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Economic Impact

Many efforts have been made in recent years to better understand the economic impacts of the Invasive Shot-Hole Borer/Fusarium dieback pest complex. In their 2017 article, Dr. Gregory McPherson (USDA Forest Service) and collaborators studied the forest structure in urban areas throughout California. They estimated that out of the 70.8 million urban trees present in Southern California, 32.8% (23.2 million trees) are susceptible to the ISHB/FD complex*. Should just 50% of these 23.2 million trees at risk die, the approximate cost for removing and replacing the trees with similar species and size would be $15.9 billion. On top of that, the loss of ecosystem services provided by those trees —including energy conservation, air quality improvement and carbon storage— would generate a cost of $616.8 million annually over the next 10 years* and these costs would be even bigger if we also consider the effects of urban forests on local economies, wildlife, biodiversity and human health and well-being.

California’s urban forests are being threatened by emerging pests like ISHB. By protecting them, we are not only preventing economic losses, but we are also investing on our future quality of life**.

*G. McPherson, Q. Xiao, N.S. van Doorn, L. de Goede, J. Bjorkman, A. Hollander, R.M. Boynton, J.F. Quinn, and J.H. Thorne (2017) The structure, function and value of urban forests in California communities. Urban Forestry & Urban Gardening 28: 43-53. 

**Beatriz Nobua-Behrmann, PhD, UCCE  Orange County & Kamille Garcia-Brucher, UCCE Ventura County.


Photo Source: Boland, JM. (2016) The impact of invasive ambrosia beetle on the riparian habitats of the Tijuana River Valley, California. PeerJ; http://doi.org/10.7717/peerj.2141



Beetle-infested trunks of arroyo willows snapped by the wind


Invasive Shot Hole Borer Threatens California Tree Species

The following articles and handouts contain information regarding the susceptibility of California's trees to the ISHB-FD complex. These publications are meant for the general public.


OC Parks ISHB Tree Expenditures: 04/17-01/18


Why Doesn't State Government Take Action to Contain Pests Threatening CA Tree Species? by Faith Campbell, Center for Invasive Species Prevention, July 2016.