Alliance for Community Trees News

Study Evaluates Performance of Climate-Ready Trees

By Conni Kunzler | January 29, 2018

Source: E. Gregory McPherson, Alison M.Berry, Natalie S.van Doorn, “Performance testing to identify climate-ready trees,” Urban Forestry & Community Greening

Davis, CA (January 2018) – California’s recent drought illustrated that many urban tree species are sensitive to stressors associated with changing climates. In anticipation of warmer, drier climates predicted for California, researchers are introducing new or under-represented tree species into urban forests that are expected to better weather these conditions.

This study intends to gradually shift the tree palette within test cities to ones that are more tolerant of heat, drought, salinity and pests. Researchers will be evaluating the performance of promising, but underused, species for the next 20 years. A five-step process has been implemented to test trees in three California climate zones, with regular monitoring updates posted to the project website at

The study describes a five-step process to identify and evaluate the performance of promising but infrequently used tree species. The approach is illustrated for the Central Valley of California, and has been implemented in the Inland Empire and Southern Coastal regions of California.

Horticultural advisors nominated 134 taxon for consideration. A filtering process eliminated taxon that were relatively abundant in a compilation of 8 municipal tree inventories, then those with low adaptive capacity when scored on habitat suitability, physiology and biological interactions.

In 2015, 144 trees were planted, with 2 trees of each of 12 species planted in 4 Sacramento parks and 4 replicates planted in the Davis, California reference site. This approach can serve as an international model for cities interested in climate adaptation through urban forestry.

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