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黄土高原次生林区植被恢复过程中土壤结构 与土壤有机碳特征研究
马 帅
Subtype硕士
2011-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword植被恢复 土壤结构 有机碳组分 贡献率
Abstract

子午岭北部次生落叶阔叶林是1866年当地人口外迁后,主要在弃耕地上逐渐恢复的,是黄土高原腹地少有的天然林。本文选取黄土高原子午岭次生林区植被恢复过程中坡耕地、弃耕地、草地、灌木林地和乔木林地的典型样地为对象,进行野外调查、采样和室内分析。应用物理方法对土壤有机碳及团聚体有机碳进行分组,研究子午岭林区植被恢复过程中土壤结构特征、有机碳库及其组分(颗粒有机碳、矿物结合态有机碳、轻组有机碳、重组有机碳)及其在团聚体中分布的变化规律,为在此基础上探讨子午岭林区土壤有机碳保护机制提供依据。主要研究结果如下:
(1)植被恢复对土壤有机碳含量及其组分的影响
0-100cm剖面整体土壤总有机碳(Soil organic carbon, SOC)、土壤颗粒有机碳和土壤矿物结合态有机碳含量随植被恢复进程表现为坡耕地、弃耕地<草地、灌木林地<乔木林地。乔木林地土壤有机碳、土壤颗粒有机碳和土壤矿物结合态有机碳含量0-100cm土层加权平均值分别为6.15,2.24和3.90mg/g,较坡耕地分别提高73.6%,173.6%和43.5%。
0-20cm土层整体土壤轻组有机碳含量随植被恢复进程表现最为坡耕地<弃耕地<草地、灌木林地<乔木林地,坡耕地土壤轻组有机碳含量0-20cm土层加权平均值为0.69 mg/g,乔木林地土壤轻组有机碳含量0-20cm土层加权平均值为2.20 mg/g,比坡耕地提高218.8%。
0-20cm土层整体土壤重组有机碳含量随植被恢复进程表现最为坡耕地<弃耕地<草地、灌木林地<乔木林地,坡耕地土壤重组有机碳含量0-20cm土层加权平均值为6.24 mg/g,乔木林地土壤重组有机碳含量0-20cm土层加权平均值为12.59 mg/g,比坡耕地提高101.8%。
不同土层土壤总有机碳及其组分(颗粒有机碳、矿物结合态有机碳、轻组有机碳和重组有机碳)含量均随植被恢复进程逐渐提高,随土层的加深,植被对土壤有机碳及其组分的影响减弱,在0-5cm土层土壤总有机碳及其组分(颗粒有机碳、矿物结合态有机碳、轻组有机碳和重组有机碳)受植被恢复影响最强,0-5cm土层土壤总有机碳、颗粒有机碳(Particulate organic carbon, POC)、轻组有机碳(Light fraction organic carbon, LFOC)、矿物结合态有机碳(Mineral associated organic carbon, MOC)和重组有机碳(Heavy fraction organic carbon, HFOC)含量分别为8.75,4.32,1.04,4.43和7.17mg/g,乔木林地分别比坡耕地提高192.7%,310.3%,366.3%,78.0%和170.2%。
(2)植被恢复对土壤结构稳定性的影响
植被恢复各阶段0-5和5-10cm土层中,>5,5-2和2-1mm粒级团聚体含量均比坡耕地有较大幅度提高,1-0.5和0.5-0.25mm粒级团聚体含量与坡耕地相比变化不大;在10cm以下土层植被恢复各阶段>5,5-2,2-1,1-0.5和0.5-0.25mm粒级团聚体含量均比坡耕地有所提高,随土层加深,>1mm团聚体含量随植被恢复进程的提高幅度逐渐减小,1-0.5和0.5-0.25mm团聚体随植被恢复进程的提高幅度逐渐增大。 子午岭林区植被自然恢复可以提高土壤中>0.25mm水稳性团聚体含量,降低团聚体破坏率和水稳性团聚体分形维数,改良土壤结构。除灌木林地土壤结构稳定性比草地有所降低外,土壤结构稳定性随植被恢复进程逐渐提高,乔木林地土壤结构稳定性达到最高。 >0.25mm水稳性团聚体含量、团聚体破坏率和水稳性团聚体分形维数与土壤有机碳含量之间呈对数相关关系。当有机碳含量低于20.9mg/g时,随土壤有机碳含量增加,>0.25mm水稳性团聚体含量、团聚体破坏率和水稳性团聚体分形维数变化较为明显,当土壤有机碳含量达到并高于20.9mg/g时,这三个指标变化渐趋稳定。根据这一阈值,在草地和乔木林地的0-5cm土层土壤有机碳含量达到并高于20.9mg/g,其土壤结构趋于稳定。
(3)植被恢复对团聚体有机碳含量、组分及其分布的影响
在0-5和5-10cm土层除弃耕地与坡耕地差异不显著,灌木林地比草地有所下降外,各粒级聚体有机碳、团聚体矿物结合态有机碳和团聚体重组有机碳含量随植被恢复进程逐渐提高。
在0-5和5-10cm土层除灌木林地比草地有所降低或与草地差异不显著外,各粒级团聚体颗粒和团聚体轻组有机碳含量有机碳含量均随植被恢复进程逐渐提高。
(4)植被恢复对团聚体有机碳及其组分贡献率的影响
