【作者】 黄双双；

【导师】 张世熔；

【作者基本信息】 四川农业大学 ， 土壤学， 2008， 硕士

【摘要】 根据流沙河流域2005年样样点调查资料,采用采用主成分、判别分析与K均值聚类分析相结合的方法对研究区土地退化进行评价,利用传统统计和方差分析等研究方法,对不同土地退化程度下土壤总有机碳密度和水溶性有机碳密度的变化过程及其变化特征进行了研究。分析了土壤类型、地形因子、植被（物）类型、土壤母质（岩）、土地利用类型等对土地退化和土壤有机碳密度变化的影响。研究结果分述如下:流沙河流域土壤总有机碳密度（TOCD）随着退化程度的加深,其值分别为5.42±1.21kg m^-2、3.61±0.94kg m^-2、1.78±0.30 kg m^-2、0.77±0.16kg m^-2,呈递减趋势。不同土地退化程度下TOCD之间存在极显著差异F=13.55^**（P＜0.01）。土壤水溶性有机碳（WSOC）是土壤有机碳的重要组成部分,土壤总有机碳密度与土壤水溶性有机碳密度呈极显著正相关（R²=0.91）。流域土壤水溶性有机碳密度（WSOCD）随着退化程度的加深,其值分别为43.79±7.63 g m^-2、38.21±9.31g m^-2、18.34±2.82 g m^-2、9.56±2.17 g m^-2,呈递减趋势。不同土地退化程度下WSOCD之间存在极显著差异F=12.83^**（P＜0.01）。母质（岩）类型、土壤类型、海拔、植被（物）类型以及土地利用类型是主要的影响因素。不同母质（岩）类型时,TOCD之间存在极显著差异F=5.35^**（P＜0.01）,WSOCD之间存在显著差异F=3.58^*（P＜0.05）。不同土壤类型时,TOCD和WSOCD在不同土壤类型之间均存在极显著差异,F=5.20^**（P＜0.01）和F=5.25^**（P＜0.01）。地形因素从坡度、坡向和海拔等3个方面分析了它们的影响。方差分析表明,不同坡度和坡向时,TOCD和WSOCD均不存在显著差异。不同海拔时,TOCD之间存在显著差异F=3.33^*（P＜0.05）,WSOCD之间存在极显著差异F=4.60^**（P＜0.01）。植被（物）类型,从植被群落和生物量两个方面进行分析。植物群落呈乔-灌-草的逆行演替,随着土地退化程度的加剧,土壤有机碳密度逐渐降低。地表生物量呈现随着土地退化程度的加剧而急剧减少的趋势。方差分析表明不同土地退化程度下生物量之间存在极显著差异F=59.79^**（P＜0.01）,土壤有机碳密度与地表生物量成极显著正相关（R²=0.95）,地表生物量低的区域是土地退化防治和治理的重点。不同土地利用类型时,不同土地利用类型下土壤有机碳密度存在极显著差异,F=9.55^**（P＜0.01）和F=9.70^**（P＜0.01）。更多还原

【Abstract】 According to the data of field investigation about plant identification and soil chemical analysis of 57 samplings in 2005 in the Liusha Basin,Hanyuan County,Sichuan Province.Land degradation of the Liusha Basin were assessed by main component analysis method,discriminant analysis and K-means cluster.This paper studied on the soil organic carbon density characteristics under different land degradation degrees by statistic methods and variance analysis,discussing the influence of soil type,orographic factor, plant type,parent material,land using type on land degradation and soil organic carbon density.The main results were as follows.The results showed that the average of TOCD in Basin declined with the degree of land degeneration were 5.42±1.21 kg m^-2,3.61±0.94 kg m^-2,1.78±0.30 kg m^-2,0.77±0.16 kg m^-2,respectively.Variance analysis indicated that TOCD highly significantly decreased, F=13.55^**（P＜0.01）.WSOC took an important part in soil organic carbon,TOeD and WSOCD had singnificant positive relationship（R²=0.91）.WSOCD in the topsoil declined with the degree of soil degeneration were 43.79±7.63 g m^-2,38.21±9.31 g m^-2,18.34±2.82 g m^-2, 9.56±2.17 g m^-2,respectively.The results of variance analysis showed that the different land degradation degree had the extremely difference with WSOCD,F=12.83^**（P＜0.01）.The main influential factors of land degradation in Liusha Basin were parent material（rock）,soil type,altitude,the types of vegetation and land use types.Under different types of parent material（rock）,the results of variance analysis showed that the different land degradation degree had both the extremely difference with TOeD F= 5.35^**（P＜0.01） and WSOCD,F=3.58^**（P＜0.05）.Different soil type,the variance analysis showed that TOeD and WSOCD both were the extremely significant differences F=5.20^**（P＜0.01） and F=5.25^**（P＜0.01） in different soils.The orographic factor analyses from slope,slope aspect and altitude.The results of variance analysis showed that both TOCD and WSOCD had no singnificant difference under different slope,F=0.12 and F=0.44（P＞0.05）.Analysis of variance showed that there were no significant differences of WSOCD and TOeD in different slopes,F=0.83 and F=1.57（P＞0.05）,respectively.Under different altitudes,the analysis of variance showed that there wre extremely significant differences of WSOCD,F=4.60^**（P＜0.01） and significant differences of TOeD F= 3.33^*（P＜0.01）.The types of vegetation can be analyzed in terms of vegetation community and biomass.The retrograde succession like Joe-irrigation-grasslands existed in vegetation community in investigative area,with the aggravation of land degradation,the density of soil organic carbon gradually decreases,and the plant evolves gradually from arbors and shrub into herbage as the main type,and the structure of community gradually become simpler,which also noted the range of the density of soil organic carbon.There was a trend that the surface biomass decreases with the aggravation of land degradation.Analysis of variance showed that there were extremely significant differences between different extents of land degradation and the biomass with the value of F=59.79^**（P＜0.01）.The value of TOCD was positively correlated to surface biomass.So the area of low biomass was the focus of regions under land degradation governance.Different soil type,the variance analysis showed that TOCD and WSOCD both were the extremely significant differences F=5.20^**（P＜0.01） and F=5.25^**（P＜0.01） in different soils.Different types of land use,the variance analysis showed that TOeD and WSOCD both were the extremely significant differences F=9.55^**（P＜0.01） and F=9.70^**（P＜0.01） in different types of land use.更多还原