1975—2018年南四湖流域景观生态风险时空变化及其驱动因素研究

研究区域的景观生态风险变化趋势及其驱动因素,可以更加科学地保护和开发流域生态系统。以南四湖流域1975—2018年9期土地利用数据为基础,借助ArcGIS 10.2和Fragstats 4.2等软件计算景观生态指数,并构建景观生态风险评估模型,通过空间自相关性分析,探究南四湖流域自改革开放40年来生态风险的时空变化,并用地理探测器定量研究驱动因子的贡献量。研究结果表明:流域最大斑块指数不断减小,景观破碎化加剧,且与景观生态风险指数呈正相关;而平均分维数、香浓多样性和香浓均匀度与生态风险指数呈负相关。在空间上,生态风险指数具有较强集聚性,东部草地和林地区域主要是高值区,湖区北部以及西部耕地和建设用地则主要是低值区;总体上,研究区大部分为低风险和较低风险区,且生态风险平均值不断降低;地理探测器分析表明,海拔和人为干扰度因子贡献量在35%以上,对生态风险有显著的解释力。据此,以后应减少人类行为对南四湖流域生态系统的干预,降低流域的景观生态风险,实现经济、社会和生态的可持续发展。

Spatio-temporal quantification of landscape ecological risk changes and its driving forces in the Nansihu Lake basin during 1975-2018

Researching the trend of landscape ecological risk changes and its driving forces is of great significance to protection and development of watershed ecosystem.Based on the land use data of the Nansihu Lake basin from 1975 to 2018,we constructed the landscape ecological risk model with ArcGIS 10.2 and Fragstats 4.2.With the help of spatial autocorrelation analysis method,we explored the spatial and temporal changes of ecological risks in Nansihu Lake basin in the past 40 years since the Reform and Opening.And we used the geographical detector to quantify the impact of driving factors.The results showed that the largest patch index was decreasing and positively correlated with the ecological risk index,while the fractal index distribution,Shannon's Diversity Index and Shannon's Evenness Index were negatively correlated with the landscape ecological risk index.The ecological risk index in the study area had a strong agglomeration effect in space.The high values were grassland and forest mainly distributed in the western part of the study area,and the low value was mainly distributed in the north of the lake and cultivated and construction land in the northern.On the whole,the landscape ecological risks in the study area were mainly low and low-medium risk areas,and the average value of ecological risk kept decreasing.Geographic detector analyzed showed that altitude and human disturbance explained much of the landscape ecological risk,and factor contributions were all above 35%.In the future,it is necessary to reduce the disturbance of unreasonable human activities to the regional ecosystem of Nansihu Lake basin,reduce the ecological risk of river basin,and realize the sustainable development of economy,society and ecology.