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.
