Oak trees are a keystone species in the Chicago area, underpinning the diversity of the region’s natural areas. Changes in land use have fragmented the oak savannas into patches, resulting in loss of over 80 percent of this oak ecosystem. Additionally, the fraction remaining is threatened by invasive species and further development. These remaining patches of oak savanna provide coastal ravines, plateaus, and woodlands with conditions that support populations of rare plants, butterflies, bats, migratory birds, and other wildlife through acorn production and habitat diversity. Changes in forest disturbance and canopy openings, as well as the spread of invasive plant species and urban development in the Chicago region, prevent oak regeneration and the environmental conditions provided by these open-canopy savannas.
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