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Urban biodiversity: State of the science and future directions


Since the 1990s, recognition of urban biodiversity research has increased steadily. Knowledge of how ecological communities respond to urban pressures can assist in addressing global questions related to biodiversity. To assess the state of this research field in meeting this aim, we conducted a systematic review of the urban biodiversity literature published since 1990. We obtained data from 1209 studies that sampled ecological communities representing 12 taxonomic groups. While advances have been made in the field over the last 30 years, we found that urban biodiversity research has primarily been conducted in single cities within the Palearctic and Nearctic realms, within forest remnants and residential locations, and predominantly surveys plants and birds, with significant gaps in research within the Global South and little integration of multi-species and multi-trophic interactions. Sample sizes remain limited in spatial and temporal scope, but citizen science and remote sensing resources have broadened these efforts. Analytical approaches still rely on taxonomic diversity to describe urban plant and animal communities, with increasing numbers of integrated phylogenetic and trait-based analyses. Despite the implementation of nature-based solutions across the world’s cities, only 5% of studies link biodiversity to ecosystem function and services, pointing to substantial gaps in our understanding of such solutions. We advocate for future research that encompasses a greater diversity of taxonomic groups and urban systems, focusing on biodiversity hotspots. Implementing such research would enable researchers to move forward in an equitable and multidisciplinary way to tackle the complex issues facing global urban biodiversity.

Graphical abstract

Word cloud from titles of 1209 publications on urban biodiversity from 1990–2018.

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Availability of data and material

The dataset  is available via the UrBioNet Database on the University of Missouri’s MOspace at

Code availability

Web of Science search terms are provided within the Supplementary Information.


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This study resulted from a workshop held at Rutgers, the State University of New Jersey, New Brunswick, New Jersey, funded by the National Science Foundation’s UrBioNet Research Coordination Network (grant no. DEB 1354676/1355151). We thank Carmela Buono, Eliana Geretz, Chris Hensley, Natalia Schneider, Hui-Anne Tan, and Christopher Trisos for their assistance with aspects of the data collection and two anonymous reviewers for comments on the draft manuscript.


This study was funded by the National Science Foundation’s UrBioNet Research Coordination Network (grant no. DEB 1354676/1355151).

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This study was developed during the UrBioNet workshop held at Rutgers, the State University of New Jersey, New Brunswick, New Jersey, 27–31 March 2017. All authors either designed the study, conducted the literature search, and/or reviewed studies resulting from the literature search. CCR-B, MFJA, MRP, AKH, and NSGW analyzed the data. CCR-B and MFJA wrote the first draft of the manuscript. All authors reviewed and edited the manuscript, and approved its final form.

Corresponding author

Correspondence to Christine C. Rega-Brodsky.

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We certify that we have no conflicts of interest regarding this work.

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Supplementary file1 (DOCX 644 KB)

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Rega-Brodsky, C.C., Aronson, M.F.J., Piana, M.R. et al. Urban biodiversity: State of the science and future directions. Urban Ecosyst 25, 1083–1096 (2022).

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  • Biodiversity
  • Publication trends
  • Research bias
  • Sampling methodology
  • Systematic review
  • Urban gradient