URISA (1994), p628-633, copyright Urban and Regional Information Association
Abstract:The red-cockaded woodpecker (RCW) was once a common bird throughout the southeastern United States. RCW populations have decreased because of loss of foraging and nesting habitat which broadly consists of old-growth pine and pine-hardwood forests. The objective of this study was to create an automated approach to determine the amount of suitable RCW foraging habitat for installation projects at Fort Benning using Geographic Resources Analysis Support System (GRASS). Results of the study show that GRASS generates reports which are used to determine total basal area and the number of pine stem required to identify the quantity of the foraging habitat, and significantly reduces the time necessary for RCW foraging habitat analysis.
The red-cockaded woodpecker (RCW) (Picoides borealis), a species endemic to mature pine forests of the southeastern U.S., was placed on the Federal list of endangered species in 1970 (Fed. Register 35:16047, 13 Oct 1970), and was one of the first species to be afforded protection under the Endangered Species Act of 1973. This act established a comprehensive program to identify and conserve threatened and endangered species and their habitat, and required all federal agencies to ensure that their actions do not jeopardize the existence of any protected species. Therefore, management of the RCW is a priority at Fort Benning and other military installations throughout the southeastern U.S.
The RCW was listed as endangered because of its perceived rarity and the destruction of its nesting and foraging habitat (Lennartz and Henry, 1985; Hooper, et al., 1982). Henry (1989) defined RCW foraging habitat as "pine and pine-hardwood stands 30 years of age or older, contiguous to and within 0.5 mile of the center of the colony." Within this 0.5 mile radius, 8,490 ft. squared
[End Page 628]
pine basal area (cross-sectional area of a tree measured at 4.5 feet above the ground, and usually summed on an acre basis) and 6,350 pine stems 10 inches or larger in diameter at breast height (dbh) (diameter of a tree measured at 4.5 feet above the ground) are considered foraging habitat requirements.
Prior to the acquisition of a Geographic Resources Analysis Support System (GRASS), foraging analysis was done by hand with dot grids. Minor changes in projects or in locations of the colony centers required the process to be re-initiated. This paper discusses an automated approach applied on proposed projects to identify existing foraging habitat and foraging needs using the GRASS system.
Fort Benning is located at the juncture of the Coastal Plain and the Piedmont Regions near Columbus, Georgia. It consists of 181,626 acres with 139,000 acres in maneuver/training areas. Approximately 170, 000 acres of Fort Benning, including ranges and impact areas, is forested. Of this, about 129,000 acres are manageable forestland, with approximately 50,000 acres considered suitable RCW habitat (i.e., pine and pine-hardwood forests 30 years of age or older). Currently, there are 180 active and 86 inactive RCW clusters on the installation.
The procedure to determine available foraging areas and to automate calculations of available forage for the RCW is conceptually simple: use Geographic Resources Analysis Support System developed by the U.S. Army Construction Engineering Research Laboratories (USACERL), Champaign, IL, as core of the managing and manipulating spatial and attribute data, and generate reports for import into Lotus 1-2-3 (Lotus 1-2-3 Release 2.2, 1989) during the final analysis.
The required input for the process consists of stand type, age and inclusion class, pine basal area, number of pine stems 10 inches or larger dbh and finally RCW cluster center location. The Geographic Information Systems (GIS) program at Fort Benning has been underway since the summer of 1992 and the data layers for the forest type, age and inclusion classes, pine basal areas and number of pine stems >=l0 inch at dbh already exist in GRASS for the whole installation. Therefore, the first step in the study was to determine colonies affected by the proposed project. According to Brooks (1994), any colony whose habitat (defined by the
[End Page 629]
0.5 mile circle around the colony center) falls in the project area is called the project colony and they have to be included in the project. Nearby colonies whose habitat overlaps with the habitat of the project colonies are also included in the project and are called secondary colonies. Finally, tertiary colonies, whose habitat overlaps the habitat of secondary colonies, are included in the project (Figure 1).
Colony centers are determined as the center of a minimum polygon defined by the outlying trees of a colony (George, 1993) (Figure 2).
[End Page 630]
Once the colony centers were found, individual site files (i.e., files which have RCW site locations) are created for each colony center and later converted into raster format. After that, 0.5 mile radius circles are generated for each colony. Finally, the foraging circles created are combined to create a cross product map composed of areas shared and not-shared by the colonies.
The second step is to determine suitable foraging habitat areas using r.infer, a GRASS program which applies commands stored in an ASCII file (Figure 3).
FIGURE 3
ASCII FILE WHICH HAS THE COMMANDS FOR r.infer
IFMAP cross.product 1-21
ANDIFMAP Forest.type 1 3-8 32 36
ANDMAP Forest.age 4-11
ANDNOTMAP Forest.incl 1-16
THENMAPHYP 1 suitable for foraging
r.infer outputs a raster map layer whose category values reflect the ability of each cell in the named input layers to satisfy the named conditions (Figure 4) (Westerwelt, et al. 1991).
[End Page 631]
Also at this stage a visual inspection is made to determine the presence of non-contiguous areas that must be eliminated. At the third and final step reports are generated for each colony with stand attributes and stand acreage (Figure 5). The reports are imported into Lotus 1-2-3 to produce a final report quantifying RCW foraging habitat for each colony.
Results of this study show that GRASS is a very valuable tool for red-cockaded woodpecker foraging habitat analysis. GRASS not only determines the suitable foraging areas geographically and produces maps, but also frees personnel from the tedious task of counting dots to determine acreage, reducing the time to do analysis from weeks to a few hours. GRASS also gives the analysis flexibility when incorporating unexpected project changes.
Brooks, T.D. 1994. Personal Communication. Fort Benning, GA: Natural Resources Management Branch, U. S. Army Infantry Center.
Henry, G.H. 1989. Guidelines for Preparation of Biological Assessment and Evaluations for the Red-Cockaded Woodpecker. Atlanta, GA: U.S. Fish and Wildlife Service, Southeast Region.
[End Page 632]
Hooper, R.G., L.J. Niles, R.F. Harlow, and G.W. Wood. 1982. Home ranges of red-cockaded woodpeckers in coastal South Caroline. Auk. 99:67S-682.
George, D.W. 1993. Personal Communication. Fort Bragg, NC: Natural Resources Branch, Fort Bragg.
Lennartz, M.R. and V.G. Henry. 1985. Red-cockaded woodpecker recovery plan. Atlanta, GA: U. S. Fish and Wildlife Service. 88 pp.
Lotus 1-2-3 User's Manual, Release 2.2, 1989. Lotus Development Corporation. Cambridge, MA.
Westerwelt, J.D., M.J. Shapiro, W.D. Goran, and D.P. Gerdes. 1991. Geographic Resources Analysis Support System (GRASS) Version 4.0 User's Manual. U.S. Army Construction Engineering Research Laboratory. Champaign, IL. pp. 272-275.
This study was supported in part by an appointment to the Research Participation Program at the U.S. Army Construction Engineering Research Laboratories administered by the Oak Ridge Institute for Science and Education through an interagency agreement with the U.S. Army Construction Engineering Research Laboratories.
[End Page 633]