Atwood Ridge
Location
Ecological and Physical Description
The Atwood Ridge RNA contains several relatively undisturbed natural community types, including: barrens, hill prairie, dry upland forest, dry-mesic upland forest, and mesic upland forest. The RNA also contains two Illinois Endangered plants (including panic grass (Panicum ravenelii)), and an Illinois Threatened plant species, the chestnut oak (Quercus prinus). Several other uncommon and relict plants occur here as well, including the Cucumber-tree (Magnolia acuminata) and the rosebud-azalea (Rhododendrom prinophyllum), both southeastern species at the northwestern edge of their range. The Federally endangered American bald eagle (Haliaeetus leucocephalus) is often seen in the area during the winter.
Total annual precipitation is 46 inches (116.8 cm), 54 % of which falls in April through September. Average seasonal snowfall is 13 inches (33.02 cm).
Climatological information is taken from the collection station at Anna, which is located 4.5 miles (7.2 km) to the southwest of the RNA.
Atwood Ridge forms part of the Mississippi Valley wall. It is an unbroken, but undulating ridge with its south end lying immediately above an abandoned meander of the Mississippi River. Closely-spaced and steep-sided canyons extend from the floodplain up to the crest. Ridge crests are capped with silty loess over Devonian siliceous limestone (Bailey Formation) and chert (Grassy Knob Formation). The entire area is dissected into narrow V-shaped valleys and narrow-crested ridges. Many slopes are scree-covered. The soils over most of the area are of the Goss-Alford complex.
Although the drainage pattern is grossly reticulate, each lateral valley has a dendritic tributary pattern. Atwood Ridge is part of the Clear Creek-Horseshoe Lake watershed. The largest stream in the area is Clear Creek Ditch.
Flora and Fauna
Common Plant Species
| Scientific Name | Common Name | Category | At Risk | Notes |
|---|---|---|---|---|
| Cercis canadensis | Redbud | Common Shrub Species | ||
| Cornus florida | flowering dogwood | Common Shrub Species | ||
| Lindera benzoin | spicebush | Common Shrub Species | ||
| Toxicodendron radicans | common poison ivy | Common Shrub Species | ||
| Rhododendron prinophyllum | rosebud-azalea | Common Shrub Species | ||
| Asimina triloba | pawpaw | Common Shrub Species | ||
| Schizachyrium scoparium | Little bluestem | Common Herbaceous Species | ||
| Elymus canadensis | Canada wild rye | Common Herbaceous Species | ||
| Panicum anceps | panic grass | Common Herbaceous Species | ||
| Helianthus divaricatus | divaricate sunflower | Common Herbaceous Species | ||
| Silphium integrifolium | prairie rosin-weed | Common Herbaceous Species | ||
| Silphium. terebinthinaceum | basal-leaved rosin-weed | Common Herbaceous Species | ||
| Lespedeza virginica | Virginia lespedeza | Common Herbaceous Species | ||
| Dicentra cucullaria | Trillium sp., Viola sp., Dutchman’s breeches | Common Herbaceous Species | ||
| Polystichum acrostichoides | Christmas-fern | Common Herbaceous Species | ||
| Pteridium aquilinum | bracken fern | Common Herbaceous Species | ||
| Asplenium rhizophyllum | walking fern | Common Herbaceous Species |
Common Animal Species
| Scientific Name | Common Name | Category | At Risk | Notes |
|---|---|---|---|---|
| Odocoileus virginianus | White-tailed deer | Common Mammal Species | ||
| Canis latran) | coyote | Common Mammal Species | ||
| Procyon lotor | raccoon | Common Mammal Species | ||
| Didelphis virginiana | Virginia opossum | Common Mammal Species | ||
| Sciurus carolinensis | ray squirrel | Common Mammal Species | ||
| Felis rufus | bobcat | Common Mammal Species | ||
| Haliaeetus leucocephalus | American bald eagle | Common Bird Species | ||
| Dryocopus, pileatus | pileated woodpecker | Common Bird Species | ||
| Meleagris gallopavo | common turkey | Common Bird Species |