Vascular Plant and Vertebrate Inventory of Saguaro ... - USGS

Executive Summary
This report summarizes the results of the
first comprehensive inventory of plants and
vertebrates at the Rincon Mountain District
(RMD) of Saguaro National Park, Arizona.
From 2001 to 2003 we surveyed for vascular
plants and vertebrates (amphibians, reptiles,
birds, and mammals) at the district to document
the presence of species within its boundaries.
Park staff also surveyed for medium and large
mammals using infrared-triggered cameras
from 1999 to 2005. This report summarizes the
methods and results of these two efforts. Our
spatial sampling design was ambitious and was
one of the first of its kind in the region to colocate
study sites for vegetation and vertebrates
using a stratified random design. We also chose
the location of some study sites non-randomly
in areas that we thought would have the highest
species richness. Because we used repeatable
study designs and standardized field methods,
these inventories can serve as the first step in a
biological monitoring program for the district.
We also provide an important overview of most
previous survey efforts in the district. We use
data from our inventory and other surveys to
compile species lists and to assess inventory
completeness.
With the exception of plants, our
survey effort was the most comprehensive ever
undertaken in the district. We recorded a total
of 801 plant and vertebrate species, including
50 species not previously found in the district
(Table 1) of which five (all plants) are non-native
species. Based on a review of our inventory and
past research at the district, there have been a
total of 1,479 species of plants and vertebrates
xv
found there. We believe inventories for all
taxonomic groups are nearly complete. In
particular, the plant, amphibian and reptile, and
mammal species lists are the most complete of
any comparably large natural area of the “sky
island” region of southern Arizona and adjacent
Mexico.
For each taxon-specific chapter
we discuss patterns of species richness and
environmental determinants of these patterns.
For all groups except medium and large
mammals, the low elevation stratum (