How Can an Urban Botanical Garden in a Densely Built-Up Landscape Develop Sustainably with Urban Renewal?—The Case of Shanghai Botanical Garden

Abstract

Urban botanical gardens collect, preserve, research, and utilize important regional plant resources and serve as ecologically friendly cores of development and renewal for urban organisms. Meanwhile, they offer garden landscape displays and public science education. Furthermore, biodiversity conservation has become important globally. Here, the connotation of urban botanical gardens is interpreted, the functional evolution of urban botanical gardens is examined, and the challenges of sustainably developing urban botanical gardens in the context of biodiversity conservation are analysed. Taking the Shanghai Botanical Garden as an example, the abilities of urban botanical gardens in high-density downtown areas to coexist with urban spaces and thrive along with cities—thus enhancing their five core functions of ex situ conservation, scientific research, popular science education, garden horticulture, and public service—are discussed. These discussions provide references for the sustainable development of urban botanical gardens in similarly high-density city centres.

1. Introduction

Botanical gardens (and arboretums) are specialized bodies responsible for the collection and preservation of live plants; they also perform important related functions, such as ex situ conservation of rare and threatened plants, scientific research, popular science education, garden displays, and public services [1]. The approximately 500-year history of modern botanical gardens has evolved via multiple modes [2]. Currently, we are in a stage where university botanical gardens, classical botanical gardens, colonial tropical botanical gardens, urban botanical gardens, and special types of botanical gardens coexist [3]. Among the various types of botanical gardens, urban botanical gardens constitute the largest group globally.

Amid the pressing challenges posed by urbanization and global climate change, urban botanical gardens, as a type of urban green space, have become crucial in maintaining the ecological balance of cities. They serve not only as the lungs of urban ecosystems but also as sanctuaries for local biodiversity, playing a crucial role in plant ex situ conservation. This importance arises from the fact that cities, as centres of dense human populations and development, are increasingly recognized as critical areas for biodiversity conservation [4]. Furthermore, the construction, management, and development of their core missions are most closely intertwined with cities and urban life.

As urbanization has progressed, many botanical gardens (and arboretums) that were originally in suburbs are now surrounded by a dense number of buildings. Given the pressures from their surrounding environment and visitors, how these old botanical gardens can sustainably develop amidst urban development and renewal is a significant issue worthy of attention. They must not only meet current demands and enhance their functions in the future, but also contribute to urban ecology and community development over the long term. The sustainable development of urban botanical gardens encompasses not only ecological conservation, but also multiple aspects, such as public education, economic promotion, community engagement, and climate adaptation [5,6,7]. Through scientific management and innovative operations, botanical gardens can significantly support urban ecosystem services, climate change adaptation, and green economic development.

Many well-known urban botanical gardens have accumulated valuable experience in sustainable development and influencing urbanization. Singapore Botanic Gardens has revitalized abandoned land around the garden through landscape restoration, as well as preserved and restored habitats within the garden, creating typical tropical forest and wetland plant communities; thus protecting one of the last remaining patches of native forest in Singapore. Additionally, the garden has built facilities such as a children’s playground and canopy walkway to provide educational and recreational opportunities for citizens [8]. Similarly, the New York Botanical Garden has preserved the Thain Family Forest, one of the only remaining old-growth forests in New York City [9]. By controlling invasive species, restoring native species, and improving water resource management [10], they have ensured that this ecosystem remains intact amidst urbanization. Moreover, many of the garden’s historical buildings have been repurposed as research and educational facilities, following green building standards to reduce energy consumption and carbon emissions. For example, the Hauser Science Center was designed to meet sustainability standards while optimally utilising limited space [11].

Therefore, the meanings and roles of urban botanical gardens are explored, and the evolution of their functions, dilemmas and challenges related to sustainable development within the context of global biodiversity conservation are analysed. Using the Shanghai Botanical Garden as an example, this paper explores how urban botanical gardens can coexist with urban spaces and thrive alongside urban renewal in terms of construction, management, and the development of core functions.

