What’s Wrong With the Deer’s Habitat?

We’ve all heard that PA’s forest are sick and are not what they once used to be. Most of the blame goes to the white-tailed deer, while the rest goes to insects, disease, and acid rain. I would say while those 4 things are factors, man is more to blame.

Prior to man's existence in any large numbers, forests were managed by Mother Nature. Plants and wildlife had a pecking order, you might say, as to what grew and survived and what didn’t. Forests grow from plant succession. In other words, the transition from one plant community to another. Grass’s and weeds, to bushes and brush, to seedlings and saplings, to pole and sawtimber in a mature forest. Events along the way can influence the species composition, and in turn the final outcome of that mature forest. The rate of change becomes slower as the community grows older until there appears to be no change. This is the final change of succession in the ecosystem and is called the climax community. Remember that forests are complex, dynamic communities that are continually evolving at varying rates. Even a climax community is constantly undergoing changes. At any time in the progression from the beginning to the climax, a new disturbance may interrupt the series and create a new beginning.

In 1681, Pennsylvania truly was "sylvan" (abounding in trees), where nine out of every 10 acres were forested. William Penn dutifully tried to ensure for England a long-term wood supply from his new domain, instructing the colonists in his 1681 Charter of Rights that ". . . in clearing ground, care be taken to leave one acre of trees for every five acres cleared, especially to preserve oak and mulberries for silk and shipping." This edict was widely ignored. By 1895 fields had largely replaced forests - only three out of every 10 acres were forested.

So by the turn of the last century, man had largely disturbed the natural succession of the forests and practically eliminated any "old growth" forests. Now if man would have left the land, I suspect it would have naturally reverted back to what it was, over the next century. However, that didn’t happen. Man has continued to influence our forests in one way or another, directly or indirectly, ever since.

Soil depletion of nutrients tends to happen in higher elevations first due to erosion and over a long period of time. The mass timbering in the early part of last century helped this erosion along, and also removed the timber material that usually gets recycled through decay. With the industrial boom of the past century, there has been a large emission of sulfur dioxide and nitrogen oxides released into the atmosphere from factories, predominately in the Ohio valley. PA happens to be "downwind" and the precipitation carries these particles back to the ground as a mild solution of sulfuric acid and nitric acid. This acidic water dissolves the nutrients and helpful minerals in the soil and then washes them away before trees and other plants can use them to grow. Higher elevations tend to get more harm from this by being bathed in this acidic fog more often, so it’s effect goes right to the trees leaves. Sugar maples, which are sensitive to acidic soils, are dying and not regenerating.

Wildfires were once a common occurrence that played a major roll in forest management. Indians even intentionally set fires to create better habitat for wildlife. Forest fires do several things. They open up the forest canopy which lets more sunlight in. It provides nutrients from decaying tree and plant material left in the ash, for recycling. Some trees release seeds due to the heat, while other seeds were protected under a layer of soil and can now grow without much competition from other invasive species hampering their growth, such as ferns. Fires also remove some of the leaf litter on the forest floor that has been shading out some seedlings.

But once again, man has suppressed fires. In PA., the average number of fires decreased more than 50% from 1914 to 1974. A lot of that had to do with an increased emphasis on prevention. So while we thought we were doing good for us, it actually had a negative effect on the forest. Oak’s, which have a high tolerance for fire and thrive afterwards, have now lost that advantage. Red maple’s that have a low tolerance for fire and have traditionally thrived in wet locations, have now spread out beyond those limits. They also have a high tolerance for shade, whereas oaks do not.

Some say that if we did have more forest fires than the handful of ones we currently have, the forests of PA. are less likely to burn now than they were 200 years ago, due to the disappearance of white pine and pitch pine. Historically, this species was abundant in Pa's forests, which were a much more coniferous environment than today's more hardwood-dominated woods. But the pines were heavily logged by our ancestors, who valued the soft, straight timber for building, and they still have not obtained their former level of dominance. We used to have more pines and oaks, both species that are more flammable, they have been replaced by maple, birch, cherry and beech, species that don't burn as well.

Though the absence of fires as a natural disturbance and it’s effects has been recognized recently and the DCNR has been testing some burns, as well as other organizations in the north & south east. They have had success and will continue these research efforts and explore options for using prescribe burning more often as a silvicultural tool. To me, this would seem to be the most time effective solution, when combined with thinning cuts.

Timbering practices, or lack of good ones, have also been a major disturbance in the forests. Some early forestry practices were geared towards maximum stand density with periodic thinnings. Selectively removing individual trees did not create enough of a disturbance in the over-story canopy to let adequate sunlight through. This, combined with the lack of fire, created a real problem for oak regeneration which wasn’t thought out ahead of time and wasn’t realized till the 1970’s. In a sense, the older oaks smothered out the baby oaks from getting a start on life, while other species of shade tolerant trees and plants passed them by. Other area’s were completely clearcut without leaving any existing seed trees, which created an even-aged forest. These areas had to try and out compete faster growing species of trees or broad leaf plants that shade out the forest floor. In the absence of fire, this becomes difficult. Now combine those problems with the spread of oak wilt, a fungus that can affect all oaks; gypsy moths, which feed on the leaves of at least 100 species of trees and shrubs; two-lined chestnut borer, a beetle that attacks and kills stressed oaks; and urban sprawl (development); and you can get a pretty clear picture of the present decline in our oak forests.

Oaks are not the only trees having problems with insects. The Hemlock Woolly Adelgid, is a fluid-feeding insect that feeds on hemlock trees throughout eastern North America. The woolly adelgid sucks fluid from the base of hemlock needles. It may also inject toxins into the tree as it feeds, accelerating needle drop and branch dieback. Although some trees die within four years, trees often persist in a weakened state for many years.

