西双版纳橡胶林土壤水稳性团聚体及其有机碳、全氮变化机理研究

发布时间：2018-06-11 23:42

本文选题：不同林龄 + 不同海拔　；参考：《云南师范大学》2017年硕士论文

【摘要】：土壤有机碳和氮素是土壤养分的重要组成部分,二者都反映土壤质量状况,是评价土壤肥力和土地持续利用的重要指标。土壤有机碳主要储存于团聚体中,其是影响土壤团聚结构的最重要因素之一,它在团聚体内的分配状况直接影响到土壤水稳性团粒结构的形成与稳定性,并且团聚体形成作用被认为是土壤固碳的最重要机制,氮素是植物生长必需的营养元素,又是陆地生态系统大多数植物光合作用和初级生产过程中最易受限制的元素之一,在陆地生态系统功能中起重要作用。近年来,西双版纳地区由于橡胶林的大面积种植,导致原始林被严重破坏,随之而来的是生态环境日益恶化,土壤肥力下降,水土流失等问题日益严重。本研究选择西双版纳境内不同林龄及不同海拔橡胶林为研究对象,分析其土壤理化性质总体特征、水稳性团聚体稳定性、水稳性团聚体有机碳、全氮特征及其相互关系,从而研究橡胶林土壤团聚体有机碳、全氮变化机理,同时与原始林进行对比,分析植被变化下土壤碳氮变化趋势,为西双版纳地区橡胶林合理种植及土壤肥力恢复提供参考依据,主要研究结果如下:(1)西双版纳地区橡胶林土壤自然含水率在21.01-31.51%,土壤容重在1.45-1.82 g.cm-3,土壤总孔隙度在31.22-43.50%;橡胶林及原始林土壤中,砂粒组分占比均值为14.01%,粉砂组分占比均值为69.91%,黏粒组分占比均值为16.08%,其土壤类型以粉砂壤土为主,其次为砂壤土和壤土;土壤有机碳含量在5.16-20.13 g·kg~(-1),土壤全氮含量0.14-2.06 g·kg~(-1),土壤全磷含量在0.24-0.32g·kg~(-1),土壤全钾含量在8.01-19.75 g·kg~(-1),其中有机碳、全氮、全磷含量自1950年代至今大致呈现下降趋势,但近十年有所回升,全钾含量自1990年代至今呈现上升趋势,这都得益于更加科学合理的人工管理。(2)土壤有机碳、全氮平均含量原始林15a5a25a,其随土层的加深而降低,不同海拔橡胶林土壤有机碳、全氮均值变化范围分别在8.32-11.95 g·kg~(-1)、0.51-1.28 g·kg~(-1),最低值出现在海拔850m处,海拔对橡胶林土壤全氮含量的影响更大,林龄和海拔对橡胶林土壤有机碳、全氮含量的影响主要体现在表层(0-15cm)土壤。(3)粒径2mm的土壤水稳性团聚体含量原始林15a25a5a,粒径0.25mm的土壤水稳性团聚体含量5a25a15a原始林,林龄对土壤大粒径和最小粒径团聚体影响较大;土壤结构稳定性表现为原始林15a25a5a,且表层土壤稳定性要高于下层土壤,林龄对橡胶林土壤结构稳定性影响较大;海拔850m处橡胶林土壤结构稳定性最差,海拔950m处橡胶林土壤结构综合稳定性最好,海拔1050m处橡胶林表层土壤结构最稳定,但垂直稳定性最差。(4)土壤水稳性团聚体有机碳、全氮含量表现为原始林15a5a25a,海拔850m橡胶林土壤水稳性团聚体有机碳、全氮含量最低,在2mm、2-0.25mm、0.25mm粒径上均值分别为8.07g·kg~(-1)、9.27 g·kg~(-1)、6.99 g·kg~(-1)和0.5g·kg~(-1)、0.56g·kg~(-1)、0.46 g·kg~(-1)。各粒径土壤水稳性团聚体有机碳、全氮含量随土层加深而递减,在同一土层上,各粒径水稳性团聚体有机碳、全氮含量大小顺序为:2-0.25mm、2mm、0.25mm,大团聚体(0.25mm)有机碳、全氮含量占主要部分,占比均在60%以上,是土壤总有机碳、全氮的主要贡献载体。(5)土壤总有机碳、全氮含量与水稳性团聚体有机碳、全氮含量呈极显著正相关(P0.01),水稳性团聚体粒级分布与其有机碳、全氮含量关系十分密切。不同林型土壤C/N表现为原始林5a25a15a,不同海拔橡胶林各粒径水稳性团聚体土壤C/N值范围在8.32-17.59,其中只有海拔850m橡胶林高于15,均值为17.09。土壤总有机碳含量与土壤全氮含量之间关系极显著(P0.01),有机碳含量对土壤C/N影响不大,但氮素含量直接影响土壤C/N,各粒径水稳性团聚体土壤C/N也直接影响土壤全氮的增减;土壤总C/N与各粒径水稳性团聚体土壤C/N极显著相关(P0.01),且各水稳性团聚体土壤C/N之间相互影响显著(P0.01),表明土壤团聚体之间碳氮相互联系又相互制约,始终维持在一个平衡的水平。(6)总体来说,原始林转变为橡胶林之后,土壤结构稳定性变差,有机碳、全氮含量降低,土壤质量下降,但加以合理的人工管理,在加上橡胶林生长过程中生态环境趋于稳定,其土壤抗侵蚀能力能够得以加强,水土保持功能能够得到一定恢复。
[Abstract]:Soil organic carbon and nitrogen are important components of soil nutrients. The two all reflect the quality of soil. It is an important index to evaluate soil fertility and land use. Soil organic carbon is mainly stored in aggregates. It is one of the most important factors affecting the structure of soil reunion. The distribution of soil organic carbon has a direct impact on the distribution of soil reunion. The formation and stability of soil water stable pellet structure, and the formation of aggregates are considered as the most important mechanism for soil carbon fixation. Nitrogen is the essential nutrient element for plant growth. It is also one of the most restrictive elements in the photosynthesis of most terrestrial ecosystems and in the primary production process, and in the terrestrial ecosystem function. In recent years, due to the large area planting of rubber forest in Xishuangbanna area, the original forest has been seriously damaged. The following problems are the worsening ecological environment, the decline of soil fertility, and the serious soil erosion. This study selected the different forest ages and different altitudes in Xishuangbanna as the research object and analyzed it. The overall characteristics of soil physical and chemical properties, stability of water stable aggregates, water stable aggregate organic carbon and total nitrogen characteristics and their relationship, thus study the mechanism of organic carbon and total nitrogen change in soil aggregate of rubber forest, and compare with the original forest, analyze the change trend of soil carbon and nitrogen under the change of vegetation, which is a reasonable species of rubber forest in Xishuangbanna area. The main research results are as follows: (1) the natural moisture content of the soil in Xishuangbanna rubber forest is 21.01-31.51%, the soil bulk density is 1.45-1.82 g.cm-3, the total soil porosity is 31.22-43.50%, and the average value of the sand composition is 14.01% in the rubber forest and the original forest soil, and the mean value of the silt composition is 69.91%. The soil types are mainly silty loam soil, followed by sandy loam and loam soil, and soil organic carbon content in 5.16-20.13 g kg~ (-1), soil total nitrogen content 0.14-2.06 G. Kg~ (-1), total soil phosphorus content in 0.24-0.32g kg~ (-1), soil total potassium content in 8.01-19.75, including