2. Development of Urban Botanical Gardens

2.1. Definition

The urban botanical gardens discussed in this paper refer mainly to botanical gardens (including arboretums) located in urban built-up areas (city centres or suburbs). These gardens not only carry out the core functions of plant collection and ex situ conservation but also play important roles in public science education by presenting featured garden landscapes and providing recreational services, owing to their proximity to urban communities. Additionally, their staff provide scientific guidance and technical support for building urban ecological foundations.

Considering their development worldwide, urban botanical gardens typically refer to those built in urban areas and suburbs after the mid-19th century. This type of garden is currently the most common and numerous type of botanical garden. In a broader sense, urban botanical gardens also include those established before this period that have undergone functional changes in response to social and economic development. For example, Singapore Botanic Gardens, a typical example of urban botanical garden, transformed from a tropical colonial botanical garden into a world-renowned UNESCO world heritage site.

2.2. History of the Development of Urban Botanical Gardens in European and American Cities

The origins of urban botanical gardens can be traced back to the rise of modern botanical gardens in 16th-century Europe, while their function as urban public spaces gradually took shape during the urbanization processes of the 19th century.

In the 16th century, botanical gardens were typically situated near universities or academic institutions and primarily used for education about medicinal plants [12]. As botanical research advanced across Europe, many cities began establishing botanical gardens to showcase plant species from around the world and to promote the dissemination and education of botanical knowledge. The significant development of urban botanical gardens occurred in the 19th century.

In the mid-19th century, urban botanical gardens were built as part of the park movement in Europe and America. Urbanization during this period expanded the functions of botanical gardens from scientific research to recreation. The Industrial Revolution in developed countries accelerated urbanization, leading many people to flock to cities. However, the limited number of royal and noble gardens available to the public could not meet the recreational needs of the growing urban population. This situation led to the creation of many projects, including urban park green spaces and urban botanical gardens. At this time, urban botanical gardens focused on displaying horticultural landscapes and providing public leisure services [13]. Compared with typical parks, they had significant advantages in terms of plant diversity, maintenance standards, and landscape effects [14]. This is largely due to the expertise of horticultural engineers, who provide targeted and professional maintenance based on the needs of various species, resulting in richer and more beautiful landscapes. However, the botanical work in urban botanical gardens during this period, especially in the United States, involved only basic tasks such as plant collection, exchange, and labelling, and lacked scientific botanical research and the development and utilisation of plants [15].

With advancements in plant evolution theory, plant taxonomy, and ecology in the mid-to-late 20th century, urban botanical gardens began to exhibit and convey more findings in botanical science. On the one hand, garden spaces consisted of several specialized gardens categorized via various classification methods, such as plant category, native habitat, and ornamental characteristics. Examples include rose gardens, herbal gardens, tropical and subtropical greenhouses, and alpine plant areas. These were combined with topography and various landscape designs to showcase the views in modern urban botanical gardens, which highlighted a rich variety of plants and beautiful scenery. On the other hand, the functions of botanical scientific research expanded to include plant species introduction and collection, domestication and breeding, and resource development. The core functions of plant conservation, development, and utilization complemented the service functions of popular science education and garden displays. Urban botanical gardens became urban ecological patches undertaking multiple missions.

Due to factors such as environmental pollution, global climate change, and human interference in the 21st century, global biodiversity has greatly decreased. In the past, the main function of botanical gardens was to study plants, aiming to enhance their utilization through selection, comparison or breeding. Since the 21st century, the focus of botanical gardens around the world has shifted from utilization to protection, especially after the International Agenda for Botanic Gardens in Conservation and the Global Strategy for Plant Conservation (adopted at the Convention on Biological Diversity Conference of Parties VI, April 2002) [16]. In this new era, the core goal of botanical gardens is mitigation of the adverse effects caused by biodiversity loss. Botanical gardens worldwide preserve 30% of all plant species diversity and protect over 41% of known endangered species [17]. Botanical gardens, together with national parks and nature reserves, have formed a biodiversity conservation network in which ex situ conservation and in situ protection are combined. Botanical gardens are usually located in urban areas, which are hotspots of biodiversity conservation [18]. In addition to the maintenance of collections, more and more urban botanical gardens focus on what plant species or plant communities contribute to the resilience of ecosystems, protect and restore plant species in the wild, and promote education and community engagement.

