若尔盖高原沼泽湿地退化风险评估及其演变分析

发布时间：2018-07-15 21:08

【摘要】：随着自然和人为因素的影响,高原湿地出现大面积退化或消失,造成了严重的生态环境以及社会问题,建立合理的风险评估模型实现湿地退化风险评估及风险演变分析,对于高原湿地的合理开发利用,维持区域生态安全具有重要意义。本文选取若尔盖高原沼泽湿地为研究对象,从外部自然、人为胁迫和内部面积、结构、功能退化的角度建立了沼泽湿地退化风险评估模型。利用该模型指标体系对2000~2014年若尔盖高原沼泽湿地退化风险进行了评估,从时间尺度和空间尺度分析了沼泽湿地退化风险空间分布格局和风险演变过程。主要研究结果如下:(1)本文根据若尔盖高原湿地情况,通过沼泽湿地退化胁迫度和退化度两方面,选取9个指标因素(干旱指数、人为干扰指数、放牧强度、面积退化率、景观破碎度、景观类型分维数、水源涵养功能、生物多样性维持功能、湿地生产力),计算得到2000~2014年沼泽湿地退化风险。(2)综合分析2000~2014年若尔盖高原沼泽湿地退化风险评估结果,得到如下主要结论。从时间分布来看,2000~2014年研究期间,若尔盖高原沼泽湿地退化风险指数由0.296增加到0.375,风险值增加26.69%,由低风险区演化为中等风险区。从空间分布来看,玛曲县、若尔盖县、阿坝县、红原县四个县交界处沼泽湿地退化风险指数较低,主要是较低风险区;较高风险区及高风险区主要分布在玛曲县和若尔盖县;中等风险区主要围绕研究区沼泽湿地四周区域分布。(3)将2000年、2005年、2010年和2014年四个时期的风险数据进行对比分析,得到风险指数变化差值、风险等级动态度和转移概率矩阵。从风险指数演变来看,2000~2014年研究期间,若尔盖高原沼泽湿地退化风险变化均值为0.079,表明整个区域沼泽湿地退化风险在增加,但从局部来看,部分地区风险增加,部分地区风险减少。从风险等级变化来看,2000~2014年研究区无风险区和中等风险区大幅增加,高风险区未发生显著变化,其他各等级面积有所下降,低风险区转化为无风险区、较低风险区、中等风险区的比例分别为53.02%、27.19%、19.79%;较低风险区转化为中等风险区、较高风险区的比例分别为78.42%、21.58%。
[Abstract]:With the influence of natural and human factors, the plateau wetland has been degraded or disappeared in a large area, resulting in serious ecological environment and social problems. A reasonable risk assessment model is established to realize the risk assessment and risk evolution analysis of wetland degradation. It is of great significance for the rational development and utilization of plateau wetland and the maintenance of regional ecological security. In this paper, a risk assessment model of swamp wetland degradation was established from the perspectives of external nature, artificial stress, internal area, structure and function degradation. The risk of wetland degradation in the Zoige Plateau from 2000 to 2014 was evaluated by using the model index system, and the spatial distribution pattern and risk evolution process of the risk were analyzed from time scale and spatial scale. The main results are as follows: (1) according to the wetland situation in Ruoergai Plateau, nine index factors (drought index, artificial disturbance index, grazing intensity, area degradation rate) were selected through the degradation stress degree and degradation degree of swamp wetland. Landscape fragmentation, fractal dimension of landscape type, water conservation function, biodiversity maintenance function, wetland productivity), the risk of wetland degradation from 2000 to 2014 was calculated. (2) the risk assessment results of wetland degradation in the Zoige Plateau from 2000 to 2014 were analyzed. The main conclusions are as follows. During the period of 2000 ~ 2014, the risk index of swamp degradation increased from 0.296 to 0.375, and the risk value increased 26.699.The risk changed from low risk area to middle risk area. From the spatial distribution point of view, the risk index of marsh wetland degradation at the junction of Maqu County, Ruoergai County, Aba County and Hongyuan County is relatively low, mainly in the lower risk area, the higher risk area and the high risk area are mainly distributed in Maqu County and Ruoergai County. The risk data of four periods in 2000, 2005, 2010 and 2014 were compared and analyzed to obtain the difference of risk index change, risk rank attitude and transition probability matrix. During the study period from 2000 to 2014, the mean value of the risk change of swamp wetland degradation was 0.079, which indicated that the risk of wetland degradation was increasing in the whole region, but in some areas, the risk increased. Risk reduction in some areas. In view of the change of risk grade, the risk free and medium risk areas in the study area increased significantly from 2000 to 2014, while the high risk area did not change significantly, and the other grade areas decreased, and the low risk area was transformed into the no risk area and the lower risk area. The proportion of the middle risk area was 53.02 and 27.197.79, while the lower risk area was converted to the middle risk area, and the higher risk area was 78.42 and 21.58, respectively.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X826

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