黄土高原人工刺槐林和柠条林土壤团聚体稳定性及其影响因素

发布时间：2018-04-02 00:13

本文选题：土壤团聚体　切入点：稳定性　出处：《中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)》2017年硕士论文

【摘要】：植被恢复是黄土高原地区提高土壤有机碳含量、改善土壤结构最有效的措施之一。本研究选取黄土高原的刺槐和柠条人工林林下土壤为研究对象,结合Yoder法和Le Bissonnais法了解黄土高原地区土壤团聚体特征及其破坏的机制,探究植被恢复过程中人工刺槐林和柠条林对团聚体结构及其稳定性和抗侵蚀能力(K)的影响,揭示环境因子和养分因子影响土壤团聚体稳定性的关系,为确定黄土高原植被恢复措施的选择及其优劣评价提供科学的实践依据。主要结论如下:(1)在北部落叶阔叶林带、森林草原带、典型草原带植被带内由东向西,林地土壤大团聚体质量分数逐渐增加。且Yoder法结果表明,四个植被带刺槐林和柠条林整体土壤团聚体各粒径平均值,0.25mm粒径的土壤团聚体:南部落叶阔叶林带北部落叶阔叶林带森林草原带典型草原带。(2)在LB法3种湿润处理下,快速湿润处理(FW)对土壤团聚体结构的破坏程度最大,处理后土壤水稳性团聚体以0.2 mm为主;慢速湿润处理(SW)对团聚体的破坏程度最小,处理后土壤水稳性团聚体主要以2 mm团聚体为主;而预湿后扰动处理(WS)对团聚体的破坏程度介于FW和SW之间。(3)黄土高原R0.25、MWD值和GMD值的空间分布特征基本呈现西部偏低,东部偏高的规律,K值相反。同纬度内,随着经度的减小,R0.25、MWD值和GMD值整体上有逐渐增大的趋势,土壤抗蚀性K值整体上有逐渐减小的趋势。(4)以环县地区经线(107o)为分界线,以其年平均降雨量(407mm)为参照值,环县以东种植刺槐,土壤团聚体稳定性和抗侵蚀能力更好;以西且降水小于407mm种植柠条,土壤团聚体稳定性和抗侵蚀能力更好。在典型草原带以西的荒漠草原带,降水越来越少,极度干旱少雨,柠条也不适宜种植。(5)影响黄土高原土壤团聚体稳定性和抗蚀性的环境因子主要是纬度、经度、降雨。R0.25、MWD、GMD与纬度、经度呈极显著负相关,与降水呈极显著正相关。土壤可蚀性因子K值与纬度、经度呈极显著正相关,与降水呈极显著负相关。影响黄土高原土壤团聚体稳定性和抗蚀性的土壤养分主要是土壤有机质、土壤全氮。R0.25、MWD、GMD与土壤有机质、土壤全氮呈极显著正相关,土壤可蚀性因子K值与土壤有机质、土壤全氮呈极显著负相关。(6)黄土高原土壤团聚体的破坏机制主要是消散和机械破坏,这与黄土高原的大雨与暴雨以及黄土高原植被覆盖度低有关,因此为了提高土壤团聚体稳定性,防治土壤侵蚀,通过植树造林进行植被恢复可提高植被覆盖度,提高土壤团聚体的稳定性,提高土壤的抗侵蚀能力。快速湿润处理和预湿后扰动处理能模拟不同降雨或灌溉方式以及地表径流对土壤团聚体稳定性的影响,LB法能够较为全面的测定土壤团聚体结构。
[Abstract]:Vegetation restoration is one of the most effective measures to improve soil organic carbon content and soil structure in Loess Plateau. Combined with Yoder method and Le Bissonnais method, the characteristics of soil aggregates and the mechanism of soil damage in the Loess Plateau were studied, and the effects of artificial Robinia pseudoacacia and Caragana korshinskii forest on the structure, stability and erosion resistance of soil aggregates in the process of vegetation restoration were investigated. To reveal the relationship between environmental factors and nutrient factors affecting the stability of soil aggregates, and to provide a scientific practical basis for determining the selection of vegetation restoration measures and their evaluation on the Loess Plateau. The main conclusions are as follows: 1) in the deciduous broad-leaved forest belt in the north. Forest steppe zone, typical steppe belt vegetation belt from east to west, forest soil mass fraction of large aggregates gradually increased, and the results of Yoder method showed that, Soil aggregates with average diameter of 0.25mm in the whole soil aggregates of Robinia pseudoacacia forest and Caragana korshinskii forest in four vegetation belts: typical steppe zone of deciduous broadleaved forest belt in the northern deciduous broadleaved forest belt of southern deciduous broadleaved forest belt. Rapid wetting treatment (FW) had the greatest damage to soil aggregate structure, and soil water stable aggregate was mainly 0.2 mm after treatment, and slow wetting treatment (SWW) had the least damage degree on aggregate structure. The main content of soil water stable aggregates after treatment was 2 mm aggregate, while the damage degree of pre wet disturbance treatment was between FW and SW) the spatial distribution of R0. 25 MWD and GMD values in the Loess Plateau was relatively low in the west of China. In the same latitude, with the decrease of longitude, the values of R0.25 MWD and GMD are gradually increasing, and the K value of soil corrosion resistance is gradually decreasing as a whole. Taking the average annual rainfall of 407mm as reference value, Robinia pseudoacacia was planted east of Huanxian County, the stability of soil aggregate and the ability of resisting erosion were better, and the precipitation to the west was less than that of 407mm planting Caragana korshinskii. Soil aggregates are more stable and resistant to erosion. In the desert steppe to the west of the typical steppe belt, precipitation is getting less and less, extreme drought and less rain, Caragana korshinskii is also unsuitable for planting.) the environmental factors affecting the stability and corrosion resistance of soil aggregates on the Loess Plateau are mainly latitude, longitude, rainfall .R0.25MW DMD and latitude. The longitude of Caragana korshinskii is negatively correlated with latitude. Soil erodibility factor K was significantly positively correlated with latitude, longitude, and negatively correlated with precipitation. Soil nutrients affecting soil aggregate stability and corrosion resistance on the Loess Plateau were mainly soil organic matter. Soil total nitrogen. R0. 25 MWDN GMD was positively correlated with soil organic matter, soil total nitrogen was positively correlated with soil total nitrogen, soil erodibility factor K was significantly negatively correlated with soil organic matter and soil total nitrogen was negatively correlated with soil organic matter. 6) the destruction mechanism of soil aggregates in the Loess Plateau was mainly dissipation and mechanical destruction. This is related to the heavy rain in the Loess Plateau and the low vegetation coverage in the Loess Plateau. Therefore, in order to improve the stability of soil aggregates and control soil erosion, the vegetation coverage can be improved by afforestation. To improve the stability of soil aggregates, The effects of different rainfall or irrigation methods and surface runoff on the stability of soil aggregates can be simulated by rapid wetting treatment and disturbance treatment after wetting. The LB method can comprehensively determine the structure of soil aggregates.
【学位授予单位】：中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714.2

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