2.3. Overview of the Development of Modern Botanical Gardens in Chinese Cities

The development history of botanical gardens in China can be traced back to about 5000 years ago [19], while modern botanical gardens in China have undergone approximately 100 years of development, covering five stages with three peak periods of development [20]. The drivers underlying the construction of Chinese botanical gardens and the core functions of botanical gardens during these three peak periods have continuously been adjusted to reflect China’s economic development trends and urbanization process. The first peak period (1950–1964) focused mainly on systematically restoring the plant science system and fostering botanical talent. The second peak period (1980–1994) aimed to meet the planning and layout of urban green spaces and residents’ recreational needs in the process of urbanization, with a focus on urban landscape and public service functions. The third peak period (1995–2020) emphasized plant diversity protection and sustainable utilization, integrating functions such as plant conservation, scientific research, public education, and resource utilization for scientific development.

3. Impact of Urbanization on the Development of Urban Botanical Gardens

3.1. Site Selection and Distribution of Urban Botanical Gardens

The process of urbanization has a significant effect on the site selection distribution and functional transformation of urban botanical gardens. As cities expand and the resource pressures increase, the role and strategies of urban botanical gardens are continually adjusted.

3.1.1. From the City Centre to the Suburbs

With the advancement of the industrial revolution and accelerated urbanization, an influx of people into cities increased the demand for public spaces, green areas, and ecological protection. Consequently, many botanical gardens were established in city centres during this period to provide ecological leisure spaces for urban residents. However, as urbanization approached saturation, land in city centres became increasingly constrained. This shift prompted the construction of new botanical gardens in suburban areas, which offered more available land for diverse planting and ecological protection projects.

For example, in the United States since the mid-19th century, approximately 60% of botanical gardens have been located in rapidly urbanizing areas. Following the completion of urbanization in the 1970s, suburban areas became preferred locations for new botanical gardens. Among the 13 newly built botanical gardens since then, only 2 were built in urban areas. In the United Kingdom, the earliest botanical gardens were also located in more developed cities. From the mid-19th century to the mid-20th century, with the development of the Industrial Revolution, the number of botanical gardens grew in both urban and suburban areas. By the mid-to-late 20th century, the majority of new botanical gardens were built in suburban areas [21].

3.1.2. Multi-Garden Layout in One City

Historically, cities typically housed only one botanical garden. However, as cities expanded and populations grew, a single botanical garden became inadequate to meet the diverse needs for urban ecological protection, scientific research, education and citizens’ leisure. As a result, more cities are opting to build multiple botanical gardens that can undertake different tasks or cooperate according to regional characteristics and functional divisions. Many famous metropolises, such as London, Washington, Chicago, and Tokyo, have established additional botanical gardens in new areas. Shanghai, a metropolis in China, already has two botanical gardens. Beijing and Hangzhou are planning to build a second botanical garden. This distributed botanical garden system helps cities address the challenges posed by urban development.

3.1.3. Suburbs Become Downtown

Urban expansion and the rapid development of residential and commercial areas have encroached upon former suburban green spaces, pushing them into city centres. Many botanical gardens initially located in suburban areas are now surrounded by buildings which are densely populated. Already, some older botanical gardens in Europe and the Mediterranean region are now surrounded by massive building development [22]. In China, many botanical gardens built in suburbs during the 1950s and 1980s became downtown botanical gardens surrounded by densely populated residential or commercial areas. For instance, the Shanghai Botanical Garden, built in the last century, was initially located on the city’s outskirts. However, as the city has expanded, it has gradually become enveloped by residential and commercial developments, and it now serves as an important green space in the centre of Shanghai. These urban botanical gardens face challenges related to urban development and renewal, resource restrictions and functional transformation, owing to limited land resources and established tree landscapes.

