Regenerating Red Oak
By Martin Streit

Why Regenerate Red Oak?

Red oak is an important tree species in the Great Lakes-St. Lawrence forest region. The strong grain and reddish tinge make red oak wood a favourite in the flooring and furniture industries. Red oak provides abundant acorns, which are valued as a food source for many wildlife species and adds important diversity to your woodlot.

Red oak is one of the highest value species of commercial hardwood in southern and central Ontario. Stumpage data from Maine, U.S.A. (D. Field, University of Maine - see Figure 1) shows that the price paid to landowners for red oak sawlog trees (stumpage) has increased 6.3% per year from 1959 to 2002. Moreover, the price increased by 2.8% per year more than the rate of inflation! Couple this with the increase in value of a growing tree in a managed woodlot and red oak is a great investment.
Figure 1: Maine stumpage values for red oak - 1959 to 2002 (US dollars, conversion factor 2.0 cords = 1,000 fbm).
As responsible stewards of our forests, we must remember that a sustainable harvest of oak sawlogs is dependent on the periodic regeneration of a new crop of oak seedlings. Many landowners have found that regenerating red oak can be quite a challenge. This article will outline my experiences and observations in methods to regenerate red oak.

How Did It Get Here?

When developing methods to regenerate any tree species, it helps to try and understand how the trees first got established 100 years ago. Remember that it’s always easier to mimic “Mother Nature” than to fight her! Most foresters believe that the oak we see today originated after serious disturbances (primarily wildfires) that were common around the turn of the 19th Century.
In the past wildfires were one of the primary disturbances that resulted in red oak regeneration.
Mature oak trees often take many years to die after a fire, which allows them to release several crops of acorns onto the newly prepared mineral soil. The slow mortality of these old oaks also provides partial shade for the new seedlings until they can get strong enough to compete for themselves. Finally, the fire cleans out other shade-loving trees (like maple) from the understory, giving the young oak seedlings a fighting chance during their tender years. By paying attention to these valuable lessons, we can develop a method to regenerate red oak by mimicking nature, but without setting fire to our woodlots!

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Red Oak Regeneration in Five Steps

Step 1. Create a few openings in the canopy as part of a regularly scheduled selection harvest of the overstory, because under a dense overstory, light-loving red oak seedlings are out competed by shade-loving species such as sugar maple and ironwood.
Looking skyward from the forest floor you can see the opening in the forest canopy that is needed to successfully regenerate red oak.

The following are recommended guidelines for creating openings:
Locate in areas of lowest quality timber;
Diameter of opening approximately equal to the tree height (18-25 metres);
South-facing aspect;
Red oak regeneration already present or seed trees nearby; and
Maximum of 5% of total forest area (1 opening every 2 acres).
Step 2. As part of the harvest, leave good seed trees with large, healthy crowns, because successful oak regeneration requires a large crop of acorns to overwhelm insect and wildlife predators.

A branch from a healthy seed tree loaded with acorns.
The best candidates for seed trees will be trees with diameters from 40 to 60 centimetres (16 to 24 inches) and large umbrella crowns. While providing ample seed for regenerating new oak seedlings, these trees will also produce enough acorns to satisfy hungry wildlife.

Step 3. Release red oak regeneration from understory competition until they are free-to-grow
(> 2 metres tall and vigorous) because in a dense understory, light-loving red oak seedlings are out competed by shade-loving species such as sugar maple and ironwood.
This healthy red oak is competition free and is large enough to compete for itself.
This is the single most important step of the oak regeneration process. Young oak seedlings simply cannot grow and will die if other competing young vegetation such as sugar maple seedlings overtops them. By using your chainsaw, brushsaw or herbicides you must remove any vegetation that is directly competing with the young red oak seedlings until they are large enough to compete for themselves.

Step 4. Monitor the growth and vigour of your seedlings and be patient, because early growth of oak seedlings (until 2 metres in height) will proceed slowly.
These small red oak seedlings are competing for space and light with ash seedlings and are close to being overtopped.
Healthy oak seedlings will grow at least one foot per year in height, and will have large, lush green leaves. If seedling height growth is suffering or if leaves are small and weak looking, the seedling likely needs to be released from understory competition again. It will take seven to ten years to develop healthy, free-to-grow oak seedlings.

Step 5. Give oak seedlings more overhead light (when they need it), because later growth of dominant oak seedlings greater than 2 m in height is fast, provided that they have room to grow.
This flat-topped red oak seedling is being suppressed and is in need of more overhead light.

Over time, mature trees growing at the edge of the forest opening will expand their crowns to fill the space. Large, flat-topped oak seedlings give an indication that the seedlings are no longer receiving enough overhead light. The remedy for this is to harvest one or two of the trees at the edge of the opening to restore the proper light conditions to the ground.

Summary

Red oak is one of the highest value hardwood trees in southern and central Ontario. By following the five steps provided, landowners can periodically harvest valuable red oak sawlogs, while maintaining other oaks to grow in value for future harvests, and ensuring that new oak trees are established for future generations.

This article appeared in the 2004 (Volume 35) edition of the S&W Report the newsletter of the Ontario Woodlot Association.

© 2004 Ontario Woodlot Association

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