1995—2016年长江沿岸芜湖区段景观格局梯度分析

Gradient Analysis of Landscape Pattern in Wuhu Section along the Yangtze River from 1995 to 2016

以沿江城市芜湖为研究对象,基于1995—2016年的遥感影像数据,沿长江两岸以5 km为间距分别建立缓冲带,采用景观指数和梯度分析相结合的方法,从类型水平和景观水平上分析了芜湖区段景观格局梯度变化特征。结果表明:(1)1995—2016年在城镇化影响下,芜湖区段景观格局总体变化明显,耕地和林地面积急剧减少,建设用地面积显著增加,景观异质性和破碎度增强。(2)类型水平方面,耕地、林地、建设用地和湿地的时空梯度特征不同。(3)景观水平方面,在空间上斑块密度、边缘密度、香农多样性、香农均匀度指数均随距长江距离的增加呈整体减小趋势,且南岸各指数值均显著高于北岸(即南岸景观破碎度和异质性高于北岸);在时间上因城镇化快速发展,后10年的各景观指数波动幅度远大于前10年。

In order to study quantitatively the interaction between the Yangtze River and cities in the period of rapid urbanization development,the paper took Wuhu City along the Yangtze River as the research object,based on the remote sensing image data from 1995 to 2016,buffer zones were established along the two banks of the Yangtze River with an interval of 5 km,and the landscape index and gradient analysis were used to analyze the gradient change characteristics of the landscape pattern in Wuhu section at class-level and landscape-level.The results showed that:(1)Under the influence of urbanization,the overall change of landscape pattern in Wuhu section was relatively obvious from 1995 to 2016.The area of cultivated land and forestland decreased dramatically,while the area of construction land increased significantly,and the landscape heterogeneity and landscape fragmentation increased continuously.(2)The spatial and temporal gradient features of cultivated land,forestland,construction land and wetland were different at class-level.(3)At the landscape-level,in terms of spatial sequence,patch density,edge density,Shannon’s diversity index and Shannon’s evenness index were overall decreasing with the increase of distance from the Yangtze River,and the landscape index values of the south bank were significantly higher than that of the north bank,which showed that the landscape fragmentation and landscape heterogeneity of the south bank were higher than that of the north bank.In terms of time series,due to the rapid development of urbanization,the fluctuation range of landscape indexes during 2005—2016 was significantly higher than that in 1995—2005.The findings of the study can serve as a reference for landscape ecological protection and construction in river-crossing areas.