Critters in the North Country Woodlot
by Joseph D. Conwill of Sandy River Plantation, ME
Your thoughts on the use of a forest may differ from what the wild animals in it are thinking, and it is good to be aware of the problems. Animal browse is of two kinds. Critters may eat the buds, foliage, twigs, and leaders, which are accessible only on young trees. Or, they may gnaw the bark of both old and young trees. Foliage and leader browse may change the composition of a young forest, but the trees eventually outgrow the problem. Bark browse is a problem for many years more, though some trees are not affected because their bark is not appetizing. These remarks pertain to northern Maine, but would apply throughout much of the border area as far west as Minnesota.
WHITE PINE is the king of the northeastern woodlot, but rarely achieves its full growth potential because people cut it first. Specimens over a hundred feet tall are scarce, but they do exist. When young it is often fast growing, but it has serious enemies. Fortunately the bark is rarely ever attacked. However, in winter, hares will strip buds, needles, and twigs right down to a lifeless trunk. A few small severed branches may remain like a worn-out bottle brush. Depending on the depth of the snow cover, damage may occur six feet up or more. The trees do not recover.
Wrapping any accessible leaders and important branch terminals with aluminum foil as soon as the snow flies will give very good protection. Obviously the covering should be removed as soon as the snow melts. Aluminum foil can be recycled, though it gets so crumpled that it is difficult to re-use it. The heavy-duty kind is not necessary. If you have a large number of pines, wrapping in foil is impractical. But there is rather little pine in my area, and all of the vigorous ones are important in the forest plan; in such woodlots, foil wrap is effective.
Deer will browse white pine, but it is not their favorite food. The only problems I have heard here occurred in areas where the deer population was abnormally large because someone was feeding them.
Pine weevils are tiny critters, but they can cause the woodlot owner much heartache. They kill leaders, which causes the tree to divide into several trunks, an effect known as “cabbage pine” because it is thought to resemble a cross-section of that vegetable. Large groves of young trees are most affected. When pine is mixed among other species, it helps not to make a large opening for it during thinning while young. Such an opening will help it to grow faster, but will also increase its attractiveness to the weevils.
Your best defense is to inspect all white pines early in the growing season. The weevils do their damage and then emerge about a month after petal fall on the apple trees. The idea is to catch them while the grubs are still in the dead leaders. Get a nursery ladder, cut off the dead leader and destroy it, then train a strong branch into a new leader. If you arrive late and find the tiny exit holes (less than a sixteenth of an inch), the weevils have left and you will have the problem again next year somewhere.
As I am dealing only with “critters” I will not describe white pine blister rust, which is still a problem in some areas. There is much literature on the subject. The important fact is that currants and gooseberries are involved in its transmission. Red pine is subject to many of the same problems as white pine, but not blister rust.
SPRUCE: white, red, and black. American foresters seem to know nothing of naturally occurring intermediate hybrids, but Canadian foresters, dealing with the same trees, say hybrids are common. In any case, enemies of spruce attack all kinds.
Hares love spruce, but not quite so much as pine. Since spruce is often more numerous, foil wrapping may be a big job, but it is effective where it can be done. Spraying with “Hinder” to make the tree smell or taste bad may work, but would have to be re-applied if the weather warms up and turns rainy. Early woodlot thinning may increase damage by making the individual spruces easier to find. I am always happy when trees achieve eight or nine feet in height, so that the leaders, at least, are out of harm’s way.
Neither deer nor moose pay much attention to spruce. Pine weevils occasionally pose a problem, especially for white spruce, or the imported Norway spruce, if you happen to have any. The remedy is the same as for pine.
BALSAM FIR, a pioneer species, predominates in many young woodlots. Wallace Nutting observed that although Maine is known as the Pine Tree State it should really be called the Fir Tree State. I have been surprised to read that fir is slow-growing. Not here! Under good conditions, and not crowded, it will put on three feet of terminal growth per year, which is a large amount in a frost-free season of only a hundred days.