在0-20cm土层,>1mm团聚体对土壤有机碳的贡献随着植被恢复进程逐渐增大,<1mm团聚体对土壤有机碳的贡献逐渐减小。在0-5cm、5-10cm土层,>1mm团聚体对土壤颗粒有机碳和轻组有机碳的贡献随植被恢复进程逐渐增大,<1mm团聚体对土壤颗粒有机碳和轻组有机碳的贡献逐渐减小;在10-20cm土层,>0. 5mm团聚体对土壤颗粒有机碳和轻组有机碳的贡献随植被恢复进程逐渐增大,<0.5mm团聚体对土壤颗粒有机碳和轻组有机碳的贡献逐渐减小。 在0-5和5-10cm土层,>1mm团聚体对土壤矿物结合态有机碳和重组有机碳的贡献随植被恢复进程逐渐提高,<1mm团聚体对土壤矿物结合态有机碳和重组有机碳的贡献逐渐降低;在10-20cm土层随植被恢复进程>0.25mm团聚体对土壤矿物结合态有机碳和重组有机碳的贡献逐渐提高,<0.25mm团聚体对土壤矿物结合态有机碳和重组有机碳的贡献逐渐降低。 关键词:植被恢复,土壤结构,有机碳组分,贡献率

Other Abstract

Secondary decidous broad-leaved forest in Ziwuling Mountain was restored from abandoned land after local population emigration in 1866. It is peculiar natural forest in hinterland of Loess plateau. Slope land, abandoned land, grassland, shrubberyland and forest land in Ziwuling Mountain secondary forest area was selected as representative site within vegetation restoration course in this study. Physical method was adopted to fractionate soil organic carbon and aggregate organic carbon. The change law of soil structure character, soil organic carbon pool, fractions of soil organic carbon pool (Particulate organic carbon, Mineral associated organic carbon, Light fraction organic carbon and Heavey fraction organic carbon) and distributing character of soil organic carbon & fractions of soil organic carbon in aggregates during vegetation restoration course was studied. Furthermore, this study could offer reference to discuss SOC sequestration mechanism in Ziwuling mountain area. The main results and conclusions were presented as follows: (1)Influence of vegetation restoration on SOC and fraction of SOC content The SOC, POC, MOC content of 0-100cm soil profile follow the order slope land, abandoned land < grassland, shrubbery land < forest land during vegetation restoration course. The weighted mean value of SOC, POC, MOC content of 0-100cm soil layer in forest land is 6.15, 2.24, 3.90 mg/g, increase 73.6%, 173.6%, 43.5% compare with slope land, respectively. The LFOC content of 0-20cm soil profile follow the order slope land, abandoned land < grassland, shrubbery land < forest land during vegetation restoration course. The weighted mean value of LFOC of 0-20cm soil layer in forest land is 2.20mg/g, increase 218.8% compare with slope land.
