I just returned from a week long trip to Colorado. (Thank you to those in Cafe Society for pre-trip suggestions). I was struck by the number of dead, standing trees (both pine and Aspen) in many areas. I’m guessing up to 75% of entire mountains in some places. As a matter of fact, the areas that didn’t have many dead pines stood out as lush. A guide called it “beetle kill” for the pines. I never asked for or got an explanation for the Aspens. We have what are locally called pine park beetles in NJ but not to the scale I saw out there. I asked a park volunteer about it and she said that the beetles are invasive and native to the area. I think she misunderstood the term “invasive”. Or maybe I do. Anyway, she also said the infestations are cyclical and that younger trees are more resistant due to more freely flowing sap. She further said that some of what I was seeing was the result of fires. Granted, the trees were far away but didn’t appear to the naked eye to be blackened by fire. Especially, the Aspens.
So, what the SD? Just part of nature or did bugs the come from somewhere else on a ship or something? Any truth to the “young tree” theory? Are there natural processes that control the beetles? How serious is the whole thing? All that dead standing timber looks like a tinder box. And what about the Aspens? BTW, I never knew that Aspen forests are, essentially, a single organism. That doesn’t bode well if its disease, as opposed to bugs, that are killing them.
I imagine you were in northern CO? I’m no expert, but the bark beetles have always been endemic in evergreens but were controlled by cold winter temps which are not really happening any more. Aspens aren’t infected (AFAIK) by any pest, but they do “time out” and a whole grove will die at the same time. They should re-sprout pretty quickly.
Don’t know about the Aspen, but it’s Pine Beetle for sure. Central Colorado mountains hit hard. Mostly lodgepole.
When a lot of logging was done for the mining industry and generally building towns. It was clear cut. The lodgepole pines replaced a lot of diversity.
Where I live, I put up pheromone packets on the trees. From what I’ve been told, the pheromones told the beetles to get your own tree, this one is occupied.
Just from what I understand, I takes seriously cold weather to eradicate them. Which we have not had for a few years.
They never got too close to my valley, but I saw some. It scared me. To have all the trees get wiped out, well… I tell people it would be like living on the surface of the moon.
Along with the winters not being cold enough to kill off the beetles, there have been droughts and really hot summer weather, which stresses the trees further and makes them less able to survive the damage.
Yes. Cold winters control their population and with global warming, just a few degrees makes all of the difference. Alaska has a similar problem. As for the tinder box, we had some major wildfires a few years ago and the beetle kill was a major factor in the spread.
I don’t know whether it’s relevant to this situation, but another phenomenon that’s definitely been observed is the migration of mountain pine beetles to colder climates where they wouldn’t normally have been able to survive.
I read the supplied wiki -link and others and it isn’t just one type of beetle but several. Some kill the trees quickly (couple of weeks) and some just weaken them and make them more susceptible to other pests and disease. It seems one more normal-ish cold winter won’t be enough to stop things. It would take several in a row and there’s no signs of that happening in the foreseeable future.
Is it wiser to just let the dead stands be or would it make more sense to harvest the dead wood? I did see where the blue-stained wood is being used in some furniture. The terrain is very difficult so I guess that would make it quite costly to use the wood as construction material. In any case, it was disheartening see so many dead trees.
The forest service in area has been cutting them down making big piles and burning them on site. Better to have a controlled burn, than an uncontrolled one.
Yeah, AIUI the dry spells really weaken the tree’s ability to repel the beetles. Sap is a natural defense and when water is scarce the tree produces less sap, which makes it easier for the beetles to set up shop. Lack of severe cold in winter isn’t helping control the bugs, either.
Arborist in Evergreen Colorado here. I’ve spent most of the past 45 years in forestry around here with both the USFS and private sector with a major focus on Mountain Pine Beetle. I could geek out about this for hours but here’s a few thoughts on this thread so far…
Yes MPB is endemic around here. Outbreaks of pandemic proportions are cyclical. Historically 30 or so years apart. Climate change including a decades long drought has changed the whole dynamic though. The other MAJOR factor is fire suppression. Since European settlement in the west we have suppressed forest fires in order to save our homes and lives. So 150 years of putting out forest fires has created unnatural, crowded forests that weren’t like that for eons.
