Rapid urbanization plays a vital role in concentrating quality human capital and increasing social prosperity. However, it also acts as a major force of deterioration in the living environment from the local to the global scale in complex and irreversible ways [1
]. Along with the accelerated process of the densification and expansion of impermeable surfaces in modern cities, significant negative consequences have emerged that are becoming increasingly prominent. These consequences are particularly exacerbated in the context of global climate change [2
] (pp. 35–42) [3
]. Currently, urban areas are being exposed, to varying degrees, to challenges ranging from daily disorders to permanent damage, including urban diseases such as traffic jams and air pollution, extreme weather events, and a variety of natural and man-made disasters. Given that the majority of the world’s population now lives in cities and this situation will follow a growing trend in the foreseeable future, focusing on the resilience and sustainability of cities is imperative and should be given precedence [4
Resilience is a historical concept with distinct definitions. It mainly refers to the ability of systems to persist, absorb, and recover from the effects of threats and adversities in a timely and resourceful manner [7
] (pp. 31–32) [8
]. Resilience-related research stems from engineering and has continued to develop in the field of ecology. In recent decades, the study of resilience has arisen in multiple disciplines, with a special focus on urban resilience [9
]. When this concept is introduced to the urban system, which is considered a complex adaptive system, more comprehensive connotations of resilience have been developed [8
]. Urban resilience has thus become a buzzword, frequently emerging in a variety of documents and discourses, but it is conceptualized differently, depending on different knowledge backgrounds and research purposes. Collectively, three paradigms are common, i.e., engineering resilience, ecological resilience, and social-ecological resilience. The engineering perspective that is characterized by efficiency and constancy is widely gaining recognition in infrastructure reinforcement projects. The ecological perspective that emphasizes persistence and change to maintain basically the same structure, function, and identity is used in hazard management and ecosystem conservation. The social-ecological perspective that focuses on dynamic interactions between social and ecological systems across multiple temporal and spatial scales is widely considered key to building adaptive capacity and transformability in the broad context of social-ecological systems [11
]. The integrative and vague essence of urban resilience makes it a malleable concept, which is beneficial from multiple perspectives for the evolution to a desirable development trajectory by embracing the ability to change as flexibly as possible over time [14
Generally, the term urban resilience is used to express the abilities of urban systems to absorb, adapt to, and transform when dealing with uncertain challenges [13
]. Compared with the conventional paradigm of risk management (e.g., disaster reduction and relief strategies), which passively relies on rigid engineering measures and works for a relatively short time, urban resilience advocates the use of active solutions to co-exist with uncertainties through the inherent adaptive capabilities of urban systems based on coordination and cooperation between their internal components [18
]. Furthermore, the resilience of an urban system involves reactions during and after both acute shocks and chronic stresses. This allows for the cultivation of a wider adaptive capacity that is conducive to improved resilience during development through the ongoing process of experiential learning, especially from failures that were previously ignored [20
]. In addition, the insights of urban resilience provide a new approach for urban systems to achieve sustainable development, which are mainly drawn from social-ecological resilience. Within the framework of social-ecological systems, urban systems are recognized as intertwined social and ecological systems in which long-term development and evolution require a harmonious and mutually promoted relationship between the social and ecological components. This further informs that it is the integration of social and ecological considerations that contributes to the sustainability of urban systems, instead of overemphasizing one while overlooking the other. Moreover, the social-ecological systems pay more attention to the capacity to adapt and transform, which is significantly affected by ecosystem services. Given that cities currently pose the challenges of double exposure to rapid urbanization and global climate change, inspirations arising from the holistic and systematic thinking of social-ecological systems are of great significance for urban systems to transition toward livability and sustainability. Enhancing the resilience of urban systems is recognized to be the long-acting mechanism for improving human well-being and achieving sustainability [14
Although it remains a relatively novel concept, urban resilience has become an increasingly favored topic [6
]. Nevertheless, despite the wide consensus regarding the importance and urgency of urban resilience for coping with uncertainties, underdeveloped gray areas remain in this concept [23
]. Most existing studies on this topic elaborate on its theoretical connotations and implications [9
], while a smaller number of empirical studies consider the vulnerability and resilience of cities to specific disasters (e.g., flooding and earthquakes) and thus make efforts to propose targeted mitigation strategies [25
]. These studies have reference significance, but also have limitations. One of the most common issues is the inadequate conceptualization of urban resilience. In fact, resilience is an intrinsic property of urban systems with a more inclusive meaning beyond mitigating vulnerability. It is also related to human well-being and sustainability, while vulnerability correlates with the possibility of exposure to disasters. In terms of the paths to disaster resilience, engineering approaches that demonstrate enhanced persistence are often encouraged. However, it should be noted that, despite the importance, an excessive concentration on engineering measures will risk destroying the long-term flexibility and adaptability of urban systems. In summary, although urban resilience has attracted growing attention and its theoretical discussion and interpretation are common, there is a clear deficiency in relation to its measurement and operationalized application, particularly in fields serving urban planning and design practices. Further study to remedy this gap is obviously needed.
