Mountain Pine Beetle (MPB)
In western North America, the current outbreak of the mountain pine beetle and its microbial associates has destroyed wide areas of lodgepole pine forest, including more than 16 million of the 55 million hectares of forest in British Columbia. The current outbreak in the Rocky Mountain National Park began in 1996 and has caused the destruction of millions of acres of ponderosa and lodgepole pine trees. According to an annual assessment by the state’s forest service, 264,000 acres of trees in Colorado were infested by the mountain pine beetle at the beginning of 2013. This was much smaller than the 1.15 million acres that were affected in 2008 because the beetle has already killed off most of the vulnerable trees (Ward).Source
Mountain pine beetles affect pine trees by laying eggs under the bark. The beetles introduce blue stain fungus into the sapwood that prevents the tree from repelling and killing the attacking beetles with tree pitch flow. The fungus also blocks water and nutrient transport within the tree. On the tree exterior, this results in popcorn-shaped masses of resin, called “pitch tubes”, where the beetles have entered. The joint action of larval feeding and fungal colonization kills the host tree within a few weeks of successful attack (the fungus and feeding by the larvae girdles the tree, cutting off the flow of water and nutrients). When the tree is first attacked, it remains green. Usually within a year of attack, the needles will have turned red. This means the tree is dying or dead, and the beetles have moved to another tree. In three to four years after the attack, very little foliage is left, so the trees appear grey.
As beetle populations increase or more trees become stressed because of drought or other causes, the population may quickly increase and spread. Healthy trees are then attacked, and huge areas of mature pine stands may be threatened or killed. Warm summers and mild winters play a role in both insect survival and the continuation and intensification of an outbreak. Adverse weather conditions (such as winter lows of -40°) can reduce the beetle populations and slow the spread, but the insects can recover quickly and resume their attack on otherwise healthy.Source
Wood from beetle-affected trees retains its commercial value for 8 to 12 years after the tree has died, but the level of value drops rapidly, for within several months, as the moisture retained in the tree seeks to escape, it blows large checks and cracks from the outer diameter deep into the heart of the tree. The balance of the moisture escapes more slowly, but in doing so, small cracks occur throughout the timber. In short, this causes difficulties for modern high-output automated sawmill operations and greatly increases the lumber losses and the labor to produce high quality wood products. This so-called ‘shelf life’ is dependent on a number of factors, including economic and stand site conditions. The trees remain commercially viable longer under drier conditions. In areas where it is wetter, the trees tend to rot at the base and fall faster, especially if they are larger. The blue staining of the wood that occurs in the outer diameter of the tree, the sapwood, as a result of the fungus that is carried by the beetles and results in the trees death has no effect on the wood’s strength properties, nor are there any harmful health effects. Source
HOW MOUNTAIN HEART WOODWORKS WORKS WITH BEETLE KILL PINE
While high-output sawmills are unable to work with the defects in the blue pine timber, we are able to cut around the majority of cracks and rot in the logs to produce quality blue pine products. Although this is the case, it is important to note that some cracks in beetle pine lumber are almost always likely to be present. We have numerous techniques to overcome and work with the cracks in the lumber such as filling them with a fiberglass resin and we always cull out lumber if the cracks compromise the board. If you would like an order with NO cracks in the lumber, we can accommodate that but for a premium charge, usually $.50-$1.50 extra per bdft.
Because the beetle kill tree is dead standing and has been for many years the moisture content in the lumber off the mill is typically between 6% and 12%. NOTE: We do not guarantee the moisture content of the material we sell. It is up to the customer to specify moisture requirements before purchasing.
The blue color that is in the log is found in the outer sap ring of the log so color varies in the lumber depending on where the board was cut from the log. Wider boards require large logs and typically large logs have small sap rings and produce less color in lumber. Smaller logs typically have deeper sap rings and produce more color. The optimal width for color is 8” material and under. 6” and 4” material produce the most color. We do find more color in Ponderosa Pine for wider timber.