3.2. Common Problems Facing Urban Botanical Gardens

3.2.1. Limited Land Provision

The development of botanical gardens relies on species introduction and conservation, which requires the support of plant introduction nurseries and experimental bases, as well as sufficient space to accommodate diverse plant species and habitats. However, the boundaries of botanical gardens are surrounded by residential areas, commercial buildings, and urban road networks or waterways, which limits the expansion of development space. The urbanization process places significant spatial competition pressures on these gardens. Limited urban land resources mean that the demands for real estate development and infrastructure construction frequently conflict with the needs of botanical gardens, preventing further expansion or modernization. The variety and number of plant species within the garden are constrained by space limitations, making it particularly difficult to protect species that require larger habitats. Maximizing the limited space available for biodiversity conservation are urgent concerns that urban botanical gardens must tackle.

3.2.2. Spatial Balance Between Scientific Research and Public Education

Botanical gardens serve dual roles as scientific research institutions and public education venues. Beyond their responsibilities for plant ex situ conservation, botanical gardens also provide urban green spaces for tourists and local residents. Scientific research activities need a quiet and focused environment, while public entertainment needs demand open, interactive facilities. Inappropriate behaviours by visitors, such as loud singing, trampling, or plant picking, disturb the flora and fauna of green spaces. How to handle space balance and attract more public participation to improve their environmental awareness through botanical garden education projects while meeting the requirements of scientific research activities is a key challenge for the sustainable development of urban botanical gardens.

3.2.3. Pressure from the Urban Environment

The ecological functions of urban botanical gardens can be weakened by the negative factors of urbanization. Urban exhaust, the heat-island effect, noise and light pollution are also significant. These disturbances affect the natural phenology of plants to some extent. Due to the influence of the urban heat-island effect, temperatures within urban centres (where botanical gardens are located) are often higher than the surrounding natural environment, which affects the growth environment of plants [23]. The intensity of this effect varies across cities, with warmer urban centres exerting greater pressure on trees, making them more susceptible to pests and diseases [24].

3.2.4. Climate Change

Global warming affects the present and future of botanical gardens. Research on climate predictions indicates that the annual average temperature of many cities will rise to varying degrees in the future [25]. Extreme climate events are increasing. For example, in summer, there will be more heat waves, and the temperature at night will rise faster than during the day. Moreover, the rainfall pattern will become more extreme, the dry season will become drier, and the rainfall in the rainy season will increase, which may lead to more frequent floods. Botanical gardens are particularly sensitive to climate change due to their characteristics of cultivating diverse plant species. Rising temperatures, changes in precipitation patterns and extreme weather causes damage to existing conserved species. For example, the freezing rain of 2023 in Wuhan killed a tree that had been preserved ex situ for approximately 50 years. Similarly, in 2022, the drought in the UK resulted in the highest recorded mortality for trees and shrubs at Kew Gardens [26]. However, global warming enables the introduction of species that previously would not have survived [22,27,28]. To adapt to climate change, botanical gardens must adjust their planting strategies, including the introduction of resilient plant varieties and studying the impacts of climate change on plant physiology and ecology. This necessitates a reassessment of conservation techniques and future goals, placing higher technical demands on garden managers.

4. Shanghai Botanical Garden

4.1. Basic Information of Shanghai Botanical Garden

Established in 1974, the Shanghai Botanical Garden covers an area of 81.86 hectares and is located in the central urban area of Shanghai. It has 24 specialized gardens and 2 greenhouse groups (Figure 1). The southern area features the traditional Northeast China garden landscape style, whereas the newly developed northern area presents a modern exquisite horticultural landscape style with open woodlands. Notably, the Penjing Garden and the Orchid Room are two specialized gardens with unique characteristics, and both the Shanghai-style bonsai technique and the orchid cultivation technique have been listed as intangible cultural heritages of Shanghai. The Shanghai Botanical Garden has long been committed to the ex situ conservation of rare and endangered plants. Currently, it preserves approximately 10,500 plant species (including varieties), among which there are a total of 341 rare and endangered species (Figure 2), making it an “urban sanctuary” for rare and endangered plants. The observed wildlife includes 171 bird species (Figure 3), 5 amphibians, and 8 reptiles. Owing to limited land availability in the city centre, a large portion of gardens are used for display, whereas conservation nurseries for scientific research account for less than 10% of the total area.

