Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Mark Spencer; Kevin O'Hara
    Date: 2006
    Source: In: Frankel, Susan J.; Shea, Patrick J.; and Haverty, Michael I., tech. coords. Proceedings of the sudden oak death second science symposium: the state of our knowledge. Gen. Tech. Rep. PSW-GTR-196. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 185
    Publication Series: General Technical Report (GTR)
    Station: Pacific Southwest Research Station
    PDF: View PDF  (12 KB)

    Description

    Phytophthora ramorum is a major source of tanoak (Lithocarpus densiflorus) mortality in the tanoak/redwood (Sequoia sempervirens) forests of central California. This study presents a spatial analysis of the spread of the disease using second-order point pattern and GIS analyses. Our data set includes four plots in tanoak/redwood (Sequoia sempervirens) forests in Marin County, California. Each plot contains roughly 400 individual stems. We transformed our point pattern maps into continuous density surfaces using a gaussian kernel function for the 2001 and 2003 disease symptom surveys. Subtracting one year from the other with a cut and fill function we in turn developed a triangulated irregular network (TIN). The TIN provides a means to estimate the spread of symptoms, directionality of spread and the average increase of symptomatic stem density. Our analysis indicates an average median spread of 2.1 meters and an average density increase that ranged from 32 to 100 symptomatic stems per hectare between 2001 and 2003. We detected no signs of anisotrophy. Our localization of the scale of spread using Ripley’s L(t) analysis supports the GIS analysis results. Together these results reflect a spread of disease from existing foci without the development of new foci within the stands.

    Publication Notes

    • You may send email to psw_communications@fs.fed.us to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Spencer, Mark; O''Hara, Kevin. 2006. A spatial analysis of Phytophthora ramorum symptom spread using second-order point pattern and GIS-based analyses. In: Frankel, Susan J.; Shea, Patrick J.; and Haverty, Michael I., tech. coords. Proceedings of the sudden oak death second science symposium: the state of our knowledge. Gen. Tech. Rep. PSW-GTR-196. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 185

    Keywords

    sudden oak death, Phytophthora ramorum, spatial spread analysis

    Related Search


    XML: View XML
Show More
Show Fewer
Jump to Top of Page
https://www.fs.usda.gov/treesearch/pubs/26615