Deciphering the Evolution, Frontier, and Knowledge Clustering in Sustainable City Planning: A 60-Year Interdisciplinary Review

Abstract

Scholars have sought to integrate sustainable principles, attitudes, and methodologies into urban development, drawing insights from the natural and social sciences as well as historical contexts. However, current sustainable urban planning (SUP) research has a broad scope, unclear boundaries, and an absence of systematic literature reviews. To fill this research gap, this review presents a visual analysis of 38,344 publications on SUP indexed in the Web of Science (WoS) from 1964 to 2023, with the aim of detailing the trajectory of SUP research. Utilizing data retrieval and scientific metrology techniques, we: (1) Identified distinct phases in SUP research: budding (pre-1990s), exploration (1990s), foundation (2000s), and maturation (2010–present). (2) Discovered that publications predominantly focused on urban research, landscape architecture, and ecological studies, with publishing trends favoring developed, highly urbanized, and coastal nations. (3) Employed visualized dual map overlays, co-citation clustering networks, and keyword statistical charts to construct a knowledge framework of the interdisciplinary progression and thematic shifts in SUP. Key knowledge clustering included ‘community planning’, ‘urban expansion’, ‘ecosystem services’, and ‘nature-based solutions’. (4) Described the progression of SUP, green innovation is the most promising direction for future research. (5) Defined its scope and elements and advocated for three foundational principles: equity and justice, value articulations, and practical needs, offering a path to actualize SUP efforts.

1. Introduction

Over the past 200 years, under the leadership of three industrial revolutions, humanity has made unprecedented strides in development, whereas environmental discourse has largely remained marginalized [1]. The eco-conscious movement gained momentum during the 1960s and 1970s [2], propelled by the exigencies of urban sprawl and global climate change, subsequently infiltrating urban domains. This paradigm shift necessitated the re-conceptualization of the urban environment and mandated construction aligned with ecological principles. Sustainable urban planning (SUP) has emerged as a pivotal discipline for addressing societal challenges [3]. However, integrating sustainability into urban planning presents a paradox because such planning inherently diminishes residents’ access to verdant expanses [4]. Moreover, urbanization engenders profound ecological transformations, culminating in ‘urbanatura’, a complex and often undesirable fusion of natural and urban terrain [5]. Having been confronted with a burgeoning global crisis, scholars have sought to synthesize urban paradigms with auspicious sustainability models: ecological urbanism [6], biodiverse city planning [7,8,9], biophilic urban design [10,11], nature-based urban planning [12,13], nature-inclusive city planning [14], and eco-friendly urban development [15]. Despite the pejorative implications associated with cities in environmental and health discourses, the imperative for urban sustainability remains undiminished. The inherent tensions of urban environments foster a yearning for natural encounters, which is a sentiment emanating not from rural romanticism but from urban dwellers’ fundamental needs [16]. SUP research has evolved considerably and now epitomizes the interdisciplinary science of studying coexistent human and ecological systems in urban research. This approach encompasses a holistic inquiry into interconnections and relational dynamics [17].

On 25 September 2015, marking a milestone in the field of sustainable development, the 70th United Nations General Assembly formally adopted Transforming Our World: The 2030 Agenda for Sustainable Development [18]. This agenda introduced the 17 Sustainable Development Goals (SDGs), with 169 specific targets. Subsequently, the Global Sustainable Development Report has been compiled every four years. In this context, Goal 11, directly relevant to SUP, aims to “make cities and human settlements inclusive, safe, resilient, and sustainable.” Despite being more than halfway to 2030, achieving this goal remains distant, with primary challenges centered on public transportation, infrastructure equity, air pollution, insufficient public space, and uncontrolled urban expansion [19]. In a broader context, SUP encompasses the application of the Sustainable Development Objectives to both the research and practical aspects of urban planning. Literature in this domain typically addresses three interdependent dimensions: social, economic, and environmental [20]. Urban elements such as form, transportation, landscape, architecture, and energy supply are evolving towards sustainability. However, the term “sustainability” is increasingly used to label solutions for contemporary urban planning issues, leading to a blurred and uncertain meaning. Distinguishing “sustainability” from other prevalent terms in new-era urban planning, such as “green” [21], “ecology” [22], “rationality” [23], “wisdom” [24], and “health” [25], remains challenging. Nevertheless, it is evident that sustainability represents a comprehensive research and practice framework encompassing these terminological concepts. Notably, SUP encounters the emergent attributes of complex urban systems and multifaceted, multi-level, and multi-stage goals. Consequently, scholars and urban planners lack a comprehensive understanding of the holistic theory of SUP. Adequately grasping the scale and scope of SUP research and practice poses challenges in methodology.

In this context, this study evaluates and organizes a corpus of SUP research by uniquely probing interdisciplinary arenas and thematic trajectories through a temporal lens, aggregating evolutionary academic trends, and crafting a comprehensive knowledge network. We engaged in interactive scientometric assessments by utilizing CiteSpace’s analytical visualization capabilities [26]. Bibliometric methodologies serve as integral analytical instruments that facilitate cohesive evaluations [27], which are evident in various thematic investigations within SUP research. They include visual and quantitative retrospectives on smart cities [28], systematic assessments of the effects of green roofs on water, temperature, and air quality [29], and the interplay of green infrastructure with ecological and human health [30]. Notable studies also encompass urban resilience [31], climate change [32], carbon footprints [33], and stormwater governance [34]; however, comprehensive and panoramic insights into SUP remain conspicuously absent. This manuscript provides an immersive and panoramic examination of SUP, offering invaluable insights for both scholars and practitioners.

Section 2 delineates our methodological approach, including data sources, retrieval processes, analytical tools, and scientometric justifications (Section 2). Section 3 quantitatively appraises SUP research dynamics, keyword highlighting, and disciplinary segmentation through the construction of network architectures that elucidate interdisciplinary progressions and thematic nexuses. This approach offers a lucid scientific cartography of SUP macroscopic, academic, and thematic developments. This analysis, primarily sourced from the Web of Science (WoS) and enhanced with CiteSpace and ArcGIS visualizations, embodies knowledge cartography comprising scholarly trend analyses, journal activeness, geographical publication distributions, keyword trajectories, and co-citation clusters. This study also investigates publication trends categorized by WoS, interdisciplinary synergies via dual-map overlays, and chronological and comprehensive academic progressions through the time-zone network. Section 4 provides a comprehensive overview of SUP progression, focusing on the expansion of the research scale and diversity of elements; the basic principles and potential methodologies that could advance SUP research endeavors are also investigated. Section 5 encapsulates our findings, advocates prospective urban planning, and acknowledges the transformative potential of SUP research for future urbanistic and environmental endeavors.

