Measuring the effects of road mediated long-range transport on infection risk for Port Orford cedar

Graduation Date

2014

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Environmental Systems: Mathematical Modeling, 2014

Committee Chair Name

Christopher Dugaw

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Humboldt State University -- Theses -- Mathematical Modeling, Survival analysis, Phytophthora lateralis, Biological invasion, Root pathogen

Abstract

Biological invasions are an important topic in today's global economy. Thousands of animals, plants, and pathogens are being transported through human activity into new ecosystems with sometimes disastrous consequences. Phytophthora lateralis is a water-borne invasive root pathogen that is currently affecting Port Orford Cedar in riparian zones. Once a tree near a stream is infected the pathogen spreads rapidly down the stream. Thus it is reasonable to consider the infection of streams as opposed to individual trees. Probability of infection for stream crossings within the study site are hypothesized to depend on environmental factors and logging traffic. Data on infection dates, environmental variables, and logging traffic was collected for 77 stream crossings. The data were then used to parametrize infection probability models using maximum likelihood methods and optimization. The resulting model set was analyzed using AICc. Site characteristics were found to be significant and logging traffic was found to be somewhat significant.

https://scholarworks.calstate.edu/concern/theses/9z903215q

Share

 
COinS