北川震后滑坡体表层土壤理化性质空间变化特征

发布时间：2018-06-25 10:54

本文选题：“5.12”汶川地震 + 滑坡体　；参考：《四川农业大学》2016年硕士论文

【摘要】：汶川大地震及其次生灾害严重破坏了该区山地生态系统。本文以北川擂鼓镇凤凰山震后滑坡体表层土壤为研究对象,结合网格采样和室内分析,运用经典统计学、地统计学和GIS等方法研究了滑坡区(Ⅰ)、过渡区(Ⅱ)和未破坏区(Ⅲ)土壤物理性质和土壤养分的空间分布特征。结果表明：(1)在干筛处理下,Ⅰ样地中5mm的风干性团聚体含量最低,样地Ⅱ次之,样地Ⅲ最高。湿筛处理下,3种样地的土壤水稳性团聚体均以2mm的粒径为主,总体上呈现出团聚体数量随粒径的减小而增加的趋势。干湿筛处理下土壤团聚体的平均重量直径(MWD)和几何平均直径(GMD)值均表现为ⅠⅡⅢ,与土壤团聚体分形维数值变化规律相反。各稳定性参数值在样地Ⅱ和Ⅲ之间均不存在显著性差异,但都与Ⅰ样地之间差异性显著。样地Ⅰ中除团聚体D值以外的其他稳定性参数值均表现为随海拔升高而增大,而其他样地的稳定性参数值随海拔升高无明显规律。综上所述,样地的土壤稳定性顺序应为样地ⅠⅡⅢ。(2)干筛和湿筛两种处理方式下团聚体稳定性参数和土壤颗粒组成的半方差函数理论模型拟合程度均较好。其中,除湿筛MWD表现为中等强度空间自相关以外,其他各团聚体稳定性参数都表现为强烈空间自相关性；粘粒表现为中等空间自相关性,其块基比为45.9%,粉粒和砂粒表现为强烈的空间自相关,块基比分别为0.1%和8%。干筛和湿筛的土壤团聚体MWD和GMD值大致呈由研究区左侧(Ⅰ)至右侧(Ⅲ)逐渐增加的变化规律,而团聚体分形维数值与此呈相反变化规律;土壤颗粒组成呈现出从Ⅰ至Ⅲ砂粒含量逐渐减少而粘粒含量逐渐增加的规律。3个样地的土壤颗粒组成均以砂粒为主,且显著性大于粘粒和粉粒含量,研究区土壤为砂质土壤。土壤颗粒组成质量分形维数值与砂粒含量呈极显著性负相关关系,与粘粒和粉粒含量均呈极显著性正相关,但粉粒含量的相关性相对较弱。(3)研究区土壤养分整体含量水平较低,变异程度较大,其中土壤有效磷(AP)为高强度变异,其余养分为中等强度变异。各土壤养分随海拔的变化规律不明显,而从Ⅰ至Ⅲ则呈明显增加趋势。其中,滑坡区表层土壤全磷(TP)含量较未破坏区减少10.3%,减幅最小,而AP减幅最大,达79.7%；过渡区各养分含量占未破坏区的31.1%-87.2%,降幅最小和最大仍为TP和AP。土壤TP的半方差函数模型拟合较差,而其他土壤养分的半方差函数模型拟合均较好。土壤AP和有机碳(SOC)的块基比为27.9%和28.8%,表现为中等强度空间自相关,其他土壤养分均表现为强烈空间自相关性。(4)土壤养分含量与各粒级土壤团聚体的相关性规律不明显,主要表现为土壤养分含量与5mm的风干性团聚体和2mm的水稳性团聚体呈正相关,与0.25mm风干性和水稳性团聚体呈负相关；土壤TP和AP与团聚体各稳定性参数之间无显著性相关性,其余各土壤养分含量与各团聚体稳定性参数均呈现一定的极显著和显著相关性。各土壤养分基本均与粘粒和粉粒含量呈显著或极显著正相关,而与砂粒含量呈显著性或极显著性负相关关系。土壤颗粒分形维数与土壤TP和AP的相关性不显著,与其他土壤养分均呈显著性或极显著性正相关关系。滑坡体上土壤质地、土壤团聚体和土壤养分等表征土壤质量及相应稳定性参数指标均呈下降趋势,地震滑坡扰动是导致滑坡体上土壤性质空间变化的主要因素。
[Abstract]:In this paper , the characteristics of soil physical properties and spatial distribution of soil nutrients were studied by means of classical statistics , geostatistics and GIS .
The soil aggregate MWD and GMD values of the soil in the study area were significantly correlated with the content of clay and silt . The content of soil available P ( TP ) decreased by 10.3 % and the decrease was the smallest , while the maximum of AP was 79.7 % .
The results showed that the soil nutrient content was positively correlated with 5 mm dry aggregates and 2 mm water - stable aggregates , and negatively correlated with 0.25 mm air - dry and water - stable aggregates .
There was no significant correlation between the soil TP and the stability parameters of the aggregates . The soil nutrient contents were significantly correlated with the contents of soil TP and AP . The soil texture , soil aggregates and soil nutrients showed a significant or significant positive correlation with other soil nutrients . The soil texture , soil aggregates and soil nutrients in the soil showed a downward trend , and the disturbance of the seismic landslide was the main factor which resulted in the spatial variation of soil property on the landslide mass .
【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S153

【相似文献】