The main objective of this research is to propose an operational framework with the aim of contributing to progress on the quantitative assessment of urban resilience and further informing planning practice with respect to the urban social-ecological system. Based on urban landscapes, this study explores the spatial characteristics of urban resilience and its evolution by establishing the connections between landscape-based indicators and resilience potential. A close relationship is confirmed between the composition, configuration, and dynamics of the urban landscape and urban resilience [6
]. As a complex system shaped by human-nature interactions, the urban landscape may serve as a lens through which the evolution of the urban system is reflected. Additionally, it is apparent that reasonable landscape allocation plays an important role in buffering risks and helps the urban system recover quickly from disturbances. Furthermore, from the perspective of the social-ecological system, the optimized distribution of the social landscape (which is represented by built-up land and can reflect the potential of social factors such as social institutions and social capital to deal with uncertain changes to some extent) and the ecological landscape (which is represented by natural or semi-artificial land and enables the provision of ecosystem services) is beneficial for the collaborative influence of social adaptability and ecological benefits, thus leading the urban system to a livable and sustainable state [29
]. More importantly, because landscape characteristics can be expressed intuitively by using the tools and methodologies of landscape ecology (e.g., landscape metrics), the introduction of urban landscapes will facilitate the measurement, interpretation, and visualization of urban resilience. In addition, urban landscapes are useful as carriers for human interventions to shape resilience potential. In short, urban landscapes that can reflect and in turn be shaped by social-ecological interactions enable an available and effective medium for the quantification and operationalization of urban resilience.
This is the context in which the current investigation is conducted. The remainder of the paper is structured as follows. Section 2
introduces the study area, data sources, and research methods. The results of the characteristics and the spatial and temporal evolution of urban resilience, as well as the related analysis, are presented in Section 3
. Section 4
further discusses the findings, suggestions, and limitations of this research. The concluding remarks are summarized in Section 5
The growing challenges of uncertainty in urban systems, especially in the context of global environmental change, indicate that it is necessary and urgent to nurture resilience potential to achieve long-term sustainable development. Investigations of urban resilience have aroused wide interest among multidisciplinary scholars, practitioners, and policy-makers. However, there is little quantitative research related to this relatively new issue. This study constructed an operational framework that combines the measurement and assessment of urban resilience with the broader purpose of advancing the practice of quantitative assessment and decision-making, as well as better understanding the integrated social-ecological system. Within this framework, urban resilience is seen not only as the capacity to provide effective responses to and timely recovery from disturbances, but also as the ability to transition to a sustainable trajectory in relation to maintaining a harmonious relationship between humans and nature. Through introducing the perspective of the urban landscapes, not only can the intuitively simplified features of resilience be captured, but the dynamic evolution of the urban system is reflected. More importantly, connections between landscape characteristics and resilience potential make the measurement of and human interventions to foster urban resilience more approachable. Four proxies, i.e., diversity, connectivity, decentralization, and self-sufficiency, were employed to represent urban resilience, and landscape-based tools, i.e., landscape metrics and the budget of ecosystem services, were used for their measurement. Landscape-based and spatial analysis methods were then applied to analyze the characteristics and temporal-spatial evolution of urban resilience in the central city of Shenyang from 1995 to 2015. The main findings and conclusions are summarized as follows.
The multi-scale analysis of landscape metrics (SHDI, IJI, and CONNECT) indicated that 1500 m is suitable for use as the characteristic scale for landscape pattern analysis in the study area.
The changes in landscape metrics revealed that there was an increasing tendency for the diversity and decentralization of the landscape, while the connectivity decreased.
A core-periphery pattern of the four landscape-based indicators was displayed, although it weakened in 2015.
During the study period, apparent changes in the landscape characteristics mainly occurred in the peri-urban areas, where increased diversity, a more balanced configuration, and reduced connectivity and self-sufficiency (of ecosystem services) of the landscape were clearly presented.
The spatial pattern of the urban resilience level exhibited a ring-layer difference over the study area. In the central ring, it was almost at a homogeneously low level, while in the outer ring, it became much more complex and heterogeneous, presenting a low and high mixed interphase.
Within the past two decades, the spatial variations of urban resilience have demonstrated directional preferences. Urban resilience decreased in most directions, with the exception of the south and the northwest. It indicated that appropriate modifications to safeguard good interactions between the social and ecological landscape help increase urban resilience. In contrast, high-intensity artificial construction that pays more attention to economic and social benefits while neglecting ecological benefits plays a larger role in destroying resilience.
An evident distance effect with regards to the spatial variations of urban resilience emerged. From the city center to the edge, resilience remained almost the same before decreasing, and then showed a tendency to increase. This result implied that the development and growth of urban space has a two-sided impact on urban resilience.
The evolution of urban resilience suggested that the resilience level of the entire area was slightly improved, and the internal differences were reduced.
It is essential for urban systems to build responsive structures and maintain sustainable ecosystem services to achieve resilience and sustainability. Efforts to shape urban resilience based on urban landscapes are of great significance and deserve prominent attention. The coordination and trade-offs of landscape characteristics which are referred to in this paper, i.e., diversity, connectivity, decentralization, and self-sufficiency, to maintain and move to the trajectory of benign interactions between social and ecological components, can be effective to enhance resilience. Specifically, using the central city of Shenyang as an example, high-intensity construction should be regulated in the main urban area, and more emphasis should instead be placed on increasing the number of ecological patches wherever possible and organizing them appropriately. In the outskirts, moderate artificial development should be guided to disperse the development pressure. At the same time, the integrity of the core patches that provide important ecological functions must be guaranteed. Overall, a balanced, connected, and modular landscape pattern that can simultaneously satisfy basic human needs and maintain sustainable human-nature relationships is encouraged for the improvement of urban resilience.