Abstract: Urban green spaces are represented in a variety of spatially and temporally diverse forms – rooftop gardens, city parks, community gardens, urban orchards, and private gardens. These types of green city infrastructure provide important ecosystem services such as enhanced biodiversity, improved soil health, and increased carbon sequestration. In addition, people benefit from green spaces in cities via improved food security, and cultural and educational opportunities. City parks and community gardens are common urban green spaces and have attracted a lot of attention from researchers in the past few decades. However, urban orchards are comparatively understudied, despite their ability to serve as a potential multipurpose landscape to promote environmental health in cities. In this study, we assessed 9 sites across three types of urban green spaces (community gardens, parks, and urban orchards) in Louisville, KY, from April-October 2021 and April-October 2022. We measured several aspects of biodiversity and ecosystem services including monthly surveys of plant diversity and abundance, pollinators abundance, tree physiological parameters, and crown health. We used the US Forest Service I-Tree Software to calculate stored and sequestrated carbon, yearly produced oxygen, prevented runoff, and air pollution removal.
While community gardens had the highest overall plant species richness, urban orchards had three times more total plant species richness than parks, especially later in the season. Native plant and flowering plant species richness were also higher in urban orchards than in both parks and community gardens, which was correlated with increases in solitary bee abundance in these sites. Orchards also were able to sequester five times more carbon and produce twice as much oxygen per hectare than parks, while having similar abilities to store carbon, prevent runoff, and remove air pollution. Our results show that small-scale urban orchards can be important habitats contributing to biodiversity and can provide ecosystem services on par with larger urban parks.
