CO2 {MEMSS} | R Documentation |
Carbon Dioxide uptake in grass plants
Description
The CO2
data frame has 84 rows and 5 columns of data from an
experiment on the cold tolerance of the grass species
Echinochloa crus-galli.
Usage
CO2
Format
This data frame contains the following columns:
- Plant
-
an factor giving a unique identifier for each plant.
- Type
-
a factor with levels
Quebec
Mississippi
giving the origin of the plant - Treatment
-
a factor with levels
nonchilled
chilled
- conc
-
a numeric vector of ambient carbon dioxide concentrations (mL/L).
- uptake
-
a numeric vector of carbon dioxide uptake rates (
sec).
Details
The uptake of six plants from Quebec and six plants
from Mississippi was measured at several levels of ambient
concentration. Half the plants of each type were
chilled overnight before the experiment was conducted.
Source
Potvin, C., Lechowicz, M. J. and Tardif, S. (1990) “The statistical analysis of ecophysiological response curves obtained from experiments involving repeated measures”, Ecology, 71, 1389–1400.
Pinheiro, J. C. and Bates, D. M. (2000) Mixed-effects Models in S and S-PLUS, Springer.
Examples
require(stats); require(graphics)
coplot(uptake ~ conc | Plant, data = CO2, show.given = FALSE, type = "b")
## fit the data for the first plant
fm1 <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0),
data = CO2, subset = Plant == 'Qn1')
summary(fm1)
## fit each plant separately
fmlist <- list()
for (pp in levels(CO2$Plant)) {
fmlist[[pp]] <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0),
data = CO2, subset = Plant == pp)
}
## check the coefficients by plant
sapply(fmlist, coef)