Difference between revisions of "Module Vegetation"

Revision as of 10:53, 13 February 2009

Overview

Vegetation Model handles information about vegetation cover and interacts with atmosphere and soil properties. Vegetation dynamics can be handled by the model in two different manners: i) reading from file (time serie, hdf, grid); ii) using a vegetation growth model. The first option is the previous formulation where LAI and root depth properties are provided by user and water uptake is simulated. The second option uses a SWAT based vegetation growth model and plant biomass, LAI, nutrient content and nutrient uptake are explicitly simulated.

SWAT vegetation growth model uses the concepts from EPIC crop model (Izaurralde et al., 2006) of radiation-use efficiency by which a fraction of daily photosynthetically active radiation is intercepted by the plant canopy and converted into plant biomass. Gains in plant biomass are affected by vapor pressure deficits and atmospheric CO2 concentration. Stress indices for water, temperature, nitrogen, phosphorus and aeration are calculated using the value of the most severe of these stresses to reduce potential plant growth and crop yield. Nutrient uptake is done based on plant target (optimal content) and availability in soil.

Concepts

Property

See the list of allowed properties names

Main processes

Other Features

Outputs

Time series

Box integration

Maps (HDF5 format)

To write 3D results use keyword OUTPUT_TIME and define keyword:

OUTPUT_HDF           : 1

in each property that you whish to write results.

To write results only in the surface use keyword SURFACE_OUTPUT_TIME and define keyword:

OUTPUT_SURFACE_HDF   : 1

in each property that you which to write results. Surface results can be written with a different frequency than the normal 3D maps.

Statistics

References

Izaurralde, R.C.; Williams, J.R. ; McGill, W.B.; Rosenberg, N.J.; Quiroga Jakas, M.C. (2006) - Simulating soil C dynamics with EPIC: Model description and testing against long‐term data. Ecol. Model. 192(3‐4): 362‐384.

Other

Some keywords/properties od the input file vegetation_x.dat are:

<beginvegetationtype>

ID                        : 1
NAME                      : Sample vegetation type

<<begin_property>>
!total leaf are / projected crown area
PROPERTY_NAME             : leaf area index
IS_CONSTANT               : 1
CONSTANT_VALUE            : 0
<<end_property>>

<<begin_property>>
!the depth of water that can be retained by leaves of a particular species per unit leaf area
PROPERTY_NAME             : specific leaf storage
IS_CONSTANT               : 1
CONSTANT_VALUE            : 0
<<end_property>>

<<begin_property>>
!factor for lowering evapotranspiration due to the crop type based on a reference evapotranspiration 
PROPERTY_NAME             : evtp crop coefficient
IS_CONSTANT               : 1
CONSTANT_VALUE            : 1
<<end_property>>

<<begin_property>>
!self declaring...
PROPERTY_NAME             : root depth
IS_CONSTANT               : 1
CONSTANT_VALUE            : 0
<<end_property>>

<<begin_property>>
!Parameter of the root water uptake model after FEDDES (1978): 'Simulation of field water use and crop yield'
PROPERTY_NAME             : feddes h1
IS_CONSTANT               : 1
CONSTANT_VALUE            : -0.1
<<end_property>>

<<begin_property>>
!Parameter of the root water uptake model after FEDDES (1978): 'Simulation of field water use and crop yield'
PROPERTY_NAME             : feddes h2
IS_CONSTANT               : 1
CONSTANT_VALUE            : -0.25
<<end_property>>

<<begin_property>>
!Parameter of the root water uptake model after FEDDES (1978): 'Simulation of field water use and crop yield'
PROPERTY_NAME             : feddes h3
IS_CONSTANT               : 1
CONSTANT_VALUE            : -5.0
<<end_property>>

<<begin_property>>
!Parameter of the root water uptake model after FEDDES (1978): 'Simulation of field water use and crop yield'
!Wilting point
PROPERTY_NAME             : feddes h4
IS_CONSTANT               : 1
CONSTANT_VALUE            : -80.0
<<end_property>>

<<begin_property>>
!self declaring...
PROPERTY_NAME             : permeable fraction
IS_CONSTANT               : 1
CONSTANT_VALUE            : 1.0
<<end_property>>

<endvegetationtype>