Invasive species of plants are also on the rise. Herbaceous plants such as hay-scented fern and non-native stilt grass can inhibit regeneration. Hay-scented ferns inhibit root branching and suppress above and below ground biomass accumulation of first-year northern red oak seedlings. Acidic soils do not inhibit their growth and they are shade tolerant. Notice how many "fern fields" you see when your out in the woods. Stilt grass works to out-compete other species then creates shade, and is even more shade tolerant than ferns. Herbicides have been used in some area’s to control this invasion, but they aren’t without controversy either. Some of these extreme eco groups are against any foreign chemical use in the wild, but yet offer no practicle alternatives. They say that these could cause adverse health effects, not only to humans but toxic to animals as well, and have the possibility of depleting native biological diversity. While these are valid concerns, I’m not sure why "Roundup" and "Oust" are okay for gardens and farms, but not for forests. But then there are studies from the ANF (Allegheny National Forest) that show herbicides used to control interfering plants in the forest understory are not toxic to small mammals at operational application rates. There’s also a 50 yr. herbicide research project done by Asplundh in SGL #33 on a 2 mile stretch of Penelec right of way. The conservationists’ and sportsmen’s concerns about the harmful impact that herbicides might have on the flora and fauna on or near the right-of-way proved unfounded. In fact, the data showed a positive impact. While meeting the objective of keeping trees away from the power lines on the right-of-way, vegetation management with herbicides actually created a habitat in which plants and animals flourished.

So what does all this have to do with deer you ask? Consider this. The diversity of wildlife is dependent upon the diversity of available wildlife habitat. These habitats are a combination of successional stages and vegetation types (cover types). Wildlife species richness is influenced by forest successional stages. For example, in the ANF, early successional forests (seedling and sapling habitat, 0-19 years old) are utilized by about 30 species exclusively, while another 150 species utilize a combination of mature and regenerating forest communities for feeding and reproduction. Mature forests (50-109 years old) are utilized exclusively by about 10 wildlife species while another 160 species utilize a mature forest in combination with other successional stages.

Deer are all about survival, and to survive they seek food and cover. Cover isn’t a real problem for them. As most of you know, they can hide just about anywhere. Even 15 feet beside you.

Food on the other hand plays a much larger role in their day to day survival. This is also their link to forest ecology issues, and the habitat problems we hear so much about. As the available food supplies shrink, it affects the intake of not only the deer, but bears, turkeys, squirrels, grouse, etc. Deer can survive on a low nutrient diet, but it comes with a price. On a poor diet a deer’s body weight will be low, female fawns won’t breed, adults have a single offspring or even fail to come to term, antlers will be small, disease becomes more common, and winter mortality becomes higher. This all translates to less deer in the herd.

Deer are picky eaters and can be very selective when a variety is available. They have their preferred foods for each season of the year. Food intake or appetite decreases with decreasing daylight in fall and winter; and increases during spring and early summer with increasing daylight. And they won’t limit their consumption just because supplies are low. They’ll just move on to "greener pastures". Diverse understories of hobblebush, maple-leaf viburnum, Canada yew, and other palatable shrubs and wild flowers have been replaced by monocultures of New York and hay-scented fern, striped maple, and beech.

Man helped to inadvertently create the forest problems. It would be wrong to ignore it or let it for the next generation to fix. It’s not good for the forest, it’s not good for man, and it’s not good for the deer. No matter who you think or what you think, about the driving force behind new deer management strategies, The problem still exists and it’s not just confined to PA either. To keep a lot of deer you must have a lot of food. Take away some food, you must take away some deer too.

In the spring when their energy needs have been boosted 200-300%, they’ll feed on fresh green sprouts of clover like ladino and trefoil, grasses and legumes like wild rye, winter wheat, and timothy, dandelions, and wildflowers; as well as woody plant buds like red maple, elm, oak, dogwood, sugar maple, & sassafras. This is a time they need to replace lost body weight, start antler growth, and the females need to get ready for fawning and milk production.

During the summer month’s food is plentiful. They now have a wide selection of leaves to eat such as red maple, white ash, sumac, sassafras, etc. More grasses are now available too such as orchard grass, bluegrass, wheat; and forbs like wild lettuce, goldenrod, sunflowers, and jewel weed. Fruiting plants like blackberry and huckleberries. Ag crops like corn, soybean, buckwheat, and alfalfa are also available.

Towards the end of summer and into fall, they start to pack on fatty foods for energy reserves to get them through winter. Now their eating hard and soft mast like oak acorns, beechnuts, apples, grapes, various berries, and pears. Clovers, wheat, sorghum, and soybeans are high in nutrition. Fat reserves can supply almost one third of a deer’s winter energy needs. At the same time they’re exerting more energy due to the breeding season.

As winter sets in a deer’s metabolism changes once again. Most of the food sources it had are now gone till spring and they have to rely more on browse, especially when there’s snow cover. So the food supply has shrunk and is more concentrated on what’s available. Woody browse might include oak, sumac, dogwood, blackgum, hemlock, and hawthorn. But if some of these preferred foods aren’t available, they’ll start eating less nutritious foods or even filler foods if things get scarce. I’ve heard of instances where a deer will die with a full stomach. This is due to their instinct to survive by eating, but the food was so low in nutrients that it didn’t help them recover, or their stomach enzymes were unable to break down these foods. When you start to notice these "starvation" foods being browsed, such as spruce, beech, red pine, balsam fir, and mountain laurel; pickin’s are getting’ slim…. Houston, we have a problem.

by Denny Patterson – PABucks.com ProStaff Writer