白水河小流域石漠化治理初期土壤养分空间变异研究

发布时间：2018-08-17 09:20

【摘要】：喀斯特地区的石漠化是制约该区经济发展和人民生活水平的一大障碍,其土壤肥力状况是石漠化治理的重要依据。流域作为一个相对完整的汇水单元,基本涵盖大部分地形条件和水文过程。以流域为尺度研究土壤养分的空间变异规律能够客观的揭示地形、水文、土地利用方式等因素对土壤养分空间变异的综合驱动作用。白水河小流域属典型的喀斯特峰丛谷地地貌,地形破碎,地貌复杂,土壤空间分布复杂,表现出高度的空间异质性,土地利用方式的改变伴随着生态因子的变化,土壤养分随之变化。本研究以地形、土地利用方式和植被类型为依据,分层采集了0-5 cm、5-10 cm、10-20 cm土层的土壤样品,并测定了土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、有效氮(AN)、有效钾(AK)的含量,利用地统计学与GIS技术相结合的方法,分析了土壤养分水平方向上的空间变异规律和垂直方向上的变化,探讨了成土母质、地形及土地利用方式对土壤养分空间变异的影响,应用相关性分析和主成分分析对土壤养分进行综合分析,绘制了土壤肥力的空间分布图,并分析了不同土地利用方式下土壤的肥力状况。得到以下主要研究成果:(1)研究区土壤养分的变异性在46.95%~82.50%之间,均为中等程度的变异,其中,全磷的变异性最大,有效氮最小,有机碳和全氮的变异性相差不大,且全氮的变异性大于有效氮,全钾的变异性大于有效钾。有机碳、全磷和有效钾总体表现出强烈的空间自相关性,主要受自然因素的影响。全氮和有效氮一样,随土层的加深空间自相关性减弱,在0-5cm土层有很强的空间自相关性,5-10 cm土层的空间自相关性为中等,10-20 cm土层的空间自相关性很弱,随土层的加深,人为因素的影响增加。土壤全钾的空间自相关性很弱,有朝着均一化方向发展的趋势,主要受人为因素影响。土壤养分的变程在169~3996 m之间,空间自相关范围较大,空间自相关范围整体表现为全钾最大,有机碳和全氮次之,全磷、有效氮和有效钾最小。以上结果表明白水河小流域土壤的养分具有较高的变异性。(2)研究区内土壤有机碳的含量较高,高值区主要在流域的东北部,且分布的面积较大,南部的含量较低;土壤全磷的含量较低,呈零星斑块状分布,高值区与低值区交错分布,高值区主要集中在北部和中下部,低值区以南部为主;全氮含量为中等水平,有效氮含量很丰富,全氮和有效氮在0-5 cm土层和5-10 cm土层的分布较为相似,以北部和中下部含量较高,西部和南部含量较低,在10-20 cm土层中,全氮含量以北部最高,高值区分布的面积较大,有效氮以中部最低,向东北和西南方向逐渐递增;全钾含量处于极低水平,含量以流域中间最低,且贯穿南北,由中间向西部和东部扩散,含量逐渐增加。有效钾含量为中等水平,总体由北往南为高-低-高-低的分布趋势。白水河小流域土壤养分的空间异质性较强与其境内多样土地利用方式和复杂的地形地貌有关。(3)白云岩发育的土壤有机碳、全氮、全磷、有效氮和有效钾的含量最高,除有效钾外,其他养分指标在石灰岩发育的土壤中含量次之,砂页岩的含量最低,而有效钾则是砂页岩含量次之,石灰岩含量最低;全钾在石灰岩下的含量最高,在砂页岩下最低。石灰岩发育的土壤养分指标除全钾外均随土层的加深而减小,砂页岩发育的土壤除全磷外均随土层的加深而减小,白云岩发育的土壤各养分指标随土层的变化规律不明显。坡度对各层土壤有机碳都有极显著的影响,对全氮和有效氮有显著影响,对全磷的影响较小,对全钾和有效钾的影响最小,且与全钾整体为负相关关系。有机碳、全氮和有效氮整体随坡度的增加而增大,全磷、全钾和有效钾整体随坡度的变化不明显。有机碳、全氮、有效氮在疏林地、灌木林地和天然草地下的含量较高,在耕地下的含量较低;全磷在天然草地下的含量较高,在马尾松林地下的含量较低;全钾和有效钾在耕地和樱桃林地的含量较高,在天然草地下的含量较低,全钾在疏林地下含量最低,而有效钾在马尾松林地下的含量最低。(4)有机碳、全氮、有效氮和全磷之间相互呈极显著或显著正相关关系。有效钾与其他土壤养分的相关性较小,全钾与其他土壤养分的相关性最小。流域内土壤肥力较高的区域主要在东北部,由北往南呈高-低-高-低的分布趋势,地势较低的区域肥力较低,地势较高的区域肥力较高。不同土地利用方式下土壤肥力大小表现为:疏林地灌木林地樱桃林地耕地撂荒地天然草地马尾松林地。虽然马尾松作为喀斯特地区主要的人工造林树种,但其保持土壤养分的能力并不高。
[Abstract]:Rocky desertification in karst area is a major obstacle to economic development and people's living standard, and its soil fertility status is an important basis for controlling rocky desertification. Baishuihe small watershed is a typical karst peak-cluster-valley landform with fragmented topography, complex topography, complex soil spatial distribution, showing a high degree of spatial heterogeneity, land use changes accompanied by ecological factors. Based on topography, land use patterns and vegetation types, soil samples in 0-5 cm, 5-10 cm and 10-20 cm layers were collected, and soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), and available potassium (AK) were determined by geostatistics and GIS. The spatial variability of soil nutrients in horizontal and vertical directions was analyzed, and the effects of parent materials, topography and land use patterns on the spatial variability of soil nutrients were discussed. The main results were as follows: (1) The variability of soil nutrients in the study area ranged from 46.95% to 82.50%, with moderate variability. Among them, the variability of total phosphorus was the greatest, available nitrogen was the smallest, the variability of organic carbon and total nitrogen was little, and the variability of total nitrogen was greater than that of total phosphorus. Organic carbon, total phosphorus and available