城市河岸带土地利用和景观格局演变研究

Study on the Evolution of Land Use and Landscape Patterns in Urban Riparian Zones

河岸带是水陆生态系统之间的过渡带,对保护水体和改善生态环境质量具有重要作用。研究河岸带的土地利用和景观格局演变规律,对于维持城市河流生态系统健康、改善城市河流污染具有重要意义。以云南省高原湖泊城市昆明为研究对象,基于1996年、2007年和2015年3期Landsat TM遥感影像,在ArcGIS软件支持下,以城市河流两侧500 m范围作为研究区域,提取土地利用信息,借助土地利用类型特征参数、景观格局指数等对河岸带的土地利用和景观格局演变进行分析,结果表明:(1)从时间变化来看,20年来河岸带的土地利用类型发生了明显的改变,耕地的减少和建设用地的增加是主要的变化趋势,尤其自2007年以来,建设用地的动态度由前一阶段的4.66增长为5.53,表明建设用地呈现越来越快的增长趋势;(2)从空间变化来看,1996年耕地是河岸带各缓冲区的主要用地类型,至2007年,建设用地在各缓冲区的占比已跃居首位,到2015年,建设用地持续快速增长,占比达到各缓冲区的60%左右,成为各缓冲区的景观基质,河岸带的景观结构发生明显改变;(3)从景观类型水平的指数分析来看,20年间,耕地的最大斑块指数(LPI)快速减少且分离度指数(SPLIT)急剧增长,表明其分布呈现破碎化发展;绿地斑块的完整性有所提高,建设用地面积快速增加并呈大面积连片分布的趋势,这与土地利用变化分析结果一致。基于对不同缓冲区景观格局指数的分析,得出昆明市河流生态廊道功能的影响范围为距离河道200 m宽的缓冲区范围,200 m以外的区域景观连接度降低,破碎化程度加剧。

The riparian zone is the transition zone between aquatic and terrestrial ecosystems.It plays an important role in water protection and improving the quality of the ecological environment.Exploring the land use and landscape pattern evolution of the riparian zone has great significance for maintaining the ecosystem health of urban rivers and improving the pollution of urban rivers.This paper takes Kunming,a plateau lake city in Yunnan Province,as the research object.Based on the Landsat TM remote sensing images of 1996,2007 and 2015,with the support of ArcGIS,the 500 m range on both sides of the river in the main urban area of Kunming was taken as the research area to extract land-use information and analyze land use and landscape pattern evolution in riparian zone by means of land use type characteristic parameters and landscape pattern index.The results showed that:(1)From the perspective of time,the type of land use in the riparian zone had changed significantly over the past 20 years.The reduction of cultivated land and the increase of construction land were the main trends.Especially since 2007,the dynamics of construction land had increased from 4.66 to 5.53,indicating that construction land was showed an increasing trend of growth.(2)For the spatial changes,in 1996,cultivated land was the main type of land used for each buffer zone in the riparian zone.By 2007,the construction land occupied the first place in the area of each buffer zone.By 2015,the proportion of construction land had reached about 60%of the buffer zone,which had become the landscape matrix of each buffer zone,and the landscape structure of the riparian zone had changed significantly.(3)From the index analysis of the landscape type level,the largest plaque index(LPI)of cultivated land was rapidly reduced from 1996 to 2015,and the degree of splitting index(SPLIT)increased sharply,which indicated that the distribution of cultivated land was fragmented;the integrity of green patch was improved;the area of construction land increased rapidly and showed a trend of large areas of contiguous distribution,which was consistent with the results of land-use change analysis.Based on the analysis of the landscape pattern index of different buffer zones,it is concluded that the influence of river ecological corridor function in Kunming City is 200 m wide from the river channel,and the landscape connectivity outside the 200 m zone is reduced,and the degree of fragmentation is intensified.