W. McClain

A COMPARISON OF THE VEGETATION OF THREE LIMESTONE GLADES IN CALHOUN COUNTY, ILLINOIS

Abstract Three limestone glades in Calhoun County, Illinois were studied. These relatively rare herbaceous plant communities are dominated by grasses of the tallgrass prairie that grow where limestone is at or near the surface and the shallow soils do not support much woody vegetation. Occasionally associated with hill prairies on the bluffs of the Illinois and Mississippi Rivers, the thin soil and bare rock prevent the growth of many hill prairie species. Vascular plant species found included three ferns, one gymnosperm, 33 monocots, and 87 dicots for a total of 124 taxa. Thirteen alien taxa were encountered (10%). Juniperus virginiana (eastern red cedar) was common on and around the glade edges. The common grasses were Schizachyrium scoparium (little bluestem), and Bouteloua curtipendula (sideoats grama), while Andropogon gerardii (big bluestem) and Sorghastrum nutans (Indian grass) were occasionally found in crevices. Common forbs included Hedyotis nigricans (narrow-leaved bluets), Ruellia humilis (wild Petunia), and Croton capitatus (capitate croton).

Vascular Flora of Gray's Post Oak Woodland, Saline County, Illinois

Abstract Grays Post Oak Woodland is an open wooded community located on the western edge of the Wabash Border Natural Division about 9 km southeast of Harrisburg, Saline County, IL. Associated with a clayey soil missing most of the surface layer, the trees were stunted and gnarled. Quercus stellata dominated the canopy, accounting for nearly all of the importance value. Although six other tree species were present, few individuads exceeded 15 cm dbh. The open understory contained few saplings, averaged 1520 stems/ha, with young post oaks common. The herbaceous layer was sparse with a bare ground and litter cover of 48.90%. Danthonia spicata dominated, along with various moss and lichen species, some tree seedlings, and Carex spp.

Revisiting dogwood anthracnose in Illinois

Abstract Dogwood anthracnose (Discula destructiva) was first discovered in Illinois in 1995 at Dean Hills Nature Preserve, Fayette County. In the original study, individuals of flowering dogwood (Cornus florida) showed a 97% increase in infection by dogwood anthracnose between July 1995 and August 1996. As all size classes of flowering dogwood were infected, it was predicted that the disease would probably cause the extirpation of this species at the site. Though not extirpated, flowering dogwood has not recovered from the initial infection (1995), when 3475 healthy stems/ha were encountered. Since that initial study, total flowering dogwood stems recorded for the site ranged from a low of 110 stems/ha in 1996, to 540 stems/ha in 2002, and 345 stems/ha in 2004.

Dynamics of Species Composition and Importance from 1965–1998 in Baber Woods Nature Preserve, Edgar County, Illinois: Evidence of the Effects of Fire Suppression

ABSTRACT Presently Acer saccharum (sugar maple) dominates the overstory of Baber Woods Nature Preserve with an importance value (IV) of 75.4 (possible 200), more than half the total density (148.4 of 289.4 stems/ha), and numerous individuals in the smaller diameter classes. Second is Quercus alba (white oak) with an IV of 45.9, one-third of the basal area (9.28 of 26.95 m2/ha), which dominates the larger diameter classes, and averages 56.9 cm dbh. Total IV for all oaks combined was 64, and 30 for all hickories combined. Since Baber Woods was first surveyed in 1965, sugar maple has continued to increase in importance, with a corresponding decrease in the importance of oaks and hickories. Data suggest that this woodlot was an open white oak savanna in presettlement time. Fire suppression has resulted in canopy closure and an increase in shade-tolerant, fire-sensitive mesic species like sugar maple.

Naturalized Mimosa (Albizia julibrissin Durazz., Fabaceae) in Illinois

ABSTRACT  Populations of naturalized mimosa (Albizia julibrissin Durazz., Fabaceae) are reported from 32 counties in the southern third of Illinois. Literature and field studies suggest a significant range expansion of this taxon within Illinois during the last 50 yr. Most populations occur in open areas or along roadsides and forest edges, but a high-quality loess hill prairie on the Mississippi River bluffs contains high densities of mimosa seedlings and saplings. Mimosa is expected to continue to spread into suitable habitat based on its long history of invasion.

Herbaceous Plant Succession at Sand Prairie-scrub Oak Nature Preserve, Mason County, Illinois

Abstract The herbaceous vegetation was studied at one-, three-, and twelve-year intervals following clearing of a pine plantation at the Sand Prairie-Scrub Oak Nature Preserve, Mason County, Illinois. The annual species Setaria faberi (giant foxtail), Bidens bipinnata (Spanish needles), and Digitaria sanguinalis (crabgrass) dominated the first year. The native perennial grass Dichanthelium villosissimum (hairy panic grass) along with the exotic species Mollugo verticillata (carpetweed) were prominent the third year while Diodia teres (buttonweed) and Eragrostis trichodes (sand love grass) dominated the 12th year. Many native species commonly associated with dry sand prairies were present by the 12th year, but some exotic and native weedy species were still present.

