亚热带森林不同景观位置土壤理化性质的变化特征与森林的可持续发展

发布时间：2018-03-28 21:32

本文选题：景观位置　切入点：植被　出处：《中国科学院武汉植物园》2017年硕士论文

【摘要】：森林作为陆地生态系统的重要组成部分,其面积占陆地总面积的30%,且森林土壤碳库占陆地土壤碳库的70%左右,因此,森林和土壤的微小变化都会对全球碳循环和碳库动态产生重大影响。地形作为影响植被分布和土壤理化特征的重要因素,其对土壤有机碳的影响已经受到广泛关注。由于不同的地形所承载的水热条件有所差异,使得在水文过程的作用下,土壤中的物质循环和能量流动表现出一定的空间变异性,进而影响土壤性质的变化。通过研究不同景观位置上植被的分布状况和土壤的理化特征,有助于我们了解土壤有机碳发生空间变异的影响因素,为改善森林土壤有机质水平提供科学对策。此外,对不同景观位置土壤有机碳组分的研究,对于预测分析全球气候变化下森林土壤碳的动态变化具有一定指导意义。本研究选取了湖南省八大公山lha永久性样地不同景观位置(坡顶、坡中、坡底和沟谷)和土壤层次(0-10cm、10-20cm和20-40cm)的土壤为研究对象。在野外采样调查和室内分析的基础上,结合线性混合效应模型分析了不同景观位置土壤理化特征的差异,并采用偏最小二乘通径分析探究影响土壤有机碳组分差异的因素。此外,通过室内培养实验探究不同景观位置土壤有机碳稳定性的差异。主要结果如下:坡顶位置相比于下坡位置具有更为良好的植被状况,枯枝落叶层厚度和土壤根系生物量从坡顶到沟谷逐渐下降。对于土壤基本理化性质的探究发现,土壤机械组成在不同坡位间差异不显著,但沟谷石砾(2mm)的含量要显著高于上坡位的石砾含量。而土壤pH值从坡顶到沟谷表现为显著升高的趋势。土壤有机碳和总氮的含量在坡位间差异不显著,但从坡顶到沟谷各自呈现出降低和升高的变化趋势。土壤碳氮比从坡顶到沟谷呈现出显著降低的趋势。此外,各变量在四个坡位之间的差异变化,主要发生在表层土壤。四个坡位之间土壤有机碳的含量并无显著差异,但对土壤活性碳组分(土壤可溶性有机碳和非保护性颗粒有机碳)的分析发现,二者均表现出了从坡顶到沟谷含量显著降低的趋势。基于偏最小二乘通径分析的结果表明,相较于地形、植被、碳源输入等因素的影响,表层DOC含量的变异主要是受土壤理化特征(pH、碳氮比、铁铝氧化物和沙粒含量)的直接控制,而中层DOC含量的变异主要是由表层DOC含量所引起的。此外,表层和中层POC含量在坡位之间的变化主要由土壤理化因素所控制,深层土壤POC在坡位间的变化则主要受上层POC含量影响。土壤有机碳的稳定性仅在表层的坡位之间表现出了显著差异,坡顶的稳定性相对较低。基于偏最小二乘回归分析的结果表明,0-10cm 土壤有机碳稳定性主要受颗粒有机碳的影响,而10-20cm和20-40cm的土壤有机碳稳定性则主要受土壤颗粒组成影响。
[Abstract]:As an important part of terrestrial ecosystem, forest accounts for 30% of the total land area, and forest soil carbon pool accounts for about 70% of terrestrial soil carbon pool. Small changes in forests and soils have a significant impact on the global carbon cycle and carbon pool dynamics. Topography is an important factor in the distribution of vegetation and the physical and chemical characteristics of soils. The effect of soil organic carbon (SOC) on soil organic carbon (SOC) has been widely concerned. Due to the difference of the water and heat conditions carried by different topography, the material circulation and energy flow in the soil show certain spatial variability under the action of hydrological process. By studying the distribution of vegetation and the physical and chemical characteristics of soil in different landscape locations, it is helpful for us to understand the influencing factors of spatial variation of soil organic carbon. In order to improve the level of organic matter in forest soil, scientific countermeasures were provided. In addition, the soil organic carbon components in different landscape locations were studied. It has certain guiding significance for predicting and analyzing the dynamic change of forest soil carbon under global climate change. In this study, we selected different landscape locations of lha permanent sample land in Badgongshan, Hunan Province (slope top, slope, slope, etc.). On the basis of field sampling and indoor analysis, the differences of soil physical and chemical characteristics in different landscape locations were analyzed with linear mixed effect model. Partial least square path analysis was used to explore the factors influencing the difference of soil organic carbon components. The differences of soil organic carbon (SOC) stability in different landscape locations were investigated through indoor cultivation experiments. The main results are as follows: the slope top position has a better vegetation condition than the downhill position. The thickness of litter layer and the biomass of soil root decreased gradually from the top of slope to the valley. The soil pH value increased significantly from the top of the slope to the valley, and the soil organic carbon and total nitrogen content were not significantly different between the slope position, the soil organic carbon content and the soil total nitrogen content were significantly higher than those in the upper slope position, while the soil pH value increased significantly from the top of the slope to the gully valley, and the soil organic carbon and total nitrogen content were not significantly different between the slopes. The soil C / N ratio decreased significantly from the top of the slope to the gully. In addition, the variation of each variable was different among the four slope positions, and the soil carbon and nitrogen ratio decreased significantly from the top of the slope to the valley. There was no significant difference in the content of soil organic carbon among the four slope sites, but the analysis of soil active carbon components (soil soluble organic carbon and unprotected particulate organic carbon) showed that, The results of partial least square path analysis show that, compared with terrain, vegetation, carbon source input and other factors, both of them show a tendency to decrease significantly from the top of the slope to the valley, and based on the results of partial least square path analysis, the results show that, compared with the factors such as topography, vegetation and carbon source input, The variation of surface DOC content is mainly controlled by the physical and chemical characteristics of soil pH, C / N ratio, iron and aluminum oxide and sand content), while the variation of DOC content in middle layer is mainly caused by surface DOC content. The changes of surface and middle POC contents between slope positions were mainly controlled by soil physical and chemical factors. The change of POC in the deep soil was mainly affected by the POC content in the upper layer, and the stability of soil organic carbon was significantly different from that of the topsoil. The results of partial least square regression analysis showed that the stability of soil organic carbon from 0 to 10 cm was mainly affected by particulate organic carbon, while that of 10-20cm and 20-40cm was mainly affected by soil particle composition.
【学位授予单位】：中国科学院武汉植物园
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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