There has been a lot of hysteria in Montana over dead trees, and so-called “unhealthy forests” creating “catastrophic” fires. The basic theme is that fire suppression has led to fuel build-ups that are supporting unnaturally large blazes. Unfortunately, most of this perspective is based on “old” science or the misapplication of fire ecology from other places like the Southwest U.S. ponderosa pine forests.
Inappropriate science has led to inappropriate responses, including many who argue we should log our forests to reduce fire hazard or to “restore” forest health.
Most of the forests in the Northern Rockies are not out of whack or “unhealthy,” as some suggest. Some 96 percent of the forests in the region are characterized by mixed to high severity fires that occur at long intervals. Almost none of these forest types have been affected by fire suppression or fuel buildup because effective fire suppression hasn’t been in place long enough to significantly alter natural fire. The other 4 percent of our forests that might have been affected are largely at lower elevations, and much of that is on private lands.
The role of climate/weather in regional fire history is often ignored. There is now evidence that changes in ocean temperatures and currents known as the Pacific Decadal Oscillation, as well as similar changes in the Atlantic Ocean, influence regional climate and hence fires. It turns out that PDO created dry conditions in the Rockies at the turn of the century and we experienced some huge fires including the historic 3 plus million acres 1910 blaze that raged across Idaho and Montana. This was long before there was effective fire suppression to create so called “fuel buildups.”
Then beginning in the 1940s the PDO shifted and brought cool, moist weather to the region that lasted until the 1980s n with the 1988 Yellowstone fires signaling this change in regional climatic conditions. This post-war period coincides exactly with the period when some suggest fire suppression led to fuel buildups. But it may be that the fires that started just didn’t burn well because wet, cool weather limited fire spread. In other words, we probably would not have had large blazes whether we suppressed fires or not.
Since the 1980s the PDO has shifted once again bringing overall dry conditions, higher temperatures and high winds. Despite much more sophisticated fire fighting abilities we have been unable to halt large blazes. And thinning/logging appears to have little impact on fire spread when climate/weather conditions are severe.
When viewed from this larger regional climatic condition, current large fires and large beetle outbreaks are the “natural” response to these circumstances. The best we can do is make sure that our homes are fire safe, and try to avoid building in forested locations.
A second problem with all the rhetoric about “healthy” forests is that some suggest that dead trees will somehow lead to more fires, and are “wasted” if not logged.
First, dead trees under most conditions are often less flammable than live green trees when severe drought dominates. The reason is that it is mostly small flashy fuels that burnlike needles and small branches. Live trees have an abundance of resin-filled and highly flammable needles and branches, while dead trees, once they lose their needles are relatively difficult to ignite. That is why you get mostly standing snags after a blaze n the majority of tree boles do not burn, only the branches and needles.
A forest with a lot of dead trees is actually a sign of a healthy forest ecosystem. There are even some ecologists who believe we don’t have enough dead trees.
More than 45 percent of North American birds depend on dead trees at some point in their lives. And another study estimates that two-thirds of all species depend on dead trees at some point in their life. Dead trees help to sustain forest soils and the physical snags are critical to my terrestrial species. Dead trees that fall into streams support aquatic ecosystem-indeed, so far no one fisheries biologists have found that there are “too many” logs in a stream.
We need to rethink our entire way we characterize what is a healthy forest. Logging/thinning does not contribute to forest health, rather it removes biomass, creates new roads, alters water drainage, compacts soils, spread weeds, and a host of other impacts.
GEORGE WUERTHNER is editor of Wildfire: a Century of Failed Forest Policy.
This op-ed originally ran in the Missoulian.