Growth in forest biomass exceeding drain due to harvesting and natural mortality explains this removal. However, between 2000 and 2005, the Danish forests were a carbon source releasing between 1 and 2 million tonnes of CO2 each year. During that period the age distribution became skewed towards mature forests, which were eventually harvested and the cleared land was regenerated with saplings (Danish CEE 2012). This resulted in negative net increment in forest biomass and thus turned the Danish forests as a net source of carbon.