2. Materials and Methods

2.1. Data Sources and Screening

The Web of Science and Scopus are the predominant databases used for bibliometric analysis, each with distinct merits [35]. The WoS core collection database encompasses a range of reputable and impactful journals, earning its status as a premier resource across numerous academic disciplines. However, Scopus has emerged as a formidable contender, vying for market dominance against WoS [36]. Although Scopus boasts an extensive repertoire of unique journals, it parallels WoS in coverage within Natural Sciences and Engineering (NSE) [37]; this indicates negligible disparities in bibliometric outcomes, regardless of database preference. The WoS distinguishes itself from a meticulously curated array of journals [35], as it facilitates the extraction of pertinent and precise bibliometric indicators. This investigation evaluated publications from the WoS core collection, undertaking a comprehensive literature exploration on 15 October 2023, without initial publication date constraints. We employed specific phrases synonymous with SUP research (

Table 1. Search terms applied to titles in the Web of Science.

Terms

TS=sustainable city planning OR TS=ecologically sustainable urban design OR TS=sustainable urban ecology OR TS=sustainable urban infrastructure OR TS=urban ecological design OR TS=eco-friendly urban development OR TS=green city design OR TS=ecological urbanism OR TS=biophilic urban design OR TS=nature-based urban planning OR TS=resilient urban design OR TS=eco-urban development OR TS=biodiverse city planning OR TS=urban green space design OR TS=ecological regeneration in cities OR TS=urban environmental planning OR TS=ecological resilience in cities OR TS=eco-urbanism OR TS=urban ecosystem restoration OR TS=green urban development OR TS=urban sustainability and ecology OR TS=ecological urban design and planning OR TS=urban biodiversity planning OR TS=ecologically smart city design OR TS=sustainable urban greening OR TS=nature-Inclusive city planning OR TS=ecological urban development OR TS=cityscape sustainability OR TS=ecological design for urban areas OR TS=sustainable urban habitats OR TS=eco-city design and planning OR TS=green urban infrastructure OR TS=urban ecology and design integration OR TS=biocentric urban planning OR TS=sustainable cityscape architecture

) as the cornerstone of our thematic inquiry, thus confining the language to English. Our methodology included only journal articles and reviews; peer-reviewed original articles offer the highest quality and present more quantifiable information [38], and they are pivotal in illustrating the innovative scientific trajectory of this study’s focal point. The initial probe surfaced 48,591 publications, from which we distilled the entries by eliminating those with deficient metadata. To minimize extraneous academic noise, disciplines with no direct relevance, including biology and medicine, were omitted (see Supplementary Materials File S1), culminating in a refined assemblage of 38,344 scholarly works (circulated before 15 October 2023). A historical investigation revealed that the inception of SUP-themed scholarly discourse dates to 1964.

2.2. Research Methods

Systematic reviews of bibliometric analyses are recognized as effective tools for comprehensive explorations within specific research fields [39]. These reviews utilize statistical techniques and visualization tools to characterize the types of literature, evaluate central themes, and identify research trends and potential directions in the field, thereby providing a method for comprehensively quantifying SUP research. We used CiteSpace 6.1 R6 64-bit Advanced in our analysis because of its relative stability and comprehensive features. We also utilized CiteSpace 6.2.R5 64-bit Advanced to perform a cluster dependency analysis, which is a unique feature available in this new version. Auxiliary analysis was conducted using ArcGIS 10.8 software.

Thomas Kuhn’s concept of scientific revolutions (1962) undergirds the philosophical foundation of CiteSpace, suggesting that shifts in scientific understanding—paradigmatic changes—can be traced through academic literature [26]. Subsequently, Paulus Franciscus Wouters posited that citation culture reflects a deep and objective reality within the physical world [40]. CiteSpace, grounded in co-citation analysis theory, can visualize these complex academic shifts, making tangible the ‘concrete in thought’ within specific fields [40]. Our bibliometric approach mapped the development, proliferation, and transformation of SUP research citation clusters by systematically reviewing the emergence and evolution of research frontiers and knowledge bases in this area. In our content analysis, we highlighted high-frequency keywords in each period to provide key insights.

We acknowledge that during our cluster analysis, the cluster labels generated in the network symbolized the content of citation groups and reflected the reasons for cluster formation. Although we primarily used the log-likelihood ratio (LLR) algorithm to generate original cluster labels, reliance on LLR alone can result in labels that are vague or lack interpretative power. Emerging trends may be obscured by broader themes [41]. Consequently, we manually evaluated and, if necessary, replaced cluster labels to maintain clarity and relevance. Additionally, a modularity Q value exceeding 0.3 and an average silhouette value above 0.7 indicate significant cluster structures and clear thematic distinctions, respectively [42]. The network density, Q, and average silhouette values in our study remained within reliable ranges, confirming the analytical and reference validity of the generated networks.

3. Results

3.1. Interdisciplinary Evolution of SUP Research

3.1.1. Trends in Annual Publications

After analyzing data encompassing 38,344 publications in active journals from 1964 to 2023, four distinct developmental stages of SUP research emerged: (1) budding: pre-1990s; (2) exploration: 1990s; (3) foundation: 2000s; and (4) maturation: 2010s to the present. By comparing the growth of SUP publications with the growth of urban planning (UP) publications during the same period, the rationality of the research is supported (Figure 1). Between 1964 and 1989, 16 papers were intermittently published across 26 years, indicating that SUP research was embryonic and characterized by fragmented initiatives and a paucity of substantive research or practical endeavors. An inflection point occurred in 1991, as evidenced by the release of 25 papers in one year. The decade-spanning 1990–1999 period demonstrated a consistent uptick in annual publication output. Despite the relative dearth of comprehensive studies during this epoch, the period was marked by audacious and fruitful forays in SUP research.

