g in living-understory layer, litterfall layer and soil layer (0-60 cm depth), respectively within the five afforestation patterns. Three years later after the conversion of farmland to forests, soil organic carbon density was increased 53.6%, 39.2%, 38.6%, and 248% in Michelia chapensis and Manglietia insignis mixed forests, Elaeocarpus sylvestris and Michelia chapensis mixed forests, Elaeocarpus sylvestris and Cinnamomum camphora mixed forests and Cinnamomum camphora forests, but decreased 18.7% in Pinus massoniana forest when compared with pre-converted farmland. Carbon storage in different organs was positively related to the biomass of these respective organs. It was found that Elaeocarpus sylvestris and Cinnamomum camphora mixed forest had the highest carbon stocks in the tree biomass pools (1.22 tC/hm2), while Elaeocarpus sylvestris and Michelia chapensis mixed forest had the lowest value (020 tC/hm2). Trunk and root stored more carbon than other organs, and the two organs accounted for 57.5% of the total carbon storage in all tree organs. At the early stage of the five forested ecosystems, the soil layer (0-60 cm) had the largest carbon storage, ranging from 74.52 to119.31 tC/hm2, and accounted for more than 96.2% of the total carbon storage in the ecosystems. Carbon storage in the plant layer ranged from 063 to 2.96 tC/hm2, which accounted for 064 to 3.8% of the total carbon storage of the ecosystems. The litterfall layer had the smallest proportion of the carbon storage within the ecosystems. After conversion of farmland to forestland, the carbon storage was increased 19.48, 27.72, 41.64, 26.82 tC/hm2 in Cinnamomum camphora pure forests, Cinnamomum camphora and Elaeocarpus sylvestris mixed forests, Michelia chapensis and Manglietia insignis mixed forests, Elaeocarpus sylvestris and Michelia chapensis mixed forests, respectively, but decreased 1.68 tC/hm2 in Pinus massoniana pure forests.. Our results indicated that ‘Grain for Green’ program, especially in the patterns of farmland to mixed forests, had great potential to enhance carbon sequestration in terrestrial ecosystems of southern China.
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