【作者】 刘守赞；

【导师】 张建平； 郭胜利；

【作者基本信息】 河北农业大学 ， 作物栽培学与耕作学， 2005， 硕士

【摘要】 土壤有机碳（Soil organic carbon,SOC）是评价土壤质量的重要指标,也是陆地生态系统碳循环的重要组成成分。SOC在改善土壤结构、保持水分、防止土壤侵蚀和退化、提供植物养分特别是氮素等方面具有重要作用。黄土高原是我国主要的生态脆弱区,SOC含量低下。了解这一地区生态环境建设对SOC储量和分布的影响具有重要意义。本文以高原沟壑区典型小流域（王东沟流域）为单元,通过对土壤表层（0-20cm）448个点和29个典型剖面点的取样分析,结合GIS技术,分析了流域SOC的空间变异性特征,并探讨土地利用、地形、植被类型对SOC积累的影响。在此基础上,估算流域SOC储量。其主要结论如下: 流域内,塬面SOC含量6.41～9.50 g·kg^-1内,平均值为7.77 g·kg^-1;梁坡地在2.71～15.97 g·kg^-1内,平均值为6.84 g·kg^-1;沟道在3.59～15.18 g·kg^-1内,平均值为9.09 g·kg^-1。变异系数表明塬面（7.5%）为弱变异,梁坡（25.7%）和沟道（26.7%）为中等变异。整个王东沟流域SOC平均含量为7.58g·kg^-1,变异系数为26.9%,属于中等变异。流域内SOC含量有多个高值中心,这些高值中心主要集中在地势较低的主沟及支沟的沟底和两侧沟坡,土地利用方式为林地和草地的梁坡地上也出现高值中心。SOC含量在6.95～8.69g·kg^-1和5.80～6.95 g·kg^-1两个级别各占流域总面积的62.9%、27.6%。 塬面不同土地利用方式下SOC含量有所差异,农地SOC含量在6.41～9.50g·kg^-1内,平均值为7.99g·kg^-1;果园在6.25～8.54g·kg^-1内,平均值为7.48g·kg^-1;苜蓿地在8.28～9.10g·kg^-1,平均值为8.56g·kg^-1。农地改种植苜蓿三年后,SOC含量提高7.1%,改建为果园后下降5.3%～9.1%。梁坡地不同土地利用方式下SOC表现方式为:林地>草地>苜蓿地>农地>果园,其中林地SOC含量在4.76～14.41g·kg^-1,平均值为7.98 g·kg^-1;草地在2.71～15.97g·kg^-1,平均值为7.46 g·kg^-1;农地SOC含量在4.89～8.68g·kg^-1范围内,平均值为6.38g·kg^-1;果园在4.42～8.43g·kg^-1变化范围内,平均值为6.20g·kg^-1。梁坡农地转变为果园20年后降低5.5%,退耕还林还草后SOC增加16.6～47.4%,随着林龄年限的增长,SOC含量也呈增加趋势。沟道内林地SOC含量为3.59～15.18 g·kg^-1,草地5.08～13.78g·kg^-1。不同土地利用方式下SOC含量均随土层的加深而降低,但下降幅度不同。 不同植被类型下SOC含量有所差异,与荒草（白羊草）群落相比,油松群落条件下,SOC含量提高9.3%（P>0.05）,而果园SOC含量降低40.1%（P<0.05）。沙棘、侧柏和刺槐群落下,SOC含量虽低于荒草群落,但尚未达到显著水平（P>0.05）。果园和刺槐群落下坡面SOC含量从上到下变化趋势不明显;白羊草地群落下坡面SOC含量从上到下逐渐增加;而杏树群落条件下,坡面SOC呈中间高两头低的分布模式。 地形变化影响SOC的分布,流域纵断面显示,除在梁嘴处含量较高外,从塬面到梁末端SOC含量呈逐渐降低趋势;塬面-塬边坡-梁坡-沟坡和梁顶-梁坡-更多还原

【Abstract】 Soil organic carbon（ SOC） is a large component of the global carbon cycle and an important index to evaluate soil quality. Soil productivity is strongly linked to SOC because SOC plays important roles in improving soil structure, soil water holding, infiltrating and capacities, and the nutrients supply to plants. It is significant that effect of land-use, vegetations types and landform on soil organic carbon turnover , distribution and storage in gully area of the Loess Plateau. In this thesis, 448 observed points of surface （0²0cm） and 29 observed profile （0²00） were made in Wangdonggou watershed in gully region of Loess Plateau. Spatial variability of SOC content was analyzed by geostatistics approach. The complex factors affected spatial variability of soil carbon content was preliminarily discussed. The storage of SOC C pool was estimated in the whole watershed. The main results were as follows:Soil content of Wangdonggou watershed was in the range of 3.59-15.97 g·kg^-1, the average were 7.58g·kg^-1. The variability coefficients of SOC were 26.9%,it’s belong to middle intensity .SOC content on table land, on slope land and in valley were in the range of 6.41-9.50 g·kg^-1, 2.71-15.97 ·kg^-1 and 3.59-15.18 g·kg^-1 respectively. The variability coefficients of SOC on table land was 7.5%, belong to low intensity, on slope land and in valley were 25.7 %and 26.7%respectively and belonged to the middle intensity.SOC concentrations under different land use patterns have significant differences in table land, soc concentration of cropland , orchard and clover were in the range of 6.41⁹.50g·kg^-1, 6.25-8.54 g·kg^-1 and 8.28-9.10 g·kg^-1 respectively. Compared with cropland, SOC content increased by 7.1% for clover and decreased by 5.3%⁹.1% for orchard on tableland. The content of soc could be put in orders as: forestland > grassland > clover > cropland > orchard. The average content of soc in cropland was 6.38 g·kg^-1, it was decreased by 5.5% after converting from crop land to orchard and soc content was increased by 16.6-47.4% after converting from crop land to forestland or grassland. Soc content was increased with the increased of the year of forest. Soc content of forest and grassland were 3.59-15.18 g·kg^-1and 5.08-13.78 g·kg^-1 respectively in valley. The distribution of the SOC concentration or inventory in soil profile would change with the change of land use in wangdonggou watershed.Compared with grass （Bothriochloaischaemum（L.）Keng）land, SOC content更多还原