In the 21st century, publication volumes have experienced a precipitous ascent. By 2009, there had been a fivefold surge in annual publications relative to 2000, complemented by a quadrupling of active periodicals. Currently, SUP research has established a distinct theoretical framework and methodology, concentrating predominantly on residential areas. Post-2010, the field attained its zenith, as characterized by an exponential proliferation of scholarly articles. Currently, SUP research has attained a sophisticated level of maturation, replete with an elaborate theoretical corpus and diversified methodological approaches, branching into variegated sub-disciplines and applicative domains. Trend trajectories suggest an unabated acceleration in the publication velocity until 2023.

3.1.2. Publication Analysis by Country

Prior to 1990, most publications were published in the United States.

Table 2. Countries ranked by quantity of sustainable urban planning publications per decade from 1990 to 15 October 2023 are listed in descending order.

1990–1999			2000–2009			2010–2019			2020–2023
Countries	Urbanization Rate	Publications	Countries	Urbanization Rate	Publications	Countries	Urbanization Rate	Publications	Countries	Urbanization Rate	Publications
USA	75.30	141	USA	79.06	768	USA	80.94	3656	China	63.89	6875
UK	78.14	64	UK	78.65	243	China	47.50	2988	USA	82.70	2700
Canada	76.58	36	China	36.22	219	UK	79.15	1415	UK	83.90	1309
Netherlands	68.68	17	Canada	79.48	154	Australia	85.18	1275	Italy	71.00	1163
Australia	85.70	14	Australia	87.20	149	Italy	68.22	1054	Australia	86.20	1125
Germany	73.12	14	Netherlands	76.80	77	Germany	73.82	823	Germany	77.10	953
China	26.41	12	Germany	73.07	75	Canada	80.55	771	Spain	80.80	796
India	25.55	11	Italy	67.22	64	Spain	77.28	679	India	34.90	749
Finland	62.00	9	Sweden	84.00	64	Netherlands	82.75	655	Canada	81.60	673
Italy	66.73	9	Turkey	64.74	57	Sweden	85.06	498	Poland	60.20	607

The urbanization rate (%) denotes the percentage of urbanization observed in each country at the beginning of every decade.

delineates the national publication trends from 1990 to 15 October 2023. Throughout the initial three epochs, the United States persistently led in publication volumes. However, as the 2020s commenced, China assumed a dominant role, demonstrably outpacing other countries. Evaluating the urbanization rates of prolific publishing countries revealed that, barring China and India, the front-runners are developed countries with high urbanization rates. Conversely, China and India are emblematic of developing economies that have strong economic growth momentum. As the world’s most populous nations, China and India face heightened Malthusian dilemmas [43] resulting from rapid urban expansion. Increasing population challenges have driven their urgent need to implement SUP. Notably, those absent from the list are certain early urbanized developing countries, such as Argentina and Peru.

Utilizing ArcGIS10.8, global maps and extracted literature data are integrated into the software. The “country” field serves as the linkage between the two datasets, and the range and color spectrum of the graded quantity are configured for spatial data quantitative analysis, as illustrated in Figure 2. The 2000s witnessed an upsurge in contributions from Asian coastal countries in contrast to a paucity from inland regions. Distinct regional disparities are evident on the African continent between the east and west; nearly all countries along the east coast were engaged in pertinent research activities, whereas those on the west coast exhibited stagnation in this arena. Post-2010, SUP research proliferated among coastal nations, albeit with inland exceptions. The correlation between coastal proximity and SUP research intensity references insights by Marcus Vitruvius Pollio in ancient Rome, who asserted that the health repercussions for towns south or west facing the sea are exacerbated by rising temperatures [44]. Coastal regions face substantial urban planning challenges [45] and heightened ecological fragility [46]. Despite accounting for only four years in the 2020s, the spectrum of publishing countries has broadened in this decade. This trajectory underscores the enduring predominance of major western economies in SUP research over the past six decades. Additionally, a correlation between a nation’s developmental status, degree of urbanization, and SUP emphasis was evident. Countries demonstrating high urbanization but with economic constraints tended to sideline sustainable urban research initiatives.

3.1.3. Research Evolution as Categorized by Web of Science

Interdisciplinarity, a trait discernible and quantifiable through the classification standards of journals in various databases [47], significantly influences the landscape of scholarly literature. This study undertook a systematic analysis of the retrieved literature based on the Web of Science (WoS) subject categories. The precision of subject classification matching is exceptionally elevated when dealing with the extensive aggregation and substantial quantity of publications in the WOS [48]. Considering the limited volume of publications prior to 1990, the analysis commenced that year and was segmented by decade, with a distinct segment from 2020 to 2023 (

Table 3. Predominant Web of Science categories in SUP research: A decadal review from 1990 to 15 October 2023.

1990–1999		2000–2009		2010–2019		2020–2023
Category	Publications	Category	Publications	Category	Publications	Category	Publications
Environmental Studies	137	Environmental Studies	630	Environmental Sciences	5524	Environmental Sciences	8688
Urban Studies	129	Environmental Sciences	623	Environmental Studies	4377	Environmental Studies	6267
Regional Urban Planning	102	Urban Studies	541	Urban Studies	3142	Green Sustainable Science Technology	4666
Environmental Sciences	97	Ecology	521	Green Sustainable Science Technology	2800	Urban Studies	2526
Geography	86	Regional Urban Planning	466	Ecology	1990	Ecology	1368
Ecology	84	Geography	393	Regional Urban Planning	1873	Energy Fuels	1241
Geography Physical	53	Geography Physical	269	geography	1793	Geography	1241
Engineering Civil	34	Public Environmental Occupation Health	139	Engineering Environmental	1036	Construction Building Technology	1205
Energy Fuels	27	Engineering Environmental	137	Geography Physical	821	Regional Urban Planning	1157
Public Environmental Occupational Health	23	Engineering Civil	136	Energy Fuels	816	Public Environmental Occupation Health	1123

). The inaugural publication in 1964, categorized under ‘Public, Environmental, and Occupational Health’ [49], was followed 7 years later by another within the same category [50]. The fourth publication examines the interplay between environmental challenges and urban development dynamics within tropical African cities, exemplified by Nigeria, marking a concentrated shift toward the realm of ‘Environmental Sciences and Ecology Geography’ [51]. Thereafter, sustainability concepts began to permeate the discourse in urban studies.

