长沙市区马尾松人工林生态系统碳储量及其空间分布

Spatial distribution of carbon storage in a 13-year-old Pinus massoniana forest ecosystem in Changsha City,China

采用样方法和取样法,研究了长沙市区13年生马尾松林生态系统碳含量、碳储量及其空间分布特征。结果表明:马尾松林木各器官平均碳含量为511.17 g/kg,从高到低排列顺序为叶>干>根>皮>枝;林下灌木层、草本层、枯落物层的平均碳含量分别为531.66、465.53、393.92g/kg。林地土壤层有机碳含量为9.40—24.73 g/kg,各层次碳素含量分布不均,表层(0—15cm)土壤碳素含量较高,并随土壤深度的增加而逐渐下降。生态系统碳库的空间分布序列为土壤层>植被层>枯落物层。植被层的碳储量为34.50t/hm2,占整个生态系统碳总储量的21.57%;乔木层碳储量占整个生态系统的20.27%,占植被层碳储量的93.97%。乔木层碳储量中,树干的碳储量最高,占乔木层碳储量的65.52%,其次为根,占乔木层碳储量的19.15%,树皮最少,仅占2.10%;枯落物层碳储量为3.81 t/hm2,仅占整个生态系统碳储量的2.38%;林地土壤层(0—60cm)碳储量相当可观,为121.62 t/hm2,占系统碳储量的76.05%。马尾松林年净生产力为4.88 t.hm-.2a-1,有机碳年净固定量为2.50 t.hm-.2a-1,折合成CO2的量为9.16 t.hm-.2a-1。

Abstract： Increasing concentrations of atmospheric CO2 and other greenhouse gases are widely recognized to be contributing to the rising average temperature of Earth＇s atmosphere since the late 19tb century. Urban forests have great potential to affect global warming by removing greenhouse gases and sequestrate carbon into its biomass and the soils. Carbon storage and its special distribution in urban forests are important indicators to accurately determine carbon sequestration capacity in urban ecosystems, to completely evaluate urban ecosystems＇ functions and services, and to efficiently develop sustainable urban＇ carbon forests＇ management. To improve understanding of the influence of urban forest structure on carbon pools in urban ecosystems, the content, storage and spatial distribution of carbon in a 13-year-old Pinu3 massoniana forest ecosystem were investigated in Changsha City, Hunan Province, China. Results showed that carbon concentrations varied with tree organs in the same tree species and with tree species in the same tree organ as well in the Pinus massoniana forests. The average carbon content was 511.17 g/kg for different organs of Pinus massoniana forest and decreased in the order leaf 〉 trunk 〉 root 〉 bark 〉 branch. The amount of carbon stored in shrub, herb and litter-fall layers was 531.66, 465.53 and 393.92 g/kg, respectively. Carbon content ranged from 9.40 to 24.73 g/kg in the soils and gradually decreased with the increase of soil depth. The ecosystem stored 159.93 t C/hm2, of which 20. 1% in above-ground part （ living and deadvegetation）and 79.9% in below-ground part （roots and soil organic matter in 0-60 cm depth）. Carbon stocks in the different components of the studied forest ecosystems were in an order as： soil 〉 vegetation ＂, litterfall. The vegetation component stored 34.50 t C/hm2 and represented 21.57% of the total carbon storage in the forest ecosystem. Carbon storage was about 32. g t/hm2 in the overstory layer, which accounted for 20.27% of the tota）amount of carbon in the ecosystem, and approximately represented 94% of carbon in vegetation component. Of the overstory layer, 65.5% was in stemwood, 19.2% was in roots, 13.2% was in branch and leaves, and 2.1% was in stembark. Carbon storage in litter fall layer was 3.81 t/hm2, which accounted for 2.38% of the total carbon storage in the ecosystem, rhe soil was the largest of carbon storage component （121.62 t/hm2 in 0--60 cm depth） and represented about 76% of the total ecosystem carbon storage. The annual net primary productivity was estimated to be 4.88 t· hm^-2·a^-1 in the Pinus massoniana forests and annual carbon storage was 2.50 t- hm^-2·a^-1, which was equivalent to approximately 9.2 t· hm^-2· a^-1 of carbon dioxide. In other words, the studied 13-year-old Pinus massoniana forest ecosystem has the capacity to remove about 9 t CO2 from the atmosphere in Changsha City. Our study demonstrated the important role played by forests in mitigating global climate change, and the research results would provide scientific reference for accurately evaluating carb, m balance of urban forest ecosystems