Details - CALS Networking Lab - University of Arizona

vegetation by point intercept along six, 50-m
transects (see Chapter 3 for more information).
To map the location of plots, we designed
a footprint of the sampling grids using an
Avenue Script (“View.CreateTransectLines,” by
Neal Banerjee, October 5, 2000; downloaded
from ESRI ArcScripts website) to create grid
lines every 100 m that were perpendicular (90
degrees) to a “dummy” transect (Fig. 1.1A).
These grid lines were converted from graphics to
shapes using the XTools extension for ArcView
(developed by the Oregon Department of
Forestry). We then generated points where each
grid line intersected the transect using the Themes
Intersections to Points extension for ArcView
(developed by Arun Saraf, November 11, 1999;
downloaded from ESRI ArcScripts website) (Fig.
1.1B).
We created 100 x 100 m squares
centered on each intersection point to generate
the amphibian and reptile plots using the
Square Buffer Wizard extension for ArcView
(developed by Robert J. Scheitlin, May 12, 2000;
downloaded from ESRI ArcScripts website).
These squares were numbered 1 to 10 in the
direction of the transect bearing (Fig. 1.1C). The
same process was repeated to create the mammal
plots (Fig. 1.1D). Four bird survey stations were
created by selecting the center of mammal plots
6
3, 8, 13, and 18 and buffering each of these
points with a radius of 125 m (Fig. 1.1E).
These circles were numbered 1 to 4 in the
direction of the transect bearing.
Non-random Selection of Study Sites
Many areas of the district contain unique areas
requiring special surveys for all taxa. Riparian
areas, cliffs, rocky outcrops, and ephemeral
pools were likely to be missed if we located
our study sites only in random areas. Yet these
areas are diversity “hotspots” and are therefore
crucial to visit in order to complete the species
inventories. We selected these study areas
based on our knowledge of the district. The
area deemed to be of importance differed
by taxonomic group, but we chose to do
surveys for all taxa in low-elevation riparian
areas (e.g., Rincon Creek). For plants, we
concentrated on Rincon Creek and drainages
on the east slope of the Rincon Mountains. For
reptiles and amphibians we searched dozens of
canyons at low and medium elevations, and for
mammals we concentrated on middle elevation
semi-desert grasslands (for more complete
descriptions of survey areas, see each taxonspecific
chapters.