co2
Carbon Dioxide Uptake in Grass Plants
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.
- Keywords
- datasets
Usage
CO2Details
The $CO2$ uptake of six plants from Quebec and six plants from Mississippi was measured at several levels of ambient $CO2$ concentration. Half the plants of each type were chilled overnight before the experiment was conducted.
This dataset was originally part of package nlme, and that has
methods (including for [, as.data.frame, plot and
print) for its grouped-data classes.
Format
An object of class
c("nfnGroupedData", "nfGroupedData", "groupedData", "data.frame")
containing the following columns:
- Plant
-
an ordered factor with levels
Qn1<Qn2<Qn3< ... <Mc1giving a unique identifier for each plant. - Type
-
a factor with levels
QuebecMississippigiving the origin of the plant - Treatment
-
a factor with levels
nonchilledchilled - conc
- a numeric vector of ambient carbon dioxide concentrations (mL/L).
- uptake
- a numeric vector of carbon dioxide uptake rates ($umol/m^2$ sec).
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
library(datasets)
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
print(sapply(fmlist, coef), digits = 3)