Ponderosa Pine Tree Point Pattern
The data record the locations of 108 Ponderosa Pine (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
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.
data(ponderosa) gives access to two objects,
ponderosa is a spatial point pattern
(object of class
representing the point pattern of tree positions.
ppp.object for details of the format.
ponderosa.extra is a list containing supplementary
data. The entry
id contains the index numbers of the
three special points A, B, C in the point pattern. The entry
plotit is a function that can be called to produce a nice plot
of the point pattern.
Prof. Janet Franklin, University of California, Santa Barbara
Franklin, J., Michaelsen, J. and Strahler, A.H. (1985) Spatial analysis of density dependent pattern in coniferous forest stands. Vegetatio 64, 29--36. Getis, A. and Franklin, J. (1987) Second-order neighbourhood analysis of mapped point patterns. Ecology 68, 473--477.