Abstract
Plant communities in urban gardens consist of cultivated species, including ornamentals and food crops, and wild growing species. Yet it remains unclear what significance urban gardens have for the plant diversity in cities and how the diversity of cultivated and wild plants depends on the level of urbanization. We sampled plants growing within 18 community gardens in Berlin, Germany to investigate the species diversity of cultivated and wild plants. We tested species diversity in relation to local and landscape-scale imperviousness as a measure of urbanity, and we investigated the relationship between cultivated and wild plant species within the gardens. We found that numbers of wild and cultivated plant species in gardens are high – especially of wild plant species – independent of landscape-scale imperviousness. This suggests that all community gardens, regardless of their urban contexts, can be important habitats for plant diversity along with their role in urban food provision. However, the number of all species was negatively predicted by local garden scale imperviousness, suggesting an opportunity to reduce imperviousness and create more habitats for plants at the garden scale. Finally, we found a positive relationship between the number of cultivated and wild growing species, which emphasizes that community gardens present a unique urban ecosystem where land sharing between cultivated and wild flora can transpire. As the urban agriculture movement is flourishing worldwide with gardens continuously and spontaneously arising and dissipating due to urban densification, such botanical investigations can support the argument that gardens are places for the reconciliation of plant conservation and food production.
Highlights
Rapid urbanization has led to the loss of green spaces in cities, with a majority of the world’s population currently living and projected to live in cities by 2050 (UN-Habitat 2016)
We elaborate on three main findings of our work: (1) community gardens harbor both high cultivated plant diversity that supports urban food production and high wild plant diversity, potentially representing a high fraction of diversity within the urban landscape; (2) this plant diversity is independent of landscape-scale imperviousness, though local-scale imperviousness may reduce the potential for novel ecosystems to support wild plant diversity; and (3) cultivated and wild plant species coexist with potential for reconciling conservation-production trade-offs sensu “land sharing”
Community gardens are a nexus of urban food production, urban greening, humannature connection and public health – and can be refugia for diverse wild growing plant communities (Cabral et al 2017; Lin et al 2018b; Lin and Egerer 2020)
Summary
Rapid urbanization has led to the loss of green spaces in cities, with a majority of the world’s population currently living and projected to live in cities by 2050 (UN-Habitat 2016). Gardens thereby support a wide array of ecosystem functions, including food provision, habitat for biodiversity, carbon sequestration, climate mitigation and water retention (Lin et al 2015), and are the focus of recent urban ecology research (Gaston et al 2005; Guitart et al 2012; Vergnes et al 2013; Philpott and Bichier 2017; Clucas et al 2018; Frey and Moretti 2019). The composition of plant populations in cities is influenced by multiple urban drivers including human management, climate, pollution, land use change and biological invasions (Pyšek et al 2010; Kowarik 2011; Lososová et al 2012; Aronson et al 2016; Piana et al 2019; Swan et al 2021). In contrast to rural regions, cities are characterized by high habitat heterogeneity including novel urban habitats with great potential for biodiversity (Kowarik 2011; Swan et al 2021),
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