ftemp_inst_vcmax: Calculates the instantaneous temperature response of Vcmax
In rpmodel: P-Model

Description Usage Arguments Details Value References Examples

Given Vcmax 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

1	ftemp_inst_vcmax(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 `tcleaf` (in degrees Celsius). Defaults to `tcgrowth = tcleaf`.
`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=71513 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 = 668.39 J mol-1 K-1, and bS = 1.07 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.

1
2
3

## Relative change in Vcmax going (instantaneously, i.e. 
## not acclimatedly) from 10 to 25 degrees (percent change):
print((ftemp_inst_vcmax(25)/ftemp_inst_vcmax(10)-1)*100 )