potassium showed strong spatial autocorrelation, which was mainly affected by natural factors. Total nitrogen, like available nitrogen, had strong spatial autocorrelation in 0-5 cm soil layer, and the spatial autocorrelation in 5-10 cm soil layer was medium. The spatial autocorrelation of soil total potassium is very weak, and the spatial autocorrelation of soil total potassium is very weak, which is mainly influenced by human factors. The results showed that the soil nutrients in Baishuihe watershed had high variability. (2) The content of soil organic carbon in the study area was high, the high value area was mainly in the northeast of the watershed, and the distribution area was large, and the content of soil total was low in the south. The content of phosphorus is low and sporadic patchy, and the distribution of high and low value areas is interlaced. The high value areas are mainly concentrated in the north and the middle and lower parts, while the low value areas are mainly in the south. The total nitrogen content is middle level, and the available nitrogen content is very rich. In the 10-20 cm soil layer, the total nitrogen content is the highest in the north, the area of high value area is larger, the available nitrogen is the lowest in the middle, and increases gradually to the northeast and southwest; the total potassium content is at the very low level, and the content is the lowest in the middle of the basin, and runs through the north and south, and diffuses gradually from the middle to the West and east. The spatial heterogeneity of soil nutrients in Baishuihe small watershed is related to the various land use patterns and complex topography in the region. (3) Soil organic carbon, total nitrogen, total phosphorus, available nitrogen and available potassium content in dolomite development is the highest. Except available potassium, other nutrient indices in limestone-developed soils were the second, the lowest in sandy shale, the second in sandy shale and the lowest in limestone, the highest in total potassium under limestone and the lowest in sandy shale. Small, except total phosphorus, the soil developed by sand and shale all decreased with the deepening of soil layer, and the change rule of soil nutrient index with soil layer was not obvious. Organic carbon, total nitrogen and available nitrogen increased with the increase of slope, while total phosphorus, total potassium and available potassium did not change significantly with the increase of slope. The contents of total potassium and available potassium were higher in cultivated land and cherry forest, lower in natural grassland, lowest in sparse forest, and lowest in available potassium in Masson Pine forest. (4) The contents of organic carbon, total nitrogen, available nitrogen and total phosphorus were significantly or significantly positive each other. The correlation between available potassium and other soil nutrients was small, and the correlation between total potassium and other soil nutrients was the smallest. Soil fertility is shown as follows: loose woodland shrub woodland cherry woodland cultivated land abandoned land natural grassland masson pine woodland.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S158

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