Beetles, Fire and Changed Environments

Unlike most of the posts this Blog Action Day, this one won't be about human-caused pollution or overpopulation or resource depletement. Rather I'll tell the tale of the environmental losses caused by a tiny beetle

I first met with this insect while working for Kurisu International, a high-end Japanese landscape design / build firm, some twenty years ago. We would find the telltale heavy pitch flow caused by the female beetle tunneling under the bark to lay her clutch of eggs. Sometime sawdust would be present. The only cure was to dig out the bug, or death to the pine would be sure. We called it the pitch beetle, due to the obvious pitch usually near the base of the tree, but sometimes up the trunk near branches. Unfortunately, most homeowners did not recognize the risk revealed by this pitch. Once hatched, the many larvae each consumed its own tunnel, with a fan shape quickly forming. If the pine did not die that year, it certainly did the second, as many more beetles were present then. Many a handsome landscape pine died. No tree-sized species seemed to escape. and no chemical spray was effective against it, as it was protected under the bark.

The same process is occurring in the Cascade Mountain forests. All types of pine can succumb to this problem. One year some or many pines will die, and the second sees the loss of most or all of the mature trees old enough to have thick bark. Young thin-barked saplings are not affected. One season after dying, the bark falls in lodgepole pines, with the heavy bark of white and ponderosas lasting several years. In two or three years, the lodgepoles begin to fall to the ground, and in ten to twenty most are gone. Again, with the massive white and ponderosa pines the big boles last much longer, with isolated snags still present after the lodgepoles are part of the forest duff.

What are the environmental effects of this loss?

Alteration of forest makeup
In the Olallie Scenic Area, the adjacent Warm Springs Indian Reservation and many other locations, all the mature pines died over a period of a few years. Some forests were pines almost exclusively for miles, all dead above a certain size.

Will the pines return over time? Will fir replace them? Or will meadows and shrubfields take over? Most likely all these will occur, depending on local conditions. Its clear that we just don't know, but certain is that these forests will never be the same. And of course they never have been before. Forests were more open two hundred years and more back, and only the high level of fire supression has allowed the thick woodlands of recent decades. And the beetle has opened the woods back up. The following has the potential to open them up much more.


In the foreground are pine dead for a year or more (no needles), those which died this year (red-brown needles still on the tree), and on the distant slopes the large grey areas are dead pine forest, with the deep green areas predominately fir forest. Looking east, with Olallie Lake on the left. This is environmental change on a large scale!

Fire Danger
All that dead wood becomes ready to burn each dry summer. Its both kindling and fuel for potentially massive burns. We lucked out with this summer, wet and cool as it was. Next year if hot and dry will likely see some big burns in the beetle kill areas.

Fire encourages lodgepole pine, most of whose cones release their seeds in response to the heat of a fire. The firs, now green and lush, will be the victims here.

The current scenic and recreational values will be greatly diminished. Two previous posts overview Olallie area outings and have more info - Olallie Scenic Area Highlands and Clackamas Headwaters Tour.

And forest fires are huge polluters of the air, especially by particulates. In the days before effective fire control, smoky summers were accepted as the norm for the Northwest. Nowadays they are an occasional nuisance, with Portland, Seattle and other Northwest cities getting rare health warnings about excess smoke and particulates.

Death to the beetle
The bark beetle has eliminated its food over large areas. They will die off virtually to nothing from their current spike in population. Without mature pine, they starve. So the pines, now seemingly on the ropes, will get their chance to come back in time. Fire will speed that process for lodgepoles and to a lesser extent ponderosas.

A small beetle has altered many miles of Western woodlands. A more open forest, with more flowers in newfound bright light, may be the result. Or perhaps in areas fire will come and return large areas to domination by pines. Time will tell us the results. With the large areas involved every possibilty may play out somewhere.