Oak-Hickory Forests
What Does an Oak-Hickory Forest Look Like?
Oak-Hickory forests are dominated by oak trees, with a smaller but significant presence of hickories. At ONSC, these forests are common, though shortleaf pine may dominate in certain areas, such as ridges.
Common Oak Species in Oak-Hickory Forests:
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White Oak
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Post Oak
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Northern and Southern Red Oak
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Chinquapin Oak
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Black Oak
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Blackjack Oak
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Bur Oak
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Pin Oak
These oak species fall into two categories:
White Oaks (e.g., Post Oak, Chinquapin Oak, White Oak, Bur Oak):
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Leaves have rounded lobes.
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Leaves typically turn yellow in the fall.
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Bark is pale and flaky, with deep furrows.
Red Oaks (e.g., Northern and Southern Red Oak, Black Oak, Blackjack Oak, Pin Oak):
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Leaves have pointed or bristled lobes.
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Leaves turn a vibrant red or orange in the fall.
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Bark is darker and smoother, with large furrows.
Common Hickories:
Hickories are also prevalent in these forests, with species like bitternut, shagbark, shellbark, and mockernut hickories. These trees, along with black walnut, often feature a distinctive X pattern on their bark. Shagbark and shellbark hickories have especially flaky bark that peels off in sheets.
Red Oak Bark
Dr. Roy Winkelman, trunk of a red oak tree, https://etc.usf.edu/clippix/picture/trunk-of-a-red-oak-tree.html
Bitternut Hickory
William Friedman https://arboretum.harvard.edu/plants/image-search/?keyword=carya+cordiformis&submit=Search
Oak-Hickory Forest Soil and Topography
Oak-Hickory forests tend to grow in upland areas with shallow, rocky soil. The soil is usually composed of silt loam, a mixture of sand, silt, and clay. Soil composition may vary, becoming sandier on ridges. North-facing slopes tend to be more humid and retain more moisture, while south-facing slopes receive more direct sunlight, making them drier. These differences influence the types of species that grow on each slope.
Forest Layers
Oak-Hickory forests, like all forests, are made up of several distinct layers, each with unique plant and animal species.
https://content.ces.ncsu.edu/print_image/11378
The canopy is the highest layer and is dominated by species like oaks and hickories. These trees have less shade tolerance and provide shelter for birds that avoid ground-based predators.
Plants in the Canopy: White Oak, Red Oak, Black Oak, Chinquapin Oak, Shagbark Hickory, Mockernut Hickory, Black Walnut
Birds in the Canopy: Owls , Woodpeckers, Thrushes, Warblers, Hawks
Photo Credit: https://commons.wikimedia.org/wiki/File:Pileated_Woodpecker_(6258355443).jpg
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Acorns and Hickory Nuts
The trees in Oak-Hickory forests produce acorns and hickory nuts, essential food sources for wildlife like white-tailed deer, wild turkey, black bears, eastern chipmunks, and eastern gray squirrels. Nut production varies by year, with mast years (years of high nut production) occurring every 2-6 years for oaks and every 3 years for hickories, on average.
Fire in Oak-Hickory Forests
Periodic, low-intensity fires are essential for the health of Oak-Hickory forests. These fires reduce competition by killing less fire-resistant plants, allowing oaks and hickories to thrive. Oaks have adaptations like thick bark and a deep root collar, enabling them to survive these fires. Hickories, while more vulnerable to hot fires, can regrow through suckers if the trunk is damaged.
However, fire suppression has led to an increase in fire-intolerant species like maples and ashes. Without fire, these species can dominate, resulting in a loss of biodiversity in Oak-Hickory forests.
Glades: Special Habitats Amidst the Forests
Glades are open areas with shallow, rocky soil, often found on upland forests. These sun-soaked habitats support species typically found in prairies or deserts, such as tarantulas, scorpions, collared lizards, and prickly pear cactus. The glades at ONSC are limestone/dolomite glades, influenced by calcium-rich soil, while nearby sandstone glades host different plant species. The sandstone glades, which lie in the McIlroy Madison County Wildlife Management Area, have been receiving fire management, and are now supporting a small population of reintroduced Eastern collared lizards.
Glades, like Oak-Hickory forests, also need periodic disturbances such as prescribed fire to maintain their unique ecosystem. Without these disturbances, nuisance species such as Eastern redcedar can invade, shading out native glade species.
Helpful Links
Fire and Disturbance in Oak-Hickory Forests:
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USDA Forest Service: The Presence of Fire in Oak-Hickory Forests
Explore the role of fire in the ecology of Oak-Hickory forests. -
USDA Southern Research Station: Fire and Disturbance in Oak-Hickory Forests
In-depth research on fire disturbances and their ecological impact. -
University of Arkansas: Fire and Oak-Hickory Forest Disturbance
A scholarly article examining the role of fire in the Oak-Hickory forest ecosystem.
Forest Variations and Ecosystems:
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National Park Service: Forests in Buffalo National River Park
Overview of different forest types found in the Buffalo National River Park, typical of the Ozarks ecoregion.
Oak-Hickory Forests, Plants, and Animals:
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USDA Southern Research Station: Oak-Hickory Forests
Detailed information about Oak-Hickory forests and their plant and animal communities. -
Hudson Valley Farmscape Ecology Program: Oak-Hickory Forest Overview
Insight into Oak-Hickory forests, their ecological importance, and conservation. -
Missouri Department of Conservation: Forests and Woodlands
Comprehensive guide to forests and woodlands in Missouri, including Oak-Hickory habitats.
Missouri Department of Conservation Resources (Plants and Animals):
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Upland Forests and Woodlands
Information on upland Oak-Hickory forests in Missouri. -
Oaks Field Guide
Detailed descriptions of oak species in Missouri. -
Hickories Field Guide
A guide to hickory species found in Missouri forests. -
Eastern Gray and Fox Squirrel Guide
Learn about squirrel species in Oak-Hickory forests. -
Wild Turkey Guide
Discover more about wild turkeys and their habitat needs in Oak-Hickory ecosystems.
Hickory Tree Species:
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Botany Live: Hickory Trees Overview
Guide to identifying and understanding various hickory species. -
Conserve Energy Future: Types of Hickory Trees
Comprehensive descriptions of different hickory tree types.
Tree Identification:
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Trees Atlanta: Tree Identification Resources
Descriptions of various tree species, including many from Oak-Hickory forests.
Mast Trees:
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Nature Mentor: Mast Trees
Information about mast-producing trees like oaks and hickories and their ecological role.
Forest Layers and Habitat:
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Wikipedia: Tree Species by Shade Tolerance
A list of tree species categorized by their shade tolerance levels. -
ThoughtCo: Structure of a Forest
Overview of forest layers and the animals that utilize them. -
City of Portland: Habitat Restoration
Information on restoring and managing forest habitats, focusing on wildlife and plant interactions. -
Texas Parks and Wildlife: Woodland Habitat and Wildlife
A guide to woodland habitats and the species that thrive there.