Indian Cave State Park (ICSP) and Ponca State Park (PSP) are important conservation properties in Nebraska that are owned and managed by the Nebraska Game and Parks Commission (NGPC). Both parks border the Missouri River and are two of the largest continuous tracts of undeveloped upland deciduous oak forest in Nebraska (Kaul and Rolfsmeier 1993). ICSP totals 1,336 hectares (ha) and is located in northeast Richardson and southeast Nemaha counties (Figure 1). PSP totals 813 ha and is located in northeast Dixon County. Both parks are part of Biologically Unique Landscapes identified by the Nebraska Natural Legacy Project (Schneider et al. 2011).
Changes in grazing and fire regimes have altered oak forests, woodlands and savannas in the Midwestern United States (Apfelbaum and Haney 1987). Oak (Quercus spp.) woodlands and savannas are disturbance-mediated ecosystems that require periodic fires. Fires burn understory, foster oak regeneration and increase the density and diversity of ground-layer vegetation. A dense woody understory of shade-tolerant trees and shrubs will grow in absence of fire reducing oak regeneration. Fire has been absent at both ICSP and PSP for decades, if not over a century, and a dense understory of trees and shrubs has indeed developed. Furthermore, the understory has been invaded by non-native plants such as common buckthorn (Rhamnus catharitica), honeysuckles (Lonicera spp.) and garlic mustard (Allaria petiolata)
