Uncertainties related to climate change and forest management with implications on climate regulation in Finland

Forests play an important role in one of the most important ecosystem services, climate regulation. In order to mitigate climate change, various international agreements aim at decreasing emissions through Land-Use, Land-Use Change and Forestry (LULUCF) activities. In a legislative proposal by the European Union, emissions from forests are accounted for in relation to an estimate of average emissions for a range of years in the past. However, different forest structures, management activities, growth variations and impacts of changing climate may result in considerably different future emissions. We assessed the magnitude of potential uncertainties due to changing climate and forest management to the projections of carbon stocked in above- and belowground forest biomass in Finland until 2050. We used an area-based matrix model, which was developed to incorporate climate-induced tree growth as a time-inhomogeneous Markov chain. The potential amounts of both the carbon stored and extracted varied considerably depending on the level and allocation of future harvests. If realized, climate- or management-induced growth improvements could increase the carbon stocks by up to one third in the end of the simulated period. Projections based solely on business-as-usual transitions and harvests could therefore lead to inefficient decisions regarding future carbon stocks and harvesting possibilities.