​Stop 2 — Oak Savanna

​​As you enjoy this hike, you may pass in and out of savannas and woodlands. Savannas usually transition the woodland to the prairie. Keep looking up at the tree canopy cover to determine if you are in a woodland, prairie or savanna.

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Historically, oak savannas were very common in the midwestern states. However, after the early settlers arrived, their home construction, agriculture, and lack of fire soon damaged the oak trees and their understory plants — the oak savannas began to disappear. Now, oak savannas in the Midwest are very rare.
 
How is an oak savanna different from a woodland?
LOOK UP AT THE TREE CANOPY. The savanna tree canopy will cover 10%-50% of the sky, with the trees well–spaced from one another.

• Note that the savanna trees tend to still have all their lower limbs because the trees are well–spaced from one another and more sunlight pours through the canopy to reach the lower branches. The oaks in a savanna have a beautiful, majestic shape, similar to that seen in a community park. In contrast, woodland trees grow closer together, and since less light reaches the lower branches, these branches usually die off.

 

​LOOK AT THE UNDERSTORY.

• Both grasses and forbs can be found in the savanna. Where the sky is covered by only 10% tree canopy, there is more available sun and the prairie–like plants will flourish. When the tree canopy covers the sky by 50%, woodland–like plants that require more shade will thrive. There are also savanna specialists, plants that prefer part–sun and part–shade. Since the savanna provides all three light conditions of full sunlight, partial sunlight and shade, there is more specie diversity here than in either the prairie or the woodland.

 
Try to find the Pennsylvannia Sedge! (Carex pennsylvanica) This sedge (a grass–like plant with triangular stems) grows along the hill slopes and is the dominant ground cover in a black oak savanna. This sedge spreads clonally and forms large patches.

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