4.2. Impact of Shanghai Urban Development and Renewal on Botanical Gardens

In addition to the common challenges faced by urban botanical gardens, the Shanghai Botanical Garden has encountered unique issues resulting from urban development and renewal.

Shanghai, which is located on the eastern coast of China, has a subtropical monsoon climate. With a resident population of 24.8943 million, it is a megacity in China. In 2023, Shanghai proposed restoring the city’s natural ecosystem and creating a biodiversity-friendly city. By focusing on the development of the Yangtze River and Huangpu River, “Around-the-City Ecological Park Belt”, and “Thousand Parks Project”, the city aims to improve the quality of its urban and rural ecological environment. Under the concept of “People-Centred Urban Development”, an increasing number of urban parks have removed their walls. Following this trend, the Shanghai Botanical Garden cancelled its admission fee two years ago. Currently, this 81.86 hectare botanical garden receives 3.8 million visitors annually; entry is free of charge. Most of the visitors are elderly residents living nearby. The constant flow of visitors places considerable pressure on maintenance and management.

The removal of entrance fees has also affected the garden’s finances. As a municipal institution, the garden previously received around 70% of its annual operating budget from the government before 2021, with the remainder being generated through main entrance ticket sales, educational activities, and venue rentals. However, since implementing free admission in 2021 (with only a few specialized gardens, such as the exhibition greenhouse, orchid house, and bonsai garden still charging fees), nearly the entire annual budget of approximately 100 million yuan now comes from government funding. Although the total budget has remained unchanged, the current annual visitor numbers have increased by 30% compared to before the introduction of the free admission policy. Consequently, the Shanghai Botanical Garden must expand its operational projects and educational activities to enhance the quality of the garden and better serve the growing number of visitors.

The removal of entrance fees is a crucial step towards increasing accessibility to the Shanghai Botanical Garden. In the future, the garden may pursue further openness by removing parts of its perimeter walls. Xuhui District, where the Shanghai Botanical Garden is located, is the centre of southern Shanghai. It features the southern section of the Huangpu riverside and is intended to be developed into a world-class waterfront reception area in the future. This section of the Xuhui riverside is only 3 km away from the Shanghai Botanical Garden. In the latest Xuhui riverside plan, many old residential areas are undergoing renovation, and the Shanghai Botanical Garden has become the only large green space in this community (Figure 4). To gain better access to shared green space, many citizens hope that the Shanghai Botanical Garden can become an open green space such as New York City’s Central Park. Therefore, the Shanghai Botanical Garden may have its walls removed. Ex situ conservation, scientific research, and the sustainable use of plant resources are essential features that differentiate botanical gardens from ordinary urban parks and green spaces. Supporting these three functions involves much greater management complexity and requires more stringent control over human disturbances compared to common urban green spaces. The act of demolishing walls would present multiple challenges, such as maintenance difficulties, resource security, and uncontrolled interference with scientific research.

The Shanghai Botanical Garden is not the only botanical garden in the city; therefore, it also faces the challenge of developing in a complementary and differentiated manner alongside another botanical garden. In addition to the Shanghai Botanical Garden, Shanghai has the Chenshan Botanical Garden, located in the suburbs, which has been in service for 14 years and covers 207 hectares. The two botanical gardens that serve the same city need to be developed in a different manner.

4.3. Solutions

In addition to the common challenges faced by urban botanical gardens, such as overall spatial limitations, internal competition for resources, urban environmental impacts, climate change challenges, and the isolation akin to islands, the Shanghai Botanical Garden confronts unprecedented challenges related to resource management, including the removal of entrance fees and partial perimeter walls.

