Ecological Research Evaluation

Blanco County

 

Aerial & Soils Map

Topographic Map

 

 

 

 

 

 

 

 

Acreage:  65

County:    Blanco     

Nearest Town:  Johnson City

General Property Location:  Central Blanco County. 

 

Photo 1:  View from shallow soil, south facing, xeric shrubland over Pedernales River in background.  Shrub layer dominated by persimmon, though some hogplum and live oaks present.  Prickly pear abundant.  Sideoats grama and King Ranch (KR) bluestem comprise bulk of herbaceous layer. 

 

 

Photo 2:   Grazing cell adjacent to Pedernales river.  Bermudagrass, johnsongrass, and eastern gamagrass present. 

 

 

Photo 3:   View of river edge.  Eastern gamagrass and goldenrod in foreground. 

 

 

Photo 4:  Drainage feeding into Pedernales river.  Flows ephemerally. 

Photo 5:   Juniper/oak parkland.  Healthy herbaceous layer consisting of mostly little bluestem. 

 

 

 

 

Photo 6:  Spring-fed pool in un-named creek.  Cattails on right.   

Photo 7:  Juniper parkland.  King Ranch bluestem dominant herbaceous plant. 

 

 

 

Photo 8:   Small karst feature. 

 

 

 

 

 

Site Description

 

The 65-acre property is located in central Blanco County off of FM 1323.  The property consists of two land owned by two landowners.  The irregular-shaped property is bordered to the southwest by the Pedernales River and has approximately 1100 feet of river frontage.  An un-named creek runs from northeast to southwest through the center of the tract and into the Pedernales River.  Several small karst habitats are present on the tract, though it was not thoroughly examined.  The property has steep slopes near the creek and light to moderate slopes on upland areas.  The low point of the property, 1140 ft MSL, occurs along the Pedernales frontage while the high point of 1270 ft MSL, occurs in the tract’s northwest corner. 

 

 

Habitat Description

 

With the exception of a several-acre grazing unit near the river, the bulk of the property has not been grazed in over a decade.  Three habitat types are present on the property.  A shrubland is present on the south-facing slopes just north of the river.  The dominant shrub was persimmon, though several Texas kidneywood, and hogplum shrubs were also present.  Herbaceous plant included sideoats grama, King Ranch bluestem, Lindheimer senna, little bluestem, nolina, and orange zexmania.  Pricklypear was observed in moderate amounts.

 

A flat, riverine bench is present along the Pedernales River.  A fenced pasture is present here and is currently being grazed by one donkey.  This pasture contains bermudagrass, eastern gamagrass, and Johnsongrass.  Vegetation along the river edge includes riparian-associated species such as rattle bush, black walnut, sycamore, switchgrass, and indigobush.  The river pasture and river frontage undergo fairly regular flooding. 

 

The bulk of the property consists of a live oak/juniper parkland with an average canopy cover of about 30%.  While live oak and juniper were the dominant tree species, cedar elm and mesquite were also present.  Due to lack of recent grazing, later successional plants such as little bluestem and sideoats dominate the herbaceous layer.  Other herbaceous plants include croton, ragweed, seep muhly (near creek areas), twisted leaf yucca, and Japanese brome.  

 

Like much of the area, the white-tailed deer population is moderately-high to high based on observed herbivory on woody plants. 

 

 

 

Soil Descriptions (source: NRCS)

 

Eckrant-Rock outcrop association, rolling (Map unit 10).  Located in western half of property in upland areas. 

 

The Eckert series consists of soils that are shallow to petrocalcic horizon. They are well drained, undulating to rolling soils of uplands. The soil formed in and is underlain by dolomitic limestone. In a representative profile, the soil is dark brown, silty loam 4-14 inches thick that contains about 50 percent limestone fragments. Soil permeability is moderate and available water holding capacity is very low. The soil has a low natural fertility and shallow rooting depth. It is almost exclusively used as rangeland. The climax vegetation includes scattered scrubby live oak, elms, and other shrubs, associated with little bluestem, green sprangletop, sideoats grama, fringeleaf paspalum, yucca; and forbs such as sagewort.  The Eckert - rock outcrop association is classified in the Stony Loam ecological site.

 

Tarpley association, undulating (Map Unit 42).  Located in eastern half of property in upland areas.

 

This association is present on uplands.  It is made up of shallow, stony, clayey soils that are underlain by limestone.  Typically, these soils have a surface layer that is very firm, dark reddish gray stony clay about 8 inches thick.  These soils are well drained.  Runoff is medium.  Permeability is slow, and available water capacity is very low.  The root zone is shallow.  The hazard of water erosion is severe.  The historic climax community is an oak savanna.  In this climax condition, there is about 20 percent live oak and post oak overstory,that includes blackjack oak and Texas oak in places.  Dominant grasses are little bluestem, indiangrass, big bluestem, Canada and Virginia wildrye, sideoats grama, Texas wintergrass, vine-mesquite, tall dropseed, feathery bluestem, plains lovegras, Texas cupgrass, and buffalograss.  This soil is classified as a Redland ecological site. 

 

Riverwash, frequently flooded (Map Unit RW).  Located along river frontage. 

Riverwash, gravelly consists of unstabilized gravel beds in the floor of intermittently flooded streams.  These areas are mostly barren of vegetation due to the scouring during flooding.  Permeability is rapid and available water holding capacity is very low. 

 

 

Research Possibilities

 

Perhaps the property’s most unique feature from a research standpoint is the Pedernales River frontage.  Various aquatic birds, fish, and amphibians can be found in these aquatic areas. 

 

The karst habitat may be home to endangered karst invertebrates, but further investigation will need to be conducted to verify. 

 

The parkland habitat is typical for that in this part of the Edwards Plateau.  Attract features of the upland habitat include the proximity to the river and the lack of recent grazing pressure. 

 

Keith Olenick

Senior Wildlife Biologist

Plateau Land & Wildlife Management