We employed a forest ecosystem model (SIMA) to study how the changes in forest conservation area and management affect the volume growth, harvested amount of timber, carbon stock, and amount of deadwood in Finnish boreal upland forests under current and changing climates (RCP4.5 and RCP8.5) over 2010–2099. Simulations were carried out on National Forest Inventory plots using three different forest conservation scenarios (baseline and 10% and 20% increases of conservation area) and three thinning regimes (baseline and maintenance of ±20% stocking in thinning compared with recommendations). An increase of forest conservation area increased the volume growth, carbon stock, and quantity of deadwood in forests, as did the maintenance of 20% higher stocking in thinning. Maintenance of 20% lower stocking in thinning increased, in general, the amount of harvested timber, but it could not compensate for the decrease of harvested timber due to increase of conservation area. Climate warming greatly increased all of the studied variables in northern Finland but decreased them in southern Finland, the most under the strongest climate warming scenario, RCP8.5. Climate warming also increased the quantity of deadwood throughout Finland. To conclude, we found clear trade-offs for production of different ecosystem services.

We studied how the use of certain tree species in forest regeneration affected the volume growth, timber yield, and carbon stock of boreal forests in Finland under the current climate (1981-2010) and recent-generation global climate model (GCM) predictions (i.e., multi-model means and individual GCMs of CMIP5), using the representative concentration pathways RCP4.5 and RCP8.5 over the period 2010-2099. Forest ecosystem model simulations were conducted on upland national forest inventory plots throughout Finland. In a baseline management regime, forest regeneration was performed by planting the same tree species that was dominant before the final cut. In alternative management regimes, either Scots pine, Norway spruce or silver birch were planted on mediumfertility sites. Other management actions over rotation were done as in a baseline management. Compared to baseline management, an increased planting of birch resulted in relative sense highest increase in the volume growth, timber yield, and carbon stock in forests in the south, especially under severe climate projections (e.g., multi-model mean RCP8.5, and GCMs such as HadGEM2-ES RCP8.5 and GFDL-CM3 RCP8.5). This situation was opposite for Norway spruce. In the north, the volume growth, timber yield, and carbon stock of forests increased the most under severe climate projections (e.g., multi-model mean RCP8.5 and CNRM-CM5 RCP8.5), regardless of tree species preference. The magnitude of the climate change impacts depended largely on the geographical region and the severity of the climate projection. Increasing the cultivation of birch and Scots pine, as opposed to Norway spruce, could be recommended for the south. In the north, all three species could be cultivated, regardless of the severity of climate change.

We investigated how recent-generation (CMIP5) global climate model projections affect the volume growth, carbon stock, timber yield and its profitability in managed Scots pine, Norway spruce and Silver birch stands on medium fertile upland sites under southern and northern boreal conditions in Finland. Forest ecosystem model simulations were conducted for the current climate and changing climate, under two representative concentration pathways (RCP4.5 and RCP8.5), using 10 individual global climate model (GCM) projections. In addition to the baseline thinning, we maintained either 20% higher or lower stocking in thinning over a 90-year period. In the south, the severe climate projections, such as HadGEM2-ES RCP8.5 and GFDL-CM3 RCP8.5, as opposed to MPI-ESM-MR RCP4.5, considerably decreased the volume growth, carbon stock and timber yield, as well as its profitability, in Norway spruce stands, but also partially in Scots pine stands, compared to the current climate. Silver birch gained the most from the climate change in the south and Scots pine in the north. The impacts of the thinning regime varied, depending on tree species, site and climate applied. Depending on the severity of the climate change, even opposing adaptive management measures may be needed in different boreal regions.

This study employed scenario analyses to evaluate the effects of forest management and different CMIP5 climate projections on timber production and carbon stocks of upland boreal forests in Finland. The forest ecosystem model simulations were conducted over a 90-year period from the stand to regional level by using both model stand data (Paper I) and national forest inventory data (Papers II-III). In simulations, it was employed data from the current climate and several CMIP5 projections (multi-model means and individual climate model runs) under the RCP4.5 and RCP8.5 forcing scenarios. More specifically, it was studied the impacts of different climate projections and thinning regimes (Papers I and III), tree species preferences in forest regeneration (Paper II) and forest conservation scenarios (Paper III) on volume growth, carbon stocks and timber production (Papers I-III), economic profitability (Paper I), and the amount of deadwood of forests (Paper III).The effects of different climate projections on volume growth, carbon stocks, timber production and its economic profitability and the amount of deadwood varied largely, depending on geographical region, tree species, and severity of climate change. The degree of differences in the responses of tree species and boreal regions increased with the severity of climate change (Papers I-III). Regardless of the tree species, the positive impacts of climate change were larger in the north. In the south, Silver birch benefitted most from the climate change projections and the most under severe climate change. This was unlike Norway spruce and also partially, Scots pine (Papers I-II). An increase in forest conservation area increased volume growth, carbon stock, and the amount of deadwood in forests, unlike timber production. Depending on boreal region, tree species, and severity of climate change, different adaptive forest management measures would be needed to utilize the positive impacts of climate change and to minimize harmful ones.