Friday, August 28, 2009
A Colorado pine forest is a peculiar thing. In the depths of one you have the sense that you are wandering through the land which inspired Grim's Fairy-Tales and most of the more earthy old gods. Pan peeks out at you from around the trunks of the majestic natural residents and you get a sense that the trees are all very, very old.
This is not, of course, generally the case.
While periodically, on the lower slopes, you do run into a pine of unusually grand stature and robust character, for the most part the trees rise to a certain point and then rise no farther. The reasons for this are as simple as they are complicated. The forests of Colorado, certainly around the area of the fourteeners, are marked by a particular cycle of life, death, and rebirth, a cycle they share both symbiotically and parasitically with the pine-borer beetles.
A tree that is damaged becomes particularly vulnerable to these little buggers, but they can and will bore straight through the bark of a healthy tree to lay their eggs underneath. When the eggs hatch, the larvae roam around eating the "live" part of the tree (xylem, phloem) in random directions, a process which ultimately causes large strokes of the bark to fall off, and which kills the tree.
The tree will then gradually dry out. A dry tree is a fire-hazard, and as the number of these fire-hazards in a given area grows, the likelihood that one of them will be struck by lightning also increases. When this happens, the tree in question ignites like a bomb, burning down itself and igniting neighboring dry trees. The inferno is generally broken by the live-trees at the edge of the infestation (pine-needle carpets discourage underbrush from taking hold, which in turn makes it harder for fires to spread through healthy, live trees... no kindling to speak of).
Pine-cones in the Colorado forests do not open and release their seeds until incited to do so by extreme heat. The ash from the dead trees lays down a thick carpet of fertilizer that allows the new trees to grow quickly through their vulnerable adolescence and to a point where they can, again, wipe out all local ground-cover.
And the pine-borers? The inferno kills the majority of the pine-borer beetles in the area, preventing a massive exponential outbreak.
For years, the forestry teams in Colorado (it isn't just their mistake, remember Smokey the Bear? Cute lil' animals a'la 'Bambi' fleeing the great flaming evil?) have been tamping down forest fires. Initially the idea was preservation of forest, but more recently the problem has changed, and the strategy, unfortunately, has remained (by necessity) largely the same. They have, however, begun to use controlled burns in an effort to bring the forest back under control (unless my information is inaccurate in this area, which it might be).
You see, because they tamped down the forest fires, the pine-borer beetles got out of hand. Now, as you drive through Colorado, you may notice that the "evergreen" forests are abnormally brown. Entire mountainsides of trees are dead, rotting husks of their former selves. Forest fires of the magnitude created by a mass of dead trees that large, without intervention, become legitimate dangers to human settlements in the area, and the rangers must now run around determining (as much as possible) the extent of each blaze that takes hold.
Well-meaning human intervention has created the necessity of well-meaning human intervention, you might say.
There's a lesson in there somewhere, but I'm not sure I like what it teaches.
Had the pleasure of a chat with RR on a long hike the other day, on which the subject of the borer beetles came up. RR is a recently-retired Colorado ranger, so he knows his stuff regarding those.
The major infestation at present is actually the result of a long string of warm winters. In the normal borer cycle, the larvae are largely killed off every few years by a winter which reaches temperatures below 35 degrees F. This temperature is necessary because at that stage in their lives, pine borer blood is literally (chemically) antifreeze. Thus, while such massive infestations as the one presently menacing Colorado are not common, they are possible without human interference.
In fact, the first fire of such magnitude happened in Yellowstone in 1910, and was in fact the reason rangers started engaging in fire-control.
Additional random tidbits I picked up from RR- pine borers attack Lodgepole pines in particular, and all pines in general, with a certain voracity, however Fir trees (and to a limited extent Spruce trees) are extremely resistant to attack. RR theorizes that differences in sap discourage infestation, and also that thinner bark provides insufficient shelter for the larvae.
The borer beetles attack the entire tree, from top to bottom, but where they attack it is more or less random. In cold winters, the beetles deep under the snow level are much more likely to survive than those above (insulation), and this allows many to survive all but the harshest of winters. No winter is cold enough to eliminate the entire population, of course, but the percentage that survives the cold is small.
Some lodge-pole pinecones open and drop seeds like normal pine cones, and some drop seed only in extreme heat. The reason for this, according to RR, is that some pine cones are covered by the lodge-pole's sap, which seals them up until the sap is melted away, a process that (usually) takes just long enough for the fire to move on to somewhere else before the seal weakens sufficiently that they pop open.
I realize that this additional information doesn't feed well into the article, but hey. I don't feed you inaccurate information if I can help it, and usually I can help it, even if it hurts my point.