Search

Abstract With the boom in urban living has come a boom in urban gardening. In particular, urban community gardening is an increasingly popular form of horticultural production, community involvement and connection to nature. Through the establishment and management of community gardens, biodiversity can flourish, with community gardens as ‘hotspots’ of flora and fauna within the urban matrix. Gardeners can deeply connect with the natural elements of gardens and thus learn about and gain appreciation for the natural world. Such interactions can combat the loss of nature experiences in cities. Despite their benefits for nature and for people, community gardens are threatened ecosystems as often temporary fixtures in city landscapes due to lack of land tenure and policy protection. In this perspective, we recognize community gardens as an important ecosystem in urban conservation and argue for the defence of urban community gardens by city policy. We formalize this activity and the value of these ecosystems with scientific evidence from ecological and social‐ecological research in 39 community gardens in Berlin and Munich, Germany. Although our data reveal that these gardens support large amounts of biodiversity and catalyse human‐nature connections, a lack of comprehensive documentation of social‐ecological benefits at the city level can make community gardens vulnerable to urban planning threats; we have seen losses of multiple research sites in the last 4 years of biodiversity research. Policy implications: To protect community gardens now and for future urban generations, we call for systematic and comprehensive data collection on community gardening activities and policy support for these urban ecosystems. Some cities are starting to do this and this can be scaled out. We argue for the recognition of urban community gardens as a physical land use and also of the gardeners themselves as important habitat managers and stewards of urban biodiversity. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Biotic and abiotic factors at local to landscape scales influence insect pest and disease dynamics in agricultural systems. However, relative to studies focused on the importance of these drivers of crop plant damage in rural agricultural systems, few studies investigate plant damage from herbivore insects and plant diseases in urban agroecosystems, and consequently, most urban farmers lack knowledge on crop protection tactics. Here we use three common crop species within urban agroecosystems (community gardens) distributed across an urban landscape as a model system to ask how local, landscape, and microclimate factors relate to herbivore and disease plant damage. We hypothesized that plant damage would be lower in gardens with greater local vegetation complexity, landscape‐scale complexity, and less variable temperatures, but that the importance of factors is species‐ and damage‐specific. By measuring Brassica, cucurbit, and tomato insect pest and disease damage across the growing season, we confirmed that the importance of factors varies with crop species and by damage type. Both local complexity factors (e.g., number of trees and shrubs) and landscape complexity (percent natural cover in the landscape) relate to lower incidence of herbivore and disease damage on some crops, supporting our prediction that habitat heterogeneity at both local and landscape scales lowers plant damage. Greater temperature variability related to higher disease damage on tomatoes linking microclimate factors to disease prevalence. Yet, local complexity factors also related to higher incidence of plant damage for other crop species, indicating variable species‐level impacts of local management factors on plant damage. By measuring the abundance of fungus‐feeding lady beetles (Psyllobora) on cucurbits, we confirmed a strong association between natural enemies and powdery mildew. We provide a case study on how changes in local to landscape‐scale factors relate to plant damage in urban agroecosystems and suggest how urban farmers and gardeners can apply this ecological knowledge to improve sustainable urban food production.