Assessing the performance of a citizen science project for monitoring urban woody plant species diversity in China

Citizen science has been increasingly used for monitoring urban biodiversity in North American and European cities. However, there is scant information about its applicability outside of these regions. In this study, we have set up a citizen science project to monitor urban woody plant diversity in China and evaluated the performance of the project. We analyzed the participants? behavior and the quality of the collected data. In 12 months, 275 of 898 registered citizen scientists have contributed a total of 4674 valid checklists of urban woody plant species in 112 cities through a WeChat mini program called ?Utrees? and a website with the same name. The mean number of monthly active participants was 33 (SD = 29), and the mean number of monthly submitted images of plants was 549 (SD = 592). The participants have tried to identify 60 % of submitted plant images, and 40 % of their identifications could match experts? identifications. The mean identification accuracy by the citizen scientists was 31.3 % (SD = 34.9), which has been improved after adding an automatic plant image identification function to the mini program. While the participation and identification accuracy were lower than those reported by similar projects in North American and European cities, the data collected through the project are still useful in revealing woody plant diversity patterns in urban China. At the national level, the project has identified 557 woody plant species in China?s cities in one year, 21.2 % of the number of species reported in a list compiled from literature over 35 years. At the individual city level, the number of species recorded by the project in Beijing was three times more than the number reported in a recent field study. Our results proved that citizen science is a promising approach for monitoring urban biodiversity in China, but serious efforts are needed to engage the public to unlock the full potential of citizen science.