Hur stora är växthusgasutsläppen vid naturvårdsbränning?

How large are the global warming emissions from prescribed fires in the European boreal? This report addresses emissions of greenhouse gases during prescribed fires, which are done in Sweden for increased biodiversity. Focus is on CO2-emissions during the combustion. There are large instantaneous emissions to the atmosphere. However, the CO2-debt, i.e. the difference in atmospheric CO2 if the burning is conducted or not, decreases rapidly in the years following the burn as carbon is stored in soil and growing plants. The emissions from prescribed burning on protected land can be assessed using field observations of fuel loads, fuel consumption during the fire and post fire plant/litter accretion. The net change in atmospheric CO2 is thereafter calculated from these data sets for different time since fire. Instantaneous emissions are estimated, for a characteristic fuel type, at 14.4 tonnes CO2 per hectare. After only ten years 78 % of this is again fixed in the vegetation on the forest floor, and litter. The same number 20 years post fire is 90 % and at 50 years, 98 %.