Post-1990 publications were bifurcated into four epochs to chronicle evolution within the Web of Science categories. Initially, the studies focused predominantly on environmental and urban themes, occasionally branching into geography, ecology, civil engineering, and residential environments. In the 1990s, ‘Public, Environmental, and Occupational Health’ emerged as a prevalent field. Although interest in the field waned between 2000 and 2019, it witnessed a resurgence post-2020, potentially linked to the onset of the COVID-19 pandemic in 2019. Gradually, the research trajectory transitioned from a purely urban-centric approach toward embracing green and sustainable practices, maintaining an unwavering emphasis on environmental concerns. Notably, the period before 2010 prioritized environmental studies over environmental sciences, a trend that was reversed in the subsequent decade. Environmental science, which applies rigorous scientific methodologies to understand the anthropogenic and natural impacts on terrestrial ecosystems, exhibits interdisciplinary features. Conversely, environmental studies, with their extensive purview encompassing both environmental science and the humanities, have greater depth in interdisciplinary research. This shift toward environmental studies in SUP research underscores the growing imperative of interdisciplinary integration.

3.1.4. Exploring Research Development through Dual-Map Overlays

Dr. Chaomei Chen, the creator of CiteSpace, posited that the evolution of a distinct research domain functions as a complex adaptive system, emphasizing that the entity often surpasses the aggregate of its components. This perspective necessitates an investigation of the individual elements within a research field as well as a comprehensive analysis of the interrelations among them [52]. To effectively illustrate the dispersion, citation trajectories, and focal shifts concerning urban ecological design across multiple disciplines, it is crucial to address the inherent challenges and opportunities presented by the multidisciplinary trajectories and cross-disciplinary shifts in SUP research. Rafols and Meyer (2007) identified the frequency of a study’s cross-disciplinary citations as a pivotal indicator of its interdisciplinary caliber [53]. Employing the dual-map overlay feature of CiteSpace facilitates the discernment of prospective trends, expansions, interdisciplinary engagements, convergences, bifurcations, obsolescences, and revivals within SUP research, thus contributing to a holistic re-evaluation of SUP research’s historical, contemporary, and prospective stages across the academic spectrum.

The compiled data were integrated into CiteSpace’s dual-map overlay function, generating an atlas predicated upon a duo of global scientific maps from JCR (2011); the left side signifies the research application domain of SUP, encompassing cutting-edge research topics and hotspots (text indicated in yellow). Meanwhile, the right side represents the knowledge foundation of SUP, delineating the field of cited literature (text indicated in Blue) [52]. This method marks the imprints of foundational knowledge and emergent research within both maps and delineates the overarching framework of the evolution of urban ecological design, thereby graphing interdisciplinary correlations. Operationally, the Blondel algorithm identifies clusters within journal networks, which are subsequently termed ‘journal clusters.’ Leveraging the Z-Score mechanism to compute the Z-value, and display it in the map. The Z-Score is a metric indicative of the significance of a journal or another entity. Essentially, it standardizes the original count value to have a zero mean and unit variance. The Z-value represents the quotient obtained when the difference between the observed value and the population mean is divided by the standard deviation [18]. Furthermore, in the left figure, the horizontal axis of the ellipse denotes the number of papers published in the corresponding journal, and the vertical axis indicates the number of authors. In the right figure, the horizontal axis of the ellipse represents the number of cited authors, while the vertical axis illustrates the count of journal citations. Within CiteSpace’s dual graph overlay of journals, the Z-Score aids in ascertaining a journal’s influence or importance in comparison to other journals. A high positive Z-Score suggests an above-average influence of the journal, whereas a negative Z-Score implies a below-average influence. The predominant citation trajectory is underscored and highlighted using the Z-Score mechanism, as depicted in Figure 3.

This visualization distinctly highlights 10 citation trajectories: (1) Plant, Ecology, Zoology → Ecology, Earth, Marine; (2) Plant, Ecology, Zoology → Veterinary, Animal, Science; (3) Plant, Ecology, Zoology → Economics, Economic, Political; (4) Environmental, Toxicology, Nutrition → Ecology, Earth, Marine; (5) Environmental, Toxicology, Nutrition → Veterinary, Animal, Science; (6) Chemistry, Materials, Physics → Ecology, Earth, Marine; (7) Psychology, Education, Social → Economics, Economic, Political; (8) Economics, Economic, Political → Ecology, Earth, Marine; (9) Economics, Economic, Political → Veterinary, Animal, Science; and (10) Economics, Economic, Political → Economics, Economic, Political. This result demonstrates the interdisciplinary nature of SUP research and underscores the prevalence of disciplines such as ecology, environmental science, and political economics. It also elucidates the reliance of SUP advancements on a diverse academic foundation, drawing significantly from domains including, but not limited to, ecology, botany, geology, environmental science, economics, sociology, materials science, and political science. Dynamism at the research frontier is evident, with theoretical insights from multiple disciplines catalyzing thematic investigations within the SUP, thereby fostering novel interdisciplinary dialogues and revealing an integrated developmental trajectory with immense potential. Critical support for pioneering ecological inquiries emerges prominently from disciplines such as ecology and botany, whereas economics and political science provide extensive foundational support across various research themes. Moreover, literature from ‘Landscape Urban Plan’ (56,224), ‘SCI Total Environment’ (28,791), ‘Clean Production’ (27,708), and ‘Urban for Urban Green’ (23,734) features prominently in citations, underscoring the influence of diverse scholarly contributions, including those from health sciences, life sciences, and geology, within SUP discourse.

3.2. Evolution of Research Themes

3.2.1. Keyword Evolution

To thoroughly investigate the hotspots and trends in the SUP field, we performed a keyword analysis on 38,344 publications. Considering the negligible number of publications before 1990, which undermines the validity of high-frequency keyword analysis, we initiated our investigation in 1990. We divided the timeline into decades, treating 2020–2023 as a separate segment.

Table 4. Prominent keywords in SUP literature: A decadal analysis from 1990 to 15 October 2023.

