# Allocation

 FORGEM

Allocation is the distribution of assimilates produced by photosynthesis over the different plant components. In the ForGEM model, empirical equations are in ForGEM used for allocation $f_{y$

based on tree allometry. The fraction of net primary production allocated to the different plant components is set such that the tree strives for partitioning ratios between plant organs. A fixed fraction of NPP is allocated to the roots.


The coefficients of these equations are indicated as ${\displaystyle C_{n}}$, with ${\displaystyle {n}}$ a numeric identifier. See allocation parameters for the values of ${\displaystyle C_{n}}$ for different tree species.

${\displaystyle \ln \left({\frac {Wfl}{Wst}}\right)=C1+C2\cdot \ln \left(Wsh\right)+C3\cdot \ln \left(Wsh\right)^{2}+C4\cdot \ln \left(Wsh\right)^{3}}$

${\displaystyle \ln \left({\frac {Wbr}{Wst}}\right)=C5+C6\cdot \ln \left(Wsh\right)+C7\cdot \ln \left(Wsh\right)^{2}+C8\cdot \ln \left(Wsh\right)^{3}}$

${\displaystyle \Rightarrow {\frac {Wst}{Wsh}}={\frac {1}{1+\ln \left({\frac {Wfl}{Wst}}\right)+\ln \left({\frac {Wbr}{Wst}}\right)}}}$

with:

W: weight (kg tree-1)
fl: foliage
br: branches
st: stem (= heartwood + sapwood)
sh: shoot (= foliage + branches + stem)

## References

Collet, Lanter, & Pardos, 2001.

Gansert & Sprick, 1998.

Garcia-Plazaola & Becerril, 2000.

Grubb et al., 1996.

Hättenschwiler, 2001.

Hees 1997;Lof, 2000.

Lof & Welander, 2000.

Minotta & Pinzauti, 1996.

Welander & Ottosson, 1997.

Welander & Ottosson, 1998.