西安都市圈道路网络化对景观格局的影响

在快速城市化过程中,道路网络快速扩张对区域生态景观的分割、隔离、破坏等是导致生态景观过程与格局演变的重要原因。研究道路网络化对景观格局的影响可为快速城市化地区生态、道路建设和区域可持续发展规划提供参考。本文以西安都市圈为例,利用GIS和RS技术,基于西安都市圈TM遥感影像和Arcgis 10.1、Fragstats 4.2软件平台,通过构建道路网空间指数,定量评价了路网空间结构和景观格局变化,并从空间上分析了道路网络化对景观格局的影响。结果表明:1)1985—2015年,西安都市圈路网发育不断成熟,基本呈现以西安市区为中心、空间指数向四周递减(除杨陵区和阎良区外)且东高西低的趋势。2)随着城市化进程的不断推进,西安都市圈景观呈现多样化、复杂化和破碎化。其中:园地、林地和建设用地规模扩大,景观聚集度上升;耕地、水域及滩涂景观破碎化程度不断加深。3)30年间,高等级道路的修建、低等级道路的不断完善以及市内环路打通等,使得西安都市圈路网逐渐完善,景观优势度下降,破碎化程度上升,形状趋于规则化。此外,路网发育的程度不同对不同地类的影响各不相同:路网成熟的区域,建设用地面积较多,形状较规则,呈聚集状态,林地面积较少,且零星分布,破碎化程度较高;道路结构简单的区域,林地聚集成片,聚集度较高,耕地、水域及滩涂在路网空间指数各等级影响域内均呈现破碎化状态,且形状较不规则。

Influence of Road Network on Landscape Pattern in Xi'an Metropolitan Zone

The fast extension of traffic network results in the fragmentation of ecological landscape due to the division,isolation and damage and largely transforms the landscape process and pattern in urbanizing area.In this paper,the Xi'an metropolitan zone was analyzed as a case study.Based on remote image and employing spatial analysis method,the spatial structure of road network and the evolution of landscape pattern were evaluated.Furthermore,the influence of road network on landscape pattern was analyzed in term of spatial perspective.The results show as follows:1) From 1985 to 2015,the road network of Xi'an metropolitan zone had been improved and make complicated constantly.Basically,except for Yangling and Yanliang district,the spatial index of road network tends to gradually decrease away from the downtown of Xi'an,and that tends to be higher in the east than in the west.2) With the improvement of urbanization,the landscape characteristics in whole were more fragmented,diversified and complicated in Xi'an metropolitan zone.Specifically,the areas of orchard,forest,and built-up land were expanding and that caused the increase of the degree of landscape aggregation whilst the fragmentation degree of farmland,water body and beach land has increased seriously.3) During recent three decades,with the increasing construction of traffic road in whole region,the road network of Xi'an metropolitan area is gradually improved;While the landscape dominance is decreased,the fragmentation degree is increased.In addition,the influences of the road network on different land types were varied due to its development degree:In road developed area,the built-up land is large,regular in shape,and aggregated,but the forest area is less,that scattered and more fragmented;While in road poor area,the degree of aggregation of the forest patches is high,but the farmland,water body and beach land are more fragmented,and their shape is irregular.