North America is seeing a lot of bark beetle activity these days. The upsurge began with the spruce beetle outbreak in Alaska in the 90s which was soon followed by the massive mountain pine beetle, spruce beetle, and Ips outbreaks of the 90s, 00s and 10s in Canada and the continental US. These outbreaks have exceeded all previous records, sometimes by an order of magnitude in size.
Now it appears it is Mexico’s turn. Extreme drought is driving extremely rapid expansions of several bark beetle species in the genera Dendroctonus, Ips and Scolytus in forests across the country. Entomologists and foresters alike are shaking their heads, pondering what to do.
I am currently attending the Simposio Nacional de Parasitologia Forestal in Durango, Mexico, where climate change is a big topic this year. Last night, I presented a keynote address on how climate change is affecting the interactions between beetles and the fungi upon which they depend on for nutrients. This morning there was a full length symposium on climate and bark beetles. Speaking with scientists and foresters it is clear Mexicans get the connection between beetles and climate, and that they are worried.
I found one talk to be particularly interesting. The speaker listed what are perceived to be the biggest challenges to controlling the spread of the beetles. These were: extreme climate, failed management efforts, fragmented ownership of forested lands, and lack of interest in managing by landowners.
Last week, I revisited a site near the Big Hole River where mountain pine beetle rebounded after a cold snap knocked it back big time in October 2009. Well, it got cold early again this year-so I wondered what that meant for the beetle this time. The mountain pine beetle used to fly in a discreet period around mid-July which meant it would enter winter at the right time to survive freezing temperatures. But now they fly and attack trees from May to October which has big effects on increasing tree mortality as well as beetle survival. In years that are warm, overall there is high beetle survival. But, when things get cold early, like this year, a large number of beetles can be killed. From what I can tell, the young of the beetles that flew in the early part of summer (June and July) this year are doing just fine because thy were in the right stage to enter winter, but those that flew late in September were killed by freezing temperatures-they just didn’t have time to reach the stage they needed to be in to be protected from cold. Oddly enough, on Oct 14th, there were trees we found that had successful attacks that had occurred within the last week! Totally crazy stuff for this insect. Climate deniers, deal with that!
It will be very interesting next year to see what happens with this population of beetles. I would love to see a collapse of this one -the Big Hole River is one of my favorite fishing spots- but, I am not going to hold my breath. The last cold snap only knocked them back and then they came back with a vengeance three years later because the conditions that support them - hot and dry- did not go away. And I don’t see that changing any time soon.
All we need is one good cold winter and the mountain pine beetle will be toast. Have you heard that? Unfortunately, many people think that is the case. I can’t blame people for hoping for an easy fix (even if it is an increasingly unlikely one), but the reality is, it is not so much a lack of cold winters, as it is a preponderance of long warm summers with lower moisture that kicks it all into high gear for the beetle. That is why, when cold snaps have knocked them back in recent years, they have still come back each time with a vengeance.
But really, aren’t cold winters hard on the beetle? Yes, but it is not the only, or even the major, factor affecting beetle populations right now. In fact, many areas where the beetle is currently a major problem have never had the extreme cold winters it takes to kill the beetle. To understand what is happening with the beetle these days, we need to look at how the beetle fares in the other seasons.
I am back in my home after a nearby wildfire put my neighborhood on evacuation warning, yet again. While this wildfire has not been blamed on beetle-killed trees, many wildfires in the western US are blamed on ‘beetle fuel’ these days. But is there really a link? Conventional wisdom says beetle kill is highly flammable tinder, that once ignited, leads to catastrophic fire. But, conventional wisdom is defined as belief by convention. In other words, because it has always been believed to be so, therefore it is correct . It is not necessarily based on facts. So what does the science say? And are policymakers using science, scientists as advisors, and facts, to develop policy regarding beetle kill and fire?
I work on bark beetle ecology, evolution and management. I am not a fire scientist. But, because of what I do I stay very current on the research on bark beetles and fire. In the next few coming days I will blog on what the current science is on the perceived link between beetle-killed trees and fire. I will also synthesize how policymakers are, or are not, incorporating science on this topic into policy. The big question, in regard to policy, comes down to - does science and fact get incorporated into policy fast like a wildfire, OR as a slow smolder, OR is it actively suppressed? And of course, If science is excluded, why?