*IF DEF,A19_2A LOTKA2A.2
C *****************************COPYRIGHT****************************** LOTKA2A.3
C (c) CROWN COPYRIGHT 1997, METEOROLOGICAL OFFICE, All Rights Reserved. LOTKA2A.4
C LOTKA2A.5
C Use, duplication or disclosure of this code is subject to the LOTKA2A.6
C restrictions as set forth in the contract. LOTKA2A.7
C LOTKA2A.8
C Meteorological Office LOTKA2A.9
C London Road LOTKA2A.10
C BRACKNELL LOTKA2A.11
C Berkshire UK LOTKA2A.12
C RG12 2SZ LOTKA2A.13
C LOTKA2A.14
C If no contract has been raised with this copy of the code, the use, LOTKA2A.15
C duplication or disclosure of it is strictly prohibited. Permission LOTKA2A.16
C to do so must first be obtained in writing from the Head of Numerical LOTKA2A.17
C Modelling at the above address. LOTKA2A.18
C ******************************COPYRIGHT****************************** LOTKA2A.19
!!! Subroutine LOTKA -------------------------------------------------- LOTKA2A.20
!!! LOTKA2A.21
!!! Purpose : Updates fractional coverage of each functional type. LOTKA2A.22
!!! Based on the Lotka-Volterra equations of interspecies LOTKA2A.23
!!! competition. LOTKA2A.24
!!! LOTKA2A.25
!!! LOTKA2A.26
!!! Model Modification history: LOTKA2A.27
!!! version Date LOTKA2A.28
!!! 4.4 10/97 New Deck. Peter Cox LOTKA2A.29
!!! 4.5 12/05/98 Operate only on points indexed with TRIF_INDEX ABX1F405.1641
!!! and correct calculation of NOSOIL. Richard Betts ABX1F405.1642
!!! LOTKA2A.30
!!!END ---------------------------------------------------------------- LOTKA2A.31
SUBROUTINE LOTKA (LAND_FIELD,TRIF_PTS,TRIF_INDEX 1,1ABX1F405.1643
&, C_VEG,FORW,FRAC_VS,GAMMA,G_ANTH,LAI,PC_S ABX1F405.1644
&, FRAC,DFRAC) LOTKA2A.34
LOTKA2A.35
IMPLICIT NONE LOTKA2A.36
LOTKA2A.37
*CALL NSTYPES 
LOTKA2A.38
LOTKA2A.39
INTEGER LOTKA2A.40
& LAND_FIELD ! IN Total number of land points. LOTKA2A.41
&,TRIF_PTS ! IN Number of points on which ABX1F405.1645
! ! TRIFFID may operate ABX1F405.1646
&,TRIF_INDEX(LAND_FIELD) ! IN Indices of land points on ABX1F405.1647
! ! which TRIFFID may operate ABX1F405.1648
&,K,L,M,N,T ! WORK Loop counters. ABX1F405.1649
&,DOM(LAND_FIELD,NPFT) ! WORK Dominance hierachy. LOTKA2A.46
LOTKA2A.47
REAL LOTKA2A.48
& C_VEG(LAND_FIELD,NPFT) ! IN Carbon content of vegetation LOTKA2A.49
! (kg C/m2). LOTKA2A.50
&,FORW ! IN Forward timestep weighting. LOTKA2A.51
&,FRAC_VS(LAND_FIELD) ! IN Total fractional cover of ABX1F405.1654
! ! vegetation and soil. ABX1F405.1655
&,GAMMA ! IN Inverse timestep (/360days). ABX1F405.1650
&,G_ANTH(LAND_FIELD) ! IN Anthropogenic disturbance rate LOTKA2A.53
C ! (/360days). ABX1F405.1651
