Pine Beetles- the Global warming aspect

Pine Beetles- The Global Warming aspect to the outbreak

The Summit Pine Beetle Task Force met to discuss the recent outbreak of tree-killing insects.  Tania Schoennagel, a Colorado State University forest researcher, voiced a theory that the distinct rise in temperatures over the last 100 years is the single biggest factor in beetle outbreak.  Temps of minus-40 degrees a night for at least a week are needed to kill beetle larvae; the rising temperatures of global warming are preventing the cold-killing of the beetles.  Schoennagel showed a graph from the National Oceanic and Atmospheric Administration (http://www.noaa.gov)  showing the clear rise in temperatures measured at the Dillon station.  Although more research is to be done on the subject, it appears as though north-central Colorado is experiencing a more pronounced warming trend than the rest of the state. 

Schoennagel admits that research for a long-term historical perspective, thousands of years back, is weak.  Current research, however, shows that drought and high temperatures together increase the infestation epidemic.  Aggregate numbers of various species of western bark beetles were actually higher during the 1980's severe drought than they are now.  More research has shown that widespread management of forests in the form of logging have not decreased the spread of the beetles dispelling the myth that Colorado can log it's way to a healthy forest.

     Shoennagel tackled the notion that fire suppression is a significant factor in the current outbreak.  She pointed out that forests were dense 100 or 500 years ago.  Longer intervals between fire may actually result in less dense forests as individual trees die  from various causes.  According to her theory, climate is a bigger factor than stand density and age when it comes to the beetles.  However a cycle of extreme drought in the late 1800's brought stand-replacing fires which have left us with our current even-age forest that is prime for insect invasions.  The link between fire risk and beetle kill is a sensitive one in the High Country as the residence of this county are always watching for the catastrophic fire to be, but big fires and lodgepole forests are an inevitable paired cycle.  Massive crown fires are the dominant change agent for these ecosystems.  When beetles attack they don't change the amount of fuel in the ecosystem but the arrangement and types of fuels.   Lodgepole trees do increase in fire danger significantly during the short span when the trees are full of dead, red needles.  However, once the needles fall off leaving the gray snags, fire danger actually goes down below that of a live green tree.  Fire danger then increases as the tree falls and becomes part of the understory.

     Not surprisingly, Carl Spaulding, the president of the Colorado Timber Industry Association, thought that Shoennagel's findings were biased and aimed at finding any excuse in the world not to utilize the material that's growing out there. 

     Summit County is in limbo on this one.  Some don't want their neighborhoods to burn, others think that it's our own fault for suppressing fire.  Some feel that the beetle kill is ugly and will bring down housing prices, others think a thinned forest will make for better snow sports.  Whether its global warming, fire suppression or drought, there is definitely a tree kill issue.

Blog by Jason Brewer