1990–1999		2000–2009		2010–2019		2020–2023		1964–2023
Keywords	Count	Keywords	Count	Keywords	Count	Keywords	Count	Keywords	Count
city	18	city	169	city	2343	city	3146	city	5676
sustainable development	12	land use	136	impact	1367	impact	2479	impact	3951
urban planning	11	sustainable development	118	ecosystem service	1239	ecosystem service	1791	ecosystem service	3065
urban	7	management	107	management	1205	urbanization	1375	management	2513
community	6	conservation	105	climate change	1073	climate change	1326	climate change	2443
conservation	6	impact	105	land use	949	management	1200	urbanization	2374
behavior	5	urban planning	104	biodiversity	921	model	1194	model	2151
population	5	biodiversity	102	urbanization	913	green infrastructure	1127	urban	2082
diversity	5	urban	89	model	892	urban	1100	land use	2070
policy	5	landscape	86	urban	886	land use	983	biodiversity	1881
developing country	4	urbanization	82	system	832	health	958	green infrastructure	1847
south africa	4	community	81	urban planning	818	green space	922	system	1816
ecosystem	4	pattern	75	sustainable development	731	system	918	urban planning	1732
forest	4	ecology	66	green infrastructure	717	biodiversity	857	sustainable development	1708
growth	4	system	64	landscape	668	sustainable development	847	health	1663
urbanization	4	model	63	green space	663	area	805	green space	1605
climate change	4	environment	62	area	656	urban planning	799	area	1521
design	3	diversity	59	health	653	china	751	landscape	1446
emission	3	forest	59	conservation	636	design	738	environment	1403
area	3	quality	57	environment	611	environment	728	pattern	1380

displays the prevalent keywords associated with SUP across these timespans.

Irrespective of the individual sub-periods or the entire duration under study, ‘city’ emerged as the most recurrent keyword, highlighting the necessity for SUP research to be rooted in urban contexts [54]. Keywords from the 1990s diverged significantly from those in subsequent periods. The 2000s served as a transition phase, displaying an evolution from keywords of the 1990s to presaging high-frequency keywords post-2010. The keywords in the 2010s and 2020–2023 periods were remarkably similar. Before 2010, the emphasis was on the ‘community’ and ‘forest’ terms, suggesting that certain studies lacked a comprehensive urban perspective. However, post-2010, the focus broadened from the health of residential zones to a wider urban ambit, with ‘impact’ gaining prominence owing to issues like ‘climate change’, ‘biodiversity’, and ‘green infrastructure.’ The coronavirus disease (COVID-19) pandemic has further necessitated the increased appearance of ‘health’ as a prime concern.

3.2.2. Evolution of Co-Citation Clusters

Derek John de Solla Price, the Father of Scientometrics, posited that scientists’ propensity to cite recent articles delineates the research frontier within specific fields, as manifest in collections of actively cited articles [55]. Pursuant to this insight, the vanguard of SUP research emerged through an examination of 40–50 contemporaneously cited articles, whereas historically significant works undergird the present knowledge base [42]. This study utilized CiteSpace, with nodes designated as ‘References’, facilitating a co-citation analysis [56]. We define co-citation as the circumstance in which both Papers A and B cite Paper C.

The initial CiteSpace-based cluster analysis yielded 22 primary clusters. We manually amended certain potentially misleading labels, including ‘#7 walking’, ‘#12 particulate matter’, ‘#16 digital economy’, ‘#24 local knowledge’, and ‘#35 Canada’, to preclude analytical distortion (see Supplementary Materials File S2). We enhanced inter-nodal connections by instituting a minimum degree of 10, as visualized in Figure 4, which details the relational and evolutionary dynamics within SUP research. Nodes, scaled according to citation metrics such as counts and bursts, underscore pivotal research junctures. Notably, betweenness centrality, a salient metric, is visually encoded as a purple periphery when it exceeds 0.1, signifying a node’s communicative prominence and designating research inflection points. The thickness of the periphery is proportional to its centrality, denoting the node’s intermediate significance. The absence of prominently central nodes, notwithstanding the extensive data, attests to SUP research’s inherent diversification and intricacy.

The co-citation network reveals the thematic trajectory of SUP research. Before the 1990s, investigations predominantly addressed urban ecological challenges, public verdure, and sustainability, subsequently evolving to encompass residential ecological design underpinned by urban greenery and flora studies. This progression paralleled broader urban research trends, as epitomized by Lynch’s (1984) characterization of urban design as the multifaceted artistry of orchestrating neighborhood functionality [57]. In the first decade of the 20th century, focal shifts included comprehensive urban design and nature-centric inquiries into atmospheric, aquatic, and thermal contexts. Concurrently, contemporary perspectives permeate SUP studies, as evidenced by burgeoning discourses on smart urbanism and ecological innovation, as well as the field’s responsiveness to exigencies such as the COVID-19 pandemic. Co-citational interconnectivity indicates thematic cohesion, particularly between urban ecology and residential eco-design, thus underscoring the pivotal role of urban ecology in bridging diverse research themes. After 2010, substantial uncertainty exists in the literature in addressing the themes of green innovation and urban expansion. Green innovation, although at its nascent stage and somewhat disconnected from established research trajectories, has considerable potential as a pivotal catalyst for future SUP inquiries. By contrast, urban expansion, despite being the most substantial entity in the co-citation network, demonstrates minimal interdisciplinary engagement.

3.2.3. Direction of Co-Citation Cluster Dependencies

To detail the thematic evolution of SUP research, we employed CiteSpace’s cluster dependencies to substantiate the macro-developmental trajectory of the discipline. The paucity of publications in the budding and exploration stages precluded effective clustering, thus constraining our analysis to the foundation and maturity stages. We further dissected the maturity stage into two distinct periods: the 2010s and 2020–2023. Prior to the analysis, we manually rectified ambiguous or non-descriptive labels within the network, such as ‘scenarios’, ‘vulnerability’, and others identified in publications from the 2000s through 2020–2023 (refer to Supplementary Materials File S3, Tables S2–S4). A notable observation was the discrepancy in non-compliant clusters across different periods, indicative of the research’s evolving maturity (Figure 5). The 2000s marked the nascent phase of SUP research, as characterized by exploratory efforts and a lack of definitional clarity, thereby affecting cluster label generation. Conversely, the 2010s witnessed a consolidation of SUP research, establishing coherent directions and stable cluster labels. The advent of the 2020s saw a paradigmatic shift, with SUP research assimilating interdisciplinary methodologies and catalyzing innovative yet indistinct phrases recognized as co-citation cluster labels. Throughout this period, numerous emerging research topics and directions, relatively isolated in nature, surfaced, demonstrating a minimal correlation with conventional systematic research themes and directions.

