Development of the Shrub Submodel for the Community Land Model-Dynamic Global Vegetation Model (CLM-DGVM)
Xubin
Zeng, University of Arizona, xubin@atmo.arizona.edu
(Presenting)
Xiaodong
Zeng, University of Arizona (now IAP, China), xdzeng@mail.iap.ac.cn
Mike
Barlage, University of Arizona (now NCAR), barlage@ucar.edu
Koichi
Sakaguchi, University of Arizona, sakaguch@atmo.arizona.edu
Zhuo
Wang, University of Arizona, zhuowang@atmo.arizona.edu
Arid and semiarid regions represent a large fraction of the global land, but most of the existing Dynamic Global Vegetation Models (DGVMs) do not include shrubs or do not effectively distinguish shrubs from grasses, and hence cannot realisticaly reproduce the ecosystem formation and variability there. A shrub submodel (X.D. Zeng, X. Zeng, and M. Barlage, 2008, GBC, accepted with revision) has been developed here for the Community Land Model(CLM)-DGVM, and the major revisions include: 1) explicit consideration of shrub's drought tolerance in the photosynthesis computation 2) use of apropriate phenology type and morphology parameters for shrubs 3) consistent treatment of fractional vegetation coverage 4) development of tree/grass/shrub hierarchy for light competition and 5) improvement of the allocation scheme to avoid unphysical behaviors. Global offline CLM-DGVM simulations for 400 years show that, with the shrub submodel, the simulated global distribution of temperate shrubs agrees with the MODIS data. More recently, we have also preliminarily extended the shrub submodel to polar regions by replacing the water-limited nature over arid regions to temperature-limited nature over polar regions, and these results will be presented as well.
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