Not Prairie, Not Woods

Not Prairie, Not Woods. . This scattering of widely spaced trees is a habitat called a savanna. The branches of savanna trees are able to stretch out horizontally, absorbing the abundant sunlight available. , , In the past, these landscapes were kept open by natural wildfires and the Native American custom of burning, which eliminated plant competition beneath mature, fire resistant trees. This savanna habitat is maintained by mowing. , , The Transition to Forest , Savannas are an early stage of what's called forest succession, nature's gradual transformation of treeless prairie land into forest. , , What would happen if we stopped mowing our savanna? Plants, shrubs, and saplings would sprout up amidst the savanna trees, and savanna would become woodland. , , As plants grow they shade smaller plants growing beneath them. The amount of sunlight, water, and available nutrients determines which plant species will thrive. As growing conditions change, plant and tree species change, too. , , The Oldest Tree at Knoch Knolls Park , Look for the tree with the thickest trunk closest to this sign, This venerable Bur Oak may be nearly 500 years old. This tree was here when Stephen Scott first settled on the confluence land in 1830. , , What's Growing on Our Savanna? , 1 Late Horse Gentian, Triosteum perfoliatum , 2 Prairie Shooting Star, Dodecatheon meadia , 3 Virginia Bluebells, Mertensia virginica , 4 Cup Plant, Silphium perfoliatumn , 5 Toad Trillium, Trillium sessile , , The Mighty Bur Oak (Quercus macrocarpa) , Bur oaks are "pioneer trees," the first trees that sprouted up-and survived-on Illinois prairie land, transforming prairie into savanna. , , Bur Oak's survival tactics: , 1 Unusually large acorns in deep caps rimmed with a bur-like fringe, as many as 5,000 per tree (Animals bury these appetizing acorns and forget to dig them up.) , 2 Fast-growing, deep taproots that can pierce dense prairie sod , 3 Thick, fire resistant bark