北京城市景观格局时空变化及驱动力

Spatiotemporal change and driving forces of urban landscape pattern in Beijing

2004—2020年城市总体规划以来,北京经历了快速的城市化发展期,城市景观格局发生了很大变化。采用TM遥感影像为信息源,通过RS解译建立了2003、2007和2011年北京市土地利用覆盖空间数据,利用Fragstats对景观格局特征指数进行了计算和分析,分别从全市域和六环内城市化典型地区两个尺度研究了北京市城市景观格局时空变化特征,结合社会经济、城市总体规划和城市发展政策因素,分析了北京城市景观格局变化的驱动力因素。研究结果表明,过去近10年,市域景观特征发生了深刻变化,建设用地保持较快的增长速度,其比例由15.0%上升至18.0%,相反耕地面积比例由21.3%下降至18.8%。林地一直是市域的优势景观类型,比例维持在51%以上。而六环内城市化典型地区的景观变化更加明显,建设用地比例增加近10%,是六环地区的优势景观类型,耕地比例相应减少10%。建设用地的增长主要以耕地占用为主。景观格局指数的分析表明,大尺度和小尺度的景观格局变化表现出不同的特征,市域大尺度建设用地斑块破碎化程度高,景观蔓延度、聚合度下降,景观多样性增加;而小尺度六环内的建设用地斑块破碎化趋势降低,景观蔓延度和聚合度上升,但景观多样性下降迅速。大小两个尺度的景观空间形态均表现出复杂性增加的趋势。通过景观格局变化的驱动因素分析,人口规模的增加、产业结构调整、城市总体规划的实施以及城市发展政策的变化是导致景观格局变化的主要因素。

Beijing has experienced rapid urbanization after the last city＇s master planning （2004-2020）, and the city＇s landscape pattern has changed greatly in spatial and temporal scale. During the rapid urbanization process, the city occupied huge amounts of open spaces and agricultural land, which changed the distribution and constituents of landscape that impacted the ecosystem services, and resulted in series of eco-environmental problems. Based on the Landsat TM images of 2003, 2007 and 2011 as spatial data, under the supporting of RS and GIS tools and Fragstats software, we analyzed the change characteristics of urban landscape pattern during these years. Combined with social and economic statistical data, city＇s master planning （2004-2020） and urban management policies, we aim to find the driving forces of landscape pattern change. The results showed that the city＇s landscape pattern changed significantly from 2003 to 2011. The urban construction land increased from 15.0% to 18.0%, and the cultivated land decreased from 21.3% to 18.8% conversely. The forest land is the dominated landscape type and its area proportion is kept up 51% during the study period. In the extent of 6th ring road which is typical urbanized area, the construction land increased by 10% but the cultivated land decreased by 10% correspondingly during the study period. The construction land remained as the dominated landscape type. The landscape pattern within the 6th ring road area is different from the whole city, but there is a common phenomenon that the increased construction land were at the cost of disappeared cultivated lands. The landscape metrics analysis revealed that the construction land has high degree of patches fragmentation in landscape class level at city scale, and at landscape level, the landscape＇s contagion and aggregation were declined, but the landscape diversity was increased. However, there are different results in scale of the 6th ring road extent, the construction land has low degree of patches fragmentation in landscape class level, the landscape＇s contagion and aggregation increased but landscape diversity declined rapidly in landscape level. Nevertheless the complexity of landscape spatial shape increased at both scales. Driving forces analysis revealed that increasing population, urban industry regulation, implementation of city＇s master planning and local city＇s development policies are the main factors that cause the change of city＇s landscape pattern.