Unhealthy forest management may be encouraging the spread of the disease, but it is perhaps not the only way humans are furthering sudden oak deaths deadly march. In other research using Geographic Information System analysis, Meentemeyer and his colleague Hall Cushman at Sonoma State University found evidence that humans may be spreading the disease directly through the unintentional transportation of small amounts of infected soil.
There is some compelling evidence that humans could be moving the disease in infested soil, Meentemeyer said. We have found evidence for human involvement at three different scales of analysis. First of all, the pathogen is much more likely to occur along hiking and biking trails, where humans travel. Second, using some of our landscape and regional data, we have shown that highly visited state and county parks have more disease than private ranches and lands that have very limited visitation.
We have also found on an even broader scale across the state of California that forests surrounded by high human population densities are more likely to be infected. In this analysis, we carefully controlled for the effect of climate and other environmental factors known to cause disease.
The research has alarming implications, as Californias much-loved woodlands are already approximately 10 percent infected and the remainder, the models suggest, are highly vulnerable.
Only a fraction of the high risk forests are currently affected, so there is a lot of potential for more to happen, Meentemeyer said.
This is why we have also been working on more dynamic models that simulate spread through time. Weve been using this work to guide management activities for early detection surveys at sites that are likely to be infected. Once the disease is present, the only way you can c
|Contact: James Hathaway|
University of North Carolina at Charlotte