Detection and Analysis of Open Space Change in Yavapai and Southern Mohave Counties, Arizona

Big game in the Southwestern United States have been threatened by loss of open space habitat - losses both in total amount of habitat and quality of habitat. The Arizona Game and Fish Department has identified the need to quantify change in open space in areas that are habitat for large ungulates (elk, desert bighorn, mule deer, pronghorn antelope, and white-tailed deer). Large acreage that is protected or is in a mosaic of ranches and associated grazing leases, functions as critical open space for these large ungulates. In Yavapai and southern Mohave Counties of central-western Arizona human development has fragmented ungulate habitat; however, the amount and location of fragmentation has not been documented. Also, conversion of ranch lands to non-grazing uses may be accompanied by changes in state and federal lands due to changes in grazing allotment allocations. To study these issues the United States Geological Survey (USGS) initiated a project in cooperation with and funded by the Arizona Game and Fish Department (AGFD) using the funding support of the Arizona Desert Bighorn Sheep Society, the Arizona Mule Deer Association, and the Rocky Mountain Elk Foundation. Figure 1 - Area of Study: Yavapai and Mohave Counties, Arizona. Click to view detailed shaded relief map of Arizona with area of study identified (228 kilobytes). [TOP]

The main goal of the project was to detect, map, and analyze the amount of change in open space between 1984 and 1997 within the study area and document where these changes have occurred in order to effectively evaluate change in big game habitat. Resulting digital image maps are to be used by the Arizona Game and Fish Department to help in the management of the area's wildlife habitats.

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Remote Sensing and Mapping

The regional view and repetitive coverage of remotely sensed satellite images make them a good data set for detecting and mapping changes on the Earth's surface. The Landsat Thematic Mapper (TM) satellite imaging system, launched in 1982, collects images that have an approximate spatial resolution of 30 meters and a temporal revisit resolution of about two weeks. Because of its 30-meter spatial resolution and the availability of historical images Landsat TM data can be used to help detect, monitor, and study long-term surface change. Landsat TM collects images in three visible bands (blue, green, and red), one near-infrared band, and two mid-infrared bands. The 30-meter resolution image data can be used for large regional assessment and monitoring in an efficient and relatively inexpensive manner.

In this project, Landsat TM satellite images collected during the summers of 1984 and 1997 were used to generate a digital change image that showed surface change that had occured during this time period. This surface change image shows both where change occured and the magnitude of the change. Keep in mind that in this project surface change is directly related to changes in brightness and color of the Earth's surface; brightness and/or color change can occur due to several different processes. Examples of on-the-ground changes that can affect the brightness and color seen by a satellite image are:

• changes in the amount of vegetation cover or type,
• disturbed soils or vegetated areas, and
• land use changes (i.e. new development).

Figure 2: Illustration showing the portion taken from different Landsat TM scenes to generate the two digital mosaics of the study area (220 kilobytes).

Images collected during the summers of 1984 and 1997 were selected using the rainfall information and a listing of available cloud free historical Landsat TM images. Since the project started in 1998 this gave us close to the maximum temporal separation possible using the Landsat TM satellite launched in 1982. Most of the area of interest, Yavapai and Southern Mohave Counties, were covered by two Landsat TM image path and row footprints. These images were collected on June 9th and 18th 1984 and June 22nd and July 15th 1997. However, to cover the entire area small portions of other images from several paths and rows had to be used. These images were collected on June 9th and August 3rd 1984 and June 20th and July 15th 1997 (see figure 2). The images were geometrically and radiometrically processed and used to generate two digital image mosaics or maps covering all of Yavapai and Southern Mohave Counties (see figure 3) The digital image maps were generated with a 30-meter spatial resolution and geometrically transformed into the UTM Zone 7 projection with GRS80 ellipsoid paramaters.

An open space database for Yavapai and southern Mohave counties was developed for this project. This relational database contains information on the type of land ownership (federal, state, or private), allotment assignment for public grazing lands, and ranch land use where known.

The Arizona Land Resource Information System (ALRIS) Land Ownership map (last updated in 1988) was obtained and used as the base map. It contains information related to categories of ownership and was used to generate various digital maps showing ownership types (e.g., federal, state, or private). The Yavapai County land parcel map was used to identify ranch land in this county. Such data were not available for Mohave County.

Figure 4: Habitat Maps 300 kilobytes, requires a JavaScript capable browser.

Digital big game habitat maps were obtained from the Arizona Game and Fish Department for elk, mule deer, white-tailed deer, desert bighorn sheep, and pronghorn antelope. The maps for elk, mule deer, and white-tailed deer were for both summer and winter habitats, while the bighorn sheep and pronghorn antelope were a single map. These maps were originally compiled and drawn manually by various wildlife managers within the Game and Fish Department in the late 1970's and digitized in 1983 and 1984; the maps were last updated in 1988.

The habitat maps show the distribution of the particular ungulate by a density rating, which are not the same for each species. The numbers refer to the estimated number of animals per square mile.

Surface Change Analysis

An analysis was conducted using the surface brightness change image map and the open space database and other digital land cover/use maps to evaluate surface changes within the big game habitats. The digital maps and database were used to answer the questions concerning the amount and quality of open space land available to big game ungulates. In the GIS software environment the surface change image map and database were used to answer questions such as:

• "What is the amount of surface change in big game habitat during the 13-year time interval studied?"
• "How much of the change is high intensity change?"
• "What corridors and critical areas for big game habitat have changed the least?

A report with the in-depth details on the surface change analysis will be delivered to the Arizona Game and Fish Department and will be available on this site after official review and acceptance.

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This project was funded by the Arizona Game and Fish Department through financial contributions from the following organizations:

Rocky Mountain Elk Foundation http://www.rmef.org/	Arizona Mule Deer Association (602) 395-DEER	Arizona Desert Bighorn Sheep Society http://www.adbss.org/

For more information on remote sensing and the surface change image map contact:

Pat S. Chavez, Jr.
Email: pchavez@usgs.gov

U.S. Geological Survey
Geologic Division
2255 N. Gemini Dr.
Flagstaff, AZ 86001

Tel: (520) 556-7221
FAX: (520) 556-7169

Dr. Kathryn Thomas
Email: Kathryn_A_Thomas@usgs.gov

U.S. Geological Survey
Biological Resources Division
Forest and Rangeland Ecosystem Science Center
Colorado Plateau Field Station
Flagstaff, AZ 86003

Tel: (520) 556-7466, ext. 235
FAX: (520) 556-7500

Jim Witham
Email: jwitham@gf.state.az.us

Arizona Game and Fish Department
5325 N. Stockton Hill Rd.
Kingman, Arizona 86401
Tel: (520) 692-7700, ext. 108

• Factsheet: Open Space Changes in Yavapai and Southern Mohave Counties, Arizona (FS-135-99) (PDF/Adobe Acrobat format - download Adobe Acrobat Reader)

• Arizona Game and Fish Department
• Biological Resources Division: Colorado Plateau Field Station
• Rocky Mountain Elk Foundation

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