The initial research direction in the 2000s emphasized urban ecology and societal components, prioritizing sustainability in residential sectors and biodiversity with a specific focus on avian studies. The subsequent decade witnessed the contraction and intensification of research themes, facilitated by inter-referential dynamics among various topics, culminating in a robust research framework. The exceptional interest in urban heat islands epitomized this era and emerged as a consistent research frontier. This period heralded the ecological reconsideration of environmental and landscape equitability. Central thematic clusters such as ‘urban ecology’ and ‘ecosystem services’ strongly influenced SUP research, branching into diverse themes, including ‘urbanization’, ‘smart city’, and others, which coalesced around the ‘urban heat island’ phenomenon. This convergence underscores the thematic fluidity and overarching research coherence. With the onset of the 2020s, ‘sponge city’ research emerged as a pivotal reference point, amalgamating a broad citation spectrum. Despite its prevalence, the ‘urban biodiversity’ theme, although an important citation attractor, exhibited a dearth of exploratory potential, suggesting a limited capacity for pioneering breakthroughs.

3.2.4. Development Trajectory of Co-Citation Clusters

We utilized CiteSpace to produce temporal visualizations of co-citation clusters, segmenting the co-citation network into distinct chronological axes to facilitate visual analysis of their evolutionary trajectories. The primary cluster labels are denoted on the right, featuring milestone articles. Informed by the previously summarised trajectory of SUP research, we partitioned the timeline into four segments. Strikingly, the graphical representations of each segment were closely aligned with the narrative descriptions of the respective phases. Over time, there has been a discernible broadening in the scope of SUP research (Figure 6), accompanied by a sustained upsurge in research intensity. Temporal visualizations enabled the clear identification of the emergence and decline of specific SUP thematic clusters. Certain themes, including ‘public lands’, ‘conservation planning’, ‘simulation modeling’, and ‘Canada sustainable development’, lack seminal works and received high citations primarily during the exploration and foundation phases, only to wane in current academic discussions. Conversely, themes such as ‘urban expansion’, ‘COVID-19’, ‘urban heat island’, and ‘nature-based solutions’ have persisted as contemporary focal points of discussion. Notably, the ‘green innovation’ cluster, a recent development, is marked by a concentrated surge in citations, underscoring the optimistic outlook for its trajectory as inferred in our cluster dependency analysis.

4. Discussion

4.1. Evolution: Historical Presence and Development Trajectories

Currently, sustainable development stands as a pivotal mission for governments as well as a substantial focus for a multitude of researchers, planners, and practitioners worldwide. However, the research content and interdisciplinary mechanisms explored by SUP are notably intricate, encompassing sub-research directions of considerable complexity. This study employs bibliometric methods and visual graphs to analyze publication activity data, research focus, progress, and trends of SUP from 1964 to the present day, considering three dimensions: discipline, keywords, and co-citation. Employing a combination of qualitative and quantitative methods, we explored in depth the advancements and future prospects of SUP research. Goal 11 in the 17 Sustainable Development Goals (SDGs) concentrates on diverse aspects of urban construction, including housing, public transportation, urban pollution, public spaces, and disaster risk reduction [18]. Additionally, SDGs encompass ensuring basic human living standards, fostering societal advancement, promoting global industrial development, attending to biological life, and fostering harmonious and friendly partnerships worldwide, constituting objectives for sustainable urban practices [18]. In light of this, our objective is to meticulously select relevant publications grounded in SUP research, aligning with the stipulated requirements of the SDGs. This endeavor aims to systematically address the broad issues reflected by SUP in the urban research interface, spanning urban physical environment planning to immeasurable human living experience and perception. In the pertinent graphical representation in the preceding text, we observe the gradual expansion of SUP research from the study of residential areas at small-scale physical spaces to encompassing all aspects of urban planning and construction. Simultaneously, the early research entry point was rooted in macro perspectives such as urban management and public environment philosophy, eventually evolving toward scientific evaluation and the scientific planning and construction research of individual objects.

In the nascent stages of urban planning, research on sustainability has been construed within a rather limited scope. The first publication was published by Brown (1964), the Environmental Health Director of the Maryland Health Department, USA. He argued that the mitigation of urban pollution necessitates a ‘we’ perspective, one that transcends the boundary of urban dwellers to include planners and environmental health professionals [49]. Brown associated urban planning with both environmental health and communal living; however, this concept of ‘us’ is patently anthropocentric, neglecting the existence and value of non-human entities. Subsequent studies have emphasized the criticality of urban public health [50], with the contradiction between public health and urban development influencing SUP. The 20th-century philosopher Lewis Mumford (1969) believed that the sustainability of cities requires people to make efforts to build a balanced and self-renewing environment that includes all necessary components, such as the prosperity of human biology, social cooperation, and spiritual inspiration [58]. Mumford (1961) asserted that revitalizing cities most effectively necessitates nurturing their core values and intellectual spirit [59]. His humanistic ethos profoundly influenced subsequent research. Sallis et al. (2006) advocated the use of ecological strategies in establishing dynamic communities [60], echoing Mumford’s ideology. Their model, which incorporates multidisciplinary methodologies, suggests innovative and interdisciplinary strategies for enhancing community spaces, transit systems, and recreational amenities and invigorating communities through resident engagement. Although sustainable practices have been perennially implemented via urban settlement pathways [61], researchers have investigated the potential advantages provided by SUP. Contemporary research has focused on public health [62,63,64], social welfare [65], psychological and physiological well-being [66,67], and environmental impacts [68]. The research subjects included children [69], adolescents [70], seniors [71], and individuals with disabilities [72]. However, Mumford’s humanistic approach restricts SUP to the ecology of human habitats. Concurrently, the urban construction process appears to have eroded the principles of residential area development [73].

