ASU Program Stresses Ecological Approach to City Planning

With one acre of desert land developed every hour in the Phoenix metro area, preserving open spaces is an important and timely issue. In a cooperative effort to meet the challenge, Arizona Sate University's School of Planning and Landscape Architecture (SPLA) is providing a valuable community service by integrating ecological thinking into the urban planning process.

The City of Phoenix Parks, Recreation and Library Department (PRLD) contacted SPLA when it began work to develop 12,000 potential preserve acres in North Phoenix. North Phoenix was rapidly growing, raising fears the encroaching sprawl would overtake the entire area.

Faculty and Students from ASU's School of Planning and Landscape Architecture survey vegitaion along Skunk Creek. Photo by Joseph Ewan.

At the time little was known about the biota in the area to be preserved in North Phoenix. In 1996, PRLD requested SPLA to conduct a study of the area, to determine preservation boundaries consistent with the existing ecology of the Cave Creek Wash and adjacent landscape. SPLA Professor Joseph Ewan coordinated the project with the City of Phoenix.

A team made up of ecologists, landscape architects and planners inventoried and assessed plant communities within and along the wash corridor. Using vegetation data collected from the field, maps were created, and the team classified four plant communities. With this information researchers then developed three recommended alternative preservation boundary scenarios: maximum, moderate and minimum preservation. Each included goals and concepts, a boundary map, suggested acreage for preservation and a list of benefits and constraints.

In recommending preservation boundaries consistent with the existing ecology of the wash system and the adjacent lands, the researchers were breaking new ground in Phoenix. Boundaries traditionally were set with reference to topography, i.e. visual landmarks like slopes, hillsides and mountains or land ownership. Not reflecting the ecological systems within a landscape, the boundaries were thus established without due consideration of the impact of preserve size, shape, connectivity to other preserved open space and other factors impacting plant and wildlife habitats.

In its review of the submitted report, PRLD acknowledged that it learned that "the process of establishing preserve boundaries should be based on scientific understanding of the natural systems instead of property ownership and topography, as was commonly done in the past." Responding to the SPLA recommendations, both the Parks Board and the City Council endorsed the maximum recommended preservation scenario of 4,500 acres of land along Cave Creek Wash.

In 1997, SPLA began the next phase of the study. Study areas included Apache Wash, Skunk Creek Wash and its tributaries, and Deadman Wash. Completed in November 1998, this study complemented the Cave Creek Wash study by completing the inventory of all major washes in the north area. After vegetation sampling was completed, vegetation was categorized on the basis of the sampling, aerial photographs and field observations, and mapped using GIS. Vegetation was classified according to vegetation composition and landscape physiognomy. A separate "damaged" classification was established for areas sufficiently damaged by human interference that vegetation could not be characterized.

Researchers also studied wildlife populations on Cave Creek and Skunk Creek washes, to identify wildlife species and distribution. This survey enabled them to determine which areas of the wash and adjacent uplands are important to native species.

The next phase, to begin in the spring, is to conduct a habitat suitability study. This study will work out correlations between the vegetative and wildlife inventories, to be used in future planning. Information gathered in the various separate studies will thus be integrated into a single study encompassing approximately 25 square miles.

Graduate and undergraduate students involved in this project acquired valuable real-world, hands-on experiences, by working in the field, studio and lab, and collecting and analyzing data. For example, a vegetation management class participated in vegetative sampling and developed management plans for the washes. Two landscape architecture students received national recognition by winning a first place design award in a American Society of Landscape Architecture competition for their concepts on developing the preserve edge.

Persons involved in the above project have organized the North Sonoran Collaborative. This is an informal discussion group, its participants including municipal planners, developers, Arizona Game and Fish officials and ASU personnel. Its next scheduled meeting is January 20.

For additional information about SPLA's involvement in the above work contact Joseph Ewan at ASU, phone: 480-965-7167; email: joseph.ewan@asu.edu

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