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Plants and Animals:
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much of the prairie at Midewin is degraded as the result of
industrial and agricultural activity, several identifiable plant
communities are present, including seeps, marshes, sedge meadows,
dry prairie, wet prairie, mesic prairie, dolomite prairie, forests,
savannas, and groves. These communities rarely exist as sharply
delineated entities, but rather blend into one another and exist
among the pastures and hayfields currently at the site.
The pre-European settlement vegetation map of Midewin shows most of the site was prairie prior to the arrival of European settlers.The northwestern corner of the site along Jackson Creek was forest. Another small, forested area existed in the extreme southwest corner of Midewin along the Kankakee River and Prairie Creek. Two groves large enough to merit naming occurred, Hoff Woods and Starr Grove. The larger of the two, Hoff Woods, is now smaller than it was prior to European settlement (Glass,1994). Spreading sedge (Carex laxiculmis), a grass-like plant, which is listed as threatened in Illinois, occurs in Hoff Woods (Glass, 1994).
Prior to European settlement, the forests at Midewin were dominated by bur oak (Quercus macrocarpa), white oak (Quercus alba), and black oak (Quercus velutina). Minor components included hickory (Carya), black walnut (Juglans nigra), basswood (Tilia americana), ash (Fraxinus), sugar maple (Acer sacharum), elm (Ulmus), and hackberry (Celtis occidentalis). Early surveyors also mention hazel (Corylus americana) which occurred in open woodlands and sometimes in brush prairie.
The dominant, thick-barked oaks were tolerant of fire; whereas sugar maple, hackberry, ash, and elm are fire sensitive, and grew in more protected habitats. Annual fires swept through the grasslands, savannas, and groves, clearing out the understory vegetation and eliminating seedlings and saplings of fire sensitive trees. The oaks, though scarred, were able to withstand these fires. The presence of fire sensitive species in groves, forests, and savanna today is a testament to fire suppression by European settlers. Prior to European settlement, Starr Grove was dominated by oak, with only a few maple trees. Today, maple and other fire sensitive trees dominate.
Oak also dominated the riparian (streamside) forests. Bur oak, white oak, black oak, and hickory were most common. Minor components included ash, elm, black walnut, and sugar maple. Streams formed firebreaks which protected the more fire sensitive trees.
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