What grows in community gardens? Insights into agrobiodiversity across community gardens in Brisbane and the Gold Coast, Australia

Community gardens have multiple social, environmental and economic benefits, but information about what they grow is sparse, limiting our capacity to evaluate their contribution to agrobiodiversity. Here we assessed the types of food plants and varieties grown in 27 community gardens in Brisbane and the Gold Coast in Australia. We evaluate factors potentially accounting for variation among gardens including size, age, gardening practices, as well as levels of urbanization, population density, socioeconomic status, income and age of those living around the gardens. The gardens ranged from 42 to 21,481 m² in size (average 2634 m²)^, and 1–24 years in age (average 14 years), and were mostly in medium to high density parts of the cities. A diversity of plants was grown (248 varieties, average 77 per garden), mainly vegetables (100 % gardens, 54 varieties), herbs and spices (100 %, 39), fruit (96 %, 56) and Australian native plants (bushtucker, 96 %, 33), with Basil, Lettuce, Eggplant, Ginger, Marigolds, Mint, Nasturtium, Parsley, and Cherry tomatoes common. Applying Generalised Linear Modelling we found that younger gardens, those on the Gold Coast, and gardens with permaculture practices and/or individual plots had higher agrodiversity. These results, combined with 10 other studies, highlight the value of community gardens as hotspots of biodiversity and how they act as dynamic germplasm banks for agrobiodiversity. Ongoing support is key to maintaining these benefits, as is further research including in other cities, into adaptations to climate change and into the motivations of gardens to grow specific food plants.