Parameter |
Description |
Units |
Valid Values |
Default Values |
---|---|---|---|---|

BIOFLG |
Specifies if production should be reduced by physical obstruction. BIOFLG is a boolean value, either 0 or 1. If zero, production should not be reduced at all. If 1, production should be reduced according to the amount of standing dead biomass and litter, and the BIOK5 parameter. | 0 or 1 | ||

BIOK5 |
Level of aboveground standing dead + 10% STRUCC(1) (g
C m^{-2}) (or fixed parameter PMXBIO,
whichever is less) at which production is reduced to half maximum due to
physical obstruction by the dead material. Used only when BIOFLG =
1. |
0.0 to 2000.0 | ||

BIOMAX |
Biomass level above which the minimum and maximum C:(N, P, S) ratios of the new shoot increments equal PRAMN(*,2) and PRAMX(*,2) respectively. See figure 3-13 for a graph of how these parameters apply. | g biomass m^{-2} |
0.0 to 1000.0 | |

CO2ICE(1,1,E) |
The effect on minimum C:(N, P, S) ratio of the atmospheric CO_{2} effect
from a doubling of CO2 concentration.
A value of 1 will have no effect. A reduction will
have a negative effect. And an increase will have a positive effect. E =
1 for N, 2 for P, 3 for S. |
0.5 to 1.5 | ||

CO2ICE(1,2,E) |
The effect on maximum C:(N, P, S) ratio of the atmospheric CO_{2} effect
from a doubling of CO2 concentration.
A value of 1 will have no effect. A reduction
will have a negative effect. And an increase will have a positive effect. E =
1 for N, 2 for P, 3 for S. |
0.5 to 1.5 | ||

CO2IPR(1) |
The effect on plant production of the atmospheric CO_{2} effect
from a doubling of CO2 concentration.
A value of 1 will have no effect. A reduction will
have a negative effect. And an increase will have a positive effect. |
0.5 to 1.5 | ||

CO2IRS(1) |
The effect on root-shoot ratio of the atmospheric CO_{2} effect
from a doubling of CO2 concentration.
A value of 1 will have no effect. A reduction will
have a negative effect. And an increase will have a positive effect. |
0.5 to 1.5 | ||

CO2ITR(1) |
The effect on transpiration rate of the atmospheric CO_{2} effect
from a doubling of CO2 concentration.
A value of 1 will have no effect. A reduction will
have a negative effect. And an increase will have a positive effect. |
0.5 to 1.5 | ||

CRPRTF(E) |
Fraction of (N, P, S) transferred to a vegetation storage pool from grass/crop
leaves at death, where E = 1 for N, 2 for P, 3 for S. |
0.0 to 1.0 | ||

DEL13C |
Delta 13C value for stable isotope labeling. | -30.0 to 0.0 | ||

EFRGRN(E) |
Fraction of the aboveground (N, P, S) which goes to grain, where E =
1 for N, 2 for P, 3 for S. |
0.0 to 1.0 | ||

FALLRT |
Fall rate (fraction of standing dead which falls each month). | 0.0 to 1.0 | ||

FLIGNI(P,1) |
Intercept and slope for equation to predict lignin content
fraction based on annual rainfall for aboveground biomass. P = 1 for
intercept, 2 for slope. For crops, set slope to
0. |
0.0 to 1.0 | ||

FLIGNI(P,2) |
Intercept and slope for equation to predict lignin content
fraction based on annual rainfall for belowground biomass. P = 1 for
intercept, 2 for slope. For crops, set slope to 0. |
0.0 to 1.0 | ||

FRTCINDX |
DayCent only:
Value = 0: Use Great Plains equation. Value = 1: perennial plant. Value = 2: annual plant. |
0, 1, 2 | ||

FRTC(1) |
Initial (maximum) fraction of C allocated to roots.
Century only: Value = 0, use Great Plains equation based on precipitation. The maximum root:shoot will be: R:S = FRTC(1) / (1.0 - FRTC(1))
Conversely, FRTC(1) can be calculated from the maximum expected root:shoot: FRTC(1) = R:S / (1 + R:S) |
0.0 to 1.0 | ||

FRTC(2) |
Final (minimum) fraction of C allocated to roots. | 0.0 to 1.0 | ||

FRTC(3) |
Time after planting (months with soil temperature greater than RTDTMP) at which the final value is reached; must not equal 0. | months | 1.0 to 12.0 | |

FRTC(4) |
DayCent only: For annuals only, specifies the fraction of variabilty in FRTC(1).
Typical values are in the range 0.1 to 0.5. |
0.0 to 1.0 | ||

FSDETH(1) |
Maximum shoot death rate at very dry soil conditions. For calculating the monthly shoot death rate, this fraction is multiplied by a reduction factor depending on the soil water status. | fraction/month | 0.0 to 1.0 | |

FSDETH(2) |
Fraction of shoots which die during senescence month. Must be greater than or equal to 0.4. | fraction/month | 0.4 to 1.0 | |

