In a global perspective, soil can became a significant accelerating factor in the climate change. Warmer climate means higher decomposition and emissions rates and thereby faster warming. Increasing emissions from soil will also affect the national carbon balances of forested countries like Finland.
The warming has a stronger effect on the soil in Finland than in more southern countries. The carbon dioxide emission rate in our region is especially sensitive to higher spring and autumn temperatures. The decomposing microbial communities are partly different in southern and northern Finland, but warmer climate means higher microbial activity in both regions.
The expected temperature rise of 5 degrees would increase the decomposition rate in soil by some 50 percent. If the growth of forests and the production of litter as well as the amount of logging leftovers do not increase at the same rate, the carbon stocks in the soil begin to get released as carbon dioxide into the atmosphere. The carbon sinks in forests – the soil and the tree stands – are currently binding about one third of our carbon dioxide emissions.
The influence of warmer climate on the carbon dioxide emissions from soil should be taken into account when the future use of forests is planned. The role of forests as carbon sinks should not be endangered. In new climatic conditions the present flow of litter and logging leftovers to the soil will not be enough to preserve the carbon stock in the soil. This is of essential importance when the role of forests as a controlling factor in the climate change is estimated. In addition to the carbon sink effect, the use of forest biomass fuel is often mentioned as a means to control the emissions.