R Map Template

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Clusters: 8,000 bp to 6,000 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
4
5
6
7
8
 Cluster Number
 
4468
44
25
777
19
41
81025
 Sq. Kilometers
 
5.200
0.050
0.030
0.900
0.020
0.050
93.800
 % of Study Area
Taxa
.
.
.
.
.
.
.
  
Acacia greggii
.
.
.
.
.
.
.
  
Agave utahensis
X
X
X
X
X
.
.
  
Ambrosia dumosa
.
.
.
.
.
.
.
  
Amelanchier utahensis
.
.
.
.
.
.
.
  
Artemisia ludoviciana
.
.
.
.
.
.
.
  
Ceanothus greggii
.
.
.
.
.
.
.
  
Celtis reticulata
.
.
.
.
.
.
.
  
Cercocarpus intricatus
.
.
.
.
.
.
.
  
Cowania mexicana
X
X
.
x
.
.
.
  
Cryptantha
.
.
.
.
.
.
.
  
Echinocereus
.
X
.
.
.
.
.
  
Encelia frutescens
.
.
.
.
.
.
.
  
Ephedra
X
X
X
.
X
.
.
  
Ephedra nevadensis
.
.
.
.
.
.
.
  
Ferocactus acanthodes
.
.
.
.
.
.
.
  
Forsellesia nevadensis
.
.
.
.
.
.
.
  
Fraxinus
.
.
.
.
.
.
.
  
Fraxinus anomala
.
X
X
.
X
.
.
  
Juniperus osteosperma
X
X
X
X
.
X
.
  
Larrea divaricata
.
.
.
.
.
.
.
  
Lepidium
.
.
.
.
.
.
.
  
Lithospermum
.
.
.
.
.
.
.
  
Olneya tesota
.
.
.
.
.
.
.
  
Opuntia
.
X
X
.
X
.
.
  
Opuntia chlorotica
X
X
.
.
.
.
.
  
Opuntia erinacea
X
X
X
X
X
X
.
  
Opuntia phaeacantha
X
X
X
X
X
.
.
  
Opuntia whipplei
X
X
.
x
.
X
.
  
Oryzopsis hymenoides
.
.
.
x
.
.
.
  
Ostrya knowltonii
.
.
X
.
X
.
.
  
Physalis
.
.
.
.
.
.
.
  
Pinus edulis
.
.
.
x
.
X
.
  
Pinus flexilis
.
.
.
.
.
.
.
  
Pinus ponderosa
.
.
.
.
.
.
.
  
Prosopis juliflora
.
.
.
.
.
.
.
  
Pseudotsuga menziesii
X
X
X
X
X
X
.
  
Ptelea pallida
.
.
X
.
X
.
.
  
Quercus gambelii
.
.
.
.
.
.
.
  
Quercus turbinella
X
X
X
.
X
.
.
  
Quercus undulata
.
.
.
.
.
.
.
  
Rhus
X
X
X
X
X
.
.
  
Rhus trilobata
.
.
.
.
.
.
.
  
Sambucus neomexicana
.
.
X
.
X
.
.
  
Sphaeralcea
.
.
.
.
.
.
.
  
Symphoricarpos
.
.
.
.
.
.
.
  
Thelesperma longipes
.
.
.
.
.
.
.
  
 
11
14
13
10
12
5
0
 Count
 
4
1
2
5
3
6
7
 Rank