Abstract
The benefits of urban green space are well documented. Natural areas absorb stormwater, mitigate the urban heat island effect, enhance property values, support biodiversity, and contribute to the health and well-being of residents. Adding and protecting open space in proximity to population centers connects more people to the spaces that provide these benefits and helps to make communities more livable, sustainable, and resilient. A variety of models provide guidance for integrating green space into urbanized or urbanizing landscapes. In Green Wedge Urbanism: History, Theory and Contemporary Practice, author Fabiano Lemes de Oliveira examines one of several shape-based models, the green wedge. While planners worldwide are familiar with the wedge concept and many plans incorporate it, Lemes de Oliveira’s book is the first to detail its emergence. Other shape-based models, particularly green belts, are more prominent in planning literature. Green belts throughout Europe are well studied, particularly in the United Kingdom where Lemes de Oliveira describes them as “sacrosanct” (1). But evidence suggests that green belts can impact local housing markets and lead to inequities in green space access. The green wedge strategy could avoid these impacts, but remains comparatively understudied, particularly from a historical perspective. Lemes de Oliveira begins to address this with Green Wedge Urbanism. The text includes more than fifty historical and contemporary wedge-based plans and models, which support his argument for the significance of the green wedge concept. He provides examples of radial green spaces at a variety of scales and brings them together to create a broad theory of green wedge urbanism
The eponymous green wedge is both a planning model and a type of green space. As a green space type, a wedge is a linear open space that is wide in fringe and rural areas where more land is available, but narrows as it runs toward an urban center. As a planning model, the green wedge concept describes a larger-scale strategy of integrating green wedges into a city or metropolitan region. Communities that adopt the strategy typically create several wedges, which facilitate broad green space access and enable residents to move from highly populated areas to the countryside through open space corridors.
The first half of Green Wedge Urbanism is historical. Lemes de Oliveira describes the conceptual beginnings and emergence of the green wedge idea, from the relationship between man and nature in medieval Europe through 1970s-era regional planning. Some of this is already well documented. He describes, for example, the emergence of park systems and the discipline of city planning. But also running through these early chapters is the tension between radial and concentric ring development patterns and their genesis and impacts. While fundamental to modern environmental and regional planning, this debate is not addressed in other works. His brief discussion of the parallels between transportation and green space models is similarly illuminating. Archival research informs Lemes de Oliveira’s description of the transition from green belts to green wedges as the dominant green space model in the early 1900s and progression from Eberstadt’s 1910 green wedge diagram through several succeeding incarnations of radial open space. The green wedge concept supported postwar reconstruction and new town development in the United Kingdom, in particular, but also throughout Europe and into parts of Asia and North America. Green wedges were initially used to manage and direct growth at the municipal scale, but by the middle of the century, led by Nordic countries, they formed the foundation of several metropolitan regional plans. Many will recognize the 1947 Finger Plan for retaining green wedges between “fingers” of growth in Copenhagen, Denmark, which was among the first of this type.
The second half of Green Wedge Urbanism examines the contemporary theory and practice of the green wedge model. After a brief review of modern literature on green space benefits, Lemes de Oliveira situates the concepts within the perspectives of several prominent figures and ideas in environmental planning. He connects the green wedge idea to Ian McHarg’s ecological determinism and cites Lewis Mumford and Kevin Lynch as proponents of the design. Lemes de Oliveira also identifies the relevance of green infrastructure, landscape ecology, landscape urbanism, and sustainability, but these sections are insubstantial and the weakest part of the book. The remainder of Green Wedge Urbanism surveys contemporary plans that employ a wedge strategy. Lemes de Oliveira describes six metropolitan and eight smaller-scale plans that illustrate the flexibility and open space connectivity potential of the green wedge concept. While the vast majority of the examples are European, six continents are represented, a geographic diversity that illustrates the broad diffusion of the model. The case studies are descriptive rather than analytical, and their level of detail is uneven. There are also enough similarities among the communities’ motivations and benefits that the case study narratives are repetitive in places. But they capture the power structure and planning process well and the number and diversity of the plans clearly show that the green wedge model is enduring and widespread.
The book concludes with ten principles for the practice of green wedge urbanism. The suggestions are broad and emphasize design and delineation concepts like “continuity of the green wedges” and “connection between the city and the countryside” (221). But implementation and management tenets, such as “systemic integration into a comprehensive plan” and “integration of ecosystem services” are also included (223, 224). The latter categories are particularly important because, as becomes obvious from the historical section, the implementation of green wedge plans is challenging. While many communities have created and even adopted plans over the years, few have implemented them. Lemes de Oliveira identifies several reasons for this but one of the more convincing, given the chosen case studies, is the role of public control of land. In the Nordic cities that are known for the successful implementation of green wedges, most of the land is in public ownership, which means large-scale green space plans have faced few challenges from private landowners. As Lemes de Oliveira notes, in such cities “Free planning, thus, became a possibility almost detached from considerations regarding compensation and lawsuits” (108). Given that the green wedge model has been applied in communities with significant private property, some of these challenges seem to have been overcome. More focus on how large-scale wedge models have worked in such environments would strengthen the utility of the book for planning practice.
The application of Lemes de Oliveira’s theory of green wedge urbanism may be less obvious in places like the United States where plans based on regional models like green belts or green wedges are uncommon. Green Wedge Urbanism identifies just three US plans that incorporated the wedge concept, all from the 1960s. Just one, Metrotowns for the Baltimore Region, was adopted. None of the three were extensively implemented. The strong private property rights that are not present in the communities profiled by Lemes de Oliveira create challenges for regional open space planning in the United States. American planners tend to focus on park systems, greenways, and even green infrastructure networks, which can be woven opportunistically into developed landscapes or do not rely on public ownership. But Lemes de Oliveira’s principles of green wedge urbanism, such as connectivity, ecosystem services, public access, and multiple scales, do fit well with these models and suggest a coalescing of scholarship on regional green space design.
The main contribution of Green Wedge Urbanism is one of compilation and organization. Lemes de Oliveira brings together the multiple threads of the conceptual history of green wedges and over 100 years of wedge-inspired plans. Together, they create a strong argument for the significance of the concept in planning history and practice. The details of the book support this aim. Lemes de Oliveira includes images of many of the plans that he discusses and a variety of modern diagrams and photographs of the spaces that comprise existing green wedges. A few of the latter are difficult to read in black and white, but most are useful. Each chapter also helpfully concludes with a chronological list of the cited green wedge plans and models, including locations and brief descriptions. Overall, Lemes de Oliveira’s chronicle of the green wedge concept adds significantly to our understanding of this impactful model. It will be useful for environmental and regional planners, particularly those with an interest in planning history or theory. Sections of the book, such as the case studies, could also be appropriate for graduate-level courses.