In pine and oak barrens, the most common trees are jack pine, black oak, northern pin oak, and occasionally red pine. Barrens have lots of open space, with trees scattered individually, in small groups, or in dense groves. Often, most of the trees are around the same age because fire triggered the growth of the next generation of trees. Barrens historically experienced fire every 6-12 years.

Jack pine sometimes has cones that cannot open without heat. When that is the case, fire is crucial for its seeds to get out of the cones and have any chance of growing. Even when the cones open without heat, the seeds depend on exposed mineral soil, which can be created by fire.

Pine and oak barrens provide vital habitat for many rare animals and plants. Sharp-tailed grouse depend on large open areas such as those in recently burned barrens, and Kirtland’s warblers only breed in large forests of young jack pine. Often found in sunny openings such as those created by fire, lupine is the only food for the caterpillars of the endangered Karner blue butterfly.

The most common trees in Wisconsin’s pine and oak forests are white pine, red pine, jack pine, white oak, red oak, and black oak. Red maple, black cherry, paper birch and aspen are also sometimes part of the mix. The understories typically are not very diverse because many of these forests are plantations, but depending on where you are in the state, you might find huckleberries, blueberries, bracken ferns, wood anemones, starflowers, and Pennsylvania sedge. Naturally occurring pine relicts and old-growth forests tend to be more diverse in understory plants.

Pine-oak forests historically experienced fire every 6-12 years. Fire removes the organic layer at the top of the soil, exposing the mineral soil that red and white pine seeds need to start growing.

Lowbush blueberry (which is tasty for humans and wildlife alike) can be found in a variety of oak and pine landscapes. A prescribed fire will kill the aboveground portion of a blueberry bush and stimulate growth in the underground portion. The year of a fire, the bush won’t produce fruit, but for the next few years after that, it tends to offer a bountiful harvest of blueberries. Black bears eat blueberries, and a good blueberry year makes bears less likely to eat crops, beehives, or livestock.

Oak woodlands in Wisconsin usually feature white and bur oak. Red oak, black oak, and shagbark hickory are also common. In healthy oak woodlands, somewhere between 40% and 65% of the ground is in the shade at noon.

In the past, fires would pass through oak woodlands every 1 to 5 years. Oaks are well-adapted to resist fire: mature oaks have thicker bark than other hardwood trees, young oaks can resprout after a fire kills their aboveground growth, and acorns sprout underground where they are protected from fire.

When an oak woodland doesn’t have frequent enough fire, it gradually becomes a closed-canopy forest with shade-tolerant trees like sugar maple and basswood. Shade-intolerant trees like oaks struggle to survive and reproduce in these conditions. Prescribed fire gives oaks an advantage over competing plants, prepares the soil for the growth of new trees, and helps manage invasive plants.

Oak savannas are similar to oak woodlands, but more open and prairie-like. Oak savannas have 1 to 17 trees per acre, and only 5% to 40% of the ground is shaded at noon. Bur oak, white oak, chinquapin oak, black oak, and shagbark hickory are the most common trees.

Like oak woodlands, oak savannas historically experienced fire every 1 to 5 years. Fire plays a key role in keeping a savanna open and not dominated by woody brush, creating habitat for a multitude of prairie plants and animals. After a burn, big bluestem grows more vigorously and leadplant sends up extra sprouts. As a result, they produce more flowers than they would in an unburned area.

The ornate box turtle, which is endangered in Wisconsin, provides an example of the nuances involved in planning prescribed fires. These turtles need grass or prairie areas, so they benefit in the long term from burns. But if they get caught aboveground during a fire, they can die. Timing prescribed burns to happen while ornate box turtles are hibernating underground protects them from the flames.