Urban development research has recently pivoted from residential themes toward micro-environmental and ecological urban elements such as roadside greening [74,75], green roofing [76], open spaces [77], parks [78], and brownfields [79]. Individuals frequently depart from their residential zones, engaging in extensive physical activities that permeate various urban sectors, with transportation playing a pivotal role [80]. Transit-Oriented Development (TOD) necessitates the integration of green urbanism principles [81], placing paramount importance on pedestrian and cycling infrastructures [82]. Furthermore, an environment saturated with artificial elements and dominated by human-made structures can precipitate mental exhaustion, compromising vitality and health [83]. These findings align with the revelation of ‘#7 physical activity’ as a thematic node within the co-citation networks. Modern studies have extended the research scope beyond humans to broader biological constituents, notably avian [84,85], insect populations [86,87], and other wild animals [88]. In this narrative, collective actions contribute to urban complexities. Comprehensively, urban ecology examines the interactions among various concepts and processes within environmental cycles and assesses how societal groups and environmental factors impact the sustainability of individual units [89]. SUP research highlights the symbiosis between ecocentrism and anthropocentrism [90]. Although each facet of urban planning plays a crucial role in achieving sustainability, the challenges involved are multifaceted. The artificial environment, specifically the urban landscape, is the most fundamental aspect to be addressed [54]. Consequently, research on SUP has reverted to a comprehensive approach to urban development. Current discourse has explored methodologies for optimizing urban infrastructure [91], adapting to urban climates [92], conserving biodiversity [93], enhancing aquatic environments [94,95], mitigating urban heat islands [96], and developing strategies for cities to respond to major public events [97]. City planning requires addressing global challenges such as land utilization and cover alterations, biogeochemical cycle disruptions, climate anomalies, biodiversity depletion, and biological insurgencies [98].

In summary, prior to 1990, research in sustainable urban planning (SUP) predominantly concentrated on environmental concerns and social responsibility within urban planning. Concepts like urban greening and environmental impact assessment [99,100] were progressively incorporated into the realm of urban planning. The 1990s and 2000s witnessed a reinforcement of the sustainable development concept. During this era, urban sustainability research evolved into a more systematic and theoretical framework, encompassing various dimensions, including the economy, society, and the environment. The focus of the research expanded to encompass urban transportation, housing, social inclusion, and other critical aspects. Post-2010 witnessed a surge in data science and technology. As technology advanced, the pivotal role of data science and information technology in urban planning became evident. Research outcomes encompass the utilization of big data for urban mobility analysis [101], the implementation of smart city technology, and the incorporation of renewable energy. Since 2020, contemporary society has confronted global challenges, including climate change, urbanization, resource scarcity, environmental pollution, and the COVID-19 pandemic. Scholars have proposed diverse solutions in urban planning, such as advocating for renewable energy, establishing low-carbon cities [102], fostering community participation, and innovating urban regeneration.

4.2. Principles: Achieving Sustainability in Urban Planning

The contemporary sustainability framework perceives a city as a dynamic and heterogeneous landscape that embodies a complex, adaptive socioecological system. Within this system, the delivery of ecosystem services bridges the social and ecological domains across multiple tiers [103]. This approach integrates natural science methodologies with social science theories and recognizes the impact of the urban environment on socioecological systems well beyond city boundaries [104]. SUP broadly encompasses equity [105], reciprocity among humans and other life forms, consonance with nature, human welfare [106], progressive urban development [107], environmental refinement [108], and facets of ‘green’ initiatives, including construction [109], economics [110], culture [111], aesthetics [112,113], and policies [114]; these subjects are in tandem with ecological ethics [115], smart urbanism [116], urban agriculture [117], and public health. This resonates with both green romanticism and rationalism [118].

In surveying the extensive research domain of SUPs, we have discerned principal focal points and advocated three cardinal principles to avert uninformed and inefficacious sustainability strategies. A paramount aspect is a commitment to equity and justice. The 1960s’ urban planning veered toward modernistic, visually appealing urban contours, often at the expense of fairness or cultural considerations, given the authoritative, design-centric, and, at times, aggressive construction methodologies [119]. Jacobs (1961) contended that cities can provide something to everyone only because, and only when, they are created by nobody [119]. In 1964, Brown declared urban environmental health an inalienable right [49]. Since the 1990s, the concept of ‘smart, sustainable, resilient cities’ has permeated global urban planning and is heavily influenced by Jacobs [113]. This ideology, now at an inflection point, demands urgent reform [113]. Green gentrification [120] and insufficient greenery potentially fuel social discord [121], and the indiscriminate addition of green spaces may intensify social disparities [122]. Compounding these challenges, relentless demands for green access and ill-conceived policies can disrupt community cohesion [123] and marginalize critical racial, economic, and environmental justice concerns [124], notably in the burgeoning urban centers of developing nations. Massive and imminent urban migration will predominantly occur in regions such as Africa and Asia over the next three decades [125]. In Section 3, we engaged in a detailed statistical examination of the countries on these continents and discovered a notable absence of SUP initiatives in developing countries, especially those undergoing significant urbanization. Being previously identified primarily in impoverished shantytowns, informality is now recognized as a prevalent urbanization pattern within metropolitan regions [126]. SUP inquiries should also encompass informal land utilization [127], settlements [128,129,130], and green areas [131]. Although nature-centric urban designs are presumed to be inherently just [132], true sustainability mandates continual development to harmonize fairness, democracy, and diversity [133].

The second principle underscores the importance of this value. Sustainable aspirations in urban planning have emerged and evolved in response to various crises, with inherent uncertainties propelling the expansion of sustainability research into unprecedented realms. A fundamental question arises: Should SUP serve as a reaction to historical and geographical pressures [134], a conduit for real estate ventures and investments [135], or a rallying cry for socioeconomic resurgence [136]? The development of SUP is a multidisciplinary approach. However, this multifaceted perspective is not merely palliative for superficial security; it is a beacon leading toward innovation, especially when traditional disciplines show vulnerability [137]. This innovation must be predicated on constructive values, eschewing superficial ‘greenwashing’ [138] in favor of authentic environmental and health considerations. In the future, the collective focus may shift from advocating for the urban planning process itself [139] to a steadfast dedication to urban ecological ethics [115], positioning sustainability as a source of enlightenment in urban planning.

