Declining oak forests could mean big changes for future deer herds.
I’ve hunted a lot of different places over the years, but there are a few spots I hunt every year. One in particular I’ve been hunting for nearly two decades. At first glance, it doesn’t look like anything special — just another stand of mixed hardwoods. Even from the different perspectives of aerial photos and topo maps, it doesn’t reveal much about its hidden potential.
In an average fall, someone unfamiliar to the area could spend several days there with little to show for their efforts. But when conditions are right, it becomes a very special place. About every two or three years, the oaks in that particular woodlot produce a bumper crop of acorns. When they do, the place becomes a deer magnet.
Each fall, I make a preseason visit. Leaving the field and heading down into the hardwoods, I cross my fingers and hope, wondering, “Will this be an ‘on’ year?”
The first indication usually comes when I reach the brook. If we’ve had any recent wind or rain, acorns collect in strands where high water pools along the banks. The real story, though, is revealed when I hike up onto the bench.
If I find grounded nuts, I know I’ll be spending a lot of time there in the coming weeks. If not, I shrug it off, knowing that maybe next year, or the year after, the acorns will drop and the pieces will fall into place — literally.
I shudder to think about the possibility of losing such a place, yet it lingers in my mind. What if the landowner should sell it or decide to develop it? Even something as seemingly innocuous as a light firewood cut could impact the site’s potential for years. In any case, losing those oaks would be a tragedy that few save myself and the wild creatures that live there would notice.
Meanwhile, there’s a much greater threat looming that could negatively affect every deer hunter in the eastern United States.
According to several researchers, oak forests throughout the East are in peril. Not only have existing oaks been in decline for some time now, but the rate of regeneration also continues to drop. And oaks are being replaced by non-mast-producing hardwoods. Some researchers are already suggesting that if this trend continues, it could have a dramatic effect on wildlife populations, especially species like deer, that rely so heavily on hard mast.
HISTORY
When the Europeans first set foot in the new world, the most abundant producers of hard mast were oak, beech, hickory and chestnut. Since then, American chestnut has been virtually eliminated, and American beech greatly reduced.
Hickories are still abundant, but the hard shell limits the value of hickory nuts as a food source for deer. That has increased the importance of oaks. According to U.S. Forest Service researchers, no other tree species does what oaks do for wildlife in Eastern forests. They are virtually irreplaceable, and signs indicate something very drastic might already be happening.
Periodic widespread decline and death of oaks have occurred in the past. These outbreaks, sometimes called oak declines, are caused by a variety of environmental stresses including drought, waterlogging, frost or insect pests. Once weakened, trees are more susceptible to these and other stresses such as defoliating or sucking insects that cannot successfully attack healthy trees.
Oak decline is considered a normal process of a mature hardwood ecosystem, albeit one that negatively affects wildlife, timber value and recreation. The likelihood can be reduced, and the harmful effects reduced to some degree through sound forest management. In the past, forests have recovered over time.
NEW THREAT
The present problem is not readily apparent, because the overall proportion of oak forests hasn’t changed much. What’s changing is the structure of these forests. More specifically, oaks are declining in dominance relative to other species. This is most recognizable in the overstory, but it is in the understory where the real threat lies.
A substantial dropoff in oak regeneration means there are no longer enough stems in the mid- and understory layers to replace the mature oak trees.
If left unaddressed, oaks will continue to decline. The threat exists over most of the Eastern U.S., but is particularly menacing in the central and southern Appalachian states, west into Arkansas and Missouri.
Some have suggested the current scenario represents a kind of perfect storm of environmental stresses, one from which oaks might not be able to recover.
Fragmentation and parcelization have reduced the size of forest patches and the ability to properly manage them. Forests have been able to outlast native pathogens but are more susceptible to the many exotic insects and diseases introduced in recent years.
Meanwhile, fire suppression and current preferred forest management practices discourage oak regeneration. The ultimate irony is that the greatest threat to the future of oak forests is one of the principle reasons for protecting them. More on that in a bit.
HOW IMPORTANT ARE OAKS?
The importance of oaks cannot be understated. They comprise what ecologists call a foundation genus, meaning they control population and community dynamics and modulate entire ecosystem processes. And they are particularly important to several species, not the least of which is the white-tailed deer.
Numerous food habit studies have shown that, where they occur, acorns are by far the whitetail’s preferred food. In non-agricultural areas, acorns are what send deer into winter with a layer of fat, representing the most valuable and energy-rich plant food available outside the growing season.
