Dennison Hollow Research Natural Area

[photo:]National Forest RNA signs a marking boundary of the Research Natural Area and defining the management of an RNA. Photo taken by Elizabeth Shimp, Shawnee National Forest Botanist.

Dennison Hollow RNA includes high quality dry upland forest, sandstone glade, and sandstone cliff communities. The RNA contains three State threatened species: Loggerhead Shrike (Lanius ludovicianus), chestnut oak (Quercus prinus) and an aster (Aster undulatis); and one Federally threatened listed species: Mead's Milkweed (Asclepias meadii).

Ecological Information

Physical and Climatic Conditions

Nearest weather station, with distance and direction from RNA:
Closest weather station is in Harrisburg, 9 miles west-northwest of Dennison Hollow.
Annual precipitation (type, seasonal distribution) :
Annual precipitation averages about 42 inches and ranges from about 25 to 72 inches.
Maximum and minimum temperatures:
Annual temperature range is 100° F. Summer maximums reach 100° F (37.8 ° C) or more during 8 out of 10 summers. Winter minimums are 0° F (-17.8° C) or below during 6 out of 10 winters.
Elevation at Dennison Hollow ranges from 920 feet at the west edge of the area to 420 feet at the east edge.
Geology and Soils:
A relatively thin layer of silty loess covers the area, generally thickest high on the ridge. The large ridge on which Dennison Hollow is located is composed of 1) massive sandstone, come conglomeritic, 2) sandstone with alternating shale lyers on the ridge crest and back slope, and 3) shale and limestone on the sharp face.
Aquatic Features:

Ecological Classification & Inventory

Plant Communities:
Post oak-black oak-black hickory: Dry upland forest
White oak-red oak-hickories: Dry upland forest
Post oak-red cedar-broomsedge: Sandstone glade
SAF Cover Types (list acres): Kuchler Types (list acres):
40 Post oak-blackjack oak (52) 91 oak-hickory forest (775)
44 Chestnut oak (15)  
52 White oak-black oak-northern red oak (50)  
53 White oak (46)  
110 Black oak (42)  

View or download complete Vascular Flora List (pdf)

Common Shrub Species:
Hydrangea (Hydrangea arborascens)
Common Herbaceous Species:
Poverty oats (anthonia spicata), farkleberry (Vaccinum arboeum), greenbriar (Smilax bona-nox), woodland sunflower (Helianthus divaricatus), butterfly pea (Clitoria mariana), pussytoes (Antennaria plantaginifolia), dittany (Cunila origanoides), little bluestam (Andropogon scoparius) and Indian grass (Sorghastrum nutans), poison ivy (Rhus radicans), Virginia creeper (Parthenocissus quinquefolia), pineweed (Hypericum gentianoides), rough buttonweed (Diodia teres), Christmas fern (Polystichum acrostichoides), alumroot (Heuchera parviflora).
Common Mammal Species:
White-tailed deer (Odocoileus virginianus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), opossum (Didelphis marsupialis), and gray squirrel (Sciurus carolinensis)
Common Bird Species:
Pileated woodpecker ( Dryocopus pileatus), eastern wood-pewee (Contopus virens), and blue-gray gnatcatcher (Polioptila caerulea), wild turkeys (Meleagris gallopavo).

Related Reports and Publications

Hutchinson, Max D. 1989. Establishment record for the Dennison Hollow Research Natural Area within the Shawnee National Forest, Saline County, Illinois. (pdf) Unpublished report on file at the Northern Research Station, Rhinelander, and the Shawnee Supervisor's office, Harrisburg, IL. 82 pages with appendixes.

Last Modified: May 6, 2021