Introducing Long Point’s oak trees
The Long Point Basin has 8 species of oaks, distributed widely across many different ecosystems, from oak savannas (displayed in the rightmost photo) to swampy woodlands! These oaks are categorized into two major groups – red oaks (Quercus section Lobatae) and white oaks (Quercus section Quecus), with a few notable differences in the fruit structure and leaf morphology. For species in the white oak group, it takes one year for an acorn to fully mature, while red oak acorns require two years to mature. White oak acorns are sweet, and red oak acorns are bitter. All of Ontario’s species in the red oak group have pointed leaf lobes, whereas species of the white oak group have smooth leaf lobes. Black Oak (Quercus velutina), Northern Red Oak (Quercus rubra), and Northern Pin Oak (Quercus ellipsoidalis) are part of the red oak group, whereas White Oak (Quercus alba), Bur Oak (Quercus macrocarpa), Swamp White Oak (Quercus bicolor), Chinquapin Oak (Quercus muehlenbergii) and Dwarf Chinquapin Oak (Quercus prinoides) are in the white oak group.
White Oak description, ecology, and habitat
White Oak is one of the Long Point Basin’s most important oak species. It is a large tree, often exceeding 30 m in height on fertile soils. The foliage of Red Oak is typically 10-20 cm long, with 7-11 pinnate lobes with smooth edges, loosely reminiscent of a finger. The sinuses usually extend more than halfway to the . The leaves are deep green above, and pale green on the underside. Autumn foliage is burgundy, scarlet or purplish-brown, with the foliage change occurring later than other tree species. White Oak has grey bark with long, plate-like vertical ridges. White Oak acorns are more elongated acorn measuring 1.5 to 2.5 cm in length, with the cup covering less than 1/3 of the acorn. This species has very uneven fruit production – in most years, few or no White Oak acorns are produced. However, once in every 4-5 years, White Oak yields a massive quantity of acorns. In these heavy production years, termed “mast years”, white oak acorns far outnumber the acorns of other oak species. A substantial number of these acorns are consumed by wildlife, but many are left alone, resulting in a large number of seedlings.
White Oak occurs throughout most of the southern Great Lakes Region. It is primarily found south of the Canadian Shield, with the exception of populations extending into the Cataraqui (Frontenac), Kawartha Highlands, and Muskoka regions. Since White Oak is shade intolerant, is more abundant in areas where the growth of shade tolerant species (i.e., Sugar Maple, Acer saccharum and Beech, Fagus grandifolia) is limited. While it is widely distributed. White Oak is found in a wide variety of habitats, including oak savannas, dry-mesic forests, moist mesic forests, and swamp margins. However, it is most abundant in oak savannas and dry forests, although high populations of White Oak also occur on poorly-drained lake plains (the largest examples of these ecosystems occur at Skunk’s Misery in Middlesex County and Bickford Oak Woods in Lambton County, although smaller areas likely occur within the Long Point Basin). Across North America, White Oak is distributed from the Atlantic Ocean southwards to Florida, west to Texas, and north to Minnesota.
Regarding associating plants, White Oak grows most frequently with Black Oak, Red Oak, Chinquapin Oak, Red Maple (Acer rubrum), Black Cherry (Prunus serotina), Sassafras (Sassafras albidum), Ironwood (Ostyra virginiana), White Pine (Pinus strobus), and Red Pine (Pinus resinosa). Collectively, these plants dominate oak savannas and dry woodlands. Within moist forests, White Oaks also occurs alongside Basswood (Tilia americana), Shgabark Hickory (Carya ovata), Bitternut Hickory (Carya cordiformis), Bigtooth Aspen (Populus grandidentata), White Ash (Fraxinus americana), Tuliptree (Liriodendron tulipifera), and more infrequently, Sugar Maple and American Beech. The understory of Red Oak forests are usually dominated by a wide diversity of shade-tolerant perennial wildflowers. Shrubs with an affinity for Oak Forests include American Witch-Hazel (Hamamelis virginiana), American Hazel (Corylus americana), Flowering Dogwood (Cornus florida), Chokecherry (Prunus virginiana), and in moist forests, Red Elderberry (Sambucus racemosa), Blue-beech (Carpinus caroliniana) and Pagoda Dogwood (Cornus alternifolia).
Ecological importance of White Oak
In mast years, White Oak acorns are devoured by many wildlife species, especially squirrels (Sciuridae), mice (Muridae), White-tailed Deer (Odocoileus virginianus), Wild Turkeys (Meleagris gallopavo), grouse, Blue Jays (Cyanocitta cristata), and Black Bears (Ursus americanus). Oaks also support highly biodiverse insect community, including 534 species of lepidopterans (butterflies and moths). White Oak is a host plant for the Yellownecked Caterpillar Moth (Datana ministra), Fall Cankerworm Moth (Alsophila pometaria), Buck Moth (Hemileuca maia), Hornless Oakworm Moth (Anisota finlaysoni), and Oakleaf Blister Moth (Bucculatrix ainsliella). White Oak leaves are consumed by caterpillars of the invasive Spongy Moth (Lymantria dispar), large infestations which can defoliate entire trees. Fortunately, trees often recover fully from insect infestations during the following growing season.
White Oaks are slow growing trees that require open landscapes or substantial forest disturbance to regenerate. They have exceptional longevity, with some specimens reaching 500 years or more. In consideration of this, the presence of mature White Oak trees are indicative of a high-quality forest, and since White Oak trees produce quite merchantable timber, they are sometimes sometimes removed during unsustainable “high-grading” logging practices, which changes forest composition and reduces biodiversity (In contrast, sustainable forestry can improve habitat for White Oak in a few situations by reintroducing forest disturbance favourable to regeneration, though impacts are site-dependant – it is not recommended everywhere). Old growth forests on drier soils often have an abundance of White Oak trees – ideal habitat for many forest wildlife species, many which have been impacted by habitat loss. In Norfolk County, White Oaks are also frequently a component of young forests which often establish on recently acquired conservation lands, typically on habitat restoration projects launched by the Nature Conservancy of Canada or Long Point Basin Land Trust. In oak savannas and forests of all ages, White Oak supports a vast amount of biodiversity and sensitive species, including those at-risk.
Fun facts
- White Oak acorns germinate in the autumn, immediately after falling from the tree. This contrasts with many tree seeds, including Red Oak acorns, which require a cold period to properly germinate, termed winter stratification.
- The name “White Oak” refers to the whitish colour of the inner bark. The inner bark of Red Oak is red or orange.
- The wood of White Oak is extremely decay resistant, often lasting for decades in the forest understory.
Written by Matthew Palarchio, HBSc in Environmental Sciences, Western University.
Photos of form, leaves, and bark are provided by Matthew Palarchio. Acorn photo is a stock image retrieved from Canva.
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To view a directory of all species featured on our website, visit: https://longpointlandtrust.ca/featured-species
