Figure 3. Theoretical model of the WWE impacts. Box colors indicate the overall direction of changes (red=increase, blue=decrease) in the variables based on the literature. Thick outlines and bold text indicate a disagreement between the literature and our simulations. Arrow colors show the direction of the change exerted by each process. Dashed lines refer to ROS-related processes. Grey boxes and lines refer to uncertain processes and responses. Green ticks and red crosses indicate WWE-related processes that are, or are not, implicitly implemented in the current model version.
5 Conclusions
We applied future-simulated WWE experiments in LPJ-GUESS to investigate the potential effects of these events on four dominant ecosystems in subarctic Sweden. The modeled impacts of WWEs on the ecosystem variables were substantial and of magnitudes often comparable to those of altered winter climatologies. These events induced reductions in GTwhich altered numerous biogeochemical processes and resulted in substantial changes in ecosystem CO2 uptake. This highlights the need to realistically represent the effects of WWEs in ecosystem models -which are still largely overlooked especially in regional and large scale studies- to improve estimates of the current and future high-latitude C budget. The direction of the modeled impacts on GT differed from the majority of the observation-based literature. We identified the current model limitations contributing to this mismatch, including 1) the lack of surface energy balance, 2) the model’s daily timestep, 3) and the simplistic water retention scheme applied in the LPJ-GUESS snow scheme.