Invasion of blister rust, pine beetles, global warming, and forest extinction
by Jonathan DuHamel on Jul. 20, 2011, under Climate change, Natural HistoryWe learned from a story in the always reliable Arizona Daily Star that:
The Fish and Wildlife Service determined Monday that whitebark pine, a tree found atop mountains across the American West, faces an “imminent” risk of extinction because of factors including climate change.
And:
An invasive disease, white pine blister rust, along with insects such as mountain pine beetles, has infiltrated the historically colder altitudes where whitebark pines thrive. Fish and Wildlife Service biologist Amy Nicholas said these factors, along with fire patterns and global warming more broadly, are undermining the tree’s viability.
The implication is that global warming is encouraging the rust disease. But according to forestpathology.org regarding white pine blister rust:
The disease is often most severe in areas and following years with extended, cool, moist conditions during late summer and early fall.
Regarding beetles, we find from the Ecological Society of America:
Unusually hot, dry weather patterns are already responsible for increased insect outbreaks in forests from the US Southwest to Canada and Alaska.
The obvious conclusion is that a hot, dry, cool, moist climate is endangering our forests. So which is it?
The article from Ecological Society of America also says:
Forest insects and pathogens are the most pervasive and important agents of disturbance in North American forests, affecting an area almost 50 times larger than fire and with an economic impact nearly five times as great.
And:
Even though insect outbreaks greatly affect forest ecosystems, they may not be detrimental from a long-term ecological perspective.
It seems that the issue is complex and still poorly understood, which means that the Fish & Wildlife Service has no real scientific basis to declare an “imminent” risk of extinction.
