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Clusters: 6,000 bp to 4,000 bp

This map defines ecological communities using image data analysis of GIS-generated images. We downloaded data from the 30 nearest packrat middens using North American Packrat Midden Database and brought the resulting 1340 records into FileMaker Pro. We selected the perennial taxa and parsed the records out to chronological categories based on Carbon-14 dated material in each midden. Using the century-old “law of latitudinal equivalent in elevation” (Lowe 1972) from the Merriam Life Zone System, one degree of latitude = 77 meters (250 feet) elevation in Arizona, we brought each record into our study area and adjusted the elevation of the packrat midden in which the taxa were found. Each taxon’s highest and lowest actual occurrence became its elevation range. The map calculator function in ArcView 3.2 (Spatial Analyst extension) distributed taxa across the study area’s two latitude ranges, 32 degrees to 33 degrees N and 33 degrees to 34 degrees N. Each pixel has a one-square-kilometer resolution. These grids were merged and exported as images. We linked each taxon image by time period in MultiSpec and ran a cluster analysis using the number of taxa as the initial cluster solution. Taxa in each community cluster are shown in the table below.

 
1
2
3
4
5
6
 Cluster Number
 
360
47
24
138
4010
82180
 Sq. Kilometers
Taxa
0.420
0.054
0.028
0.160
4.620
94.720
 % of Study Area
Abies concolor
.
.
.
.
.
.
  
Acacia greggii
.
X
.
.
.
.
  
Allionia incarnata
.
X
X
.
.
.
  
Artemisia ludoviciana
.
.
.
.
.
.
  
Berberis
.
X
X
.
.
.
  
Carnegia gigantea
.
X
X
X
X
.
  
Celtis pallida
.
X
X
X
.
.
  
Cercocarpus intricatus
.
.
.
.
.
.
  
Encelia farinosa
.
X
X
X
.
.
  
Ephedra
.
.
.
.
.
.
  
Euphorbia
.
X
X
.
.
.
  
Fendlera rupicola
.
.
.
.
.
.
  
Fraxinus anomala
.
.
.
.
.
.
  
Janusia gracilis
.
X
X
.
.
.
  
Juniperus
.
X
X
X
.
.
  
Juniperus osteosperma
.
.
.
.
.
.
  
Lepidium
.
.
.
.
.
.
  
Mammillaria
.
X
X
.
.
  
Opuntia
.
.
.
.
.
.
  
Opuntia acanthocarpa
.
X
X
.
.
.
  
Opuntia bigelovii
.
X
X
.
.
.
  
Opuntia chlorotica
.
X
X
X
.
.
  
Opuntia erinacea
.
.
.
.
.
.
  
Opuntia phaeacantha
.
X
X
X
.
.
  
Opuntia spinosior
.
X
X
.
.
.
  
Physalis
.
X
X
.
.
.
  
Pinus edulis
.
.
.
.
.
.
  
Pinus monophylla
.
X
X
.
.
.
  
Pinus ponderosa
.
.
.
.
.
.
  
Prosopis juliflora
.
X
X
.
.
.
  
Pseudotsuga menziesii
.
.
.
.
.
.
 
Quercus turbinella
.
X
X
.
.
.
  
Rhus
.
.
.
.
.
.
  
Ribes
.
.
.
.
.
.
  
Sphaeralcea
.
X
X
.
.
.
  
 
0
20
19
6
1
0
 Count
 
5
1
2
3
4
5
 Rank