Prairie Inventory for Vascular Plants at Lincoln Memorial Garden, Springfield, Sangamon County, Illinois

An inventory of the vascular plants at nine grassland reconstruction sites at Lincoln Memorial Garden (LMG), Springfield, Sangamon County, Illinois was conducted during the 2022 growing season. The grassland sites were selected prior to conducting field surveys by evaluating aerial photography of the LMG complex and referencing the prairie reconstruction areas indicated on the LMG trail map. Although all nine sites have been planted with grassland or prairie vegetation, they are of three distinct types. Four sites are traditional Tallgrass Prairie Reconstruction sites, two sites have some native woody composition and are considered Tallgrass Prairie/Savanna Reconstructions, and three sites are Forest Openings (smaller openings in a surrounding forest matrix). These three community types will be described and discussed separately in this report. In all, a total of 313 taxa including 251 Illinois native species were recorded in 19.25 acres. Tallgrass Prairie Reconstruction sites were the largest sites and occupied 16.05 acres and totaled 253 taxa (200 native), Tallgrass Prairie/Savanna Reconstruction sites occupied 2.3 acres and totaled 164 taxa 138 native), and the Forest Openings occupied 0.9 acres and totaled 147 taxa (129 native). Mean C/FQI scores for individual sites ranged from 2.7/22.2 to 3.3/37.0 while cumulative floristic quality scores were 3.4 and 53.5, respectively. One Illinois listed plant species was observed (Silene regia, Royal Catchfly; IL-Endangered) and 33 conservative species (Coefficient of Conservatism score [C] of ≥ 6) were recorded. Overall, the sites have good species richness. The primary concerns are overabundant dominant native grass species, woody invasion, and invasive species. Tallgrass prairie reconstruction sites are largely dominated by one or a few large prairie grasses, especially Andropogon gerardii (Big Bluestem). This and other aggressive native species are suppressing diversity and reducing potential ecological value. The two Tallgrass Prairie/Savanna 2 Reconstruction sites (Sites 5 and 7) have a significant native woody tree and shrub component, especially around the perimeter, and are reminiscent of savanna. The forest openings (Sites 4, 8, and 9), because of their small size and position in the landscape, are composed of species found in both prairie and forest. These smaller sites are especially vulnerable to closure by adjacent and invading woody species. Several invasive species are present. A few already impacting the restoration trajectory (i.e. Lespedeza cuneata, Sericea Lespedeza). Management considerations for invasive species are suggested in this report. Additional recommendations are given related to increasing plant diversity, introduction of conservative plant species, and managing native and non-native woody species. Information from this baseline survey should be helpful in site planning and management going forward and can be used to help determine success of future management actions.