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Background Information Report

Biological Resources

An initial visit to CSSA was made on December 1, 1992, when a general evaluation of the vegetative condition of the property was made, primarily from the vantage point of various roads and trails which cross the site. Particular attention was given to identifying areas which might contain suitable habitat for rare, threatened, or endangered species.

On December 2, 1992, a more focused site evaluation was made, primarily on foot, of several areas which might contain sensitive species' habitat. Additionally, brief interviews were conducted with resource management personnel and persons with knowledge of the land use history of the site.

Appropriate aerial photographs and topographic maps were analyzed to confirm the findings from the site visits and to identify any additional areas which may have been missed, but which appear similar to sensitive areas which were noted during the visits. Soils and geological maps were referenced to evaluate the current condition of the vegetation at the site relative to its potential vegetation condition.

Native Vegetation

The site physiography is typical of Balcones Canyonlands, encompassing a complex of limestone hills, drainages and valleys with several springs and intermittent streams dispersed throughout (Riskind and Diamond, 1988). The upper drainages of Salado Creek occupy much of the central portion of the site. The general upland vegetation community type is classified as mainly an ever­green woodland of the Ashe juniper-oak (Juniperus ashei-Quercus sp.) series, and there is a minor riparian component of the sugarberry-elm (Celtis laevigata-Ulmus sp.) series (Diamond, et al., 1987).

The current condition of the soils and vegetative cover in the "undeveloped" two-thirds of the site suggests previous overgrazing, land clearing for agricultural purposes, and suppression of natural fires. Management directed toward cattle grazing and game production has resulted in most of the property being maintained in an open grassland or disturbed savanna condition. Selective brush removal, particularly of Ashe juniper, and mowing of some areas occur periodically. In recent years, controlled burns have been conducted to facilitate growth of native plant species. Supple­mental food and water for stock and wildlife are provided throughout the site.

The majority of the wooded uplands are characterized, generally, by a broken canopy of older live oaks (Quercus fusiformis) with somewhat younger Ashe junipers occupying the midstory and invading open areas in the woodlands. Where active juniper removal is occurring, the vegetative cover type has more of an oak/oak motte savanna appearance. Spanish oak (Quercus buckleyi) is present in some areas, but is not abundant, and very little mixed shrub development was noted.

The broader floodplain areas have generally been maintained as open fields. The smaller drainage areas over most of the site contain very little cedar elm (Ulmus crassifolia) or other mixed hardwood species normally associated with such areas, and instead are generally dominated by stands of live oak and Ashe juniper.

Wildlife and Livestock

CSSA lands are managed to meet three objectives: to accommodate military activities; to satisfy a cooperative grazing lease with the USDA-ARS in Kerrville; and to provide hunting opportunities for military personnel. Land management decisions are made ultimately by the installation's Commander based on military needs, recreational interests, informal cooperative agreements with other agency resource specialists, and recommendations made by the installation's Environmental Officer.

The Environmental Officer on the site consults with the Texas Parks and Wildlife Department (TPWD) in annually counting the deer, planning the hunting program, and recommending land management activities focused on game species, primarily white-tailed deer and turkey, according to the habitat evaluation (ES, 1993b). A free-ranging herd of axis deer is present at the site and is also hunted. The active and successful hunting program is helping to keep the deer population within the carrying capacity of the site. The Command has also consulted with the Alamo District Conservation Office of the NRCS relative to farm pond construction and restoring habitat to native conditions.

The grazing lease is administered through a cooperative agreement between the Alamo District Conservation Office of the NRCS and the USDA-ARC in Kerrville. Stocking rates and range management recommendations are made by USDA-ARC personnel based on research needs and in accordance with general guidelines developed in 1983 (ES, 1993b).

Endangered, Threatened, and Rare Species

Two federally listed endangered bird species, the black-capped vireo and the golden-cheeked warbler are known to nest in the general upland habitat type which occurs to the northwest of San Antonio. One federally listed endangered plant species, the Tobusch fishhook cactus, is known from similar habitat in counties to the northwest of CSSA. The Texas blind salamander is federally listed as endangered and the San Marcos salamander is federally listed as threatened. Both of these species are known to occur in the southeastern Balcones Canyonlands portion of the Edwards Plateau in the Edwards aquifer. Endangered and threatened species which could potentially be found at CSSA are listed in Table 2.

Several federal category 2 and state-listed threatened or endangered animal species, the widemouthed blindcat catfish, the toothless blindcat catfish, the Comal blind salamander, the Blanco blind salamander, and the Texas horned lizard also occur to the northwest or adjacent to San Antonio.

Three species of cave invertebrates, known to occur in caves in the geographic region, were listed as endangered on January 20, 1998 (62 FR 66295). These include the Comal Springs dryopid beetle, the Comal springs riffle beetle, and Peck’s cave amphipod. During a downhole video camera survey of wells at CSSA, an unidentified invertebrate and a vertebrate (a salamander) were found in well 2 (ES, 1993a). The invertebrate was present at 100 feet below static water level and appeared to be an isopod. The salamander was observed at the bottom of the well (346.5 feet bgl).

Additionally, CSSA adjoins Camp Bullis (28,000 acres) which has many areas designated as habitats for endangered species.

Black-capped vireo. In general, this bird requires a patchy arrangement of well-developed shrubs and mid-successional overstory irregularly interspersed with bare or grassy openings. The brush component should be complete to the ground to provide suitable nest sites (Graber, l961). The species composition of the vegetation tends to be less important than its structure, but broad-leaved species are more favorable than others, and juniper may be underrepresented in occupied habitat. Suitable habitat development for this species is strongly associated with the rocky soils of the Lower Cretaceous limestones of the Fredricksburg Group (Sexton, 1990).

There were several areas at CSSA on the east side of the main drainage of Salado Creek observed in 1993 which may have the vegetation structure and composition suitable for nesting habitat for this species (Figure 11). One pair of vireos was observed in the northeast portion of CSSA during 1993 spring field studies (ES, 1993b).

Golden-cheeked warbler. The nesting range of the golden-cheeked warbler corresponds to the range of Ashe juniper in central Texas (Pulich, 1976). Prime habitat for this warbler consists of mature Ashe juniper in association with mature stands of mixed hardwoods to meet both its nesting and foraging requirements (USFWS, 1992). From field investigations conducted in the area, it also appears that canopy closure should exceed 40 percent for the stand, in general.

Although much of the woody vegetation at CSSA has been fragmented and juniper removal has been conducted, there are several areas which could provide some amount of adequate nesting habitat for this species (Figure 11). One male warbler was observed during 1993 spring field studies in the northeast portion of CSSA.

Other species of concern. The overall habitat condition and current land use practices at CSSA do not appear to be suitable for any of the other rare, threatened, or endangered terrestrial species, with the possible exception of the Texas horned lizard. This species very likely did occur at the site in times past. However, its population numbers have declined to such a degree that it has only rarely been documented from the general area in recent years. Reasons for this decline are unknown at this time.