If an old oak tree could talk, it would tell tales of childhood hardships that would make the "walked uphill both ways" stories of our grandparents seem weak and whiny.

Including accounts of being burned, browsed and desiccated by drought, it would reflect on all the less-fortunate trees that could not endure. If asked how it survived, it would simply say, "I'm pretty hard-core."

Despite its seeming indestructibility, the oak does have one weakness: Its seedlings cannot grow in impenetrable shade. Oak woodlands historically burned quite frequently because of fires started by lightning and Natives. Fires limit the growth of shade-tolerant species such as ironwood, elm, ash, hackberry, pawpaw and dogwood, allowing more sunlight to reach the forest floor and stimulating oak regeneration.

Since 2008, the woodland at Indian Cave State Park has been managed to increase oak regeneration. Before these efforts, the woodland was composed of large, mature oaks with a dense understory of shade-tolerant species. Prescribed fires are being used to reduce the understory and increase light within the woodland. Young, shade-tolerant trees also are being thinned out.

The 2,400-acre oak woodland at Indian Cave is one of the largest remaining blocks of this habitat in the state. Hundreds of animal and insect species depend on this area for food and shelter. The survival of many is directly dependent on oaks.

The trees not only provide a valued food source — acorns — but are paramount in facilitating a robust plant community. Woodland and prairie plants coexist in this unique ecosystem as a result of varying amounts of light penetrating the tree canopy. With woodland plants thriving in shadier spots and prairie species occupying areas with sun, a mosaic of microhabitats is created.

Before this restoration was initiated, the woodlands lacked many of the vegetative features mentioned above. Few oak saplings were present, prairie plants were rare, and woodland wildflowers were losing out to dense shrubs. Through the use of prescribed fire, woodland light levels have increased while shrub dominance has decreased, resulting in a ground layer composed of an assortment of grasses, sedges and wildflowers. The wildflowers attract pollinators, feed and house other insects, provide palatable food and produce seed used by all wildlife.

Control of invasive plants has been a priority. Non-native plants will spread rapidly in the woodland if left unchecked, decreasing native plant diversity. Prescribed fires, removal and herbicide are part of an integrated approach to reduce their abundance.

Rare plant and animal populations within the park are monitored to determine the effects of management activities. Time-lapse cameras in the park document change in the woodland structure. Also, several vegetation surveys have taken place to monitor changes in ground layer vegetation, oak seedlings and forest communities. These efforts will guide future management decisions.

Restoration of oak woodlands is a long-term process; oaks are notoriously slow growers. But, as an oak seedling would say, "I'm one tough nut. Give me enough light, and I'll withstand the rest."

Jordan Marquis and Krista Lang are woodland ecologists with Northern Prairies Land Trust working at Indian Cave State Park.


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