Management of Phytophthora ramorum at plot and landscape scales for disease control, tanoak conservation, and forest restoration - insights from epidemiological and ecosystem models

Abstract

Phytophthora ramorum has continued to spread in forests in the western United States, the United Kingdom, and the Republic of Ireland, and continues to challenge vegetation and ecosystems in temperate regions (Brasier and Webber 2010, Grünwald et al. 2012). Disease management in the wild has been applied with some success in localized outbreaks in northern California and in Oregon, and in trial treatments; for example, using host removal and host protection (phosphonate application) at plot and stand levels. However, there is still very limited observational data on the efficacy of these treatments, both at the individual-tree level and at community and landscape scales. A central question to decision-making and the deployment of resources, is how to design management strategies that have the greatest and most durable impact and the least expenditure. In order to address this question, we need to gain a better understanding of which treatments work best for a specific scale, forest composition, and set of resources available. We also need to use population models that integrate epidemiology and community ecology. In this context, two main action goals arise: shortterm management to reduce disease damage and pathogen spread, and long-term management for species conservation and forest restoration. How to deploy existing tools most efficiently depends on which goal applies, on the spatial scale of the outbreak (e.g., stand with single landowner or watershed), and on practical constraints. As observation data on the efficacy of treatments at individual-tree and community levels are still very limited, we use parameterized mathematical models (Cobb et al. 2012, Filipe et al. 2012) that represent the spatial spread of the pathogen, the competing recruitment of tree species, and the changing forest composition in order to assess the efficacy of management strategies at two spatial scales.

Parent Publication

• Proceedings of the sudden oak death fifth science symposium

Citation

Filipe, João A.N.; Cobb, Richard C.; Salmon, Maëlle; Rizzo, David M.; Gilligan, Christopher A. 2013. Management of Phytophthora ramorum at plot and landscape scales for disease control, tanoak conservation, and forest restoration - insights from epidemiological and ecosystem models. In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 137-140.