喀斯特地区不同林分土壤团聚体稳定性及其有机碳特征

发布时间：2018-03-15 18:28

本文选题：喀斯特　切入点：土壤团聚体　出处：《北京林业大学》2016年硕士论文　论文类型：学位论文

【摘要】：以土壤团聚体稳定性及其有机碳分布特征为对象的研究已经有很多报道,在喀斯特地区相关研究相对薄弱。为阐明该地区主要人工林和次生天然林土壤团聚体稳定性及其有机碳特征,本研究选取了广西地区主要的4种人工林营造树种(马尾松林、桉树林、毛竹林、杉木林)和次生天然林为研究对象,基于野外调查和室内实验分析,对5种林分类型下表层土壤(0～20 cm)和亚表层土壤(20～40 cm)养分、土壤团聚体稳定性及粒径分布、水稳性团聚体有机碳以及0～40 cm平均土壤碳密度进行了研究。主要结果如下：(1)次生天然林改造为人工林后,对土壤质量产生不利影响,相对次生天然林其土壤养分、团聚体稳定性(水稳性和机械稳定性)、林地土壤碳密度整体上出现一定程度下降。其中部分林分土壤团聚体水稳定性和次生天然林存在显著差异,4种人工林土壤碳密度与次生林相比,下降幅度为：12.2%～41.8%。4种人工林2个土层土壤团聚体水稳定性均为较浅土层高于较深土层,且2个土层杉木林最高,桉树林最低。(2)土壤理化性质对团聚体机械稳定性影响较小,和团聚体水稳定性关系密切程度较高。干筛处理下,土壤理化指标(全N、P、K、土壤容重、土壤有机质)除全N与分形维数存在显著正相关关系外,其余与平均质量直径、几何平均直径、土壤分形维数3个指标均不存在显著相关关系。湿筛条件下,土壤理化指标(除全P、全K外)和平均质量直径、几何平均直径关系密切。平均质量直径与土壤有机质呈极显著正相关关系；与土壤容重呈极显著负相关关系；与土壤全N呈显著正相关关系。几何平均直径分别和土壤有机质、全N呈极显著正相关关系,与土壤容重呈极显著负相关关系。分形维数和全N呈显著正相关关系。(3)5 mm粒级水稳性团聚体含量、土壤有机碳含量的增加有利于增强土壤抗侵蚀能力,而0.5～0.25 mm和0.25mm粒级水稳性团聚体含量的增加会降低土壤团聚体稳定性,土壤结构较差,降低土壤抗侵蚀能力。(4)5种林分土壤团聚体有机碳贡献率最小值均出现在0.5～0.25 mm粒级团聚体,其中4种林分(桉树林除外)贡献率最大值出现在5 mm粒级团聚体,提高土壤中大团聚体比例有利于增加土壤有机碳含量。(5)5种林分类型(桉树林、马尾松林、毛竹林、杉木林、次生天然林)0-40 cm土层土壤有机碳密度分别为：7.75、9.72、11.12、11.70、13.32,kg/m2。5种林分类型0-20 cm土层土壤有机碳密度均高于20-40 cm土层。在营造人工林时,相对其他3种人工林而言,增加杉木林的面积可以提高喀斯特地区林地土壤碳储量。
[Abstract]:There have been many reports on the stability of soil aggregates and their organic carbon distribution. In order to elucidate the stability of soil aggregates and the organic carbon characteristics of main plantation and secondary natural forest in this area, four main artificial forest species (Pinus massoniana) were selected in this study. Eucalyptus, Phyllostachys pubescens, Chinese fir (Cunninghamia lanceolata) and secondary natural forest were studied. Based on field investigation and laboratory experimental analysis, soil aggregates stability and particle size distribution were studied. The organic carbon of water-stable aggregates and the average soil carbon density of 40 cm were studied. The main results were as follows: 1) after the secondary natural forest was transformed into artificial forest, the soil quality was adversely affected, and the soil nutrient of the secondary natural forest was compared with that of the secondary natural forest. The aggregate stability (water stability and mechanical stability), the carbon density of forestland soil decreased to some extent, among which there were significant differences between water stability of some stand soil aggregate and secondary natural forest. Carbon density compared with secondary forest, The water stability of soil aggregates in 2 kinds of plantations was higher than that in deep soil layer, and the soil physical and chemical properties of soil physical and chemical properties had little effect on the mechanical stability of aggregates, and the soil physical and chemical properties of two soil layers were the highest in Chinese fir forest and the lowest in eucalyptus forest. Under dry sieve treatment, soil physical and chemical indexes (total N Pu K, soil bulk density, soil organic matter) had significant positive correlation with fractal dimension, and the other indexes had significant positive correlation with mean mass diameter. There was no significant correlation between geometric mean diameter and soil fractal dimension. Under wet screening condition, soil physicochemical index (except total P, total K) and mean mass diameter were obtained. Geometric mean diameter is closely related to soil organic matter, significant negative correlation with soil bulk density, significant positive correlation with soil total N, and significant positive correlation between geometric mean diameter and soil organic matter. Total N was positively correlated with soil bulk density and negatively correlated with soil bulk density. Fractal dimension and total N showed significant positive correlation. The increase of soil organic carbon content can enhance soil erosion resistance, while the increase of 0.5mm and 0.25 mm water stable aggregate content will reduce the stability of soil aggregate, and the soil structure will be poor. The minimum contribution rate of organic carbon to soil aggregates in five stands, I. e., reducing soil erosion resistance, appeared in 0.50.25mm grain aggregates, and the maximum contribution rate of four stands (except eucalyptus forest) appeared in 5mm aggregates. Increasing the proportion of large aggregates in soil is beneficial to increase the soil organic carbon content. 5 forest types (eucalyptus, Masson pine, Phyllostachys pubescens, Cunninghamia lanceolata, Cunninghamia lanceolata). The soil organic carbon densities of 0-40 cm soil layer of secondary natural forest were: 1: 7.75 ~ 9.72 ~ 11.12 ~ 11.70 ~ 11.70 kg / m ~ (2.5) 0 ~ 20 cm soil layer > 20 ~ 40 cm soil layer, respectively. The soil organic carbon density of 0 ~ 20 cm soil layer was higher than that of the other three kinds of plantations, and the soil organic carbon density of 0 ~ 40 cm soil layer was higher than that of the other three types of plantations. Increasing the area of Cunninghamia lanceolata forest can increase soil carbon storage in karst area.
【学位授予单位】：北京林业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S714.2

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