Two Closed-canopy Barren Plant Communities in East-central Illinois

Abstract Pre-settlement barrens of Illinois were fire-maintained communities with an open tree canopy and a grass-dominated ground layer. Found on rolling topography, they were commonly underlain by well-drained, nutrient poor, clayey soils. Fire suppression following the arrival of the European settlers resulted in canopy closure and the loss of many prairie species that once dominated the ground layer. Both barrens studied had closed canopies due to decreased fire frequency, though both are currently being managed by fire. Quercus alba (white oak) and Q. stellata (post oak) dominated the overstory and accounted for more than 50% of the importance value. Very few shrubs, woody seedlings, and saplings were present, probably due to recent fires. Stephen A. Forbes State Park Barren in Marion County had been subjected to one burn before the study, and few prairie species were present there. The Buhnerkempe Barren in Clay County was subjected to occasional burns prior to our study and had higher prairie species diversity.

Vascular Flora of Buettner Xeric Limestone Prairies, Monroe County, Illinois

ABSTRACT Xeric limestone prairies occur in southwestern and southern Illinois. These small grassland communities are present on thin soil and commonly have relatively extensive areas of exposed rock. Warm-season clump grasses, primarily Schizachyrium scoparium and Bouteloua curtipendula, are dominant along with a mixture of prairie and open-forest species. The vascular flora of two xeric limestone prairies, located near the bluff line of the Mississippi River on the property of Mr. and Mrs. Ralph Buettner in Monroe County, Illinois, were surveyed in 2011. A total of 174 vascular plant species were recorded from the two prairies, with 60 species present in survey plots. Bouteloua curtipendula dominated the East prairie followed by Schizachyrium scoparium, Andropogon gerardii, and Ruellia humilis. Andropogon gerardii dominated the West prairie followed by Bouteloua curtipendula, Solidago ulmifolia, Aster oblongifolius, Tridens flavus, and Schizachyrium scoparium. Vegetation covers 38.0% and 33.5% of the surface in these two prairies, while exposed rock was between 17% and 19%, and bare ground and litter was from 40% to 44%.

Surveys of Stylisma pickeringii var. pattersonii (Convolvulaceae), Its Associated Plant Species, and Its Insect Visitors

Abstract Stylisma pickeringii var. pattersonii (Convolvulaceae) is endangered in Illinois and Iowa, and occurs in scattered populations in other states. During 1999 and 2000, two insect species previously unreported from Illinois were observed visiting its flowers. This study was undertaken to survey additional insect visitors, as well as to characterize the plant community where S. pickeringii occurs. The objectives were to survey: 1) floral traits (anthesis and flower density) of S. pickeringii, 2) associated plant species, and 3) insect visitor characteristics. Floral traits were determined and associated plant species surveyed in Mason County (degraded hay field on private property) and Henderson County (dry sand prairie at the Big River State Forest), Illinois. Insects visiting flowers were collected at 10:00 a.m., 12:30 p.m., and 3:00 p.m. during June, July, and August in 2001 and 2002. Individual flowers lasted one day and remained open for 6–8 hours. Peak flowering occurred from early to the middle of July when S. pickeringii was the dominant species in flower. Henderson County contained a greater diversity of native plant species with less bare ground and fewer non-native species than the Mason County site. Forty-seven insect species were observed visiting S. pickeringii flowers. Most frequent visitors were Apis mellifera (Hymenoptera: Apidae), Bombylius fraudulentus (Diptera: Bombyliidae), and Heterostylum croceum (Diptera: Bombliidae). The diversity of visiting insects was higher earlier than later in the day, in July and August than June, and in Henderson than Mason County.

Vegetation composition and structure of Eversgerd Post Oak Flatwoods, Clinton county, Illinois

Abstract Eversgerd Post Oak Flatwoods is a 16 ha woodlot that is part of an extensive band of timber associated with the broad Kaskaskia River valley in the Southern Till Plain Natural Division of Illinois. This flatwoods was studied to determine its woody composition and structure, and the effects of fire suppression on canopy closure and plant succession. Tree density within the site averaged 266 trees/ha with a basal area of 24.8 m2/ha. Quercus stellata Wang. (post oak) dominated the overstory and woody understory with an importance value of 171 (200 possible). Quercus bicolor Willd. (swamp white oak) and Q. palustris Muenchh. (pin oak) were common species in a shallow depression, accounting for their second and third in importance value ranking. The forest has an open, park-like appearance. Small woody saplings averaged 820 stems/ha and large saplings averaged 221 stems/ha. Grasses and sedges dominated the herbaceous layer; Danthonia spicata (L.) Roem. & Schultes and Carex cephalophora Willd. were the dominant species. The large number of post oaks with low branches and branch scars indicate that this forest was more open in the past.