Impact of forest management and climate change in 3 European forests

Forests represent about the 90% of global biomass of carbon and the capability of plants to fixed carbon from atmospheric CO2 via photosynthesis is influenced by competitive interaction for light, water and nutrient. The competition can be regulated by the stand dynamics and the terms to describe interactions are: plant species, tree sizes, age distribution, spatial (vertical and horizontal) arrangement and tree canopy layering. The main silvicultural practices (e.g. thinning, harvest and replanting) heavily affect the stand structure and influence the nutrient cycling, decomposition rates, regeneration patterns, but also on stand structure dynamics. Due to the long lifespan of forest stands and lack in experiment covering such long time period, a very useful tool to understand the effect of silvicultural practices on stand structure and carbon dynamic are the forest models. The forest models involve the abstraction of real forest dynamics in a conceptual environment which allows the systems behavior to be reproduced. The models are the only tool for estimating the effect of such different types of silvicultural practices under current climate as well as under future climate change scenarios. To simulate the effects of different management practices and climate change on Standing Woody Biomass (SWB) we apply the model 3D-CMCC-CNR FEM (v.5.4 BGC) at three different even-aged, managed, European forests: an adult (80 years old) Danish temperate European beech forest (Fagus sylvatica L.; Sorø); a moderately young (28 years old) Finnish boreal Scots pine forest (Pinus sylvestris L.; Hyytiälä) and a young (16 years old) Czech temperate-humid Norway spruce forest (Picea abies Karst.; Bílý K?í?). The study sites were selected because the three species are representative of the most common types of European deciduous and coniferous species and involved into the Inter-Sectoral Impact Model Intercomparison (ISIMIP) Project. To estimate climate change effects the simulations consider a subset of climate change scenarios data (ESM: HadGEM2-ES; RCP 2.6 and RCP 8.5) from the ISIMIP Fast Track initiative (https://www.isimip.org, Warszawski et al., 2014). We simulate the business-as-usual (BAU) management and different thinning and harvesting regimes and their combination ( rotation BAU +/- 10 years; thinning interval BAU +/- 5 years; thinning intensity BAU +/- 10%) plus the "unmanaged" forest. The effect of climate change was simulated for a period of about 100 years (1997-2099) and the total runs for each sites was about 56 (3 rotation * 3 thinning interval * 3 thinning intensity * 2 RCP plus 2 RCP in "unmanaged" forest). The simulations of different management practices under current climate condition can help the stakeholders to increase the knowledge of ecosystem response to human activity and to establish the effect of their decision in the carbon cycle and the biomass in the short period. The simulations under climate change can suggest the effects of the management in the maintain, reduce or increase the sink/source service of forest in the medium and long period. The changes in regimes of thinning, harvest and thinning intensity are mandatory to the sustainable forests and to increase the quality and increments of the woody biomass increments.