RsqEC4photo: R-squared for C4 photosynthesis simulation (von Caemmerer...
In serbinsh/biocro: Simulation of Energycane and Sugarcane

Description Usage Arguments Value Examples

This is an auxiliary function which is made available in case it is useful. It calculates the R-squared based on observed assimilation (or stomatal conductance) data and coefficients for the von Caemmerer C4 photosynthesis model. The only coefficients being considered are Vcmax, Vpmax, Vpr and Jmax.

1
2
3

  RsqEC4photo(obsDat, iVcmax = 60, iVpmax = 120, iVpr = 80,
    iJmax = 400, co2 = 380, o2 = 210,
    type = c("Assim", "StomCond"))

`obsDat`	observed assimilation data, which should be a data frame or matrix. The first column should be observed net assimilation rate (μ mol m^{-2} s^{-1}). The second column should be the observed quantum flux (μ mol m^{-2} s^{-1}). The third column should be observed temperature of the leaf (Celsius). The fourth column should be the observed relative humidity in proportion (e.g. 0.7).
`iVcmax`	Maximum rubisco activity (μ mol m^{-2} s^{-1}).
`iVpmax`	Maximum PEP carboxylase activity (μ mol m^{-2} s^{-1}).
`iVpr`	PEP regeneration rate (μ mol m^{-2} s^{-1}).
`iJmax`	Maximal electron transport rate (μmol electrons m^{-2} s^{-1}).
`co2`	atmospheric carbon dioxide concentration (ppm or μbar) (default = 380).
`o2`	atmospheric oxygen concentration (mbar) (default = 210).
`type`	Use `'Assim'` if you want an R^2 for assimilation data and use `'StomCond'` if you want an R^2 for stomatal conductance data.

a numeric object

It simply returns the R^2 value for the given data and coefficients.

data(obsNaid)
obs <- obsNaid
## These data are from Naidu et al. (2003)
## in the correct format
res <- RsqEC4photo(obs)
## Other example using Beale, Bint and Long (1996)
data(obsBea)
obsD <- obsBea
resB <- RsqEC4photo(obsD)