Species clustering, climate effects, and introduced species in 5 million city trees across 63 US cities
- Stanford University, United States
- Harvard University, United States
- Independent Researcher, United States
- Worcester Polytechnic Institute, United States
- The Biota of North America Program (BONAP), United States
Abstract
Sustainable cities depend on urban forests. City trees-pillars of urban forests - improve our health, clean the air, store CO2, and cool local temperatures. Comparatively less is known about city tree communities as ecosystems, particularly regarding spatial composition, species diversity, tree health, and the abundance of introduced species. Here, we assembled and standardized a new dataset of N=5,660,237 trees from 63 of the largest US cities with detailed information on location, health, species, and whether a species is introduced or naturally occurring (i.e., 'native'). We further designed new tools to analyze spatial clustering and the abundance of introduced species. We show that trees significantly cluster by species in 98% of cities, potentially increasing pest vulnerability (even in species-diverse cities). Further, introduced species significantly homogenize tree communities across cities, while naturally occurring trees (i.e., 'native' trees) comprise 0.51%-87.3% (median=45.6%) of city tree populations. Introduced species are more common in drier cities, and climate also shapes tree species diversity across urban forests. Parks have greater tree species diversity than urban settings. Compared to past work which focused on canopy cover and species richness, we show the importance of analyzing spatial composition and introduced species in urban ecosystems (and we develop new tools and datasets to do so). Future work could analyze city trees and socio-demographic variables or bird, insect, and plant diversity (e.g., from citizen-science initiatives). With these tools, we may evaluate existing city trees in new, nuanced ways and design future plantings to maximize resistance to pests and climate change. We depend on city trees.
Data availability
All data and code are available in the main text or the supplementary materials. The datasheets of city tree information from 63 cities Figure 1-source data 1 (63 .csv files) have been uploaded to Dryad: https://doi.org/10.5061/dryad.2jm63xsrf.
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A dataset of 5 million city trees from 63 US cities: species, location, nativity status, health, and more.Dryad Digital Repository, doi:10.5061/dryad.2jm63xsrf.
Article and author information
Author details
Benjamin Goulet-Scott
Funding
National Science Foundation (Postdoctoral Research Fellowships in Biology,2109465)
- Dakota E McCoy
National Science Foundation (Research Experience for Undergraduates (REU),1757780)
- Bulent Furkan Atahan
Stanford University (Science Fellowship)
- Dakota E McCoy
The Franklin Delano Roosevelt Foundation (Summer Research Grant)
- Hana Kiros
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, McCoy et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Species clustering, climate effects, and introduced species in 5 million city trees across 63 US cities
eLife 11:e77891.
https://doi.org/10.7554/eLife.77891
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