Barker Bluff Ridge Research Natural Area

This RNA is a relatively undisturbed glade and dry upland forest. The site contains the only whorled rosin-weed (Silphium trifoliatum) known in Illinois, which is pending designation as a State endangered species. The site is a part of scarp face of the Spar Mountain Escarpment, a prominent cuesta.

Ecological Information

Physical and Climatic Conditions

Nearest weather station, with distance and direction from RNA:
The climatological data are from the collection station at New Burnside, which has records dating from 1931. The station is located 36 miles (58 km) northwest of the RNA.
Annual precipitation (type, seasonal distribution) :
Average annual precipitation is 46 inches (116.8 cm), ranging from 32 to 70 inches. It is fairly evenly distributed, with September and October being the driest months. On average, winter snowfall is light and infrequent. The average total annual snowfall ranges from 10 to 15 inches (25.4 cm to 38.1 cm).
Maximum and minimum temperatures:
July is the warmest month, with average daily maximum temperatures approaching 90ºF for both July and August. January and February are the coldest months, with temperatures dropping to as low as -15ºF.
Elevation ranges from 435 feet (136.6 m) to 680 feet (297.3 m).
Geology and Soils:
Barker Bluff is a part of a scarp face of a prominent cuesta which extends about 10 miles northwesterly from the Ohio River. It is a complex feature with a discontinuous cliff near crest and several discontinuous ledges, mainly limestone, exposed downslope. The Bethel sandstone forms the cliff of the escarpment with Cypress sandstone forming the cap of the bluff. The underlying Downey Bluff limestone and Yankeetown shale are rarely visible because they are covered by debris fallen from above. The resistant Shetlerville and Levias limestone form ledges and clifflets which support prairie glades. Both contain abundant fossil fragments and oolites. Below the Levias limestone the Rosiclare sandstone forms a low bench. At the base of the bluff is the Ste. Genevieve limestone forming a gentle slope. This formation consists of both crystalline and oolitic limestones and is widely quarried in Hardin County with large quarries present both east and west of Barker Bluff. Loess soil deposits cover the upland with silt and sand deposits found on the lower slopes from eroding upland formations. Upper slopes contain soils of the Wellstone-Berks complex, while lower slopes are of Zanesville silt loam.
Aquatic Features:
Drainage from Spar Mountain is into a sinkhole plain and into the Ohio River as groundwater. No creeks or rivers are present within the area.

Ecological Classification & Inventory

Interior Low Plateau, Shawnee Hills (222D)
Lesser Shawnee Hills (222Di)
Plant Communities:
Little bluestem-tall dropseed-Indian grass: Limestone glade natural community
Chinquapin oak-red cedar/bluestem grasses-Indian grass: Dry upland forest/limestone glade
Post oak-black oak-black hickory: Dry upland forest
White oak-red oak-hickories: Dry upland forest
SAF Cover Types (list acres): Kuchler Types (list acres):
40 Post oak-blackjack oak (40) 74 cedar glades (6)
46 Eastern red cedar (6) 91 oak-hickory forest (54)
52 White oak-black oak-northern red oak (14)  

View or download complete Vascular Flora List (pdf)

Common Shrub Species:
Winged elm (Ulmus alata), flowering dogwood (Cornus florida), eastern red cedar (Juniperus virginiana).
Common Herbaceous Species:
Little bluestem (Schizachyrium scoparium), tall dropseed (Sporobolus asper), flowering spurge (Euphorbia corollata), whorled milkweed (Asclepias verticillata), green milkweed (A. viridiflora), obedience (Physostegia virginiana), Aster sp., goldenrod (Solidago sp.), greenbrier (Smilax bona-nox).
Common Mammal Species:
White-tailed deer (Odocoileus virginianus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), gray squirrel (Sciurus carolinensis).
Common Bird Species:
Common cardinal (Cardinalis cardinalis), yellow-billed cuckoo (Coccyzus americanus), mourning dove (Zenaida macroura), red-tailed hawk (Buteo jamaicensis), blue jay (Cyanocitta cristata), eastern wood pewee (Contopus virens), summer tanager (Piranga rubra), tufted titmouse (Parus bicolor), whip-poor-will (Caprimulgus vociferus), downy woodpecker (Picoides pubescens), Carolina wren (Thryothorus ludovicianus).

Related Reports and Publications

Grahame, A., and P. Robertson. 1994. The woody vegetation of six research natural areas (RNAs) in southern Illinois. ASB Bulletin 41(2): 214.

Hutchinson, Max D. 1987. Establishment record for the Barker-Bluff Research Natural Area within the Shawnee National Forest, Hardin County, Illinois. (pdf) Unpublished report on file at the Northern Research Station, Rhinelander, and the Shawnee Supervisor's office, Harrisburg, IL. 58 pages with appendixes.

Shimp, Jody. 1996. "Vegetation analysis of three Research Natural Areas in the Shawnee National Forest: Barker Bluff, Dennison Hollow, and Panther Hollow." MS thesis, Department of Plant Biology, Southern Illinois University at Carbondale.

Shimp, J. and P.A. Robertson. 1994. Ground layer vegetation of six Research Natural Areas (RNA’s) in Southern Illinois. ASB Bulletin 41(2): 139.

Last Modified: May 6, 2021