Despite these difficulties, the Shanghai Botanical Garden has a significant opportunity to evolve into a national botanical garden. According to the national botanical garden system layout plan in China, national botanical gardens should fulfil five main tasks: establishing an ex situ conservation network, creating a scientific research platform, promoting the sustainable use of plant resources, enhancing public education systems, and improving horticultural quality. In line with current challenges and the overall development goals of Shanghai, the Shanghai Botanical Garden plans to adopt the following six strategies for future work. The first three focus on internal adjustments within the garden, whereas the latter three emphasize the collaboration and service functions of the botanical garden to the city and communities.

4.3.1. Adjustment of the Species Introduction Strategy

In the context of rapid urbanization and global climate change, the Shanghai Botanical Garden must adapt its species introduction strategy to ensure long-term sustainability. Given the unique ecological challenges posed by the dense urban environment, such as the urban heat-island effect and pollution, it is critical to introduce species that are both resilient to these stresses and aligned with regional biodiversity goals.

Building on existing conservation efforts for wild and endangered species in East China, the botanical garden will focus on introducing resilient plants from the Yangtze River Delta and southern China. Recent studies have indicated that by mid-century, the average temperature in Shanghai will rise by 1.5 to 2 °C, with a significant increase in the frequency of extreme weather events [28]. Therefore, species such as Camellia japonica and Osmanthus fragrans, known for their tolerance to high temperatures and water stress, will be prioritized to enhance ecosystem stability. These resilient species will be selected based on their proven adaptability to extreme weather patterns, including heatwaves, typhoons, and prolonged rainy seasons.

Additionally, the quantity and variety of existing conserved plants will be strategically reviewed and adjusted. Many of the current species, while historically significant, have become overly common in urban green spaces and do not significantly contribute to biodiversity conservation. Species such as Cinnamomum camphora, which now occupy large areas at high densities, lead to suboptimal growth forms and reduced ecological function. Through adaptive management practices, including targeted thinning, selective cutting, and transplanting, the Shanghai Botanical Garden will gradually reduce the dominance of these species. This process will allow available space for the introduction of more ecologically valuable and endangered species, in line with the garden’s mission to serve as a biodiversity refuge within the urban matrix.

Furthermore, ongoing monitoring using remote sensing technology and ecological health indicators will inform future species selection and management decisions. The dynamic nature of this strategy ensures that the garden remains responsive to both climate fluctuations and the pressures of urban renewal, allowing it to continue functioning as a critical conservation node in one of the most densely populated cities in the world. This project aims to address the crisis caused by global climate change and support the development of the Shanghai Botanical Garden for the next century.

4.3.2. Concentrated Subspecies for Research

The limited space in gardens cannot support extensive species introduction and conservation or in-depth research; thus, the introduction targets are concentrated. The Shanghai Botanical Garden has adopted a focused strategy for introducing subspecies with high conservation and research value, particularly emphasizing azaleas, camellias, and irises. Key future initiatives include the establishment of a collection centre for low-elevation rhododendron resources and research on salt-alkali-tolerant rhododendrons. Additionally, over 50 new camellia varieties have emerged from ongoing germplasm innovation, while the largest collection of iris resources in China will prioritize the germplasm innovation of native candy irises.

To tackle climate change challenges, the garden will study the adaptive traits of these plants under extreme conditions. Certain camellia subspecies have shown resilience to high temperatures and prolonged drought, positioning them as ideal subjects for research on urban adaptability. Furthermore, experiments on rhododendron pollution resistance will aim to identify solutions for greening efforts in large cities such as Shanghai.

In terms of endangered species conservation, the garden will focus on native orchids, many of which are threatened in China [29]. Research will investigate their endangerment mechanisms and facilitate wild reintroduction efforts.

The limited land area supports fewer but more valuable scientific research projects. These initiatives align with the garden’s existing resources and research foundation, allowing for fewer but more impactful scientific projects. By concentrating on these specific subspecies, the Shanghai Botanical Garden aims to contribute to both regional and global conservation objectives.

