Distribution of about 180 plants of Castanea pumila (species 38) in the state of Florida, and data on the values of four climate variables which are expected to be important factors in determining the distribution of the plant species.
row: row number
col: column number
sp38: incidence of Cuastanea pumila
FZF: median freeze-free period in days
TAV: mean annual temperature in degrees Celsius
PRCP: mean total annual precipitation in millimetres
MI: moisture index = (PRCP)/(TAV x 58.93), where TAV x 58.93 = estimate of mean annual potential evapotranspiration by the Holdridge method.
X <- read.table("~/Desktop/sp38data.txt",header=T)
ggplot(X) + geom_tile(aes(col,row,fill=sp38))
ggplot(X) + geom_tile(aes(col,row,fill=mi))
Wu, H. and Huffer, F.W. (1997), Modelling the Distribution of Plant Species Using Autologistic Regression Model, Environmental and Ecological Statistics, 4, 49-64.