【作者】 曹吉鑫；

【导师】 王小平； 孙向阳；

【作者基本信息】 北京林业大学 ， 土壤学， 2011， 博士

【摘要】 由于大气中温室气体浓度的升高引起的全球变暖已成为目前人类面临的严峻挑战。森林作为陆地生态系统的主体,在陆地生态系统与大气碳库之间的碳循环过程中发挥着重要的调节作用,但由于森林生态系统本身的复杂性和人类认知的局限性,目前关于森林碳库的研究中仍存在着诸多不确定性。本文为探讨林龄对森林碳库的影响,以北京山区分布面积最广的两种针叶林(油松和侧柏)为研究对象,比较分析了不同林龄的油松(25a,65a和105a)和侧柏(12a,32a和51a)林乔木层生物量、林下植物生物量以及植被含碳率和碳密度,同时对相应林分中的土壤碳库也进行了比较分析。本文的研究工作,不仅有利于推进北京山区油松和侧柏林碳库的精确估算,同时也为北京山区人工林碳库研究提供了理论和实践依据。本文研究结论如下：(1)除侧柏根生物量以外,以胸径(D)为单一变量的Power模型可以较好地预测油松和侧柏人工林乔木层各组分生物量；预测油松叶生物量和侧柏各组分生物量时须考虑林龄的影响。(2)随着林龄的增大,油松和侧柏人工林乔木层各组分单位面积生物量均呈增大趋势,油松乔木层总生物量的变化范围在40.284-202.136 t.hm-2,侧柏乔木层生物量的变化范围在10.241～51.679 t.hm-2。(3)油松地下与地上部分生物量的比值波动很小,稳定在0.2左右；而51a侧柏的地下部分与地上部分生物量的比值达到了0.319,显著高于其他两个林龄侧柏的相应比值。(4)林下植物生物量的大小与森林类型有关,也受森林发展阶段的影响。油松人工林林下植物各层及其总生物量均随林龄的增大呈逐渐减小的趋势,林下植物总生物量的变化范围在8.680～3.533 t·hm-2之间；侧柏人工林林下植物各层生物量及其总生物量随林龄的增大呈逐渐增大的趋势,林下植物总生物量的变化范围在2.399～6.274t·hm-2之间。(5)油松各器官含碳率的变化范围在0.485～0.567,数值大小关系表现为,树皮>树叶>树枝>去皮树干>树根,侧柏各器官含碳率的变化范围在0.495～0.577,数值大小关系表现为,树叶>去皮树干>树枝>树皮>树根；不同林龄的油松、侧柏林乔木层地上部分和全树平均含碳率无显著性差异。(6)油松和侧柏人工林分植被碳密度随林龄的增大而增大,油松人工林植被碳密度的变化范围是24.470～105.326 t.hm-2,侧柏人工林植被碳密度的变化范围在6.398～30.137 t·hm-2。(7)油松和侧柏人工林中地表枯落物含碳率均随林龄的增大而增大；油松人工林土壤有机碳含量在三个土层中,均表现出随林龄增大而增大的趋势,而侧柏人工林土壤有机碳含量只在上层(0-20cm)土壤中表现出了增大的趋势；土壤有机碳含量在土壤剖面中均随土层深度的增加而减小；油松人工林中土壤总有机碳密度的变化范围在59.637～102.195 t·hm-2,侧柏人工林中土壤总有机碳密度的变化范围在49.420～69.663 t·hm-2,且二者均随着林龄和植被生物量的增大而增大。(8)油松和侧柏林中的两种土壤活性有机碳含量的变化规律与土壤总有机碳含量的变化规律相似,且三者之间具有极显著相关性。更多还原

【Abstract】 The rising of greenhouse gas concentration caused global warming, which has become a challenge for human. Forests as the main terrestrial ecosystem, play an important regulatory role in global carbon cycle. However, because of the complexity of forest ecosystems and the limitations of human cognition, now on the study of forest carbon, there are still many uncertainties. In order to explore the effects of stand age on forest carbon pool, Chinese pine (25a,65a and 105a) and Oriental arborvitae (12a,32a and 51a) forests in different ages were studied. This paper facilitated calculation of Chinese pine and Oriental arborvitae plantation carbon pools in Beijing mountainous area and provided a theoretical and technical basis for the study of forest plantation carbon pools. Results showed that:(1) Power model with tree diameter as a single input variable is the best biomass prediction equations for the most component biomass of Chinese pine and Oriental arborvitae, but except roots biomass of Oriental arborvitae. When foliage biomass of Chinese pine and all components biomass of Oriental arborvitae are predicted, effects of ages should be considered.(2) With age increasing, all of biomass in each tree component of Chinese pine and Oriental arborvitae increased. Total tree biomass of Chinese pine and Oriental arborvitae ranged from 40.284-202.136 t·hm-2 and 10.241～51.679 t-hm-2, respectively.(3) For Oriental arborvitae plantation forests, ratio of root to shoot biomass increased from 0.241 in the 12 year old stand to 0.319 in 51 year old stand, however, for Chinese pine, ratio of root to shoot biomass was steadily around 0.2 with increasing stand age.(4) Both of the forest type and age affected the biomass of understories. For Chinese pine plantation forests, shrub and herb biomass decreased with stand age increasing, total of them decreased from 8.680 t·hm-2 in 25 year old stand to 3.533 t·hm-2 in 105 year old stand; on the contrary, shrub and herb biomass of Oriental arborvitae increased with stand age increasing, total of them increased from 2.399 t·hm-2 in 12 year old stand to 6.274 t·hm-2 in 51 year old stand.(5) The carbon content of different issues of Chinese pine ranged from 0.485 to 0.567, and the carbon content of different issues of Oriental arborvitae ranged from 0.495 to 0.577. Weighted mean of carbon contents for both Chinese pine and Oriental arborvitae biomass were steadily with stand age increasing.(6) The total vegetation carbon density of Chinese pine plantation forests increased from 24.470 t·hm-2 in 25 year old stand to 105.326 t·hm-2 in 105 year old stand; similarly, the total vegetation carbon density of Oriental arborvitae plantation forests increased from 6.389 t·hm-2 in 12 year old stand to 30.137 t·hm-2 in 51 year old stand.(7) Carbon content of litter fall increased with stand age increasing. Total soil organic carbon content increased with stand age increasing in three soil horizon of Chinese pine plantation forests and 0-20cm soil horizon of Oriental arborvitae plantation forests, however, decreased with soil depth increasing. Total soil carbon organic density of Chinese pine plantation forests increased from 59.637 t·hm-2 to 102.195 t·hm-2 with stand age increasing. Similarly, total organic carbon density of Oriental increased from 49.420 t·hm-2 in 12 year old stand to 69.663 t·hm-2 in 51 year old stand.(8) Changing patterns of soil labile organic carbon contents is in agreement with that of total soil organic carbon with stand age increasing. Soil liable organic carbon was significantly related to total soil organic carbon, and the relationship between soil particulate organic carbon and soil dissolve organic carbon was also significant.更多还原