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Motivation
• Shrub density increasing in tundra
• Shrub albedo < grass albedo (leaf & stem)
• Diff. morphology (eg height) affects albedo of snow-covered sfcs
CLM has shrubs!(when vegetation is prescribed)
• Broadleaf Deciduous (Boreal & Temperate)
• Broadleaf Evergreen (Temperate)
Activating Shrubs in the DGVM
1. Bioclimatic limits:
IBIS-DGVM uses GDD0>100
But when DGVM is definedCLM can only put C3 grass in tundra…
Activating Shrubs in the DGVM
1. Bioclimatic limits:IBIS-DGVM uses GDD0>100shrubs behave too much like trees
2. C allocation to leaves, stems, roots3. Light competition with trees4. Drought & fire tolerance
Do we need higher PFT resolution?
Kaplan et al. (2003) Tundra PFTs
Cold Shrub evergreen
Cold Graminoid or Forbsummergr.
Cushion Forb evergreen
Epstein et al. 2000
Longer list…