Trees damaged by bark beetles slow their uptake of CO2 for up to a century

As noted in prior posts, bark beetles damage large forest areas, often killing or causing the death of 50% to 80% of mature trees.  As these trees decompose, they release CO2, adding to the atmospheric burden of GHG's.  New research has identified additional climate repercussions from beetle outbreaks.  Even after a forest has ostensibly recovered from a beetle infestation, the forest continues to suffer a long-term drop in the rate at which growing trees remove carbon dioxide from the air.  The result makes the forest less efficient at removing carbon dioxide emitted by the burning of fossil fuels.

Researchers have asserted in a report that a forest may regain its previous biomass in 7 to 25 years, but the rate at which the forest removes carbon dioxide may remain diminished for much longer - in some cases well over a century.  However, the issue is more nuanced. 

All forested lands do not suffer equally from beetle invasions.  Those with the highest proportion of old pines, which are the most vulnerable to attack, initially suffer the most damage.  However, young survivors are exposed to more light and have access to more of the available nutrients as the old trees die off.  As a result, the growth of the young trees help increase carbon storage.  Thus, because trees grow more slowly as they age, those stands where beetle "victims" had been oldest and the survivors youngest will pose the most limited risk to climate change.

It is therefore important to distinguish the type of forest that is attacked by the beetles in order to assess the longterm impact of the infestation on carbon storage.  No beetle attack is good, but the nature of the impacted forest determines the longterm impact on carbon storage.

Relevant studies on this issue can be found at http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2010.02226.x/abstract and http://www.nature.com/nature/journal/v452/n7190/abs/nature06777.html