ABSTRACT We conducted literature searches of records from Illinois, Indiana, Iowa, Minnesota, Missouri, North Dakota, Ohio, and Wisconsin to create a source bibliography of wildland fire descriptions occurring between 1673 and 1905. A total of 795 landscape fire records were identified within or near the eastern tallgrass prairie–forest transition region, including 32 attributed to Native Americans, 194 to Europeans from spontaneous records in the nineteenth century, and 569 to Europeans from a systematic dataset collected during the late nineteenth and early twentieth centuries in Minnesota. From these historical accounts, we find overwhelming evidence that a two- to three-week period during October and November, known then as “Indian summer,” was the primary wildland fire season. Our records indicate that Native Americans used fire primarily for hunting, whereas Euro-American fires were set to reduce fire hazards near their habitations, to eliminate crop residues, and to facilitate plowing, or they were escapes due to mere carelessness. Only five lightning-caused fires were identified. Individual fires frequently burned thousands of hectares, creating dense smoke, damaging trees, personal property, and occasionally burning inhabitants fatally. South and southwest were the most frequent wind directions during wildfires. Drought years, including 1796, 1819, 1856, and 1871, were characterized by extensive fires, which ultimately resulted in legislation to protect property owners and public welfare. Fire events for the study period are certainly underestimated by this dataset because only large, spectacular, threatening fires were recorded, especially during European settlement. In addition, our estimate of Native American fire frequency and prevalence is less than their historical/expected frequency, due to their widespread population collapse and changed hunting methods following contact and dispossession by Europeans.

We conducted field searches for populations of Mentzelia oligosperma Nutt. (stickleaf) throughout the known range of this species in Illinois during the growing seasons of 2010–2019. A species common to the prairies and plains of western North America, it is habitat-specific and rarely observed in Illinois. Populations are confined mostly to narrow limestone cliff ledges along the bluffs of the Mississippi River in Adams, Calhoun, Monroe, Pike, and Randolph counties on the western border of the state. We identified 18 potential stickleaf sites based upon herbaria searches and interviews with biologists. Subsequent field investigations determined the presence of 15 extant sites, including two new locations at Hull in Pike County and the Fults Hill Prairie Annex in Monroe County. Five historic populations are extirpated. The state total of 498 plants represents populations ranging from six to 85 individuals at 15 sites, with most locations having fewer than 20 individuals. Stickleaf is currently listed as endangered by the Illinois Endangered Species Protection Board due to its restricted habitat and low population densities.

A second population of Phemeranthus calycinus (Montiaceae, large-flowered rock pink) was confirmed for southwestern Illinois. This is the second site known east of the Mississippi River for this taxon.

ABSTRACT Large expanses of loess hill prairie were once common along the bluffs of the Mississippi and Illinois rivers of Illinois. These communities occur in forest openings on thick loess deposits overlying bedrock and frequently have expanses of exposed limestone at their margins (glades). Warm season, clump-forming grasses dominate the herbaceous vegetation along with a mixture of prairie and open forest species. Miles Hill Prairie, Monroe County, Illinois is located about 20 km west of Waterloo in the Northern Section of the Ozark Natural Division. Within the prairie, 148 vascular plant species were recorded with 40 species found in the survey plots. Schizachyrium scoparium dominated followed by Andropogon gerardii, Solidago speciosa, Sorghastrum nutans, and Bouteloua curtipendula. Common forbs include Pycnanthemum pilosum, Symphotrichum patens, and Symphotrichum oolentangiense with Cornus drummondii the most abundant shrub, and Torilis japonica the only exotic species in plots. This is a high-quality loess hill prairie that is well maintained by prescribed fire and brush removal. Most species encountered were common to loess hill prairies, with the 19 exotic species being rare and mostly restricted to prairie edges.

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%.

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.

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.

Cross-sections of 36 post oaks (Quercus stellata Wang.) were examined to determine the fire history of a post oak woodland in Hamilton County, Illinois. The 226-year tree ring record contained three distinct periods; a fire era from 1776 to 1850 having a mean fire return interval of 1.97 years, a fire-free period from 1851 to 1884, and a second fire era from 1885 to 1996 having a mean fire return interval of 1.44 years. The fire-free interval corresponds with the rapid settlement of Hamilton County during 1850-85. The fires between 1770 and 1850 are considered landscape fires associated with Native Americans and/or early European settlers, while those between 1885 and 1996 are thought to be due to burning of local woodlands, a practice that became increasingly less common in the late 20th century. Three post oak cohorts were identified, including 211-224 year-old (217-year mean), 137-151 year-old.(144-year mean), and 104-115 year-old (105-year mean) age classes. Post oak recruitment ended and fire sensitive hickories (Carya ovata and C. tomentosa), black cherry (Prunus serotina), sassafras (Sassafras albidum), and black oak (Quercus velutina) now dominate the seedling and sapling layers of the woodland.

