陕北黄土区不同土地利用方式对深层土壤水和碳分布的影响

发布时间：2019-04-21 15:47

【摘要】：干旱半干旱区黄土高原地处我国中部,气候干旱、降水稀少、地下水埋藏深,土壤水分成为植被生长的主要限制因素。自从退耕还林还草工程实施以来,土地利用方式发生巨大的变化。对黄土高原地区土壤水分以及土壤碳分布产生很大的影响。黄土高原地区土壤碳储量对于全国乃至全球气候变化和碳循环具有重要意义。不同的土地利用类型下,对于土壤水分分布和储水状况以及土壤有机碳分布及储量有了大量的研究。但对于土壤水分和土壤碳的大多数研究主要位于0-5 m和0-3 m的土壤剖面之中,而对于土壤无机碳以及深层的土壤水分和土壤碳分布和储量的研究较少。本文选取陕北米脂人工经济林、神木退耕还林和榆林榆阳区防风固沙林具有代表性土地利用方式。研究不同土地利用方式下0~20 m剖面土壤水分和碳分布特征以及土壤耗水活跃层的深度进行了研究,分析陕北黄土丘陵区不同土地利用方式对深层土壤剖面水分和土壤碳分布和储存特征的影响及生态环境效应。取得的主要研究结果如下:(1)在0~20 m土层,不同位点具有代表性土地利用方式均影响土壤含水量的垂直分布;在整个剖面中,人工经济林土壤储水量有显著差异,大小分别为:矮化枣树未矮化枣树,储水量相差587.9 mm;神木退耕还林和榆林榆阳区防风固沙林土壤剖面中土壤储水量无较大差异,在整个剖面中土壤储水量的大小分别为:退化人工草地柠条林,储水量相差98.8 mm;荒草地樟子松,储水量相差7.5 mm。可见,人工经济林矮化枣树与未矮化枣树相比减少了土壤水分的消耗,矮化枣树冠幅较小,降低了蒸腾作用,从而更加有利于土壤水分的可持续利用;人工柠条林和退化人工草地土壤水分含量无明显差异;防风固沙林樟子松与荒草地整个剖面中的平均土壤含水量较低,土壤砂粒含量较高,土壤持水性差,土壤含水量随深度的增加而增加,平均土壤含水量分别为3.4%和3.6%,且该地植物对深层土壤水分影响有限。综上,土壤剖面中土壤水分除了受土壤质地的控制,不同土地利用模式由于植物根系不同对土壤水分也产生较大的影响。为此,选择合适的植物对于土壤深层水的保护和持续利用非常重要。(2)在不同土地利用模式下,土壤剖面中pH和EC的分布范围分别是8.14~9.78和46.3~763μS/cm,且各土壤剖面pH和EC无显著性差异。土壤有机碳含量,矮化枣树(2.00 g/kg)未矮化枣树(1.54 g/kg)柠条林(0.97 g/kg)退化人工草地(0.81 g/kg)樟子松林(0.70 g/kg)荒草地(0.45 g/kg),且各剖面之间土壤有机碳存在显著性差异(P0.05);土壤无机碳,矮化枣树(11.66 g/kg)≥未矮化枣树(11.59 g/kg)柠条林(9.62 g/kg)退化人工草地(8.07 g/kg)樟子松林(4.32 g/kg)荒草地(0.47 g/kg);人工经济林和退耕还林(草)样地所有土壤剖面之间土壤无机碳无显著性差异。人工经济林和退耕还林(草)剖面与防风固沙林地剖面土壤无机碳存在显著性差异(P0.05);三个采样区域之间土壤碳密度存在显著性差异;矮化枣树、未矮化枣树、柠条林、退化人工草地、樟子松林和荒草地土壤剖面无机碳密度分别是有机碳密度的6.19、7.71、10.80、10.78、5.91和1.03倍。综上可见,不同土地利用模式之间土壤碳储量存在明显差异,无机碳的含量远高于有机碳。(3)在不同的土地利用方式下,土壤剖面氯离子含量存在一定的差异,是因为人为因素的干扰;而对于土壤耗水活跃层中氯离子剖面中的差异,部分归因于植被耗水导致氯离子积累。不同的土地利用条件下土壤耗水活跃层也存在一定的差异,土壤耗水活跃层厚度具有明显的差异,耗水活跃层厚度最大的土地利用方式为柠条林,活跃深度达到13.0 m。
[Abstract]:The arid and semi-arid area of the Loess Plateau is located in the middle of our country. The climate is arid, the precipitation is scarce, the groundwater is buried deep, and the soil moisture is the main limiting factor of the growth of the vegetation. The land-use method has changed greatly since the project has been implemented. The effect of soil water and soil carbon distribution on the Loess Plateau is greatly affected. The carbon storage of the soil in the Loess Plateau is of great significance to the national and even global climate change and the carbon cycle. The soil water distribution and water storage condition and soil organic carbon distribution and reserves have been studied in different land use types. However, most of the research on soil moisture and soil carbon is located in the soil profile of 0-5m and 0-3m, and the research on soil inorganic carbon and soil moisture and soil carbon distribution and reserves is less. This paper selects the representative land-use method of the anti-wind and fixed-sand-forest in the northern Shaanxi rice-fat man-made economic forest, the forest for returning to the forest and the Yuyang district of the Yulin. The soil moisture and carbon distribution and the depth of the active layer of soil water consumption were studied in different land use modes. The effects of different land use patterns on water and soil carbon distribution and storage characteristics of deep soil profiles and their ecological environment effects were analyzed. The main results obtained are as follows: (1) In the 0-20 m soil layer, the representative land use patterns of different sites affect the vertical distribution of soil water content; in the whole section, there is a significant difference in the soil storage capacity of the artificial economic forest, and the size is: the dwarf jujube is not dwarfed the jujube tree, The amount of water storage differs by 587.9 mm; there is no significant difference in the soil storage capacity in the soil profile of the anti-wind and fixed-sand forest in the forest of the Shenmu and the Yulin, and the size of the soil storage capacity in the whole section is: the degraded