Occurrence and diversity of poisonous plants in urban community gardens

Abstract Urban community gardens promote human health, offer recreational space and support urban biodiversity. Urban gardens are situated in diverse landscape contexts and have diverse social contexts with gardeners of various horticultural experiences and backgrounds, both of which results in the wide plant species variety of urban garden habitats. These plants represent a range of traits, one of which may be the production of substances that are poisonous to humans. These plants may also be of ecosystem functioning and biodiversity conservation value, creating an ecosystem service trade-off of human health promotion. In this paper, we report on the occurrence of poisonous plant species in 30 urban community gardens in two German cities (Berlin, Munich) and discuss potential concerns around poisonous and highly poisonous plants in urban gardens. We conclude that, depending on the garden participants as well as the goals of the garden organization, poisonous plants should be carefully monitored and managed to dually mitigate health risks while supporting biodiversity conservation. We propose possible strategies to manage potential threats posed by these plants while simultaneously allowing them to reside alongside people in urban gardens.