Southeastern Pine BeetleUTK HomepageSBPUTK Homepage
main topics FWFCASNRInstituteDirectoryContactsNewsHome
Home Info Description Occurrence ID Pine Beetles Outbreaks Prevention Harvesting Replanting TN Ecosystems Site prep Salvage Removals Aid Finacials Aid Help Email SPBM, left navigation map  

Factors Leading To Southern Pine Beetle Outbreaks

Southern Pine Beetles are native to the forest lands of the southeastern United States.  This makes the effort to eliminate the beetle impossible.  Control of the beetle and conducting practices that protect pine stands are the major emphasis within this field.

Pine beetle populations are cyclic, meaning they tend to build in population over time and then decrease.  In Tennessee, the peak population seems to occur every 10 to 12 years.  This continuous cycle brings about the beetle epidemics that we are currently seeing as well as the outbreaks in 1988 and 1975.

The beetles are more likely to attack pine stands and individual trees that are suffering from stress.  Stress can be caused by many factors.  Prolonged drought, like we have seen over the past several years, can weaken a pine's ability to defend itself from the beetle.  Prolonged moisture and flood conditions have the same effect.  Trees that have been damaged by ice and storms or damage to residual trees after a harvest are also more susceptible to the beetle's attack.  A common stress causing factor in many of the stands in east Tennessee is slow vigor and tree growth due to overstocked and over-mature stands.  The less stress a pine stand encounters the more likely it will be able to defend itself from the beetle outbreak.

Recently, with the mild winters in this part of the nation, the beetle population did not decrease as expected.  Beetles are killed when temperatures stay below freezing for a week or more.  This lack of "winter kill" has also aided the beetle in its attack on Tennessee's pine forests.



t h e   u n i v e r s i t y   o f   t e n n e s s e e