Red Oak
Red oak is a large tree that typically grows in even-aged
stands in Wisconsin. Although red oak can, under some circumstances,
withstand some light to moderate shade, individual red oak trees will
only achieve their full potential if grown in conditions of full sunlight
without overtopping competition. Additionally, if significant overstory
shade is present, red oak seedlings will rarely, if ever, thrive sufficiently
well to dominate the next stand. Typically, red oak will not regenerate
in its own shade, and, although the species is relatively long-lived,
will eventually give way to a stand of more shade tolerant species such
as sugar maple.
Red oak grows best on nutrient rich sites with deep, well-drained soils. However, on these sites, other more shade tolerant hardwoods, such as sugar maple, are also very successful, so maintenance of red oak on these extremely high-quality sites may be difficult and expensive. Red oak also performs well on well-drained dry-mesic sites with high to moderate nutrient richness, and these sites are particularly well suited for the management and maintenance of red oak without excessive cost or effort. For more details on the growth characteristics of red oak, see the USDA Forest Service Manual of Silvics.
Red oak is an important tree species in Wisconsin with very high value both for lumber and for wildlife. Interestingly, despite the value of red oak, it is a species that is becoming less abundant in Wisconsin. The reluctance of many landowners to participate in even-aged management of red oak as well as intense browsing of seedlings by whitetail deer in some locations (as well as other factors) are combining to cause red oak to be widely replaced by more shade tolerant timber types such as sugar maple.
With the diversity of values represented by red oak, the objectives of landowners managing red oak in their woodlands are equally as diverse. Jim and Marlene Zdanovec of Marathon County manage their oak woodlands for wildlife by promoting the production of acorns. Gary and Penny Shackelford of Rock County are promoting the ecological restoration of red oak on their property through prescribed low-intensity understory burns and red oak shelterwood regeneration harvests.
Tom and Mary DeWitt of Rusk County are focused on the production of high-quality sawlogs and veneer logs from their oak woodlands. The DeWitts use a single-tree selection silvicultural system with canopy gaps in their oak woodlands that promotes the long-term development of the highest quality trees. While this system does not promote as much regeneration of new oak seedlings as does the shelterwood system, the DeWitts are also taking advantage of some opportunities to promote established oak seedlings in some timber stands recently damaged by wind.
In
the absence of opportunities provided by Mother Nature, such as the situation
of the DeWitts, the most common method for managing red oak in Wisconsin
is the shelterwood silvicultural
system. Red oak does not reliably produce stump sprouts sufficient
to fully occupy a site, so the shelterwood system utilizes the acorns
naturally produced in an existing red oak stand to regenerate the next
stand. For intensive timber production, the age to regenerate a new red
oak stand ranges from between 60 –to- 120 years depending on site
quality with the higher quality sites being harvested at an earlier age
when diameter (dbh) reaches between 24-to-28 inches. However, stand ages
can fairly reliably be increased to about 130 years on most sites if landowner
objectives prefer. When regenerating a new oak stand, the overstory should
be reduced to between 40 -to- 60 percent cover of the site by dominant
high-quality oak trees. Some landowners may wish to include other desirable
associated species such as white oak, ash, or cherry to produce a more
mixed composition in the regenerating stand, but nonetheless, overstory
shade should not be more than 60 percent. Trees retained to provide seed
and shelter should be superior quality trees with healthy, vigorous, and
large crowns as well as tall, straight, and clean stems. Very little site
preparation is necessary, but if brush is present in the understory, a
landowner may want to apply herbicide during the summer prior to harvesting.
Harvesting in the fall prior to when the ground becomes completely frozen
is recommended.
Once seedlings are established, the residual overstory seed and shelter trees should not be allowed to remain on the site for more than two or three years. Waiting longer to remove these trees will likely cause excessive damage to the established seedlings and may threaten your ability to successfully regenerate the stand. When removing overstory trees, extreme care must be taken to minimize the extent of heavy equipment impacts across the site and should occur when the seedlings are dormant. If the oak seedlings are experiencing excessive competition from brush, some research suggests that controlled burning in oak seedling stands will promote the success of oak while inhibiting the competition. The oak seedlings will die back from the burn, but they will re-sprout with increased vigor while the competition will re-sprout with decreased vigor. Repeated annual application of low-intensity fire may be necessary for two or three years to achieve the desired results.
In
some areas, excessive browsing of oak seedlings by whitetail deer may
seriously inhibit success of oak regeneration. Special protective measures
may be needed in some parts of Wisconsin in order to achieve successful
regeneration of oak. Contact your local
county DNR service center or field station to inquire about deer herd
densities in your area and to determine any need and ways to protect your
oak seedlings.
Thinning is very
common in developing red oak stands and can promote a variety of objectives.
Thinning (the removal of some of the trees to promote the growth of the
remaining trees) can begin when average diameter (dbh) of dominant trees
reaches 5 inches and can continue once every ten years up to the age when
a new stand is regenerated. Thinning for wildlife purposes would focus
on the development of the largest crowns while thinning for timber objectives
would focus on the development of the highest quality stems.
More details on managing red oak is available in the DNR
Silviculture and Forest Aesthetics Handbook.