title: Unexpected redwood mortality from synergies between wildfire and an emerging infectious disease.
abstract: An under-examined component of global change is the alteration of disturbance regimes due to warming climates, continued species invasions, and accelerated land-use change. These drivers of global change are themselves novel ecosystem disturbances that may interact with historically occurring disturbances in complex ways. Here we use the natural experiment presented by wildfires in redwood forests impacted by an emerging infectious disease to demonstrate unexpected synergies of novel disturbance interactions. The dominant tree, coast redwood (fire resistant without negative disease impacts), experienced unexpected synergistic increases in mortality when fire and disease co-occurred. The increased mortality risk, more than fourfold at the peak of the effect, was not predictable from impacts of either disturbance alone. Changes in fire behavior associated with changes to forest fuels that occurred through disease progression overwhelmed redwood's usual resilience to wildfire. Our results demonstrate the potential for interacting disturbances to initiate novel successional trajectories and compromise ecosystem resilience.
authors.affiliation: Department of Plant Pathology, 1 Shields Avenue, University of California, Davis, California 95616, USA. mrmetz@ucdavis.edu
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Metz
authors.affiliation: Department of Forestry, Forest and Wildlife Research Center, Box 9681, Mississippi State University, Mississippi 39762-9681, USA.
authors.forename: J Morgan
authors.initials: JM
authors.lastname: Varner
authors.affiliation: Department of Plant Pathology, 1 Shields Avenue, University of California, Davis, California 95616, USA.
authors.forename: Kerri M
authors.initials: KM
authors.lastname: Frangioso
authors.affiliation: Center for Earth Observation and Department of Forestry and Environmental Resources, North Carolina State University, 5106 Jordan Hall, Raleigh, North Carolina 27695, USA.
authors.forename: Ross K
authors.initials: RK
authors.lastname: Meentemeyer
authors.affiliation: Department of Plant Pathology, 1 Shields Avenue, University of California, Davis, California 95616, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Rizzo
mesh_terms: D002140:California; D005390:Fires; D019015:Geologic Sediments; D010838:Phytophthora / Q000502:physiology*; D010935:Plant Diseases