&,LAI(LAND_FIELD,NPFT) ! IN Leaf area index. LOTKA2A.55
&,PC_S(LAND_FIELD,NPFT) ! IN Net carbon flux available for LOTKA2A.56
! spreading (kg C/m2/360days). ABX1F405.1652
&,FRAC(LAND_FIELD,NTYPE) ! INOUT Fractional cover of each LOTKA2A.58
C ! Functional Type. LOTKA2A.59
&,DFRAC(LAND_FIELD,NPFT) ! OUT Increment to the areal fraction LOTKA2A.60
C ! during the timestep (/timestep). LOTKA2A.61
&,B(LAND_FIELD,NPFT) ! WORK Mean rate of change of LOTKA2A.62
C ! vegetation fraction over LOTKA2A.63
C ! the timestep (kg C/m2/360days). ABX1F405.1653
&,DB_DFRAC(LAND_FIELD,NPFT,NPFT) LOTKA2A.65
C ! WORK Rate of change of B LOTKA2A.66
C ! with vegetation fraction. LOTKA2A.67
&,COM(LAND_FIELD,NPFT,NPFT) ! WORK Coefficients representing LOTKA2A.68
C ! the influence of one type LOTKA2A.69
C ! (second argument) on another LOTKA2A.70
C ! (first argument). LOTKA2A.71
&,DIFF_SUM ! WORK Difference divided by sum LOTKA2A.72
C ! for competing canopy heights. LOTKA2A.73
&,HC1,HC2,HC3,HC4 ! WORK Competing canopy heights (m). LOTKA2A.74
&,NOSOIL(LAND_FIELD) ! WORK Fractional area not available LOTKA2A.75
C ! to vegetation. LOTKA2A.76
&,SPACE(LAND_FIELD,NPFT) ! WORK Space available for invasion. LOTKA2A.77
LOTKA2A.78
*CALL TRIF LOTKA2A.79
*CALL SEED LOTKA2A.80
*CALL SIGM LOTKA2A.81
LOTKA2A.82
C---------------------------------------------------------------------- LOTKA2A.83
C Define competition coefficients and the dominance hierachy LOTKA2A.84
C---------------------------------------------------------------------- LOTKA2A.85
LOTKA2A.86
DO N=1,NPFT LOTKA2A.87
DO M=1,NPFT LOTKA2A.88
DO T=1,TRIF_PTS ABX1F405.1656
L=TRIF_INDEX(T) ABX1F405.1657
COM(L,N,M) = 1.0 LOTKA2A.90
ENDDO LOTKA2A.91
ENDDO LOTKA2A.92
ENDDO LOTKA2A.93
LOTKA2A.94
DO T=1,TRIF_PTS ABX1F405.1658
L=TRIF_INDEX(T) ABX1F405.1659
LOTKA2A.96
HC1 = A_WL(1)/(A_WS(1)*ETA_SL(1))*(LAI(L,1)**(B_WL(1)-1)) LOTKA2A.97
HC2 = A_WL(2)/(A_WS(2)*ETA_SL(2))*(LAI(L,2)**(B_WL(2)-1)) LOTKA2A.98
DIFF_SUM = (HC1-HC2)/(HC1+HC2) LOTKA2A.99
LOTKA2A.100
COM(L,1,2) = 1.0/(1+EXP(POW*DIFF_SUM)) ! BT vs NT LOTKA2A.101
COM(L,1,3) = 0.0 ! BT vs C3G LOTKA2A.102
COM(L,1,4) = 0.0 ! BT vs C4G LOTKA2A.103
COM(L,1,5) = 0.0 ! BT vs S LOTKA2A.104
LOTKA2A.105
COM(L,2,1) = 1.0-COM(L,1,2) ! NT vs BT LOTKA2A.106
COM(L,2,3) = 0.0 ! NT vs C3G LOTKA2A.107
COM(L,2,4) = 0.0 ! NT vs C4G LOTKA2A.108
COM(L,2,5) = 0.0 ! NT vs S LOTKA2A.109
LOTKA2A.110
HC3 = A_WL(3)/(A_WS(3)*ETA_SL(3))*(LAI(L,3)**(B_WL(3)-1)) LOTKA2A.111
HC4 = A_WL(4)/(A_WS(4)*ETA_SL(4))*(LAI(L,4)**(B_WL(4)-1)) LOTKA2A.112
DIFF_SUM = (HC3-HC4)/(HC3+HC4) LOTKA2A.113
LOTKA2A.114
COM(L,3,4) = 1.0/(1+EXP(POW*DIFF_SUM)) ! C3G vs C4G LOTKA2A.115