4.3.3. Rebuilding Biodiversity Conservation Habitats in Core Areas

The goal of enhancing specialized gardens is to create biodiversity-friendly habitats. Instead of the conventional enclosed garden model, a self-renewing natural vegetation approach will be adopted to form resilient green spaces and create new natural community configurations with a combination of trees and ground cover. This dynamic, adaptive vegetation strategy facilitates natural succession processes, leading to richer and more stable ecological communities. Studies have demonstrated that natural regeneration processes can enhance biodiversity by providing a mosaic of microhabitats that support various species across different successional stages [30]. Such composite landscape spaces aimed at creating biodiversity-friendly habitats allow for a greater variety of plant species to be displayed per unit area, which is especially valuable in densely populated urban environments.

To ensure the sustainability of these newly created biodiversity-friendly habitats, the Shanghai Botanical Garden will implement long-term monitoring and adaptive management strategies. Advanced technologies, such as remote sensing and biodiversity indices, will be used to track ecological changes. Through adaptive management, the species composition and habitat structure can be adjusted in response to changing environmental conditions, ensuring that the garden continues to function as a dynamic conservation space under urban pressures.

The biodiversity-friendly habitats established in the core area align with conservation priorities in the Yangtze River Delta, such as the restoration of native flora in the Yangtze River Delta region. This initiative enhances urban green infrastructure by providing critical habitat patches that serve as ecological stepping stones within a highly fragmented urban landscape.

4.3.4. Resource Sharing and Collaboration

The majority of the Shanghai Botanical Garden’s space is allocated for public access to accommodate the large number of visitors each year, making its non-public research nursery land both limited and precious. Given the high value of land resources in the city centre, the Shanghai Botanical Garden seeks additional resources and collaborations outside its existing constraints.

For instance, the garden collaborates with agricultural and forestry enterprises to establish bases in the suburbs of Shanghai for seedling propagation and plant conservation, supporting researchers in cultivating new varieties and propagating rare and endangered plant seedlings. Additionally, by sharing some key laboratories and large nurseries located at the larger Chenshan Botanical Garden in the suburbs, the garden can conduct experiments that cannot be supported under current conditions.

The complementary collaboration between the two botanical gardens comprehensively promotes research related to urban green space patterns and biodiversity conservation in megacities. The surrounding environment of Shanghai Botanical Garden is predominantly urban, consisting of buildings and commercial areas, with a plant community that has been established for 50 years. In contrast, the Shanghai Chenshan Botanical Garden is adjacent to a few residential areas and farmland, having been developed only 14 years ago. Based on the differences in establishment periods, geographical locations, and surrounding environments of the two gardens, a research project titled “Biodiversity Maintenance Mechanisms and Monitoring Based on the Botanical Garden Spaces and Typical Surrounding Green Areas”, has been initiated. Researchers utilize over 20 years of high-resolution satellite imagery, aerial photos, literature, and historical records to identify the origins and dynamic patterns of urban habitats represented by remnant habitats and newly established green spaces.

This investigation and ongoing monitoring, conducted by the Shanghai Botanical Garden in collaboration with the Chenshan Garden, reflect the biodiversity and its dynamics in the urban centre and suburbs of Shanghai. By integrating landscape characteristics and environmental factor measurements, key factors influencing the patterns and dynamics of green space biodiversity can be identified, revealing the constraints and maintenance mechanisms for enhancing urban green space biodiversity. This collaboration can foster broader and more comprehensive ecological research, enhancing the role of botanical gardens in urban environments. The findings will provide scientific evidence for policymakers, guiding the emphasis on ecological protection and biodiversity maintenance during urban renewal processes.

