ftemp_inst_jmax | R Documentation |
Given 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) |
The function is given by Kattge & Knorr (2007) as
fv = f(T, Δ Hv) A/B
where f(T, Δ Hv) is a regular Arrhenius-type temperature response function (see ftemp_arrh) with Hv=49884 J mol-1,
A = 1 + exp( (T0 Δ S - Hd) / (T0 R) )
and
B = 1 + exp( (T Δ 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
Δ 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 (!)
A numeric value for fv
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 )
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