A Vision for Biological
Corridors and Critical Habitat
The work on the biological corridors and critical habitat element
of the Sonoran Desert Conservation Plan revealed that biology
is the basis for all other elements. The strong interconnections
of all five elements are critical in forming a viable land management
plan that ensures continuing biodiversity for Pima County.
Corridors and Critical Habitat
Pima County is committed to the long-term survival of the full
indigenous plants and animals and the conservation of its cultural
The two elements that most directly express the biological basis
of Pima County, Arizona’s Sonoran Desert Conservation Plan
are biological corridors and critical and sensitive habitats.
When the Plan began in 1998, the science community did not have
a list of priority vulnerable species of concern, a set of biological
standards, or even a vegetation map that could serve as the starting
point for determining the locations in need of protection for
the species that are in decline.
After an intensive research effort involving dozens of members
of both the local and national science community much has been
achieved. A list of potentially covered species has been identified,
the best available vegetation maps are now assembled, and the
science community has identify the patches of habitat and connecting
corridors that will establish an effective and lasting biological
For the nine mammals, eight birds, seven reptiles, seven plants,
six fish, two amphibians, and numerous invertebrates that have
been identified thus far as being in need of protection, the
biological goals of the plan will be of great assistance in promoting
recovery and improving the status of these species.
This is true not only because a statement of biological goals
and objectives has been articulated, but because we are now able
to gather information in a comprehensive fashion, take actions
to improve the status of the species in the short term, and craft
an adaptive management plan that continues to improve the information
base and the conservation program over the long term. Substantial
contributions from the expert community have also built the Critical
Habitat and Biological Corridors Elements.
Sonoran Desert Ecoregion Plan
The Nature Conservancy’s prestigious ecoregional plan for
the Sonoran Desert has been published and adopted by the Science
Team. Dr. Gary Nabhan’s influential work on the ironwood
tree led to the creation of the Ironwood National Monument. The
ecosystem of the Sonoran Desert is one of the most important
earth, deserving of special attention and protection.
When the conservation plan was initiated, the scientific community
had little data collected about the interaction of land development
and the decline of biodiversity. Three years later, a scientific
basis has been established that exceeds the precision of
other national conservation plans, and represents the start
investment in research, monitoring and adaptive management.
In addition, critical habitat designations identify unique
Sonoran Desert habitat associations, not previously recognized,
promoting sustained Sonoran Desert bio-diversity. While the
flower of the protected saguaro cactus is the state flower,
science has proven that the unprotected ironwood
really the tree of life for the Sonoran Desert.
Critical Riparian Habitats
The majority of the priority vulnerable species in Pima County
are associated with aquatic and riparian-based ecosystems.
This list of species also points out the importance of other
landscape elements or features that are also threatened in
Pima County. Grasslands, desert scrub, caves, adits and talus
slopes serve as unique habitat niches that support vulnerable
A Full Spectrum of Biodiversity
Protecting indigenous species requires more than conserving
the habitat of individual species. Maintaining the
of native biodiversity requires the inclusion of vegetation
communities when assembling a viable reserve system.
Attention must also
be paid to larger ecological processes. Many areas vital to
the survival of vulnerable species may be outside of,
between, existing parks or natural preserves.
Identification of Vulnerable Species
Under the direction of the Science Technical Advisory Team,
a list of the most vulnerable plant and wildlife species was
This began with an initial list of over one hundred species
recognized as imperiled, species extirpated from Pima County,
species in decline or in jeopardy. This review resulted in
a short list of 55 species that were identified by the Team
priority vulnerable species, warranting further analysis, consideration,
Priority Habitats and Corridors
The selected Priority Habitats and Corridors include:
Eastern Tucson Riparian Complex
Organ Pipe/Goldwater Complex
San Pedro River
Santa Rita Mountains
The collection and synthesis of biological
data has been ongoing in Pima County for decades. Records date
back to the 1800s and
extend into present time to reflect agency, academic, and private
sector efforts. This information provides a broad historical
context for examining existing conditions.
The Pima County Board of Supervisors appointed the Scientific
Technical Advisory Team to develop the biological resources element
of the Sonoran Desert Conservation Plan. In May, 1999, this multi-agency,
multi-disciplinary team met to begin discussions about the biological
underpinnings for a regional conservation plan. Since that time
they and County staff, along with consultants, biologists, and
natural resource managers, have identified the plant and wildlife
species of greatest concern.
Numerous studies were prepared by experts in the fields of biology
and water resources including important new data published for
the first time. Pima County’s superlative geographic information
system was used to analyze information in ways that have never
before been possible. An extensive GIS mapping database was compiled
and numerous illustrations and diagrams were created. The information
was then released to the public for additional input and review.
Focus future growth and associated infrastructure
expansion in areas in closest proximity to existing urbanized
in areas of highest biological richness.
Significantly lower intensity of future land uses allowed in
certain biologically sensitive areas near major washes, within
ecologically rich habitats, adjacent to Saguaro National Park,
and other sensitive areas of Pima County.
Avoid or minimize future losses and fragmentation by a publicly
supported land acquisition and conservation program. Open Space
Acquisition funds and other private/public partnerships enable
the acquisition of lands or conservation easements adjacent to
the existing reserve system as well as ranches conserved through
acquisition of development rights or conservation easements,
thereby implementing the Ranch Conservation and Mountain Park
Expansion Elements of the SDCP.
Prioritize 26 percent of the CLS for conservation by the adoption
of Habitat Protection Priorities in Eastern Pima County. This
includes approximately 525,000 acres of biological core, important
riparian areas, threatened and endangered species management
areas, and special landscape elements.
Pima County will continue to nominate and pursue acquisition
of biologically sensitive lands for reclassification by the Arizona
State Land Department under the Arizona Preserve Initiative,
or through state land constitutional reform.
Conserving important biological resources has become a very important
part of future land use decisions.
and Critical Habitat Map (PDF)
GOAL AND OBJECTIVES FOR THE BIOLOGICAL ELEMENT
OF THE SONORAN DESERT CONSERVATION PLAN
Sonoran Desert Conservation Plan
Pima County Administrator’s Office
130 West Congress, 10th Floor
Tucson, AZ 85701