兰西城市群土地利用/覆被变化模式特征——基于强度分析框架

Characteristics of LUCC patterns of the Lanzhou-Xining urban agglomeration:Based on an intensity analysis framework

【目的】基于土地利用转移矩阵提出土地利用/覆被变化(LUCC)强度分析框架,从绝对和相对强度两个角度分析地类之间的转换趋势及其对土地利用/覆被结构的影响。【方法】构建土地利用/覆被变化强度图谱以直观展现区域LUCC关键模式,并以兰西城市群为例进行实证研究。【结果】土地利用/覆被变化强度图谱融合绝对和相对强度信息,既可反映如耕地倾向于转化为建设用地、水域向林地转化的强度较低等LUCC的区域共性规律;也能较好地揭示兰西城市群作为西部生态脆弱区中城市化重点区的特异性变化模式,如2010—2020年期间,兰西城市群在未利用地向水域、草地向耕地及建设用地向未利用地的转化过程中均表现出倾向性的变化模式,但受气候变化、占补平衡政策及土地整治项目管护不周等因素影响,分别表现为系统倾向性、绝对倾向性及相对倾向性的变化特征。进一步与转移矩阵及桑基图对比解析可知,绝对强度和相对强度间不存在直接关联性,所构建的强度分析框架及图谱受地类比例和区域整体LUCC强度的影响相对较小。【结论】本文提出的强度分析框架具有可行性,可为识别及解析区域LUCC关键模式及规律,优化土地资源管理政策提供科学支撑。

[Objective] Based on the land use transition matrix,a criterion of land use types conversion trend in absolute quantity was established,and a land use/cover change(LUCC)intensity analysis framework was proposed to analyze the tendency and inhibition of the conversion trend between land use types and its impact on the land use/cover structure from the perspectives of absolute and relative intensity.[Methods] The LUCC intensity map was constructed to visually display the key LUCC modes.Taking the Lanzhou-Xining urban agglomeration as an example,this study carried out an empirical analysis.[Results] During 2010-2020,the conversion characteristics of different land use types are not completely the same in the Lanzhou-Xining urban agglomeration.The LUCC intensity map integrated absolute and relative intensity information,which could reflect the regional general patterns of LUCC,such as the tendency of the transition from cropland to construction land and the low intensity of the transition from water to forest.It can also reveal the specific change patterns of the Lanzhou-Xining urban agglomeration that is a key area of urbanization in the ecologically fragile western region of China.It showed a tendency of land transition from unused land to water,grassland to cropland,and construction land to unused land.However,under the influence of the melting of glaciers and snow,permafrost degradation,precipitation enhancement,the acquisition-compensation balancing policy,and the poor management and protection of land consolidation projects,the characteristics of systematic tendency,absolute tendency,and relative tendency can be observed respectively in the changes.Further comparison with the land use transition matrix and land use transition Sankey diagram shows that there is no direct correlation between absolute intensity and relative intensity,and the constructed intensity analysis framework and map are less affected by the proportion of land use types and the overall LUCC intensity of the region,which is more helpful to determine the conversion trend between land use types and its impact on the land use/cover structure.[Conclusion] The framework of intensity analysis proposed in this study is feasible and can provide a scientific support for identifying and analyzing the key patterns and modes of regional LUCC and optimizing land resource management policies.