FSDETH(3) |
Additional fraction of shoots which die when aboveground live C is greater than FSDETH(4). Applies only when FSDETH(1) or FSDETH(2) are < 0.4. | fraction/month | 0.0 to 1.0 | |

FSDETH(4) |
The level of aboveground C above which shading occurs and shoot senescence increases. | g C m^{-2} |
0.0 to 500.0 | |

FULCAN |
Value of AGLIVC at full canopy cover, above which potential production is not reduced. Used with PLTMRF to modify potential production due to shading effect on potential growth rate for seedlings. | g C m^{-2} |
50.0 to 200.0 | |

HIMAX |
Harvest index maximum, or the fraction of harvested aboveground biomass C in grain. If a harvest event can be scheduled for this plant, the value should be > 0 (see the crop submodel for more information). | 0.0 to 1.0 | ||

HIMON(1) |
Number of months prior to harvest in which to begin accumulating water stress effect on harvest index. | months | 0 to 12 | |

HIMON(2) |
Number of months prior to harvest in which to stop accumulating water stress effect on harvest index. | months | 0 to 12 | |

HIWSF |
Harvest index water stress factor: 0 = no effect of water stress upon grain yield. 1 = no grain yield with maximum water stress. | 0 to 1 | ||

KMRSP(1) |
DayCent only: Fraction of production C that goes to maintenance
respiration storage. |
0.0 to 1.0 | ||

KMRSPMX(1), KMRSPMX(2) |
DayCent only: Maximum live C fraction that goes to maintenance
respiration. (1) = aboveground live C, (2) = belowground live C. |
0.0 to 1.0 | ||

NO3PREF |
DayCent only: Fraction of N uptake that is NO_{3}. |
0.0 to 1.0 | ||

PLTMRF |
Planting month reduction factor to limit seedling growth due to partial shading; should be 1.0 for grass. See the section Shading Effect upon Production for Crop/Grass systems. Used with FULCAN. | 0.0 to 1.0 | ||

PPDF(P) |
Parameterization of a Poisson Density Function curve to simulate temperature
effect on growth. P = index for parameter:
1 = Optimum temperature for production - the peak of the curve. 2 = Maximum temperature for production; larger values = broader bell shape, and production is less sensitive to soil temperature. 3 = Spread of the bell curve; smaller values = broader bell shape, and production is less sensitive to soil temperature. 4 = Left curve shape; smaller values = more production at lower temperatures. See the figure "Graphs_PPDF" to visualize the effects of these parameters. |
1: 10.0 to 40.0
2: 20.0 to 50.0 3: 0.5 to 5.0 4: 1.0 to 5.0 |
||

PRAMN(E,1) |
Minimum C:(N, P, S) ratio with zero biomass, where E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 100.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0. | ||

PRAMN(E,2) |
Minimum C:(N, P, S) ratio with biomass equal BIOMAX, where E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 200.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0. | ||

PRAMX(E,1) |
Maximum C:(N, P, S) ratio with zero biomass, where E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 200.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0 | ||

PRAMX(E,2) |
Maximum C:(N, P, S) ratio with biomass equal BIOMAX, where E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 400.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0 | ||

PRBMN(E,1) |
Intercept for calculating the minimum C:(N, P, S) ratio for belowground biomass as a linear function of annual precipitation. E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 150.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0 | ||

PRBMN(E,2) |
Slope for calculating the minimum C:(N, P, S) ratio for belowground biomass as a linear function of annual precipitation. E = 1 for N, 2 for P, 3 for S. | 0.0 to 1.0 | ||

PRBMX(E,1) |
Intercept for calculating the maximum C:(N, P, S) ratio for belowground biomass as a linear function of annual precipitation. E = 1 for N, 2 for P, 3 for S. | N = 1.0 to 300.0, P = 1.0 to 9999.0, S = 1.0 to 9999.0. | ||

PRBMX(E,2) |
Slope for calculating the maximum C:(N, P, S) ratio for belowground biomass as a linear function of annual precipitation. E = 1 for N, 2 for P, 3 for S. | 0.0 to 1.0 | ||

PRDX(1) |
Maximum potential aboveground monthly production for crops and grasslands. Typical values for grasslands are 100-300. Crops can be as high as 600. | g biomass m^{-2} month^{-1} |
1.0 to 9999.0 | |

RDR |
Maximum root death rate at very dry soil conditions. For calculating the monthly root death rate, this fraction is multiplied by a reduction factor depending on the soil water status. | fraction/month | 0.0 to 1.0 | |

RTDTMP |
Physiological shutdown temperature for root death and change in shoot/root ratio. | degrees Celcius | -5.0 to 5.0 | |

SNFXMX(1) |
Symbiotic N fixation maximum rate for grassland/crop. | g N fixed/g C new growth | 0.0 to 1.0 | |

VLOSSP |
Fraction of aboveground plant N which is volatilized This is applied at harvest for grain crops and at senescence for grasses. | 0.0 to 1.0 |

About the Model Internal Parameterization