三峡库区(重庆段)土地覆被质变与量变的地貌分异特征

Geomorphologic Differentiation Characteristics of Qualitative and Quantitative Change of Land Cover in the Three Gorges Reservoir Area (Chongqing Section)

【目的】以三峡库区(重庆段)为研究区,分析区域2000-2020年土地覆被质变与量变,探明山地复杂人地关系背景下土地覆被随地貌的分异特征及演变规律,并分析土地覆被变化的影响因素,以期为山地区域国土空间高效集约利用和区域生态系统的管理提供理论与数据参考。【方法】基于5期土地覆被类型数据与植被指数数据,利用土地利用转移矩阵、土地覆被变化度等方法,通过绘制分区统计和交互制表定量得到2000-2020年间土地覆被质变与量变的地貌分异特征。【结果】1)研究区超过17.3%的国土空间发生过质变,同期植被指数的量变值达0.14,增长率为22.96%;2)质变存在明显的垂直差异性,质变强度随海拔的升高而降低。量变在平原丘陵地貌主要受到质变方式影响,而山地地貌的量变规律随着海拔的增高而减弱,与质变方式呈负相关关系;3)研究区土地覆被质变程度与三峡工程的建设过程相对应,在后三峡工程时期,为配合相关生态政策和战略目标,研究区土地覆被质变加剧但其植被覆盖率仍保持在较高水平。【结论】三峡库区(重庆段)土地覆被在两个维度均发生了明显变化,地貌对两种维度的变化影响存在明显差异。人类的社会经济活动以及政策制定极大地影响了土地覆被变化方向及程度。

[Purposes]Taking the Three Gorges Reservoir Area(Chongqing section) as the study area, it analyzed the qualitative and quantitative changes of land cover in the region from 2000 to 2020, explored the differentiation characteristics and evolution rules of land cover with geomorphology under the background of complex man-land relationship in mountainous areas, and analyzed the influencing factors of land cover change. It provides theoretical and data reference for efficient and intensive utilization of land space and management of regional ecosystem in mountainous region. [Methods]Based on five periods of land cover data and NDVI data, land use transfer matrix, land cover change degree and other methods were used to draw regional statistics and interactive tabulation to quantitatively obtain the geomorphic differentiation characteristics of qualitative and quantitative land cover change from 2000 to 2015. [Findings]1) Over 17.3% of the land space in the study area underwent qualitative change, and the value of quantitative change of NDVI was 0.14, with a growth rate of 22.96%. 2) There is obvious vertical difference in qualitative change, and the intensity of qualitative change decreases with the increase of altitude. The quantitative change is mainly affected by the qualitative change pattern in plain hill landform, while the quantitative change pattern in mountain landform decreases with the increase of altitude and is negatively correlated with the qualitative change pattern. 3) The qualitative change degree of land cover in the study area corresponds to the construction process of the Three Gorges Project. In the post-Three Gorges Project period, in order to coordinate with relevant ecological policies and strategic objectives, the qualitative change of land cover in the study area is intensified, but NDVI remains at a high level. [Conclusions]Land cover in the Three Gorges Reservoir area(Chongqing Section) has changed significantly in both dimensions, and there are significant differences in the impact of landform on the change of the two dimensions. The direction and degree of land cover change are greatly influenced by human social and economic activities and policy making.