In short, they are the foundation upon which most Eastern whitetail populations are built. And the last several decades have seen whitetail populations rise like skyscrapers. A single generation of deer hunters has witnessed deer grow from rare to common, to abundant and now, in some cases, nuisance levels.
Pennsylvania provides a prime example. Under various deer management strategies, the Keystone State’s deer herd had grown continually since the early 1900s. By 2005, the herd was estimated at over a million animals — more than people or the land could tolerate.
Car-deer accidents rose to an estimated 80,000 to 100,000 per year. The state’s $4 billion dollar forest products industry was suffering. According to former deer biologist Gary Alt, deer browsing was converting Pennsylvania oak forests from oak to red maple and black birch, species that are not only less valuable for timber but also incapable of sustaining deer.
And Pennsylvania is not alone. In many eastern states, deer have literally become victims of their own success.
HOPE?
The future viability of eastern oak forests and, by association, eastern whitetail populations hinges on an effective combination of sound deer management and forest management.
There is no one-size-fits-all treatment that would be effective over the entire range of eastern oak forests. However, some type of responsible management is essential. Both indiscriminant logging and complete protection from disturbance result in oaks being replaced by other tree species.
Challenges vary with land ownership and current management. The largest public forest land holdings are under the jurisdiction of the National Park Service and the U.S. Forest Service. Currently, forest management is prohibited or severely limited within national parks and wilderness areas — a policy that will not maintain diversity of oak forests or biodiversity in general.
National forests, on the other hand, are actively managed, but management plans don’t always consider sustainability of mast-producing trees. These seem like simple problems to solve, but just as we have anti-hunters to contend with, professional foresters must constantly battle various so-called conservation groups that oppose any type of forest management — good or bad.
A greater challenge could be ensuring proper management on private, commercially-owned forests. The commercial landowner’s objective is, understandably, to maximize profit. That doesn’t always work with what’s best for the environment. But it can.
The Forest Stewardship Council (FSC) has a certification program that recognizes sound forest management practices. Market forces, in the form of greater consumer acceptance of “green” products, makes certification an economically viable option. The key, then, is to make sure certification criteria include some consideration of oak regeneration.
OH, DEER
The greatest hurdle could be the deer management dilemma. Here again, Pennsylvania provides an excellent example. Many non-Pennsylvanians might not realize that the prime impetus behind the state’s drastic shift in deer management several years ago was to reduce overall deer numbers by killing more does.
Mandatory antler restrictions to reduce the yearling buck kill was just a carrot to dangle in front of deer hunters. What probably ultimately sold the program, however, was groups like the National Audubon Society and The Nature Conservancy using phrases like “environmental catastrophe” and “ecological disaster” to describe the overabundant deer herd.
As a whole, America’s deer hunters currently enjoy the highest whitetail populations in history. And calling these “the good old days” is more accurate than many people realize.
State and federal wildlife managers are more than just deer farmers, however. They are tasked with managing all wildlife populations and their environments. When one species threatens the future viability of another, or a group of species, or an entire ecosystem, then those managers are bound by their mandate to act.
Furthermore, there is a tendency to seek solutions that are the least expensive and easiest to control over what might be the most effective. In the long run, sound forest management should be the most important tool in stemming oak forest decline. In the short term, however, state agencies will be increasingly pressured to reduce deer populations throughout much of the East.
CONCLUSION
The reduction in the abundance of oaks in Eastern hardwood forests will continue to have profound effects on wildlife communities, particularly whitetail populations.
Solutions exist, and it might not be too late to turn the tide. But as one researcher put it, “... a solution to this problem will take decades to bear fruit.”
That will occur only if the right decisions are made now. Otherwise, oak forests and the deer populations they support could be headed down an ever steeper slope.
Writer’s Note: Wildlife managers are faced with complex, dynamic and varying conditions over the broad range of habitats occupied by white-tailed deer. In some cases, as with the decline in oak forests, deer are a threat to their own environment. In others, such as areas of high coyote concentrations, they are imperiled by it. That’s why managers must be careful to consider all variables before implementing any actions to “correct” wildlife populations or habitat conditions.
CREDITS
1: USDA Forest Service Forest Insect and Disease Leaflet 165
* Much of the information contained within this article came from the manuscript: Forestry Matters: Decline of Oaks Will Impact Wildlife in Hardwood Forests. Mcshea WJ, Healy WM, Devers P, Fearer T, Koch FH, et Al. (2007) Journal of Wildlife Management: Vol. 71, No. 5 Pp. 1717–1728
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This article was published in the October 2009 edition of Buckmasters Whitetail Magazine. Join today to have Buckmasters delivered to your home.