ponderosa.Rd
\name{ponderosa}
\alias{ponderosa}
\alias{ponderosa.extra}
\docType{data}
\title{
Ponderosa Pine Tree Point Pattern
}
\description{
The data record the locations of 108 Ponderosa Pine
(\emph{Pinus ponderosa}) trees in a 120 metre square region in the Klamath
National Forest in northern California, published as Figure 2 of
Getis and Franklin (1987).
Franklin et al. (1985) determined the locations of approximately 5000
trees from United States Forest Service aerial photographs and
digitised them for analysis. Getis and Franklin (1987) selected a 120
metre square subregion that appeared to exhibit clustering. This subregion
is the \code{ponderosa} dataset.
In principle these data are equivalent to
Figure 2 of Getis and Franklin (1987) but they are not exactly
identical; some of the spatial locations appear to be slightly
perturbed.
The data points identified as A, B, C on Figure 2 of Getis and Franklin
(1987) correspond to points numbered 42, 7 and 77 in the dataset
respectively.
}
\format{
Typing \code{data(ponderosa)} gives access to two objects,
\code{ponderosa} and \code{ponderosa.extra}.
The dataset \code{ponderosa} is a spatial point pattern
(object of class \code{"ppp"})
representing the point pattern of tree positions.
See \code{\link{ppp.object}} for details of the format.
The dataset \code{ponderosa.extra} is a list containing supplementary
data. The entry \code{id} contains the index numbers of the
three special points A, B, C in the point pattern. The entry
\code{plotit} is a function that can be called to produce a nice plot
of the point pattern.
}
\usage{data(ponderosa)}
\source{Prof. Janet Franklin, University of California, Santa Barbara}
\examples{
data(ponderosa)
ponderosa.extra$plotit()
}
\references{
Franklin, J., Michaelsen, J. and Strahler, A.H. (1985)
Spatial analysis of density dependent pattern in coniferous forest
stands.
\emph{Vegetatio} \bold{64}, 29--36.
Getis, A. and Franklin, J. (1987)
Second-order neighbourhood analysis of mapped point patterns.
\emph{Ecology} \bold{68}, 473--477.
}
\keyword{datasets}
\keyword{spatial}