artificial grassland, the Caragana korshinskii and the water storage capacity of 98.8 mm; and the mongolian mongolica pine. The water storage volume is 7.5mm. It can be seen that the dwarfing date of the artificial economic forest is less than that of the undwarf jujube tree, the crown width of the dwarf jujube tree is small, the transpiration is reduced, and the sustainable utilization of the soil moisture is more beneficial; and the soil moisture content of the artificial Caragana korshinskii and the degraded artificial grassland is not obviously different; the average soil moisture content in the whole cross section of the sandalwood and the wild grass is lower, the content of the soil sand is higher, the water content of the soil is poor, the water content of the soil is increased with the increase of the depth, the water content of the average soil is 3.4% and 3.6%, respectively, And the effect of the plant on the deep soil moisture is limited. In general, the soil moisture in soil profile is controlled by soil texture, and different land use patterns have a great effect on soil moisture due to different root systems. To this end, it is very important to select suitable plants for the conservation and sustainable use of deep water in the soil. (2) The distribution of pH and EC in soil profile was 8.14-9.78 and 46.3-763.mu. S/ cm in different land-use modes, and there was no significant difference in pH and EC of each soil. The organic carbon content of the soil, the dwarf jujube (2.00 g/ kg), the non-dwarf jujube (1.54 g/ kg), the degraded artificial grassland (0.81 g/ kg) and the mongolian pine forest (0.81 g/ kg) were (0.81 g/ kg), and the soil organic carbon in each section was significantly different (P0.05); and the soil inorganic carbon, The non-dwarf jujube (11.66 g/ kg) of the dwarf jujube (11.59 g/ kg) had no significant difference in the inorganic carbon of the soil between all the soil profiles of the wild jujube (11.59 g/ kg), the artificial grassland (8.07 g/ kg) and the wild grass (0.47 g/ kg) in the degraded artificial grassland (8.07 g/ kg) in the wild jujube (11.59 g/ kg). There was a significant difference in the soil-inorganic carbon in the cross-section of the artificial economic forest and the forest for returning to forest (grass) and the ground-section of the anti-wind-fixing sand forest (P0.05); there was a significant difference in the carbon density of the soil between the three sampling regions; the dwarf jujube, the non-dwarf jujube, the Caragana korshinskii and the degraded artificial grassland, The inorganic carbon density of the soil profiles of the Pinus sylvestris var. mongolica and the wild grass is 6.19, 7.71, 10.80, 10.78, 5.91 and 1.03 times the organic carbon density, respectively. It can be seen that there is a significant difference in the carbon storage of the soil between different land use patterns, and the content of the inorganic carbon is much higher than that of the organic carbon. (3) There is a certain difference in the content of chloride ion in the soil profile in different land use modes, because of the disturbance of human factors, and the difference in the chloride ion profile in the active layer of the soil water consumption is partly due to the accumulation of chloride ions due to the water consumption of the vegetation. There are some differences in the active layer of soil water consumption under different land-use conditions, and the active layer thickness of the water-consuming active layer is different. The land-use method with the largest thickness of the water-consuming active layer is Caragana korshinskii and the active depth reaches 13.0 m.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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