Open AccessThe Magnitude of Regional‐Scale Tree Mortality Caused by the Invasive Pathogen Phytophthora ramorum
Author(s) -
Cobb Richard C.,
Haas Sarah E.,
Kruskamp Nicholas,
Dillon Whalen W.,
Swiecki Tedmund J.,
Rizzo David M.,
Frankel Susan J.,
Meentemeyer Ross K.
Publication year - 2020
Publication title -
earth's future
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.641
H-Index - 39
ISSN - 2328-4277
DOI - 10.1029/2020ef001500
Subject(s) - phytophthora ramorum , host (biology) , biology , bay , pathogen , geography , ecology , phytophthora , botany , archaeology , immunology
Forest pathogens are important drivers of tree mortality across the globe, but it is exceptionally challenging to gather and build unbiased quantitative models of their impacts. Here we harness the rare data set matching the spatial scale of pathogen invasion, host, and disease heterogeneity to estimate infection and mortality for the four most susceptible host species of Phytophthora ramorum , an invasive pathogen that drives the most important biological cause of tree mortality in a broad geographic region of coastal California and southwest Oregon. As of 2012, the most current field survey year, we estimate 17.5 (±4.6, 95% CI [confidence interval]) million tanoak ( Notho lithocarpus densiflorus ) stems were pathogen killed with an additional 71 (±21.5) million infected. We estimated 9.0 million (±2.2) coast live oak ( Quercus agrifolia ) and 1.7 million (±0.5) California black oak ( Quercus kelloggii ) stems are disease impacted (mortality and infection combined). Lastly, our estimates suggest infection in 95.2 million (±8.6) California bay laurel ( Umbellularia californica ), which does not suffer mortality from infection and represents a critical source of continued spread. Prevalent infection as of 2012 suggests the cumulative number of disease‐killed stems likely increased from 20.8 to 42.8 million between 2012 and 2019 for all species. While these impacts are substantial, most host populations occur in a yet to be invaded region of northern California indicating that the disease will intensify in the coming decades.