Prairie Glade Restoration
In the Cache River Watershed, north meets south and east meets west in a clash of ecoregional boundaries. The Central Lowlands, Ozark Plateaus, Interior Low Plateaus and Coastal Plain all meet in extreme southern Illinois, each vying for supremacy; and, in so doing, contributing to a diversity of species and natural communities seldom found in the United States. On steep, south and west facing slopes where soils are very thin and bedrock erupts at or near the surface, we find prairie glades. These community types are rare in the watershed, typically on the steepest and most inaccessible ridges in the hills that overlook the Cache Valley. Unlike prairies, glades were always natural island communities, usually surrounded by woods. Glade communities are determined by the type of rock below, such as limestone, sandstone, shale or chert. Although their foundations vary, all types of glades have extremely shallow soil – a maximum of 15 inches and usually much less – frequently disrupted by frost upheavals. Often, the bedrock itself is exposed. Dry conditions prevail throughout much of the growing season, although the ground may be saturated in spring, winter and fall. Some glades even boast seasonal or permanent spring seeps.
Glades are far more complex than they appear – and more fragile. Many glade inhabitants, both plants and animals, are dependent on this special habitat. The beautiful spring wildflower, hoary puccoon, and the six-lined racerunner lizard are two such species. Wildflowers are abundant in prairie glades, and the species in bloom change constantly throughout the growing season. Glade life sometimes seems almost incongruous. Lichens are abundant, including reindeer moss, the same plant upon which the tundra caribou depend. Yet, thriving nearby is prickly pear cactus, a settler from the Southwest.
Today, many glades continue to slowly decrease in coverage because of invasion by woody vegetation, mostly red cedar (Juniperus virginiana). Although cedar often is associated with glades (sometimes they are even called “cedar glades”), it is not found on all glades, nor does it really belong there. Its seed is probably conveyed to the glade by birds. The seeds can germinate even in the dry, hot glade environment; the roots can penetrate rocky cracks and fissures. Further, cedar’s ability to conserve moisture enables it to overcome the droughty defenses of the glade. The original glade plants are gradually shaded out by the cedar; biotic diversity and quality of habitat is subsequently lowered.
In presettlement times, glades were maintained by periodic fires and by the browsing of woody vegetation by white-tail deer and elk. But by the 1890s, the elk and most deer had been killed. Another key factor contributing to the degradation of the glades entered into the picture about the same time: fire suppression. Overwhelming evidence indicates that glades evolved under the influence of fire. For thousands of years prior to settlement, the glades were frequently burned, either by Indians or lightning. Numerous historical accounts of periodic fires exist in the written records of both explorers and settlers, and in the records of the glades themselves. Studies of cedar tree rings have shown that a radical change in fire frequency occurred about 1870.
Indeed, the glade dwellers themselves bear witness that they have adapted to frequent fires. Most plants are either deep-rooted perennials with a large part of their mass underground, or ephemeral annuals that complete their life cycles in the early spring when moisture is available. The seasonal growth of glade plants, except woody species, dies back yearly and has the next year’s growing point at or below the soil surface. While this annual dieback provides a fuel highly suitable for ignition and spread of flames, a plant having its growing point near the soil surface also avoids the most intense heat of the fire. Since the growing points of woody species are exposed above the ground, they are more likely to be killed or damaged by a fire.
Because of our past disruptive activities, most glades cannot return to “normal” without our help. Fortunately, glades can be restored, and the effort is now underway on public glade lands. Prescribed fire is a tool used to manage for the health and viability of upland oak-hickory forests and prairie glades throughout the Cache River State Natural Area. Prescribed burning, implemented appropriately (timing and frequency), is an essential tool used by resource managers to interrupt succession and control the establishment and spread of exotic and invasive species. Occasional wildfires and periodic intensive grazing and browsing by elk, whitetail deer and bison were once sources of significant natural disturbance that was necessary to maintain the quality and character of fire-dependent habitat in the Cache River watershed. Today, prescribed fire, mechanical removal and the selective, careful use of herbicides are used to mimic these natural processes. Management by these methods has restored many of our glade communities. Without frequent fires and mechanical or chemical removal of exotic and invasive species, these unique natural communities would soon be lost to woody succession.
Where to see Prairie Glades in the Cache River Watershed
Scanlin Spur Prairie Glade is also accessible from the Wildcat Bluff parking area. It is located approximately one mile west from the parking area. When the trail begins to drop away from the ridge, heading down toward the river, look northward toward the end of the ridge. Scanlin Spur Glade is located on the west end of the ridge.