4.3.5. Integration of the Garden into Urban Renewal

The concepts of “People-Centred Urban Development” and “Park City” proposed by the Shanghai government aim to enable citizens to access more urban green spaces; consequently, many parks have removed their walls. In line with this trend of urban renewal, the Shanghai Botanical Garden has been requested to remove some of its walls to enhance ecological benefits for the surrounding residents. In certain areas, the garden has removed or lowered the height of its walls, integrating with the adjacent communities, in conjunction with urban blue-green corridors and public space systems. These blue-green corridors have become part of the urban ecological network, connecting various green spaces and water bodies, which facilitates species migration and biodiversity. Additionally, this approach promotes interaction among neighbours by enhancing the accessibility and openness of the garden, providing residents with more green spaces and recreational areas.

The partial removal of walls presents a challenge in balancing public access with the preservation of the garden’s core research and conservation functions. To address this challenge, the garden will implement zoning and time-based management strategies, preserving key research areas to ensure resource security, while opening other sections for educational and recreational activities.

Additionally, advanced technologies will be employed to monitor the impact of public activities on biodiversity and ecological health, such as lawn trampling intensity and noise from recreational activities. These data-driven management approaches will enable the garden to respond dynamically to emerging challenges, ensuring a balance between its conservation goals and public engagement.

4.3.6. Citywide Network of “Botanical Garden Plus Community Botanical Garden”

As the main organizer of the Shanghai (International) Flower Show, the Shanghai Botanical Garden conducts city-wide flower exhibitions to promote new and improved plant species, and provides services for habitat restoration and urban greening efforts. Moreover, the Shanghai Botanical Garden has collaborated with the government to launch the Community Botanical Garden project, which uses community botanical gardens as platforms to promote plant resources and habitat creation techniques for urban green spaces, schools, and communities (Figure 5).

Community Botanical Gardens involve the transformation and functional enhancement of small urban green spaces, such as pocket gardens, community gardens, and campus greens; integrating the scientific research, biodiversity conservation, and resource utilization outcomes from botanical gardens. This makes them new types of urban green spaces with significant scientific relevance. Community botanical gardens serve as important vehicles for the national botanical garden’s outreach, functioning as conservation sites for plants while also facilitating public educational activities.

One representative initiative of this project is the Magnolia zenii planting programme in schools. As a plant endemic to China, Magnolia zenii has a very limited population in the wild, and is primarily found in scattered locations, making it a typical example of a critically small population species. The Shanghai Botanical Garden collaborates with the natural habitat of Magnolia zenii at Baohua Mountain National Forest Park in Jurong, Jiangsu Province, to conduct conservation research that combines in situ and ex situ protection [31]. Moreover, the garden partners with Shanghai High School to plant this endangered tree species on campus, engaging students as citizen scientists in monitoring the phenology of this endangered species.

One of the benefits of this practice is that it allows for the monitoring and protection of important species across more urban green spaces, enabling species that require larger habitats to be preserved in off-site urban environments. Furthermore, it also explores means for citizen nature education through cooperation between botanical gardens and both schools and communities. This urban botanical garden closely collaborates with other parks, green spaces, nature reserves, and plant research institutions by increasing interactions. It has responded to the needs of local communities through horticultural displays, plant collection and conservation, and various activities, conveying concepts of biodiversity conservation and sustainable development to the public. Additionally, it provides vital tools for citizen science, encouraging local communities to participate in species monitoring and habitat protection efforts. These activities represent one of the most significant objectives of urban botanical gardens in urban and community development.

5. Summary

Urban botanical gardens are a special type of ecological space. They are not only the key green core of urban organisms but also the ecological signature reflecting the core values of cities. The integrated development of botanical gardens and a city should be achieved by blending their boundaries with the city and allowing their core functions to serve the city. The Shanghai Botanical Garden, an old botanical garden in a densely populated central urban area, enhances its core while extending its functions and sharing its techniques with the entire city. The botanical garden and the city coexist within the urban system, and the construction of infrastructure is closely linked to human activities and ecosystem services, providing technical support for urban greening and creating biodiversity-friendly habitats. This case may provide some implications for the sustainable development of urban botanical gardens in other high-density urban areas worldwide that face similar challenges.