Paper Abstract
  Transmission and Epidemiology Session

The spatial pattern of SOD symptoms in coastal redwood tanoak forests

Mark Spencer¹, and Kevin O'Hara²

This paper presents the results of a spatial analysis of the point pattern of SOD symptoms and tanoak (Lithocarpus densiflorus) mortality in coastal redwood (Sequoia sempervirens) forests in Marin and Mendocino counties. The study incorporates five plots on Marin Watershed lands and three plots on Jackson State forest in Mendocino. These plots average 450 stems per plot and include data on location, species, disease status, diameter, height, and crown position for each stem. Mortality for tanoak stems ranges from 18-50% on Marin plots and from 10-18% on Mendocino plots free of SOD symptoms.

Spatial point pattern analysis does not provide direct causal understanding of the processes driving the generation of mortality and disease patterns. However comparison of Marin stand patterns against SOD-free Mendocino stand patterns and patterns generated under the Poisson distribution or other models enhances our understanding of the scale at which the underlying processes function. This paper emphasizes the implications of these results for silvicultural treatment of diseased stands and indicates the ways in which spatial pattern analysis can enhance our understanding of Phytophthora ramorum and Hypoxylon thouarsianum epidemiology.

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¹Division of Forest Sciences, 145 Mulford Hall-3114, University of California, Berkeley, Berkeley, CA 94720; (510)643-2025; spencer@nature.berkeley.edu
²Division of Forest Sciences, 145 Mulford Hall-3114, University of California, Berkeley, Berkeley, CA 94720