R/subroutines.R
ftemp_inst_jmax.RdGiven Jmax at a reference temperature (argument tcref)
this function calculates its temperature-scaling factor following
modified Arrhenius kinetics based on Kattge & Knorr (2007).
Calculates \(f\) for the conversion
$$
V = f Vref
$$
ftemp_inst_jmax(tcleaf, tcgrowth = tcleaf, tcref = 25)
| tcleaf | Leaf temperature, or in general the temperature relevant for photosynthesis (degrees Celsius) |
|---|---|
| tcgrowth | (Optional) Growth temperature, in the P-model, taken to be
equal to |
| tcref | Reference temperature (in degrees Celsius) |
A numeric value for \(fv\)
The function is given by Kattge & Knorr (2007) as $$ fv = f(T, \Delta Hv) A/B $$ where \(f(T, \Delta Hv)\) is a regular Arrhenius-type temperature response function (see ftemp_arrh) with \(Hv=49884\) J mol-1, $$ A = 1 + exp( (T0 \Delta S - Hd) / (T0 R) ) $$ and $$ B = 1 + exp( (T \Delta S - Hd) / (TK R) ) $$ Here, \(T\) is in Kelvin, \(T0=293.15\) K, \(Hd = 200000\) J mol-1 is the deactivation energy and \(R\) is the universal gas constant and is 8.3145 J mol-1 K-1, and $$ \Delta S = aS - bS T $$ with \(aS = 659.70\) J mol-1 K-1, and \(bS = 0.75\) J mol-1 K-2, and \(T\) given in degrees Celsius (!)
Kattge, J. and Knorr, W.: Temperature acclimation in a biochemical model of photosynthesis: a reanalysis of data from 36 species, Plant, Cell and Environment, 30,1176–1190, 2007.
# Relative change in Jmax going (instantaneously, i.e. # not acclimatedly) from 10 to 25 degrees (percent change): print((ftemp_inst_jmax(25)/ftemp_inst_jmax(10)-1)*100 )#> [1] 162.7662