Pan et. al (2011) estimate that the carbon sink in the world's forests is large. Asian Russia is considered to have the largest carbon sink in the boreal region. There has also been a sink increase in European Russia since 1990 due to an increase in forest areas after agricultural abandonment, reduced harvesting, and changes of forest age structure to more productive forests including deciduous forests. The biomass sink increased in Northern Europe (Nordic countries) while there has been a large net loss of soil carbon stock due to a shift from forest to non-forest. The biomass carbon sink in managed forests in Canada was reduced by half since 1990, mostly due to the biomass loss from intensified wildfires and insect outbreaks (which is often a consequence due to planted monocultures and climate change). Read more in the Science article here.