收缩城市是近年来国际与国内城市研究领域的一个热点议题。二战后，西方国家中的一些城市因去工业化、郊区化、制度变迁等原因出现了人口持续减少的现象，而被归类为收缩城市。近年来，为了解决城市中，人口规模与建成空间规模长期失衡的问题，一些美国的收缩城市提出了以减小建成空间为导向的精明收缩规划，得到了外界的广泛关注。然而，目前国内外的收缩城市研究，主要集中在对其现象与机制的探讨之上，而规划应对及实施的研究则相对较少。同时，我国的收缩城市方兴未艾但缺乏任何有针对性的规划，尚需吸取国外的经验与教训。本文聚焦于美国一个较为典型的收缩城市——俄亥俄州的扬斯敦市，在近年来所颁布的两个以建成空间减量为精明收缩导向所颁布的规划，在实施上所面临的困境和挑战以及取得的成功和经验。研究采用了实地调研、半结构访谈、编程以及基于地块的GIS评估方法等一系列研究方法。首先对扬斯敦市的城市收缩背景及地理与建成空间表征进行了分析。随后，分别分析了扬斯敦市以系统化、主动式的建成空间减量为导向，通过自上而下的方式转变城市的土地利用结构以实现精明收缩的《2010总体规划》，在其下位的《2013区划》上的实施情况；以及以分散化、被动式的建成空间减量为导向，通过自下而上的方式指定城市中的衰败建筑以实现精明收缩的《社区行动规划》，在引导建筑拆除上的实施情况。相应的，本研究主要有以下两方面发现。第一，无论是在一致性视角下还是在有效性视角下，扬斯敦市《2010总体规划》所提出的土地利用转变的减量方式，在《2013区划》中，均未得到较好地实施，这是因为《2010总体规划》忽视了规划实施中所可能涉及的产权、法律、民主、政治以及经济等一系列制度的影响。第二，扬斯敦市《社区行动规划》所提出的衰败建筑拆除的减量方式，在实施中的总体效果相对较好。但是规划的两个实施者，地方政府与土地银行，由于在实施路径、分工模式、管理模式等制度上的显著不同，使得前者的规划实施结果无论是在一致性还是在有效性上，均远远不如后者。本研究指出精明收缩规划本身并不是拯救收缩城市的万灵药，关键在于建立正当、合适的制度，从而保障收缩城市中各种建成空间减量途径的合法、经济与有效。通过分析目前我国收缩城市在规划应对上所存在的种种困境及其原因，本文从制度建设的角度，指出了扬斯敦案例值得学习的经验与应当吸取的教训。
The issue of shrinking cities is under heated discussion in the international and domestic urban scholars. In the post-war era, because of deindustrialization, suburbanization, institutional transition and other factors, many cities in the Western countries endured continuous depopulation, and thus be defined as shrinking cities. Recently, aiming at rebalance the relationship between population and built environment, some American shrinking cities proposed right-sizing oriented smart shrinkage plans, which attract widespread concerns. However, up-to-date related studies mostly focus on the causalities and effects, by leaving the corresponsing planning strategies and their implementation largely uncovered. Meanwhile, shrinking cities are also emerging in China, while few corresponding plans have been made, therefore it is worthwhile to learn from the abroad. This dissertation focuses on a typical shrinking city in the US, literally the City of Youngstown, Ohio, which recently publicized two right-sizing oriented smart shrinkage plans. The study mainly analyzes these two plans’ implementation process that engages dilemmas and challenges, as well as success and experience. The study applies a range of methods including field survey, semi-structure interview, Python programming and parcel-based GIS plan implementation evaluation. In the begining, this dissertation analyzes the context and background of Youngstown’s urban shrinkage, as well as its effects on geographical and built environment. Afterwards, this dissertation moves onto examining Youngstown 2010 Plan’s systematical, initiative right-sizing through top-down implementation on Youngstown 2013 Zoning Code, and examing Youngstown’s Neighborhood Action Plans’ scattered, passive right-sizing through bottom-up implementation on demolishing blight structures and buildings. Correspondingly, this study has the following two research findings. First, Youngstown 2010 Plan’s right-sizing method, literally land use pattern change, did not implement well on Youngstown 2013 Zoning Code, from the perspective of neither conformance nor performance. This is caused by the Youngstown 2010 Plan’s lacking consideration of property right, legally defensibility, democractic underrepresentive, political stability and economic feasibility that actually affect its implementation. Second, compared with the Youngstown 2010 Plan, Youngstown’s Neighborhood Action Plans implemented much better on right-sizing through demolishing blight structures and buildings. However, because of difference in the path of implementation, labor division method and management method, the local government’s implementing result is much worse than the land bank from the perspective of both conformance and performance. This study implies that smart shrinkage plans are not panacea for saving shrinking cities, the keypoint lies in establishing a justified and proper institution, thus ensuring right-sizing methods to be legal, economical and effective. Through analyzing Chinese shrinking cities’ multiple planning dilemmas and their causalities, this study indicates experience and lessons from the perspective of establishing institutions that can be learned from the Youngstown case.
