Climate Change and Tree Diversity in Florida’s Urban Forests

While urban areas can support surprisingly high levels of plant diversity (Alvey 2006), more can be done to encourage and conserve biodiversity in the urban forest. In north and central Florida, only four species make up 65% of the total population of trees (Koeser and Northrop, unpublished data). In Tampa, Florida, if mangrove trees are excluded from total tree counts, just 10 species make up 75% of the remaining trees inventoried throughout the city (Landry et al. 2013). This lack of diversity suggests that our urban forests are not resistant to the numerous pressures that affect them, such as pests, diseases, and climate change (Raupp et al., 2006; Lacan and McBride, 2008; Roloff et al., 2009).

In cooperation with the University of Florida IFAS Extension and the Tampa Bay Forest Working Group, the cities of St. Petersburg, Tampa, Lakeland and Orlando and members of woody plant nursery industry have instituted a multi-year project to trial run a group of underutilized tree species in west-central Florida. The group is testing for survival, growth and vitality in both challenging and ideal land use types. The choice of tree species test reflects the environmental changes suggested by projected climate change scenarios for Central Florida.

Climate change poses a serious and complex set of threats to urban forests. The urban environment already places existing vegetation under abiotic stresses, predisposing them to pests and diseases. Testing the viability of new species (native and nonnative to Florida) at regional scales is an important step toward identifying the future composition of our state’s urban forests.

Alvey, A.A. 2006. Promoting and preserving biodiversity in the urban forest. Urban Forestry & Urban Greening. 5(4):195–201.

Koeser, A.K. and R.J. Northrop. Unpublished data. Accessed March 20, 2017.

Laçan, I., McBride, J., 2008. Pest Vulnerability Matrix (PVM): a graphic model for assessing the interaction between tree species diversity and urban forest susceptibility to insects and diseases. Urban For. Urban Green. 7(4): 291–300.

Landry, Shawn M., Robert J. Northrop, Michael G. Andreu, and Carolyn C. Rhodes. 2013. City of Tampa 2011 Urban Forest Analysis: The Structure, Composition, Function and Economic Benefits of Trees and the Urban Forest. Final Report to the City of Tampa, September 2013. City of Tampa, Florida.

Raupp, M., Cumming, A., Raupp, E., 2006. Street tree diversity in eastern North America and its potential for tree loss to exotic borers. Arboricult. Urban For. 32 (6), 297–304.

Roloff, A., Korn, S., Gillner, S., 2009. The climate-species-matrix to select tree species for urban habitats considering climate change. Urban For. Urban Green. 8:295–308.

For more information on climate change and urban forest diversity visit:

https://www.fs.fed.us/research/urban-webinars/climate-adaptation/