南京城市住宅“售租比”时空格局与分异机理

“售租比”是国内外学者测度房价健康水平或泡沫风险的关键指标之一。利用中国房价行情平台提供的南京居住小区2009~2017年期间分季度平均售租价格信息,采用GIS空间分析等方法,考察南京中心城区“售租比”空间格局与演变过程。研究发现：① 城市整体“售租比”随房价波动变化明显,2016~2017年间快速增长;② 分异度先降后升,以城区内部差异为主,城区间差异越来越小;③ 高“售租比”小区多集聚于河西新城、江北新区等房价增速较快的投资热点区域。南京住宅“售租比”过快上升和空间离散加剧,意味着城市房价快速增长的合理性在降低。从地租视角解读,绝对地租决定着城市整体“售租比”的高低,级差地租和垄断地租则影响着城市内部“售租比”的空间分异。“售租比”可为判断城市内部房价相对合理性提供重要依据,但能否通过该指标准确预判城市房价风险程度及空间格局尚有待深入研究。

Spatial-temporal Pattern and Differentiation Mechanism of Price-to-rent Ratio of Nanjing

Housing price in Chinese big cities has been a focus issue in the society, which is not only high, but also ever-rising. While, the ‘Price-to-rent Ratio’ is one of the key indicators for scholars to measure housing price whether in healthy level or risk of a bubble. The study obtains the information of average sales and rent price of residential communities during 30 quarters from 2009 to 2017 in Nanjing, on the basis of “big data” about housing transaction provided by China Housing Price Market Platform. With the method of GIS spatial analysis and differentiation index, it investigates the spatial pattern and transformation process of price-to-rent ratio, as well as city housing price risk and spatial-temporal evolution characteristics of central urban area in Nanjing. The study finds that: 1) the overall price-to-rent ratio changes obviously with the fluctuation of housing price, which presents a rapid growth during 2016-2017; 2) the degree of differentiation falls first and rises later, and the differentiation in urban area is the main reason, whereas the differentiation between the inner and outer urban areas becomes increasingly blurred; 3) residential communities with a high price-to-rent ratio are primarily in the new urban areas, including Hexi and Jiangbei, where are the investment hot spots with rapid growth of housing price. The housing price risk is rising sharply in Nanjing and there is a trend of spatial generalization, which is judged from the phenomenon of extraordinary rise in price-to-rent ratio of urban houses, intensification of spatial dispersion, and housing price and rent being reversed for the first time. Based the land rent theory, it interprets the phenomenon of the price-to-rent ratio rising and spatial heterogeneity intensifying. It is the capacity of comprehensive allocation of resource elements in cities (absolute rent) that decides the overall housing price and rent level of the city; the urban spatial structure and factor input difference (differential rent) decides the spatial distribution pattern of housing price and price-to-rent ratio; while, the scarcity of high quality space and public services (monopoly rent) is likely to lead to the multi-scale space of the price-to-rent ratio. Finally, it analyzes the possibility of judging the degree of urban house price risk by using price-to-rent ratio. It suggest that the rapid rise in housing prices in Nanjing is worth vigilant; and especially in 2016-2017, both the price-to-rent ratio and the degree of space dispersion climbed to the highest value of history, due to the house prices having risen sharply and rents fall at the same time, which shows that the overall housing price risk is increasing.