黄河源区河漫滩湿地及其退化演替过程土壤和植被变化特征研究

发布时间：2018-07-02 23:15

本文选题：黄河源区 + 河漫滩湿地　；参考：《青海大学》2015年硕士论文

【摘要】：分析和研究黄河源区河漫滩湿地演替过程土壤和植被变化特征,探讨黄河源区河漫滩湿地退化的气候背景,这对于研究黄河源区湿地的演化具有指导意义。本研究从黄河源区河漫滩湿地地理地形指标、土壤指标和植物群落指标出发,分析和研究黄河源区河漫滩湿地退化演替过程中土壤和植被变化特征,并从与黄河源区河漫滩湿地水分密切相关的气温、降水、蒸发量、日照、地温等气象因子出发,分析影响黄河源区河漫滩湿地变化的气候原因。通过对黄河源区河漫滩湿地退化演替中植被特征的变化划分为未退化、轻度退化、中度退化、重度退化和极度退化5个阶段,依次命名为阶段1、阶段2、阶段3、阶段4和阶段5。主要研究结果及结论如下:(1)黄河源区河漫滩湿地土壤偏碱性;同一地区随着土层的加深,草土比逐渐减小,在0~7.5cm土层中草土比最大;其土壤均砂土类;土壤含水量随着土层的加深而减少。(2)黄河源区河漫滩湿地主要养分在垂直方向上都表现出上层高于下层的规律,土壤有机质和全氮随着湿地退化演替都呈现了逐渐减少的规律,这说明了随着河漫滩湿地退化的演替,土壤的肥力在下降。多重比较的结果,全N、全K2O和有机质,在演替阶段5与阶段1、阶段2、阶段3和阶段4之间差异显著(P0.05),阶段1、阶段2、阶段3和阶段4之间差异不显著;碱解N在演替阶段2与阶段5之间差异显著(P0.05),阶段1、阶段3和阶段4之间差异不显著;全P2O5、速效P和速效K在河漫滩湿地退化演替过程中差异虽未达到显著水平,但随着演替进展,速效P是呈现出减少趋势,全P2O5和速效K呈现出增加趋势。(3)在不同深度的土层中,微生物(细菌、放线菌和真菌)分布的差异性不显著,细菌数量随着深度的增加呈递减趋势,其原因在于植物根部在0~7.5cm的表土层分布较为集中,为细菌提供了适宜的生存环境,从而形成表层大于下层的分布特征。黄河源区河漫滩湿地退化过程中随着演替加剧,土壤含水量减少。演替阶段1、阶段2和阶段3之间差异不显著;阶段1、阶段2和阶段3与阶段4和阶段5之间差异显著(P0.05)。(4)从整个演替过程来看,在演替初期,黄河源区河漫滩湿地以藏嵩草为主,随着演替的进行,藏嵩草的重要值逐渐降低,杂草和毒草的重要值逐渐增加,并在河漫滩湿地中占有一定的位置,物种多样性增加,群落的结构趋向复杂,丰富度越来越大。(5)对湿地水分平衡主要产生不利的影响的气象因子多,而产生有利影响的气象因子较少。产生较大不利影响的气象因子为:年平均气温的升高、年平均地温差的升高、年日照时数的增加及蒸发量的减少。
[Abstract]:This paper analyzes and studies the characteristics of soil and vegetation change in succession process of floodplain wetland in the source area of the Yellow River, and discusses the climatic background of wetland degradation in the source area of Yellow River, which is of guiding significance for studying the evolution of wetland in the source area of the Yellow River. Based on the geographical landform index, soil index and plant community index of the floodplain wetland in the source area of the Yellow River, the characteristics of soil and vegetation changes during the succession of the floodplain wetland in the source region of the Yellow River were analyzed and studied. Based on the meteorological factors, such as temperature, precipitation, evaporation, sunshine and ground temperature, which are closely related to the water content of the floodplain wetland in the source area of the Yellow River, the climatic reasons affecting the changes of the wetland in the source area of the Yellow River are analyzed. The vegetation characteristics in the succession of floodplain wetlands in the source region of the Yellow River were divided into five stages: undegraded, mild degraded, moderate degraded, severe degraded and extreme degraded, which were named as stage 1, stage 2, stage 3, stage 4 and stage 5. The main results and conclusions are as follows: (1) the soil of the floodplain wetland in the source region of the Yellow River is alkaline, the ratio of grass to soil decreases gradually with the deepening of soil layer in the same area, and the ratio of grass to soil is the largest in the 0~7.5cm soil layer. The soil moisture content decreases with the deepening of soil layer. (2) the main nutrients of the floodplain wetland in the source area of the Yellow River show the rule that the upper layer is higher than the lower layer in the vertical direction, and the soil organic matter and total nitrogen gradually decrease with the succession of wetland degradation. This shows that soil fertility is decreasing with the succession of floodplain wetland degradation. The results of multiple comparisons showed that there were significant differences between stage 5 and stage 1, stage 2, stage 3 and stage 4 (P0.05), but there was no significant difference between stage 1, stage 2, stage 3 and stage 4 in succession stage 5, total K2O and organic matter. There was no significant difference between stage 1, stage 3 and stage 4 between stage 2 and stage 5 (P0.05), but there was no significant difference in total P 2O 5, available P and K between stage 2 and stage 5 in succession of floodplain wetland, but there was no significant difference in total P 2O 5, available P and K during the succession of floodplain wetlands. But with the development of succession, available P showed a decreasing trend, while total P _ 2O _ 5 and available K showed an increasing trend. (3) the distribution of microbes (bacteria, actinomycetes and fungi) was not significant in different depth soil layers. The number of bacteria decreased with the increase of depth. The reason is that the distribution of plant roots in the surface soil layer of 0~7.5cm is relatively concentrated, which provides a suitable living environment for bacteria, thus forming the distribution characteristics of the surface layer larger than the lower layer. Soil water content decreases with the succession of floodplain wetlands in the source region of the Yellow River. There was no significant difference between stage 1, stage 2 and stage 3, and between stage 1, stage 2 and stage 3, stage 4 and stage 5 (P0.05). (4). Along with the succession, the important value of Kobresia humilis decreased gradually, the important value of weeds and poisonous grass increased gradually, and occupied a certain position in the floodplain wetland, the species diversity increased, and the community structure tended to be complex. (5) there are more and more meteorological factors which have adverse effects on wetland water balance, but few weather factors have favorable effects on wetland water balance. The meteorological factors which have great adverse effects are the increase of annual mean temperature, the increase of annual average ground temperature difference, the increase of annual sunshine hours and the decrease of evaporation.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q948;S151.9

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