A few high quality prairies still exist in the sand deposits of the Green River Lowlands on a few state protected lands. The most extensive natural remnants are in the Green River State Wildlife Area, Lee County, Illinois, where some sand communities of high natural quality exist. Three upland prairie communities were surveyed; a dry sand prairie dominated by Schizachyrium scoparium, Ambrosia psilostachya, and Amorpha canescens; a dry-mesic sand prairie dominated by Sorghastrum nutans, Schizachyrium scoparium, Antennaria plantaginifolia, and Liatris aspera; and a mesic sand prairie where Sorghastrum nutans and Andropogon gerardii were the dominant grasses with Parthenium integrifolium, Fragaria virginiana, Liatris pycnostachya, and Euthamia gymnospermoides the common forbs. The lowlands, which include about 325 ha, were dominated by the exotic Phalaris arundinaceae, but high natural quality wet sand prairie, sedge meadow, and marsh communities exist. The wet sand prairies were dominated by Spartina pectinata, Helianthus grosseserratus, and Solidago canadensis; the sedge meadows were dominated by Carex haydenii, Calamagrostis canadensis, and Persicaria coccinea; while the marsh communities were divided into distinct vegetation zones. These vegetation zones were surveyed in 2002, and were subjected to a destructive fire in 2005. Surveys completed 2006 and 2007 were used to determine successional changes resulting from the 2005 fire. 1. Present address: Cornell Plantations, 1 Plantations Road, Ithaca, New York 14850

Schizachyrium scoparium, a dominant species of mature dry sand prairies in Illinois, is not found in the early stages of old field succession. A 30-year-old abandoned field at Sand Prairie-Scrub Oak Nature Preserve, Mason County, Illinois, when surveyed in 2000, was dominated by Eragrostis trichodes [importance value (I.V.) of 97.4], with Strophostyles helvula (I.V. 43.7) and Monarda punctata (I.V. 16.9) ranking second and third in I.V. (possible 200), while Schizachyrium scoparium was absent. When the authors revisited this field in the summer of 2008 Schizachyrium scoparium had become the dominant grass (I.V. 66.8), Eragrostis trichodes had dropped to fifth in importance (I.V. 11.1), while Strophostyles helvoula maintained second (I.V. 33.3). Schizachyrium scoparium entered, and established dominance in the old field sometime after the 2000 survey. The reasons for these changes are not known, but may be related to the soil mycorrhizal community.

The Matanzas Prairie Nature Preserve is located near Bath, Mason County, Illinois, in the extensive glacial sand deposits associated with the Illinois River. This Preserve contains the only remaining high quality wet-mesic sand prairie, shrub prairie, and sedge meadow associated with the Illinois River sand deposits. The sedge meadow, about 5 ha in size, was dominated by Carex stricto (Importance Value or IV of 66.6 out of 200), Calamagrostis canadensis, and Rosa palustris (both with IV's of 28.3). The wet-mesic sand prairie occurred on slightly higher ground and was dominated by Solidago canadensis (IV of 34.2), Andropogon gerardii (IV of 25.9), Carex stricta (IV of 21.9), Poa pratensis (IV of 18.0), and Euthamia graminifolia (IV of 17.7). Parts of the Preserve were shrub prairie with a ground layer similar to the wet-mesic sand prairie community. A total of 340 species of vascular plants were encountered on the Preserve: 5 fern and fern-allies; 100 monocots; and, 235 dicots. Except for Poa pratensis, which was among the dominant species in the wet-mesic sand prairie and shrub prairie, the 38 exotic species were rarely encountered (11% of the flora). The Floristic Quality Index (including exotic species) for the sedge meadow was 38.80, the wet-mesic sand prairie 43.65, and the shrub prairie 31.76.

The 590 ha Sand Prairie-Scrub Oak Nature Preserve in Mason County, Illinois contains remnant dry sand prairies, sand savanna, sand forest, and successional fields. Purchased in 1969, the abandoned agricultural fields have been allowed to re-vegetate naturally. The vegetation of a mature dry sand prairie was compared with two successional fields, one 60- and one 30-years-old. The mature dry sand prairie was dominated by Schizachyrium scoparium (little bluestem), Dichanthelium villosissimum (hairy panic grass), Tephrosia virginiana (goat's-rue), Ambrosia psilostachya (western ragweed), and Opuntia humifusa (common pricklypear). Eragrostis trichodes (sand love grass) dominated the 60-year-old successional fields. The 30-year-old successional field was dominated by Eragrostis trichodes, Strophostyles helvula (wild bean), and Monarda punctata (horsemint). A total of 393 vascular plant species were documented for the preserve.

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 trichodcs (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.

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.

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 m(2)/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.