By Dave
Apsley, Extension Natural Resource Specialist, Ohio State University
and
Dave
Jackson, Forestry Educator, Penn State Extension
Why is Oak So Important?
Responding
to this question is a difficult task since oaks are important for so many
reasons, and there are valid concerns about their future. I will share just a
few examples of the importance of oaks for wildlife and the forest products
industry in this article.
This quote
from William McShea and William Healy (2002) sums up the importance of oak for
wildlife: “Acorns are the most important wildlife food in the deciduous forests
of North America, the ecological equivalent
of manna from heaven.” Acorns are a high-energy food source that stores well.
As a result, they are a key food source that helps wildlife populations survive
winter when food supplies are most limited. More than 90 wildlife species from
songbirds and small rodents to white-tailed deer and black bear use acorns.
Even animals that do not directly consume acorns can be positively affected by
oaks. Some of these relationships are obvious, for example, many of the small
mammals that carnivores (like bobcats) feed on have a diet of acorns. While
others are not as obvious. For example, ponds and vernal pools with oak leaf
litter produce more and larger wood frog tadpoles and salamanders than those
with mostly maple litter.
The wood
from oaks is used in many applications, but most people think of flooring, cabinetry and furniture. The most recent data from the U.S. Forest service
shows that 25% of the volume of wood harvested in Pennsylvania comes from oaks
(Forest Inventory and Analysis 2016). Additionally, a huge percentage of the
lumber consumed in the Amish Furniture industry is oak. One historic use of
white oak is cooperage (barrels). White oak barrels have had many uses, but
there has been a recent resurgence in demand for use in the wine and spirits
industry which has resulted in an increased demand for white oak lumber.
Why are we concerned?
Currently,
about 47% percent of Pennsylvania’s 17 million acres of forest is classified as
Oak/Hickory. Although oaks dominate the upper canopy of much of our forests,
there is a serious lack of smaller oak seedlings, saplings and pole sized (4-10
inches diameter) trees to replace them. Instead, the trees getting established
under the oak canopies are mostly red maple, black birch, sugar maple, and blackgum.
In fact, understory abundance of species like red maple, American beech,
blackgum, striped maple, and black birch is increasing. When forests are
disturbed, either by natural or human-caused events, the existing understory
species have the potential to change the composition of the next forest. In fact,
the volume of maples (red and sugar combined) has increased to the point that
they are nearly equal to red oak.
Why is this happening?
Oaks are a
bit like Goldie Locks. Too much light from heavy cutting (clear cutting) and
they often lose the battle to sun loving species like yellow poplar, aspen, and
black cherry; too little light from no cutting or light cutting (select
cutting) and they lose to shade loving species like red and sugar maple,
blackgum, and black birch. However, when young oak seedlings receive just the
right amount of light they can invest much of their energy into the development
of large carrot-like roots. These roots give them the ability to sprout and
grow rapidly following disturbances like fire, wind throw events, and timber harvesting.
In addition
to light, browsing by deer also has a significant impact on the presence of oak
seedlings in forest understories. Deer have taste preferences; some trees, like
oak, are highly preferred while others are hardly touched. By selectively
browsing oak, deer have the ability to eliminate it from forest understories. Research
has shown that when deer population densities exceed what the land can support oak
regeneration suffers. In regions of the state where decades of overbrowsing
have severely depleted the habitat, even relatively few deer can have significant
effects.
What is being done about it?
The Northern
Research Station of the U.S. Forest Service and Penn State University have been
conducting oak research for more than 20 years. The focus of the research has
been on regenerating and
sustaining oak forests. In a nut shell what they are finding is that
eliminating much of the mid and understory
poles and saplings (mostly red maple, striped maple, black birch, and blackgum)
with herbicides (or fire) is not enough for oak seedlings to become established.
However, when combined with a harvest that allows the proper amount of light to
reach the forest floor (i.e. shelterwood harvest) and deer reduction or
fencing, oaks can be successfully established on many sites. These practices
are currently being employed on public lands across Pennsylvania; however, they
are rarely employed on private woodlands, which make up nearly 70% of Pennsylvania’s
forests.
In 2017 the
PA Natural Resource Conservation Service (NRCS) and the Allegheny National
Forest received funds for the 1st year of a 3 year project to improve and
protect the health and resiliency of Oak ecosystems in North-Central
Pennsylvania. The project, entitled “Sustaining Pennsylvania’s Oak Ecosystems through Partnership in Forest Management,”
covers a 15 county area in North Central Pennsylvania. The project is a
partnership between NRCS, the Allegheny National Forest, the Pennsylvania Game
Commission, and the Pennsylvania Department of Conservation and Natural
Resources Bureau of Forestry. The collaboration will help public and private
forest landowners maintain a diversity of forest age classes and species to
sustain forest ecosystems that are resilient to stressors. For additional
information contact your local service center.
The future of oak is in your hands!
