Botanical Gardens Are Local Hotspots for Urban Butterflies in Arid Environments

Simple Summary Botanical gardens in urban areas can provide habitat for local wildlife. Here, we show botanical gardens, although small in total urban area, have a higher number and diversity of butterfly species than areas of similar size. Thus, botanical gardens are becoming important green refugia for pollinators and other wildlife as the climate of the southwest US continues to become warmer and drier. Urban areas are proliferating quickly around the globe often with detrimental impacts on biodiversity. Insects, especially pollinators, have also seen record declines in recent decades, sometimes associated with land use change such as urbanization, but also associated with climate changes such as increased aridity. How these various factors play out in attracting and sustaining species richness in a complex urban matrix is poorly understood. Urban botanical gardens may serve as important refugia for insect pollinators in arid regions due to reliable water availability for both plants and insects. Here, we use community science data on butterfly observations to evaluate if botanical gardens can be hotspots of biodiversity in the arid urban landscapes of the southwest US. We found butterfly richness and diversity were proportionally overrepresented in botanical gardens compared with the urban landscape they were embedded in. We conclude that biodiversity-friendly botanical gardens in urban arid regions can make a valuable contribution to pollinator conservation, in particular, in face of the continued aridification due to climate change.