根据目前描述建设用地扩展空间分异所用各种指数,结合山区扩展实际情况,提出了扩展程度指数的概念。并基于土地利用详查和变更数据,测算了1993¹996,1996¹999,1999²002三个不同阶段山区建设用地的扩展变化率、扩展强度和扩展程度等指数,分析了北京山区不同类型建设用地的扩展特征及其空间差异。结果表明:20世纪90年代以来,北京山区的建设用地发生了剧烈变化,建设用地扩展程度逐年增强,郊区城市化正向远郊区扩散。山区尚处于城市化的初级阶段,建设用地扩展存在不规则性,区域差异明显。扩展变化率、扩展强度和扩展程度等指数的结合使用更全面准确地描述了山区建设用地扩展及其空间分异状况。

Since the 1990s,the city of Beijing has entered into a centrifugal acentric phase of suburbanization,and the expansion of construction land in Beijing mountainous area will take up an important position.So study on the expansion of construction land is of great significance.Some indexes were created to indicate the expansion of construction land,such as the growth intensity index,the relative growth rate,etc.and they have their(unique) advantages and disadvantages.To overcome their shortcomings and make the expansion differentiate among different districts in Beijing mountainous area notably,we put forward the growth degree index along with the above two indexes to depict the spatial differentiation of construction land expansion comprehensively. Based on the land use shift data and land use change data,these indexes in three successive phasesi.e.,from 1993 to 1996,1996 to 1999 and 1999 to 2002 respectively,were calculated and the characteristics and spatial difference of land use expansion of different construction land types were analyzed.The results indicated that since the 1990s,the suburbanization has been extending to the outer suburbs,and great changes have taken place in Beijing mountainous area,the expansion degree became increasingly great.And the spatial expansion of construction land has the characteristics of both difference and abnormity, which expanded everywhere taking irregular expansion as the characteristics and suburbanization here was still in an initial phase.At the same time,the expansion has an outwards trend.Also because of the restriction of natural conditions and the orientated function of different districts,the regional spatial difference is evident.We hold that with the maturity of pole-axis system,the process of suburbanization in Beijing mountainous area will be entering a more active phase.Relevant measures should be taken to direct the expansion to a move active way.