Allometries.f90

Go to the documentation of this file.

!==============================================================================
!
!  Module Allometries.f90!
!  Remarks: contains the functions BiomassFromDBH, DBHFromHeight, LAFromDBH
!
!==============================================================================
 
!==============================================================================
!===============================================================
REAL FUNCTION biomassfromdbh(dbh, tb, stn) !,bm )
    use all_par, only: a1, a2, c1     
 
IMPLICIT NONE
    ! Passed variables>--------------------------------------------------------------------------------
    real, intent(in)  :: dbh   ! tmp var to calculate diameters                       [=diam/nextDiam]
      integer, intent(in)  :: tb, stn  ! tree species types                      [=diam/nextDiam]
!    real, intent(out) :: bm      ! calculated biomas                              [=BioMassAtHeight(..)]
 
    ! Local variables>---------------------------------------------------------------------------------
    real  :: bm      ! calculated biomass                              [=BioMassAtHeight(..)]
    real :: lndiam, &     ! tmp var to calculate LA                                       [=rLnDiam]
            stmvol, &     ! Stem volume                                                  [=stemvol]
            stmwgt, &     ! Stem weight                                                     [=stemW]
            folwgt        ! Foliage weight                                                   [=folW]
 
    ! Here the subroutine starts>**********************************************************************
    if (dbh .le. 0.0) then
        lndiam = 0.0
        folwgt = 0.0
        stmvol = 0.0
    else
        lndiam = log(dbh*100.0)
        folwgt = c1(tb) * a1(stn) * exp(lndiam * a2(stn))
        stmvol = 0.12*exp(lndiam*2.4)
    end if
 
    !NZ: if output should only be stem volume (timber harvesting), comment next 2 lines out
    ! and set bm = stmvol instead
    stmwgt = 0.5*stmvol
    bm = stmwgt + folwgt
    biomassfromdbh = bm
    return
end FUNCTION biomassfromdbh
 
!==============================================================================
!===============================================================
REAL FUNCTION dbhfromheight(height, birthheigth, maxheigth, maxdiam) 
IMPLICIT NONE
REAL, intent(IN):: height,birthheigth, maxheigth, maxdiam
REAL :: argmt
 argmt = min(max(1.0 - ((height - birthheigth)/(real(maxheigth) - birthheigth)), 0.0), 1.0)  
 dbhfromheight = maxdiam * (1.0 - sqrt(argmt)) + 0.0127 
return 
END FUNCTION dbhfromheight
 
!==============================================================================
!===============================================================
REAL FUNCTION lafromdbh(dbh, tb, stn) 
Use all_par, only: a1, a2, c2 
IMPLICIT NONE
REAL, intent(IN)   :: dbh
INTEGER, intent(IN):: tb, stn
REAL               :: lndia
if (dbh > 0.0) then
    lndia = log(dbh * 100.0)
else
    lndia = 0
end if
lafromdbh = c2(tb) * a1(stn) * exp( lndia * a2(stn) ) 
return 
END FUNCTION lafromdbh
!==============================================================================