VIC Vegetation Library File

Vegetation parameters needed for each vegetation type used in the VIC model are provided in a column format ASCII file as described in this document. Parameters are given for different vegetation types, and are referenced by the vegetation parameter file, which provides information about the number of vegetation types per grid cell, and their fractional coverage. A header may be added to the top of the file if the first column contains a '#'. Comments can also be added to the end of each line in the vegetation library file.

Vegetation Library File Format

Variable Name Units Number of Values Description
veg_class N/A 1 Vegetation class identification number (reference index for library table)
overstory N/A 1 Flag to indicate whether or not the current vegetation type has an overstory (TRUE for overstory present [e.g. trees], FALSE for overstory not present [e.g. grass])
rarc s/m 1 Architectural resistance of vegetation type (~2 s/m)
rmin s/m 1 Minimum stomatal resistance of vegetation type (~100 s/m)
LAI fraction 12 Leaf-area index of vegetation type
FCANOPY (Only present if VEGLIB_FCAN=TRUE in global parameter file fraction 12 Partial vegetation cover fraction
albedo fraction 12 Shortwave albedo for vegetation type
rough m 12 Vegetation roughness length (typically 0.123 * vegetation height)
displacement m 12 Vegetation displacement height (typically 0.67 * vegetation height)
wind_h m 1 Height at which wind speed is measured. If using snow interception routines please read the documentation on wind_h.
RGL W/m2 1 Minimum incoming shortwave radiation at which there will be transpiration. For trees this is about 30 W/m2, for crops about 100 W/m2.
rad_atten fract 1 Radiation attenuation factor. Normally set to 0.5, though may need to be adjusted for high latitudes.
wind_atten fract 1 Wind speed attenuation through the overstory. The default value has been 0.5.
trunk_ratio fract 1 Ratio of total tree height that is trunk (no branches). The default value has been 0.2.
Ctype (Only present if VEGLIB_PHOTO=TRUE in global parameter file 0 or 1 (0 = C3, 1 = C4) 1 Photosynthetic pathway (NOTE: the previous input values of "C3" and "C4" are still accepted but are deprecated.
MaxCarboxRate (Only present if VEGLIB_PHOTO=TRUE in global parameter file mol CO2/m2s 1 Maximum carboxlyation rate at 25 deg C
MaxETransport (C3) or CO2Specificity (C4) (Only present if VEGLIB_PHOTO=TRUE in global parameter file mol CO2/m2s 1 Maximum electron transport rate at 25 deg C (C3) or CO2 specificity at 25 deg C (C4)
LightUseEff (Only present if VEGLIB_PHOTO=TRUE in global parameter file mol CO2/mol photons 1 Light-use efficiency
NscaleFlag (Only present if VEGLIB_PHOTO=TRUE in global parameter file 0 or 1 1 1 = nitrogen-scaling factors are applicable to this veg class
Wnpp_inhib (Only present if VEGLIB_PHOTO=TRUE in global parameter file fract 1 Fraction of maximum moisture storage in top soil layer above which photosynthesis begins to be inhibited by wet conditions
NPPfactor_sat (Only present if VEGLIB_PHOTO=TRUE in global parameter file fract 1 Ratio of NPP under saturated conditions (moisture fraction = 1.0) to NPP at moisture fraction = Wnpp_inhib
comment N/A 1 Comment block for vegetation type. Model skips end of line so spaces are valid entries.

Example Vegetation Library File:

#Class  OvrStry Rarc    Rmin    JAN-LAI FEB-LAI MAR-LAI APR-LAI MAY-LAI JUN-LAI JUL-LAI AUG-LAI SEP-LAI OCT-LAI NOV-LAI DEC-LAI JAN-ALB FEB_ALB MAR-ALB APR-ALB MAY-ALB JUN-ALB JUL-ALB AUG-ALB SEP-ALB OCT-ALB NOV-ALB DEC-ALB JAN-ROU FEB-ROU MAR-ROU APR-ROU MAY-ROU JUN-ROU JUL-ROU AUG-ROU SEP-ROU OCT-ROU NOV-ROU DEC-ROU JAN-DIS FEB-DIS MAR-DIS APR-DIS MAY-DIS JUN-DIS JUL-DIS AUG-DIS SEP-DIS OCT-DIS NOV-DIS DEC-DIS WIND_H  RGL     rad_atten    wind_atten  trunk_ratio   COMMENT
2   0   25.0    220.    0.000   0.000   0.000   0.000   1.000   2.500   4.000   4.500   0.500   0.000   0.000   0.000   0.10    0.10    0.10    0.10    0.20    0.20    0.20    0.20    0.20    0.10    0.10    0.10    0   0   0   0   0.0615  0.123   0.246   0.3075  0.3075  0   0   0   0   0   0   0   0.335   0.67    1.34    1.675   1.675   0   0   0   2.0 100 0.5      0.5     0.2           Corn Field
3   0   25.0    220.    0.000   0.000   0.000   0.000   1.000   3.000   5.000   6.000   3.000   0.000   0.000   0.000   0.10    0.10    0.10    0.10    0.20    0.20    0.20    0.20    0.20    0.10    0.10    0.10    0   0   0   0   0.03075 0.0615  0.09225 0.09225 0.09225 0   0   0   0   0   0   0   0.1675  0.335   0.5025  0.5025  0.5025  0   0   0   2.  100 0.5      0.5     0.2           Soy Field