spatstat (version 1.23-1)

ponderosa: Ponderosa Pine Tree Point Pattern

Description

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 is the 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.

Usage

data(ponderosa)

format

Typing data(ponderosa) gives access to two objects, ponderosa and ponderosa.extra. The dataset ponderosa is a spatial point pattern (object of class "ppp") representing the point pattern of tree positions. See ppp.object for details of the format.

The dataset 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.

source

Prof. Janet Franklin, University of California, Santa Barbara

References

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.

Examples

data(ponderosa)
   ponderosa.extra$plotit()