Supplementary Materials: Simulating shrubs and their energy and carbon dioxide fluxes in Canada’s Low Arctic with the Canadian Land Surface Scheme Including biogeochemical Cycles (CLASSIC) Gesa Meyer 1,2 , Elyn R. Humphreys 2 , Joe R. Melton 1 , Alex J. Cannon 1 , and Peter M. Lafleur 3 1 Environment and Climate Change Canada, Climate Research Division, Victoria, BC, Canada 2 Carleton University, Geography and Environmental Studies, Ottawa, ON, Canada 3 Trent University, School of Environment, Peterborough, ON, Canada Correspondence: Gesa Meyer (gesa.meyer@canada.ca) S1 Supplementary Materials The parameters in (Table 2) that were adjusted for shrub and sedge PFTs are used in the following equations. The leaf life span (τ L ; yr) is used to calculate the specific leaf area (SLA; m 2 (kg C) -1 ) as SLA = γ L τ -0.5 L (S1) with the constant γ L = 25 m 2 (kg C) -1 yr 0.5 . SLA then determines the LAI as 5 LAI = C L SLA. (S2) CLASSIC includes an age-related mortality (m intr ; day -1 ) dependent on the maximum age of a PFT (A max ; yr) with the mortality rate m intr =1 - exp(-4.605/A max ), (S3) so that only 1% of the vegetation exceeds that PFTs A max , accounting for disturbances like wind throw, insect attacks, hail 10 and others that are not explicitly taken into account in the model (Melton and Arora, 2016). The root distribution and depth are dynamically simulated in CLASSIC (Arora and Boer, 2003) and have an exponential form, where the cumulative root fraction at depth z (m) is determined as f R (z)=1 - exp (-ιz) . (S4) The depth containing 99% of the root mass (d R ; m) is given by 15 d R = -ln(1 - f R ) ι = -ln(1 - 0.99) ι = 4.605 ι , (S5) 1