| 1992—2020年横断山区植被分布与植被活动变化 |
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| 引用本文： | 杨靖,戴君虎,姚华荣,陶泽兴,朱梦瑶.1992—2020年横断山区植被分布与植被活动变化[J].地理学报,2022,77(11):2787-2802. |
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| 作者姓名： | 杨靖 戴君虎 姚华荣 陶泽兴 朱梦瑶 |
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| 作者单位： | 1.长安大学地球科学与资源学院，西安 7100542.中国科学院地理科学与资源研究所，北京 1001013.中国科学院大学，北京 1000494.中国—巴基斯坦地球科学研究中心，伊斯兰堡 45320 |
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| 基金项目： | 中国科学院战略性先导科技专项(XDA23090302);中国科学院战略性先导科技专项(XDA26010202);国家重点研发计划(2018YFA0606102);国家自然科学基金项目(41771056) |
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| 摘 要： | 横断山区位于青藏高原东缘和多条重要江河的上游，是全球生物多样性最丰富的地区和生态保护的优先区域之一，区域植被对维系区域生态安全和可持续发展起着十分重要的作用。20世纪90年代以来，中国在横断山区实施了多项重大生态恢复和建设工程，但囿于资料和调查不足，对于横断山区全域性、长时段的植被变化及其与海拔关系研究相对较少。鉴此，本文结合使用1992—2020年间多种基于卫星遥感资料生产的土地覆被数据和2000—2020年间MODIS的归一化植被指数（NDVI）数据，采用转移矩阵、Theil-Sen Median趋势分析与偏相关分析等方法研究不同植被类型转换、植被覆被面积与平均海拔变化关系以及植被活动的时空变化趋势，并分析时空变化的主要影响因素。结果表明：① 横断山区分布最广泛的植被类型是常绿针叶林与灌丛—草地镶嵌类型。植被发生变化的区域集中分布在河谷和南部低海拔区域，草地多向森林特别是常绿针叶林转换，植被覆被逐渐向好。这表明封山育林、植树造林、退耕还林等生态保护政策起到重要积极作用。时间序列数据显示，植被覆被面积变化剧烈的时期往往处在政策实施的起始阶段。② 植被活动整体呈现增强趋势。在植被类型未变化的区域中，75%以上区域植被活动增强，其中超20%的区域显著增强（P < 0.05），且森林植被活动增强趋势大于草地。③ 对植被活动影响较大的环境因子主要是气候变化和地形条件。尽管大部分区域植被活动受气候变暖影响而增强，但在干热河谷的植被活动明显受到降水减少的限制。有近1/4面积的植被活动在减弱，主要分布在山地东坡或南坡，或与降水较多、山高坡陡而造成滑坡、泥石流等自然灾害有关。这些发现可为横断山区生态保护政策效益评估、自然灾害综合风险评估和未来气候变化影响下的植被变化预测提供参考。
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| 关 键 词： | 横断山区 植被分布 植被活动 转移矩阵 Theil-Sen Median趋势分析 |
| 收稿时间： | 2022-06-02 |
| 修稿时间： | 2022-10-16 |
Vegetation distribution and vegetation activity changes in the Hengduan Mountains from 1992 to 2020 |
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| YANG Jing,DAI Junhu,YAO Huarong,TAO Zexing,ZHU Mengyao.Vegetation distribution and vegetation activity changes in the Hengduan Mountains from 1992 to 2020[J].Acta Geographica Sinica,2022,77(11):2787-2802. |
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| Authors: | YANG Jing DAI Junhu YAO Huarong TAO Zexing ZHU Mengyao |
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| Institution: | 1. School of Earth Science and Resources, Chang'an University, Xi'an 710054, China2. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China3. University of China Academy of Sciences, Beijing 100049, China4. China-Pakistan Joint Research Center on Earth Sciences, Islamabad 45320, Pakistan |
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| Abstract: | The Hengduan Mountains is one of the most biologically diverse areas in the world, geographically located in the eastern part of the Qinghai-Tibet Plateau and the upstream of several major rivers. These mountains are ecologically conservated, with an extremely important ecological barrier function. Since 1990s, China has implemented several significant ecological restoration and construction projects in the research area. Due to limited data and lack of field investigations, few studies explored the integrity and long-term vegetation changes in this area. Hardly any of them discussed the systematical relationship between vegetation changes and elevation factors of the Hengduan Mountains. In view of filling this research gap, we used the Climate Change Initiative Land Cover (CCI-LC) dataset for the period 1992-2020 and the Normal Difference Vegetation Index (NDVI) dataset from MODIS for the period 2000-2020 to reflect changes in vegetation distribution and activity, respectively. Here, we used transfer matrices to investigate the transition relationships among different vegetation types, and used Theil-Sen Median trend analysis to explore the spatial and temporal trends of vegetation activities. We also used the partial correlation analysis to quantify the influencing factors of vegetation activities. Herein, the relationship between vegetation coverage area and mean elevation change was also investigated. The results showed that: (1) The most widely distributed vegetation in the study area contained evergreen coniferous forests and shrub-grass types. Vegetation changes were distributed in river valleys, and southern low-altitude areas. The grasslands were mainly converted to evergreen coniferous forests to gradually improve the vegetation coverage. This showed that ecological protection policies played an essential role. However, vegetation coverage changes are generally in the initial stage of policy implementation. (2) The overall vegetation activity showed an increasing trend. In unchanged vegetation regions, vegetation activities increased in more than 75% of the area, and more than 20% of the area increased significantly (P < 0.05). The changing trend of forest vegetation was more significant than that of grassland. (3) The environmental factors that significantly impact vegetation activities are climate change and topographic slope. Although vegetation coverage was enhanced by increasing temperatures, the precipitation influenced the vegetation in hot and dry valleys. Nearly 25% of the total research area shows a decreasing. This decreasing trend is due to natural disasters such as landslides and mudslides caused by much precipitation and steep mountain slopes. These findings can provide a reference for the evaluation of ecological protection policies, the comprehensive risk assessment of natural disasters, and the prediction of vegetation changes under the influence of future climate change in the Hengduan Mountains. |
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| Keywords: | Hengduan Mountains vegetation distribution vegetation activities transfer matrix Theil-Sen Median trend analysis |
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