Simulating shrubs and their energy and carbon dioxide fluxes in Canada's Low Arctic with the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC)

Abstract. Climate change in the Arctic is leading to shifts vegetation communities, permafrost degradation and alteration of tundra surface–atmosphere energy carbon (C) fluxes, among other changes. However, year-round C flux measurements at high-latitude sites remain rare. This poses a challenge for evaluating impacts climate on ecosystems developing process-based models, which may be used predict regional global feedbacks system. Our study 14 years seasonal eddy covariance (EC) dioxide (CO2), water winter soil chamber CO2 dwarf-shrub site underlain by continuous Canada’s Southern ecozone evaluate incorporation shrub plant functional types (PFTs) Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC), land surface component Earth System Model. In addition new PFTs, modification efficiency with evaporates from ground was applied. addressed high evaporation bias that reduced model performance when soils became very dry, limited heat flow into ground, productivity through stress effects. Compared grass tree PFTs previously CLASSIC represent permafrost-affected regions, simulations better capture physical biogeochemical impact shrubs magnitude seasonality fluxes evaluation site. The revised model, however, tends overestimate gross primary productivity, particularly spring, overestimated late-winter emissions. On average, annual net ecosystem exchange positive all simulations, suggesting this source 18 ± 4 g m−2 yr−1 using 15 6 25 5 PFTs. These results highlight importance appropriate models simulate current future interactions.