Community-scale biodiversity conservation in cities

After three decades of setting elaborate biodiversity goals and failing to meet them, global biodiversity conservation is in need of a revamp. The post-2020 Kunming–Montreal Global Biodiversity Framework has brought new hope to global initiatives, but new approaches to implementation are required to ensure its future does not resemble the failed outcomes of decades prior. One area ripe for rethinking is urban biodiversity conservation. Current approaches to conservation in cities need to move beyond critiquing the impacts of urbanization on biodiversity and toward positive interventions to leverage the potential of cities to contribute to a more sustainable and biodiverse future (Kendal 2023). Although biodiversity conservation efforts have previously been pursued in urban settings (Mumaw et al. 2019, Kendal 2023), current global policies, investments, and the implementation of multilateral commitments still predominantly focus on nonurban areas distant from cities. When urban areas are the focus, biodiversity conservation efforts tend to prioritize natural or seminatural settings within urban areas, such as urban parks and wetlands. Rather than imposing conventional conservation models on urban settings, urban biodiversity conservation requires a radical rethinking. Community-scale design can move conservation approaches away from models based on isolated parks or preserves and toward more human-integrated urban conservation. Urban expansion is a main driver of local species extinctions and has also led to the decline of native species worldwide (McKinney 2002). As the global urban population is poised to grow by 2.5 billion over the next 30 years, urban land conversions are anticipated to continue apace, causing largescale habitat and biodiversity loss (Simkin et al. 2022). Through both direct (fragmentation and degradation of habitats, pollution, and invasive species) and indirect drivers (food and material consumption) urbanization has posed wide-ranging spatiotemporal threats to biodiversity. These threats urbanization poses to biodiversity are well known. Less explored are the potential approaches through which cities can be used to achieve biodiversity conservation. Diverse species can indeed thrive in urban habitats. Although species density may decrease along the rural–urban gradient, unique native species can persevere in cities (Aronson et al. 2014). Of the 36 biodiversity hotspots identified by Conservation International, for example, 34 include urban areas. Some species, such as the peregrine falcon (Falco peregrinus), in fact exhibit higher survival or breeding success rates in urban than in rural areas. Cities can also serve as a refuge for biodiversity, supporting populations that are threatened in regional landscapes or assisting wildlife during periods of environmental stress or extreme climate events (Knapp et al. 2021). Urban conservation does not rely on maintaining pristine natural environments but, rather, on actively engaging in collective habitat management through artificially constructed green infrastructure such as parks, gardens, and roadside trees or through individual activities, such as pet ownership and yard management (Knapp et al. 2021). In this way, cities themselves can become laboratories for innovative human–nature integrated solutions to global biodiversity conservation. Urban conservation also goes beyond biodiversity. It can synergistically address multifaceted issues across various urban domains, including urban sprawl, air pollution, public health and well-being, and climate change. Although science-based biodiversity initiatives are gradually being adopted by governments—such as the City Biodiversity Index developed by Singapore and local biodiversity strategy and action plans developed in the City of London—these agendas must be better integrated into larger processes of urban planning. By reshaping existing urban infrastructure, biodiversity conservation represents a holistic endeavor requiring collaboration across diverse disciplines, scales, and sectors to foster transformative change. The scale at which urban conservation happens is important. In the twenty-first century, conservation projects have marked a shift away from centralized project-based approaches through a set of explicit, quantifiable, and measurable goals and toward dispersed grassroots-level initiatives. For decades, urban green spaces such as community or private gardens and cemeteries have been frequently overlooked by ecologists, conservation scientists, and urban planners, despite constituting 36%–47% of total vegetation coverage in cities (Wellmann et al. 2020). Now we have the chance to target these areas in a way that moves beyond exclusive conservation spaces. Gardens are horticultural systems in which food and flower production dominates alongside other social and recreational activities. Gardens typically have wildlife-friendly elements positively correlated with biodiversity (Goddard et al. 2013). Although urban gardens have a positive effect on biodiversity, they have gained attention mainly in developed countries (Kingsley et al. 2021). Yet, developing countries can also benefit from conservation spaces integrated throughout urban landscapes. Indeed, a biodiversity protection strategy that is not as expensive and exclusive as private gardens, and not as ....Global South. Habitat gardens in Shanghai provide a unique example of community-scale conservation for cities. Integrating both habitat and garden elements, habitat gardens provide habitat functions for wildlife, as well as garden and recreational functions for humans (figure 1). They are also suitable for construction at the level of the community, such as through schools, libraries, and corporate spaces in high-density urban areas. Preferred locations are