Analysis of Climate Change and Vegetation Change in the Yangtze River Source
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摘要:
长江源处于高寒、高海拔的青藏高原腹地,生态系统脆弱。受全球气候变化和人类活动的影响,与源区生态系统密切相关的冰川冻土、沼泽湿地和植被等出现了不同程度的退化现象,引起了社会各界的广泛关注。笔者利用长时序、高时空分辨率的气象和MODIS NDVI数据,结合数理统计方法,分析了长江源气候和生态植被的时空演化特征,探讨了植被对气候和土壤水的响应机制。结果表明:近40年来长江源降雨量和地面气温在空间上从东南向西北呈递减特征,各区域气温整体上均有递增趋势;东部植被生长状况要好于西部地区,2000年以来长江源整体植被生长状况有逐渐转好趋势;受冻土对气温的敏感性影响,长江源生长季植被受气温的影响程度高于降雨;长江源生态植被受土壤含水率影响较大,影响程度由表层到深部有逐渐减弱趋势。
Abstract:The source of the Yangtze River is located in the remote and high-altitude Qinghai-Tibet Plateau, where the ecosystem is fragile. Influenced by global climate change and human activities, various elements closely related to the ecological system of the source area, such as glaciers, permafrost, swamps, wetlands, and vegetation, have experienced different degrees of degradation, which has aroused widespread concern from various sectors of society. This article analyzes the spatiotemporal evolution characteristics of the climate and ecological vegetation in the Yangtze River source region using long-term, high spatiotemporal resolution meteorological and MODIS NDVI data, combined with mathematical and statistical methods, and explores the response mechanism of vegetation to climate and soil water. The results show that over the past 40 years, the rainfall and surface temperature in the Yangtze River source region have decreased from southeast to northwest, and the temperature in each region has generally increased. Vegetation growth in the eastern region is better than that in the western region, and since 2000, the overall vegetation growth in the Yangtze River source region has gradually improved. Due to the sensitivity of permafrost to temperature, vegetation growth during the growing season in the Yangtze River source region is more affected by temperature than rainfall. The ecological vegetation in the Yangtze River source region is greatly influenced by soil water content, and the degree of influence gradually weakens from the surface to the deep layers.
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Keywords:
- Yangtze River source /
- climate /
- vegetation /
- trend analysis /
- response mechanisms
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图 12 气象监测站点分布图(冻土分布数据来源于青藏高原新绘制冻土分布图(2017)(赵林,2019))
Figure 12. Map of meteorological monitoring stations
表 1 长江源降雨与气温突变分析
Table 1 Analysis of sudden changes in rainfall and temperature in the Yangtze River source
气象要素 区域 M-K突变检验 滑动t检验 综合分析 n=5 n=10 降雨 沱沱河 2008,2010,2020 - 1999 - 五道梁 2018 2007 - - 曲麻莱 1981,2019 2012 1999,2003 - 玉树 1981,2020 - - - 气温 沱沱河 2001 2001,2015 2001 2001 五道梁 2000 1986 1997,2000 2000 曲麻莱 2002 2002 - 2002 玉树 1987 2010 - - 表 2 生长季(7~9月)逐月植被指数与降雨量相关性分析
Table 2 Vegetation index and rainfall correlation analysis for the growing season (July-September)
研究区域 皮尔逊相关性系数 Sig.(双尾) 统计数(个) 曲麻莱 0.568** 0.000 65 沱沱河 0.518** 0.000 65 五道梁 0.587** 0.000 65 玉树 0.331** 0.000 64 注:“**”表明在 0.01 级别(双尾),相关性显著。 表 3 生长季(7~9月)逐月植被指数与气温相关性分析
Table 3 Vegetation index and temperature correlation analysis for the growing season (July-September)
研究区域 皮尔逊相关性系数 Sig.(双尾) 统计数(个) 曲麻莱 0.666** 0.000 65 沱沱河 0.626** 0.000 65 五道梁 0.635** 0.000 65 玉树 0.729** 0.000 64 注:“**”表明在 0.01 级别(双尾),相关性显著。 表 4 植被指数与土壤含水率相关性分析
Table 4 Correlation analysis between vegetation index and soil water content
研究
区域土壤
深度/cm皮尔逊相
关性系数Sig.(双尾) 统计数(个) 10 0.563** 0.000 108 西大滩 40 0.487** 0.000 108 100 0.475** 0.003 37 180 −0.016 0.845 144 5 0.686** 0.000 132 50 0.653** 0.000 132 五道梁 90 0.542** 0.000 132 180 0.034 0.701 132 240 −0.123 0.159 132 沱沱河 10 0.772** 0.000 60 60 0.757** 0.000 60 90 0.763** 0.000 60 210 0.210 0.107 60 270 −0.146 0.265 60 唐古拉 50 0.648** 0.000 84 140 0.450** 0.000 84 300 −0.179 0.103 84 -
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