organic carbon, total nitrogen and total phosphorus. From 1950s to the present, the content of the total potassium content rose slightly, but the total potassium content rose from 1990s to the present, which benefited from the more scientific and reasonable artificial management. (2) the soil organic carbon, the average total nitrogen content of the original forest 15a5a25a, decreased with the depth of the soil, and the soil organic carbon in different altitudes of rubber forests. The variation range of total nitrogen was in 8.32-11.95 G. Kg~ (-1) and 0.51-1.28 G. Kg~ (-1). The lowest value appeared at the altitude of 850m. The influence of altitude on the total nitrogen content of the soil of rubber forest was greater. The influence of forest age and altitude on soil organic carbon and total nitrogen content was mainly in the surface layer (0-15cm) soil. (3) the soil water stable aggregate with the particle size 2mm. The content of soil water stable aggregate content of 0.25mm in the original forest 15a25a5a, the soil water stable aggregate content of 5a25a15a original forest, the forest age has great influence on the soil size and the minimum particle size aggregate, the stability of the soil structure is the original forest 15a25a5a, and the stability of the surface soil is higher than the lower soil, and the forest age has a great influence on the stability of the soil structure of the rubber forest. The stability of the soil structure was the worst in the rubber forest at 850m. The soil structure of rubber forest was the best stability at 950m altitude. The soil structure of the rubber plantation was the most stable at the altitude of 1050m, but the vertical stability was the worst. (4) the soil water stable aggregate organic carbon, the total nitrogen content was the original forest 15a5a25a, the soil water stable aggregate in the altitude 850m rubber forest soil water stabilized aggregate. Organic carbon and total nitrogen are the lowest. The average size of 2mm, 2-0.25mm, and 0.25mm is 8.07g. Kg~ (-1), 9.27 G. Kg~ (-1), 6.99 G. Kg~ (-1) and 8.07g. The soil water stable aggregate organic carbon, the total nitrogen content decreases with the soil layer deepened, and the water stable aggregates of each particle on the same layer are in the same soil layer. 2-0.25mm, 2mm, 0.25mm, large aggregate (0.25mm) organic carbon, the total nitrogen content is the main part, the total nitrogen content is more than 60%, and the main contribution carrier of total organic carbon and total nitrogen. (5) total soil organic carbon, total nitrogen content and water stable aggregate organic carbon, total nitrogen content is very significant positive correlation (P0.01), water stable The grain size distribution of sexual aggregates is closely related to the content of organic carbon and total nitrogen. The C/N of different forest type soils is 5a25a15a, and the C/N value of water stable aggregate soil of different grain sizes at different altitudes is 8.32-17.59, of which only the altitude 850m rubber forest is higher than 15, the mean is the total organic carbon content of 17.09. soil and the total nitrogen content of soil. There was a very significant relationship (P0.01). Organic carbon content had little effect on soil C/N, but nitrogen content had a direct effect on soil C/N, and the soil C/N also directly affected the increase or decrease of soil total nitrogen; the total C/N of the soil was significantly related to C/N in the water stable aggregate soil of each grain size (P0.01), and the soil C/N of each water stable aggregate soil was reciprocal to each other. The effect was significant (P0.01), indicating that the carbon and nitrogen interconnections between soil aggregates were mutually restricted and maintained at a balanced level. (6) in general, after the transformation of the original forest into rubber forest, the stability of the soil structure became worse, the organic carbon, total nitrogen content decreased, and the soil quality decreased, but the growth of the rubber forest was added to the growth of the rubber plantation. During the process, the ecological environment tends to be stable, and its soil erosion resistance ability can be strengthened, and the function of soil and water conservation can be recovered.
【学位授予单位】：云南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714.2

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