Concurrently, emphasizing the practice of meeting requirements has become paramount. Amidst global concerns over deteriorating urban living standards, SUP must transition from theoretical models to deciphering the underlying dynamics of observable trends [140] and establish methodologies for converting scientific insights into tangible actions [104]. Currently, designers and ecologists have initiated collaborative efforts to pioneer urban experiments that offer cultural and ecological insights [141], fostering alternative lifestyle paradigms [142]. Nonetheless, when such initiatives are spearheaded by local authorities, the constraints of compartmentalized planning and specialized acumen within these bodies become conspicuous, revealing a deficit in the frameworks for interdisciplinary integration [143]. Effective synergy among diverse fields requires concerted collaboration and synchronization among stakeholders [144], facilitating interdepartmental cooperation within governmental structures and the diverse knowledge they encapsulate, which is essential for catalyzing urban ecological design implementation [145]. Contemporary times have witnessed the continual emergence of new cities and the expansion of existing ones, yet actualizing demand remains a complex challenge. Opportunistic politicians and entrepreneurs often exploit ‘sustainability’ for their own gain within urban planning [61], proposing nominal gestures such as minimal greenery, alternative energy exploration, innovative material use, or rudimentary eco-centric infrastructural developments as adequate. If SUP practices aim solely to mitigate detrimental impacts and counteract negative political undercurrents, they are bound to encounter resistance.

4.3. Pathway: A Paradigm Shift toward Habitability

Sustainability has manifested considerable resilience, boldness, and innovation in urban planning, design, and management. In the extensive course of research, what may appear to be superfluous research findings have delineated essential correlations among human societies, the material realm, and broader ecological systems in regional and global echelons. Urban planning necessitates a paradigm shift toward sustainability, which requires the mitigation of urban disarray and ecological degradation within urban habitats. This often mandates a strategic retreat from the authoritative role of urban planning and endorsing a more harmonious coexistence and adaptability with nature [146]. Conversely, nature’s active adaptation to urban developmental strategies does not signify a concession to the Anthropocene era [147], as evidenced by the rampant spread of pandemics [148,149] and the biodiversity challenges posed by invasive species [150]. However, these adaptations offer no discernible advantages to human welfare. Accordingly, we re-engineered the urban sustainability planning framework by combining scientific insights with design methodologies. This holistic approach addresses the multifaceted aspects of sustainable development, providing a guide toward enhanced habitability (see Figure 7).

Human estrangement from nature has intensified following the Industrial Revolution. Human engagement with and exploitation of natural resources are delimited by various factors such as production [151], infrastructure [152], cultural norms [153], hierarchical structures [154,155], and racial considerations [156]. The human endeavor to dominate nature and secure sustainable advantages has paradoxically undermined these aspirations. Human relationships with nature have remained an ongoing process of trial and error [157]. Contemporary scholars utilize innovative resources such as big data [158], integrated ‘3S’ technology [159], climate-resilient [160], and low-impact developmental strategies [161] to perform urban planning that embodies sustainability principles. When applying these technologies, for humans, the correctness of behavior is the most important, and for natural feedback, effectiveness is the most important. To actualize the tenets of SUP, future inquiries must acknowledge humans and nature as co-contributors to habitability. This necessitates both an analysis of the constructed urban landscape as well as a synthesis of these insights with the intrinsic value of natural ecosystems [162].

4.4. Limitations and Shortcomings

This study, rooted in an exhaustive examination of SUP literature and employing scientometric analysis, systematically discerns the evolving knowledge base, advances, and research horizons through an analytical and discerning review. However, this method has inherent limitations. First, based on an analysis of 38,344 publications authored between 1964 and the present day, this study exclusively used data from the Web of Science database, thereby not encompassing the potential literature from other databases, such as Scopus, Dimensions, and Google Scholar. Although WoS is a pivotal repository for bibliometric analysis, this approach cannot ensure holistic literature representation. The scope of this study was further narrowed by exclusively evaluating English-language publications. Second, a considerable dataset impeded the CiteSpace 6.1.R6 64-bit Advanced and the CiteSpace 6.2.R5 64-bit Advanced software from forming an effective keyword cluster network, limiting keyword visualization analysis. Third, the predetermined minimum threshold in CiteSpace’s co-citation analysis may have skewed citation identification, potentially influencing the results.

5. Conclusions

Through incorporating 38,344 publications from 1964 to 2023 sourced from WoS, this study utilized CiteSpace, complemented by ArcGIS, to provide an intricate visual analysis that details the evolutionary trajectories and nascent trends within SUP research. This integration of quantitative and qualitative methodologies has enabled a profound delineation of the linear progression and pivotal routes of SUP research. The implementation of dual-map overlay analysis in CiteSpace elucidates the academic disciplines of both cited and citing materials, fostering a nuanced discourse on the interdisciplinary pivot and growth of SUP research from a holistic scholarly vantage point. Co-citation assessments revealed the development arc portrayed through citation clusters, structural paradigms, and reliance clusters in SUP inquiries. Methodical quantitative segmentation recognizes four distinct phases in the historical progression of SUP research, offering insights into its chronological advancements. Through generating visual networks and statistical diagrams, this study distinctly illustrates the multifaceted, interdisciplinary evolution of SUPs and their thematic knowledge matrices. These illustrative tools underscore interdisciplinary influences and dynamically capture SUP growth vectors, particularly in urban studies, landscape architecture, and ecological realms. These vectors were influenced predominantly by industrialized, urban-centric nations, with coastal states accentuating their emergent pre-eminence in these domains. This analysis provides a panoramic mapping of the contemporary landscape, foundational theories, and innovative frontiers of SUPs, facilitating a deeper interdisciplinary understanding and highlighting pivotal research motifs. This review solidifies our understanding of the inherent complexity underpinning the SUP, marked by its multidisciplinary genesis, diverse thematic pillars, and stratified research dependencies. Moreover, it evaluates the essential and interconnected corridors with the natural, societal, and historical humanities.

In short, the SUP journey, emerging from ideological currents shaped by environmental stewardship and postmodernist thought, has burgeoned into a comprehensive scientific arena anchored by a plethora of perspectives, multifaceted elements, and foundational dependencies. This development has fostered a consistent engagement with urban morphology, habitat enhancement, ecological conservation, sociocultural advancement, restorative environmental practices, human rights, social fabric, and ethical governance. In the future, confronting the rapidly accumulating corpus of SUP scholarship necessitates an appreciation of the constructive impact of interdisciplinary permeation. This perspective advocates a principled approach to sustainability, predicated on equity and justice, value articulations, and practical needs, and serves as a tripartite engine guiding the odyssey of urban planning toward symbiotic confluence and enduring advancements within the natural and social scientific continuum.