基于土地利用变化的沱江流域景观生态风险时空分异研究

Landuse-change-based space-time differentiation study of landscape ecological risks in the Tuojiang River Basin

沱江流域作为成渝经济圈和长江上游生态屏障建设的重点区域,诊断其景观生态风险及时空分异特征对促进流域经济带建设和生态安全建设具有重要意义.基于2000、2010和2020年的土地利用数据,以景观干扰度和景观脆弱度计算景观损失度,以此构建了景观生态风险评价模型,运用统计和空间自相关分析方法,揭示了沱江流域近20年的生态风险时空演化特征和空间自相关关系.结果表明:沱江流域土地利用类型以耕地、林地和草地为主,其中耕地是流域内的优势景观,对景观格局的变化起着重要作用;从数量来看,流域内的生态风险处于低风险等级,但生态风险指数逐渐增大,风险等级逐渐增高,说明整体上区内生态环境质量有所下降;2000、2010、2020年三个时段流域内全局空间自相关的莫兰指数(Moran’s Ⅰ)分别为0.4844、0.5162、0.5336,Moran’s Ⅰ均为正值且呈上升趋势,表明在空间上呈正相关且生态风险的空间聚集程度逐渐增强.以上评价结果为流域内生态风险防控和生态环境保护提供定量参考和决策依据.

The Tuojiang River basin is one of the key areas in the construction of Chengdu-Chongqing economic circle and the ecological protective umbrella in the upper Reaches of Yangtze River.It is of great significance to diagnose its landscape ecological risks and to know about its spatial-temporal differentiation characteristics and thus to promote the construction of river basin economic belt and ecological security.Based on the landuse data of 2000,2010 and 2020,the degree of landscape loss is calculated by landscape disturbance and landscape vulnerability,and the landscape ecological risk evaluation model is constructed,and by use of geostatistical and spatial autocorrelation analysis methods,the spatio-temporal evolution characteristics and spatial autocorrelation relationship of ecological risk in the Tuojiang River Basin in the past 20 years are revealed.The results show that:1)The landuse types in the Tuojiang River Basin are primarily cultivated land,forest land and grassland,of which cultivated land is the dominant landscape in the basin and plays a pivotal role in determining the landscape pattern change;2)From the quantitative point of view,the ecological risk in the basin is at a low risk level,but as the ecological risk index gradually increases,the risk level gradually also goes up,indicating that the overall ecological environment quality in the upper region has somewhat declined;3)In 2000,2010 and 2020,the Moran index of global spatial autocorrelation in the basin(Moran's Ⅰ)was 0.4844,0.5162 and 0.5336,respectively,and the Moran's index(Moran's Ⅰ)was positive and showed an upward trend,showing that the spatial correlation was positive and the spatial concentration of ecological risks in the region was on the increase.The above evaluation results can serve as the quantitative reference and decision-making basis for ecological risk prevention,control and ecological environmental protection in the river basin.