The wooded communities of the Indiana Dunes are categorized in four ways: savannas, open woodlands, flatwoods and forests. Wooded communities vary over time and space. Topography, soils, drainage and climate all help to determine the landscape and how it's divided. The different plants and soils point to the area’s history. Glaciers provided different soils. Fires once planed a major role in the life cycles of plants in all areas of the dunes, but now most fires have been suppressed.
So now lets briefly describe each of these four areas.
Savannas are basically prairies with some trees. There are different kinds of Savannas, depending on the type of soil. Those along the lakeshore have mostly sandy soil. Fires were very common in the Savannahs before man interfered. Like in the prairie, some savannah plants became fire dependent to complete their life cycles. One example is the lupine - the plant exclusively eaten by the larvae of the Karner Blue Butterfly - now an endangered species. Park rangers initiate controlled burns in the Savannas (and prairies) to help promote plants like the lupine.
Open Woodlands are one of the most diverse in the native landscape. Their Mesic soils allow all kinds of trees such as oaks and other plants to grow where no others can. You may also see some black cherries. It is sad to believe that because of man these woodlands are slowly disappearing.
Flatwoods are results of topography and the glaciers. Did you know that if you look below the surface you'll find 24-36 inches of clay!?!?! The clay helps water move across rather than downward. This is why flatwoods can be very wet places with many plants, especially trees! Some of the most common trees are Swamp White Oak, Pin Oak, and various Ash trees.
Forests are usually found along rivers, or lake areas. This is why they are located around the Indiana Dunes. However, you will hardly ever see any dense forests because they are very rare... The most common forest in the area is the "black maple red-oak forest." One of the most common trees in any forest is the American Beech. The forest understory consists of many shrubs, herbs, ferns and grasses.
