Parameter  Description  Units  Valid Values  Default Values  

BASFC2  (savanna only) A tree basal area factor used to calculate N availability for the grass/crop system. Increases (< 1.0) or decreases (> 1.0) the amount of N available to grasses relative to the size of the tree and SITPOT and mineral N amount. If not simulating a savanna, set to 1.0.  fractional factor  0.12.0  1.0  
BASFCT 
(savanna only) A constant used to calculate the tree basal area; it is equal
to (form factor * wood density * tree height). As used in the model, BASFCT = above ground wood biomass / basal area 
1  500  
BTOLAI 
Biomass to leaf area index (LAI) conversion factor for trees. This is a biomespecific
parameter. Values used by CENTURY include:


CERFOR(1,1,E)  Minimum C/(N, P, S) ratio for leaves, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(1,2,E)  Minimum C/(N, P, S) ratio for fine roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(1,3,E)  Minimum C/(N, P, S) ratio for fine branches, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1000.0  
CERFOR(1,4,E)  Minimum C/(N, P, S) ratio for large wood, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CERFOR(1,5,E)  Minimum C/(N, P, S) ratio for coarse roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CERFOR(2,1,E)  Maximum C/(N, P, S) ratio for leaves, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(2,2,E)  Maximum C/(N, P, S) ratio for fine roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(2,3,E)  Maximum C/(N, P, S) ratio for fine branches, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1000.0  
CERFOR(2,4,E)  Maximum C/(N, P, S) ratio for large wood, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CERFOR(2,5,E)  Maximum C/(N, P, S) ratio for coarse roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CERFOR(3,1,E)  Initial C/(N, P, S) ratio for leaves, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(3,2,E)  Initial C/(N, P, S) ratio for fine roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 200.0  
CERFOR(3,3,E)  Initial C/(N, P, S) ratio for fine branches, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1000.0  
CERFOR(3,4,E)  Initial C/(N, P, S) ratio for large wood, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CERFOR(3,5,E)  Initial C/(N, P, S) ratio for coarse roots, where E = 1 for N, 2 for P, 3 for S.  1.0 to 1500.0  
CO2ICE(2,1,E)  The effect on minimum C/(N, P, S) ratio of doubling the atmospheric CO_{2} concentration from 350 ppm to 700 ppm, where E = 1 for N, 2 for P, 3 for S. 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  
CO2ICE(2,2,E)  The effect on maximum C/(N, P, S)ratio of doubling the atmospheric CO_{2} concentration from 350 ppm to 700 ppm, where E = 1 for N, 2 for P, 3 for S. 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  
CO2IPR(2)  The effect on plant production of doubling the atmospheric CO_{2} concentration from 350 ppm to 700 ppm. 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(2)  The effect on rootshoot ratio of doubling the atmospheric CO_{2} concentration from 350 ppm to 700 ppm. 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(2)  The effect on transpiration rate of doubling the atmospheric CO_{2} concentration from 350 ppm to 700 ppm. 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  
DECID 
Flag for type of forest: 0 = continuous evergreen 1 = temperate deciduous 2 = droughtdeciduous 

DECW1  Decomposition rate for dead fine branch per year.  0.0 to 5.0  
DECW2  Decomposition rate for dead large wood per year.  0.0 to 5.0  
DECW3  Decomposition rate for dead coarse root per year.  0.0 to 5.0  
DEL13C  Delta 13C value for stable isotope labeling.  
FCFRAC(P,1)  C allocation fraction of new tree pools for juvenile forest. P = tree component index; P is tree part  1 = leaves, 2 = fine roots, 3 = fine branches, 4 = large wood, 5 = coarse roots.  0.0 to 1.0  
FCFRAC(P,2)  C allocation fraction of old tree pools for mature forest. P = tree component index; P is tree part  1 = leaves, 2 = fine roots, 3 = fine branches, 4 = large wood, 5 = coarse roots.  0.0 to 1.0  
FORRTF(E)  Fraction of (N, P, S) retranslocated from green forest leaves at death where E = 1 for N, 2 for P, 3 for S.  0.0 to 1.0  
FRFRAC(1:2)  DayCent5 only: Minimum (1) and maximum (2) possible allocation fraction to fine roots.  0.0 to 1.0  
KLAI  Large wood mass (g C m^{2}) at which half of the theoretical maximum leaf area ( MAXLAI) is achieved.  
KMRSP(2)  DayCent5 only: Fraction of production that goes to maintenance respiration storage.  0.0 to 1.0  
KMRSPMX(P)  DayCent5 only: Maximum live C fraction that goes to maintenance respiration storage; P is the tree part: 1 = leaves, 2 = fine roots, 3 = fine branches, 4 = large wood, 5 = coarse roots.  0.0 to 1.0  
LAITOP  Parameter determining relationship between LAI and forest production.  
LEAFDR(1..12)  Monthly death rate fraction for leaves for months 1 through 12.  0.0 to 1.0  
MAXLAI  Theoretical maximum leaf area index achieved in mature forest.  0.0 to 50.0  
MAXLDR  Multiplier for effect of N availability on leaf death rates (continuously growing forest systems only); a ratio between death rate at unlimited vs. severely limited N status.  0.0 to 1.0  
NO3PREF  DayCent5 only: Fraction of N update that is NO_{3}.  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 

PRDX(2)  Gross monthly forest biomass potential production. To disable this value and use PRDX(3) instead, set this value to be very large (e.g, 10000).  g biomass m^{2} month^{1}  0.0 to 9999.0  
PRDX(3)  Maximum monthly forest potential production excluding respiration, expressed as organic C. To disable this value and use PRDX(2) instead, set this value to be very large (e.g, 10000).  g C m^{2} month^{1}  0.0 to 9999.0  
SAPK  Controls the ratio of sapwood to total stem wood, expressed as g C m^{2}; it is equal to both the large wood mass (RLWODC) at which half of large wood is sapwood, and the theoretical maximum sapwood mass achieved in mature forest.  
SITPOT  (savanna only) Site potential for the N fraction to grass. A measure of the aboveground herbaceous layer production (kg ha^{1} year^{1}) in the absence of trees. (SITPOT = 2400 * monthly N availability in g N m^{2} year^{1}). A higher value results in more N given to grass production.  1200.0 to 9600.0  
SNFXMX(2)  Symbiotic N fixation maximum for forest in grams of nitrogen fixed per gram of carbon of new growth (g N fixed/g C new growth).  0.0 to 1.0  
SWOLD  Year at which to switch from juvenile to mature forest carbon allocation fractions for tree production.  simulation year range  
WDLIG(P)  Lignin fraction for production of tree components. P = tree component index; 1 = leaves, 2 = fine roots, 3 = fine branches, 4 = large wood, 5 = coarse roots.  0.0 to 1.0  
WOODDR(1)  Controls the proportion of leaves that drop during senescence month or at the end of the growing season when DECID = 1 or 2. This is especially useful for droughtdeciduous systems where only a portion of the leaves drop. Also useful when you are attempting to simulate a deciduous/coniferous mixed system of forest.  0.0 to 1.0  
WOODDR(P)  Monthly death rate fraction for tree component. P = tree component index; 1 = leaves, 2 = fine roots, 3 = fine branches, 4 = large wood, 5 = coarse roots.  0.0 to 1.0 