Growing temperate shrubs over arid to semiarid regions in CLMDGVM

1
Growing temperate shrubs over arid to semi-arid
regions in CLM-DGVM Xiaodong ZENG and Xubin
ZENG Department of Atmospheric Sciences, The
University of Arizona

• 1. Introduction
• 2. Model Revisions and Improvements

• 4. Global Simulation

• A large part of the land surface are arid to
  semiarid regions (e.g.., from IPCC 1981-1990
  climatology, about 27 of land has annual
  precipitation less than 300 mm).
• Shrubs are the dominant vegetations over the arid
  to semi-arid regions, but cannot compete with
  trees and grasses in the humid region.
• Observations show that shrubs are drought and hot
  tolerant. They are generally shorter than trees,
  with small leaves and small LAI, and slow growing
  rate.
• Currently released version of NCAR CLM-DGVM
  (Community Land Model 3 (CLM 3) coupled with the
  LPJ dynamic global vegetation model) has not yet
  included shrubs.

Figure 3. The global distribution of temperate
shrubs at the end of 100-year model
simulation. Fraction of coverage within
60?N60?S Bare 31 Shrub 11 Tree 36
Grass 22
Figure 1. Global land cover type map (calculated
from MODIS product 12, resolution 0.05?x0.05?)
and contour of annual precipitation (calculated
from IPCC 1981-1990 monthly mean climatology
data, resolution 0.5?x0.5?. Red line shows the
contour for 300 mm of annual precipitation, and
blue line for 800 mm) .
(A)
(B)
(C)
(D)
Figure 2. The history of vegetation coverage at
four locations showing the competition and
coexistence of shrubs, grasses, and trees. The
annual precipitations are (A) 194 mm (B) 364
mm (C) 564 mm and (D) 757 mm, respectively.
Table abbreviations C3 C3 non-arctic grass
tree broadleaf deciduous temperate tree. P
precipitation PFT plant functional type. FC
fraction of coverage LAI leaf area index Htop
height of top of canopy.