The role of informal ruralization within China's rapid urbanization

China's dramatic urbanization over the past four decades, transforming from a largely agrarian nation to one dominated by megacities, has largely been viewed through a top-down lens, minimizing the agency of rural populations within urban spaces. This research challenges this perspective by focusing on *chengshi kaihuang* (CK), an informal practice of cultivating vegetables in neglected urban areas. CK, literally translating to 'opening up wasteland in the city,' represents a bottom-up ruralizing force that reclaims and repurposes vacant urban spaces for agricultural use. The study uses Wuhan, a rapidly growing megacity, as a case study to analyze the spatial extent and impact of this informal ruralization practice. The unprecedented scale of urbanization in China provides a unique context for examining the complex interplay between top-down urban development policies and bottom-up adaptive strategies by ordinary citizens. Understanding CK is crucial for developing more inclusive and sustainable urban planning strategies that acknowledge and integrate informal practices into urban development narratives. The study aims to build upon existing scholarship on ruralization, particularly those highlighting the 'more-than-residual' processes of ruralization within urban spaces.

Existing scholarship on urbanization often portrays the rural as residual or obsolete, overshadowed by top-down forces. While planetary urbanization has expanded the concept of urban dynamics beyond traditional city limits, it has not adequately addressed rural dynamics *within* the expanding urban areas. Previous studies on ruralization primarily focus on peri-urban or suburban areas. This research distinguishes itself by examining ruralization within the central urban districts of a major Chinese megacity. While some studies have examined localized instances of informal urban cultivation, like those focusing on Hangzhou and Chongqing, they are limited in scope and lack city-wide analysis. This study aims to fill this gap by utilizing remote sensing and social media data to provide a broader understanding of CK's occurrence and impact. The study draws inspiration from existing scholarship on hybridized rural-urban phenomena in Southeast Asia, emphasizing the everyday practices of ordinary people that challenge rural/urban binaries.

This research employed a mixed-methods approach, combining remote sensing data analysis with social media data collection and contextual analysis. The social media data, gathered from Baidu News and Douyin (the Chinese equivalent of TikTok), provided valuable insights into the spatial, temporal, and physical characteristics of CK sites, as well as the social and cultural narratives surrounding the practice. This gray literature was crucial in identifying initial CK sites and understanding their context. Visual verification of CK sites was conducted using very high-resolution (VHR) satellite imagery on Google Earth Pro, enabling the identification of distinctive spatial patterns of CK. This information was then used to develop training data for a supervised machine-learning land cover classification (LCC). The LCC used Sentinel-2 multispectral satellite images from 2017 to 2022 to map CK across Wuhan's central urban districts. The random forest algorithm was used to classify CK and non-CK areas, leveraging spectral and textural features to distinguish CK from other types of land cover. The accuracy of the LCC was assessed using various metrics, including overall accuracy, kappa index, producer accuracy, and consumer accuracy. A snowballing sampling method was employed to improve accuracy by identifying and verifying additional CK sites through visual interpretation of the initial LCC results in selected sample areas. Four 3km x 3km sample areas were randomly selected for detailed analysis using VHR imagery, examining land use before and after CK emergence to understand the temporal dynamics. This detailed analysis provided insights into the emergence types and interactions of CK sites with the urban environment.

The LCC results revealed that, on average, 6.34% of Wuhan's central urban districts (approximately 12,941 acres) showed active CK between 2017 and 2022. This area significantly exceeds the known extent of urban agriculture in comparable cities. The study area contained the lowest amount of CK activity in 2018 and the highest amount in 2021. The analysis showed a clear temporal pattern: CK frequently emerges on vacant land resulting from demolition for urban development, often persisting even after removal if the land remains vacant. The land-use history analysis before CK emergence revealed five main types of conditions where CK occurred: land previously used for rural agriculture (the most common), land used as construction staging areas, land left vacant after infrastructure projects, existing urban edge conditions (e.g., riverbanks), and existing urban green spaces. Analysis of land use after CK emergence showed that approximately 69.7% of sites remained undeveloped after the emergence of CK, with some sites being subsequently redeveloped for construction or as urban green spaces. The study found that 82.2% of CK sites experience forced removal, followed by immediate development (19%), remaining vacant without CK returning (23%), or the persistent return of CK until the site was developed (40%). Social media analysis revealed that practitioners frequently used political and cultural slogans associated with hard work, self-sufficiency, and rural revitalization to justify their activities and highlight the perceived benefits of CK, like access to healthy food, relaxation, and a sense of community and connection to rural life.

The findings challenge the prevalent top-down perspective on urbanization in China, highlighting the significant role of bottom-up agency in shaping urban landscapes. The scale of CK in Wuhan demonstrates the considerable potential of informal practices to influence urban environments, surpassing the impact often attributed to other forms of urban agriculture. The study reveals how CK adapts to the spatial conditions created by the inefficiencies and rapid pace of urban development. The persistent return of CK after forced removal underscores its resilience and the unmet needs it addresses. Furthermore, the social media analysis highlights how practitioners use national narratives to legitimize their actions, navigating the tensions between informal practices and official policies. The study contributes to a more nuanced understanding of the urban-rural relationship in China, demonstrating that ruralization is not merely a residual phenomenon but a dynamic process embedded within the fabric of rapid urbanization.

This study demonstrates the significant, large-scale spatial impact of CK, an informal practice of urban agriculture, within the megacity of Wuhan. The findings challenge traditional urban-rural binaries and emphasize the importance of considering bottom-up actions in urban planning. Further research should explore the ecological, social, and economic impacts of CK, its spatial distribution beyond Wuhan, and its potential for informing inclusive and sustainable urban development strategies globally. The integration of informal practices into formal urban planning requires a more nuanced understanding of local agency and the interplay between formal and informal systems.

The study's reliance on publicly available data limits the depth of information regarding CK activities. The accuracy of the LCC might be affected by the resolution of Sentinel-2 data, potentially overlooking smaller CK sites. The social media data primarily reflects the narratives of CK practitioners and may not fully represent the perspectives of other stakeholders, such as city officials or residents. The generalizability of findings beyond Wuhan and China requires further investigation.