Teamwork makes the dream work: combining community science and expert-led surveys to study urban plant richness and composition

Abstract Maintaining diverse plant communities in cities is critical to meeting conservation goals and supporting human well-being. However, gaps persist in our understanding of the various factors that interact in urban environments to modulate plant richness, composition, and persistence. Elucidating these gaps would inform successful conservation efforts but requires extensive data to capture the many factors that impact ecological communities in time and space. These data are potentially available but vary in origin, quality, and accessibility. Professional scientists increasingly publish urban biodiversity studies, myriad community science projects engage participants in documenting nature, and local institutions often maintain species inventories. Combining these data sources could offer a more accurate portrait of urban biodiversity but requires understanding where sources overlap and leave gaps. To address this need, we use Cook County, Illinois – the second most populous county in the United States – as a case study to assess how combining peer-reviewed studies, community science, and grey literature can capture urban plant biodiversity. Results indicate that these data sources are complementary. Community science contributes more observations, particularly of new species, in more locations and habitat types. Peer-reviewed papers and grey literature contribute more observations of conservative species and typically focus on protected areas. Even with 171,162 observations across these three data sources, there are still prominent data gaps. Differences in focus, protocol, and replication suggest it would be worthwhile to coordinate data acquisition across data sources, particularly focusing on collecting repeated observations to better understand factors impacting urban plant diversity and resilience.