Keeping the Mighty Oaks
As spring finally arrived with its much-anticipated warmth and vibrant color, our oaks, the grand statesmen of our eastern deciduous forests, again waited patiently to break dormancy. It is as if they somehow understand their significance while choosing to remain wise and humble. Oaks (genus Quercus) have served a prominent role in our landscape for the last 10,000 years, influencing everything from the soil nutrient cycling, to wildlife migration patterns and habitat preferences, to the settlement of this country. Oaks sustained Native Americans with food, fuel and material for tools and shelter. The early colonies as well, were initially sustained by the profits made on oak shipped back to England for shipbuilding as the supply of these great trees had largely been exhausted in Europe at the time.
There are 25 species of native oaks in the Bay watershed from the common white oak and northern red oak to species with more limited ranges like bur oak and overcup oak. Oaks are important components in most eastern forests dominating our most common forest type, the oak/hickory forest, which now comprises over 50% of the Chesapeake watershed’s forestlands.
By volume, oaks remain the most massive trees in Chesapeake forests. However, their future is uncertain as the regeneration of oak seedlings in the last several decades have declined. According to the US Forest Service’s Forest Inventory Analysis (FIA) red maple is now the most numerous tree species growing in all of the watershed states and outnumbers all oak species combined by about a billion trees. Although a majority of these maples still remain in the understory, they will likely assume prominence in future forest canopies.
Oaks are best adapted to environments characterized by disturbance. The past dominance of the oak was due, in large part, to regular fires that occurred in the landscape. Their insulating bark and an extraordinary ability to re-sprout after disturbances enabled oaks to endure fire, which gives them an advantage over most competitors. In most places we have eliminated fire from the landscape in order to protect the places where we live and recreate. This exclusion of fire has given an advantage to more shade tolerant trees like red maple and faster growing trees like tulip poplar. Oak regeneration is further stressed by competition with invasive plants and the relentless browsing pressure from over-abundant deer populations.
In some places, selective harvesting over the last century, called “high-grading”, also affected the number of successful oak seedlings. Typically marketed as “diameter limit” cutting, this unsustainable method of harvesting removes the largest and highest value trees from the forest while leaving an abundance of lesser value or poorly formed trees. This practice is especially destructive to maintaining oak regeneration since it often removes the best acorn seed sources while not providing sufficient canopy openings to support new oak seedlings.
So What Can Be Done?
Permitting natural wildfire to proceed unabated, obviously, is not an option in restoring oaks in our highly developed and fragmented landscape. Forestry, however, can be a valuable, if not an essential, tool in mimicking the effects of natural wildland fire. Well-planned sustainable harvests can be used to open the canopy of mature forests while other forest management practices can be implemented to control faster growing competitors. Many of our public forestland managers apply these techniques and strategies in efforts to sustain oak populations. The Alliance’s Forests for the Bay program, a partnership with the US Forest Service, is working to bring this knowledge to private forest landowners who want to maintain their oaks for the future.
A majority of the woodlands in the Bay watershed are privately owned, so efforts to restore oaks in our forests often need to be initiated by individual landowners. Forests for the Bay works together with the state forestry agencies and other institutions to promote sustainable forest management while connecting people to local technical resource providers that have the necessary training and expertise. If you are interested in learning more, check out www.forestsforthebay.org.
Tree planting projects on open land can also provide a great opportunity to restore oaks in the landscape. Because they are slow growing and highly vulnerable to weed competition, oaks can be more difficult to establish. Newly planted seedlings require more maintenance effort when compared to other hardwoods, so they are often relegated to minor components of many planting projects.
The Alliance plants thousands of new trees each year with the help of landowners and hundreds of local volunteers. For these new tree planting efforts, the Alliance has been incorporating a higher percentage of oak species in our tree planting projects. To enhance oak establishment, we ensure that the right oak species is matched closely to its specific site conditions. We use 5 foot fencing or tree shelters to protect the seedlings from deer browse and provide our partners with detailed planting and 5 year maintenance plans.
Trees and forests are the best land cover by far for protecting water quality and sustaining the health of our watersheds. They are hard at work every day filtering our air and water, protecting the soil, providing habitat, and giving us beauty in our landscape.
Think about where you might like to see a new forest or add an oak or two to your landscape.
Our efforts to conserve and re-establish forests in the watershed will impact local waterways and the Chesapeake Bay. Sustaining the oaks in these forests will keep those forests working for us for the next millennium.