vacant brownfields and other abandoned or overlooked urban areas. The habitat garden model in theory and in practice. (a) Diagram illustrating the three zones of a habitat garden. (b) Comparative images before (1 and 3) and after (2 and 4) the establishment of the habitat garden in Changning District, Shanghai. (c) Map showing the distribution of habitat garden sites across Changning District. (d) Photos illustrating typical elements within the habitat garden, including ecological features in the habitat zone, such as a small pond (1) and Benjieshecken (2); artificial structures in the observation zone, such as camera trapping (3) and an observational partition wall (4); and facilities in the recreational zone, such as children's play equipment (5) and an educational fun wall (6). Photograph: Rongfei Su. Shanghai's experimentation with habitat gardens began in 2017, within residential areas along potential wildlife migration paths. The effort was spearheaded by The Nature Conservancy (TNC), in partnership with the Shanghai municipal government, in an attempt to explore innovative nature-based solutions in megacities. Their exploration revealed numerous spaces that, more or less abandoned, had developed into minimally managed but complex vegetation communities, creating sanctuaries for urban bird species. In an attempt to better integrate these spaces into the urban landscape while not disrupting their habitat functions, TNC and the municipality held collaborative discussions with residence committees and community members. The first habitat garden, Hongxu Habitat Garden, in Changning District, Shanghai, was inaugurated in 2019. By 2023, a total of 23 habitat gardens had been established across Shanghai's Changning District (figure 1c), extending from residential communities to schools and malls, thereby forming a network for biodiversity conservation in conjunction with nearby green spaces and water bodies. In partnership with TNC, local street communities, Shanghai universities, and civilian environmental organizations together formed the Habitat Cocreation Alliance to manage this network of urban biodiversity corridors. More than 400 species of shrubs and flowers, all native, were added to the gardens. Subsequent observations recorded over 70 species of wild animals, including the Siberian weasel (Mustela sibirica), the Amur hedgehog (Erinaceus amurensis), the raccoon dog (Nyctereutes procyonoides), Pallas's squirrel (Callosciurus erythraeus), the little egret (Egretta garzetta), and the black-crowned night heron (Nycticorax nycticorax) living in the vicinity. Habitat gardens are designed similarly to protected areas, including a core area, buffer zones, and peripheral areas; but they are integrated within community spaces at a very small scale. Of the three zones—the habitat zone, the observation zone, and the recreational zone—the habitat zone is essential, whereas the latter two are optional. The elements of habitat gardens are designed on the basis of the foraging, nesting, and reproductive habits of organisms to maximize the biodiversity conservation value of the garden ecosystem. Several steps are needed to design and evaluate the effectiveness of habitat gardens, such as a site survey and assessment, conservation network constructions, strategies guidance, design and construction, coordination, maintenance, and monitoring. By following this comprehensive planning process, habitat gardens can be established as integral components of urban ecosystems. Cities are complex, interdependent social–ecological–technological systems. To achieve radical improvements in urban conservation, it is essential to integrate system-based approaches into urban policy, planning, design, and management. Such integration should enhance connectivity among sectors and levels, taking into account the biophysical, socioeconomic, and cultural factors that shape urban ecosystems (figure 2). Although urban conservation initiatives can be found in various cities in the Global North, including urban greening projects in Cleveland, Ohio, in the United States (Turo and Gardiner 2020), and community gardens in Ottobrunn, Germany (Egerer et al. 2024), habitat gardens are more focused on simultaneously delivering integrated biodiversity conservation and recreational and aesthetic benefits. Framework for planning, constructing, and maintaining habitat gardens. Although functioning at the community scale, habitat gardens require both bottom-up collaboration and top-down resources and support. They demonstrate that community conservation requires not only active, full lifecycle public engagement but also external technical and financial support, especially in cities in the Global South. In urban spaces, community conservation efforts also require a delicate balance to achieve both human and biodiversity benefits. Going beyond conventional biodiversity conservation measures (such as protected areas and national parks) while also eschewing narrower approaches to urban greening that do not consider species habitats, habitat gardens represent a vital step in initiating more community-based conservation projects in cities and creating actionable pathways to support the post-2020 biodiversity agenda. Rongfei Su, Shiyu Ye, Nan Jia, and Ruishan Chen ([email protected]) are affiliated with the Department of Landscape Architecture, in the School of Design at Shanghai Jiao Tong University, in Shanghai, China. Nan Jia is also affiliated with the Center for Systems Integration and Sustainability, in the Department of Fisheries and Wildlife in the Environmental Science and Policy Program at Michigan State University, in East Lansing, Michigan, in the United States. Annah Lake Zhu is affiliated with Environmental Policy Group, Wageningen University, in Wageningen, in the Netherlands.

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