Pine Beetle Turning BC Forests into Net Source of Carbon Dioxide by 2020
Flying over British Columbia, or even driving through the interior of the province, will reveal a blight spreading throughout the province's forests. Hectares of pine trees have died and turned red, interspersed with green swathes of trees waiting for their turn to perish.
During the last decade, pine beetles have ravaged British Columbian boreal forests. The insect burrows through the outer bark of the tree, laying eggs within the phloem (channels within the inner tree bark that carries water and nutrients up to higher regions of the tree). A blue fungus piggybacks on the beetle, infecting the tree, and preventing it from fending off further beetle infection. Within two weeks, the tree eventually starves to death.
Normally, pine beetles are held back in their ravenous tracks by cold winters - several days of -35ºC weather will kill large populations of the overwintering beetle larva (source). Unfortunately, BC hasn't seen that sort of winter weather in many years.
But wait - there's more. According to a study published today in the scientific journal Nature, the pine beetle should no longer be viewed solely as a blight against the forest and tourist industry, but rather as a contributor to greenhouse gas emissions.
The study estimated the beetle to have killed off between 74,000-94,000 square kilometers of forest. To put this in perspective, the worst year of pine beetle infestation resulted in ~75% of all the trees killed and burned in BC between 1959-1999. You read correctly - that's one year compared with 40. Furthermore, it is more than 5 times greater than the annual carbon dioxide emissions from the automobiles and planes in all of Canada (source).
As the authors put it, "Climate change has contributed to the unprecedented extent and severity of this outbreak, Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon..."
By 2020, BC forests may no longer be an overall carbon sink (via the conversion of carbon dioxide into sugars during photosynthesis), but rather an overall source as the rotting timber releases CO2 into the atmosphere.