COM(L,4,3) = 1.0-COM(L,3,4) ! C4G vs C3G LOTKA2A.116
LOTKA2A.117
COM(L,5,3) = 0.0 ! S vs C3G LOTKA2A.118
COM(L,5,4) = 0.0 ! S vs C4G LOTKA2A.119
LOTKA2A.120
IF (HC1 .GE. HC2) THEN LOTKA2A.121
DOM(L,1) = 1 LOTKA2A.122
DOM(L,2) = 2 LOTKA2A.123
ELSEIF (HC1 .LT. HC2) THEN LOTKA2A.124
DOM(L,1) = 2 LOTKA2A.125
DOM(L,2) = 1 LOTKA2A.126
ENDIF LOTKA2A.127
LOTKA2A.128
DOM(L,3) = 5 LOTKA2A.129
LOTKA2A.130
IF (HC3 .GE. HC4) THEN LOTKA2A.131
DOM(L,4) = 3 LOTKA2A.132
DOM(L,5) = 4 LOTKA2A.133
ELSEIF (HC3 .LT. HC4) THEN LOTKA2A.134
DOM(L,4) = 4 LOTKA2A.135
DOM(L,5) = 3 LOTKA2A.136
ENDIF LOTKA2A.137
LOTKA2A.138
ENDDO LOTKA2A.139
LOTKA2A.140
C---------------------------------------------------------------------- LOTKA2A.141
C Calculate the space available for the expansion of each FT LOTKA2A.142
C---------------------------------------------------------------------- LOTKA2A.143
DO T=1,TRIF_PTS ABX1F405.1660
L=TRIF_INDEX(T) ABX1F405.1661
NOSOIL(L) = 1 - FRAC_VS(L) ABX1F405.1662
ENDDO ABX1F405.1663
LOTKA2A.153
DO K=1,NPFT LOTKA2A.154
DO T=1,TRIF_PTS ABX1F405.1664
L=TRIF_INDEX(T) ABX1F405.1665
N=DOM(L,K) LOTKA2A.156
SPACE(L,N)=1.0-NOSOIL(L)-FRAC_MIN*(NPFT-K) LOTKA2A.157
ENDDO LOTKA2A.158
ENDDO LOTKA2A.159
LOTKA2A.160
DO N=1,NPFT LOTKA2A.161
DO M=1,NPFT LOTKA2A.162
DO T=1,TRIF_PTS ABX1F405.1666
L=TRIF_INDEX(T) ABX1F405.1667
SPACE(L,N)=SPACE(L,N)-COM(L,N,M)*FRAC(L,M) LOTKA2A.164
ENDDO LOTKA2A.165
ENDDO LOTKA2A.166
ENDDO LOTKA2A.167
LOTKA2A.168
C---------------------------------------------------------------------- LOTKA2A.169
C Calculate the variables required for the implicit calculation. LOTKA2A.170
C Divide the update equation by FRAC to eliminate the (unstable) LOTKA2A.171
C bare soil solution. LOTKA2A.172
C---------------------------------------------------------------------- LOTKA2A.173
DO N=1,NPFT LOTKA2A.174
DO T=1,TRIF_PTS ABX1F405.1668
L=TRIF_INDEX(T) ABX1F405.1669
B(L,N) = (PC_S(L,N)*SPACE(L,N)/C_VEG(L,N) LOTKA2A.176
& -G_AREA(N)-G_ANTH(L)) LOTKA2A.177
LOTKA2A.178
LOTKA2A.179
DO M=1,NPFT LOTKA2A.180
DB_DFRAC(L,N,M) = -COM(L,N,M)*PC_S(L,N)/C_VEG(L,N) LOTKA2A.181
ENDDO LOTKA2A.182
ENDDO LOTKA2A.183
ENDDO LOTKA2A.184
LOTKA2A.185
C---------------------------------------------------------------------- LOTKA2A.186
C Update the areal fractions LOTKA2A.187
C---------------------------------------------------------------------- LOTKA2A.188
CALL COMPETE (DOM,LAND_FIELD,TRIF_PTS,TRIF_INDEX ABX1F405.1670
&, B,DB_DFRAC,FORW,GAMMA,NOSOIL LOTKA2A.190
&, FRAC,DFRAC) LOTKA2A.191
LOTKA2A.192
RETURN LOTKA2A.193
END LOTKA2A.194
*ENDIF LOTKA2A.195