The HFOC content of 0-20cm soil profile follow the order slope land < abandoned  land < grassland, shrubbery land < forest land during vegetation restoration course. The weighted mean value of HFOC of 0-20cm soil layer in forest land is 12.59mg/g, increase 101.8% compare with slope land. The content of SOC and fractions of SOC (POC, MOC, LFOC, HFOC) in different soil layers increase gradually with vegetation restoration. Effect of vegetation on SOC and fraction of SOC weaken with incrment of soil layer. The effect of vegetation on SOC and fraction of SOC in 0-5cm layer is strongest in all of the soil layers. The content of SOC, POC, MOC, LFOC, HFOC in slope land 0-5cm soil layer is 8.75, 4.32, 1.04, 4.43, 7.17mg/g, these values in forest land increase 192.7%, 310.3%, 366.3%, 78.0%, 170.2% compare to slope land. (2)Influence of vegetation restoration on stability of soil structure The content of >5, 5-2, 2-1mm aggregate of ohter vegetation restoration phases increase with big extent compare with slope land in 0-5 and 5-10cm soil layer, the content of 1-0.5 and 0.5-0.25mm aggregate of other vegetation restoration phases change unconspicuous compare with slope land in 0-5 and 5-10cm soil layer. The content of >5, 5-2, 2-1, 1-0.5 and 0.5-0.25mm aggregates of other vegetation phase is higher than those of slope land in 10-100cm soil layer, the increase extent of >1mm aggregate content reduce with vegetation restoration, the increase extent of 1-0.5 and 0.5-0.25mm aggregate content improve with vegetation restoration. Natural vegetation restoration in Ziwuling Mountain could improve >0.25mm water stable aggragate content, reduce aggregate destruction rate and water stable aggregate fractal dimension, improve soil structure. The stability of soil structure improve gradually with vegetation restoration except the stability of soil structure in shrubbery land lower than that in grassland, the stability of soil structure in forest land is highest in all of the vegetation restoration phases.
The relationship between >0.25mm water stable aggregate content, aggregate destruction rate, water stable aggregate fractal dimension and SOC is highly significant logarithm. When the SOC content is less than 20.9 mg/g, the content of >0.25 mm water stable aggregates increasing and the aggregates destruction rate and water stable aggregates fractal dimension decreasing significantly with the SOC content increasing,while the three indices don’t change significantly, it is to say that the soil structure reach  stable state in grassland and forest land 0-5cm soil layer. (3)Influence of vegetation restoration on the content and distribution of aggregate SOC and fraction of aggregate SOC The SOC, MOC, HFOC content of all size aggregates increase with vegetation restoration except the SOC, MOC, HFOC content of all size aggregates in abandoned land is nonsigficant different with those in slope land, those in shrubbery land lower than those in grassland in 0-5 and 5-10cm soil layer. The POC and LFOC content of all size aggregates increase with vegetation restoration except the POC and LFOC content of all size aggregates in shrubbery land is nonsignificant different with those in grassland in 0-5 and 5-10cm soil layer. (4)Influence of vegetation restoration on the contribution rate of aggregate SOC and fraction of aggregate SOC The contribution of >1mm aggregate to SOC increase gradually with vegetation restoration, the contribution of <1mm aggregate to SOC decrease gradually with vegetation restoration in 0-5, 5-10 and 10-20cm soil layer. The contribution of >1mm aggregate to POC and FLOC increase gradually with vegetation restoration, the contribution of <1mm aggregate to POC and FLOC decrease gradually with vegetation restoration in 0-5 and 5-10 cm soil layer. The contribution of >0.5mm aggregate to POC and FLOC increase gradually with vegetation restoration, the contribution of <0.5mm aggregate to POC and FLOC decrease gradually with vegetation restoration in 10-20 cm soil layer. The contribution of >1mm aggregate to MOC and HLOC increase gradually with vegetation restoration, the contribution of <1mm aggregate to MOC and HLOC decrease gradually with vegetation restoration in 0-5 and 5-10 cm soil layer. The contribution of >0.25mm aggregate to MOC and HLOC increase gradually with vegetation restoration, the contribution of <0.25mm aggregate to MOC and HLOC decrease gradually with vegetation restoration in 10-20 cm soil layer. Key words: vegetation restoration, soil structure, fraction of SOC, contribution rate  

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8882
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
马 帅. 黄土高原次生林区植被恢复过程中土壤结构 与土壤有机碳特征研究[D]. 北京. 中国科学院研究生院,2011.
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