The greatest threat to the boreal forest is deforestation. There is an increase in industrial logging operations which clearcut large areas of boreal forest across North America, Scandinavia and Russia for timber and pulp. Deforestation is happening faster in boreal forests than rainforests. Even though some forests are replanted, there is a growing trend in North America, Scandinavia and Russia to fell mixed conifer forest and replant with single species: Pinus contorta, Pinus sylvestris and Picea abies being common choices.
Road construction for industrial and military purposes is destroying wilderness areas.
'Acid rain' or acidification is a major cause of forest deterioration. Coniferous forests seem especially vulnerable to such pollution. Rising levels of Carbon dioxide may alter climate in the high latitudes enough to affect presently grown conifer species, some of which require a cold winter to flourish. Over half of the existing boreal forest may disappear, due to the effects of climate change.
Fire is the major natural disturbance agent in the boreal forest. Large scale insect outbreaks can weaken or kill trees over vast areas, often leading to forest fires. Where human settlements and transportation routes are present in the boreal forest the great majority of the number of individual fires are human caused. However, around 90% of the area burned in the North American boreal forest is the result of natural ignition caused by lightning. Observations from satellites indicate that during the 1987 fire season approximately 14.5 million ha were burned in Asia.
Although the boreal forests probably play little part in the global carbon dioxide budget, the trees and the soil beneath store huge amounts: possibly one-sixth of the world total above ground carbon dioxide and one-fifth of the total world below ground carbon dioxide. If the boreal forests were to die, possibly because of climatic change or acidification, there could be massive release of carbon dioxide with serious climatic consequences.