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.