Fir has few critter enemies. Hares won’t touch it unless they are starving, and moose and deer are not interested. Squirrels often lop off the terminal buds in winter, but fir usually regains a single leader without any help. Years later, a tiny jog in the trunk and a small line in the bark will be the only sign. Over several years the tree even forces the small dead stub of the old leader into the horizontal. And squirrel damage becomes less common once the trees begin producing cones, which the critters prefer.
Fir’s main enemy is the spruce bud worm, which despite its name, prefers fir. There are periodic outbreaks every few decades, apparently made worse by poor forestry practices but the pest is native to North America. It may readily be observed that the worst damage occurs in densely overstocked stands, where each tree is restricted to a small fringe of live crown. Fir is so prolific, and so tolerant of shade, that it readily develops overstocked situations, without human intervention.
Butt rot is not a critter problem, but people should be aware of it. Not all firs develop butt rot, but many do, even specimens which appear perfect from the outside. John Muir noted this problem among the true firs in the Sierra. The genus is also shallow rooted. For these reasons, it is best not to use firs as ornamentals near your house; they are more prone than other trees to blowing over. These remarks do not apply to Douglas fir, an entirely different tree, not found in the Northeast.
NORTHERN WHITE CEDAR is favored by deer, but I do not know much because I have little of it. My land is quite acidic, and contrary to popular perception, northern white cedar favors alkaline soils. I have no TAMARACK but I know that hares sometimes browse its young spring growth.
Porcupines can be a problem for any tree at all, and they really make a mess of things quickly. But they are not common, and apparently live solitary lives. The easiest solution is to live-trap them and move them away (but where?). Porcupines are unwary, so there is no need to disguise the trap with brush. Peanut butter works well as bait. Once they discover that they are trapped and that their quills will not help them, they sometimes become so terrified that you can hear their teeth chattering. Check your trap often; it won’t be long before porky is caught.
RED MAPLE is one of the most prolific hardwoods in the northern woodlot. This is good, because nearly every critter in the woods feeds on it. Foliage, twigs, and bark are all vulnerable. My program of protection is simply to leave all red maple during thinning, until it has reached a diameter over three inches, at which point the hares at least are less likely to attack it.
Moose and deer are special problems for red maple. Both will strip the bark off, even on fairly old trees. I’ve seen severe damage on trees as large as sixteen inches diameter. However, steps can be taken to reduce the problem. First, if laying out a new woodlot trail, do not come really near a nice red maple if you can help it. Trees along migration routes are far more likely to be attacked, and of course the moose and deer will follow your trails. Second, if you have a fringe of fir understory around the base of the maple, leave it. Moose and deer, like people, prefer to take the easy route, and will usually pass up a tree which is not readily accessible. Finally, the damage will generally involve a small minority of trees unless the critters are yarding nearby. Absolutely do not encourage them by feeding.
Tree books sometimes claim that red maple usually divides into several leaders, but my experience is that it usually has a long straight single leader unless damaged early in life by wildlife. People laugh at it because its lumber is less valuable than that of sugar maple but for my purposes it is equally good. In fact, the red maple on my land has sap with a sugar content equal to sugar maple; it boils down to syrup at a ration of about 1:32. This will vary from region to region. And finally red maple is just as beautiful as sugar maple in my eye.
The problems of sugar maple are about the same as for red maple, but biologist Berndt Heinrich notes that moose prefer red maple bark over sugar maple.
BIRCH, white and yellow, is much browsed by all sorts of wildlife when young. Moose will pull it completely apart to get at high twigs. But nobody likes the bark of older trees. Once they attain a height of fifteen or twenty feet they are usually safe. Grouse may rarely bud yellow birch in autumn to obtain the mint oil it contains.
“POPPLE” or ASPEN is also much browsed when young, but rarely when older. Both birch and aspen are troubled by borers, and I have not yet discovered a solution to this problem except to cut and remove heavily infested trees.
I’m not sure how “scientific” woodlot management ever is, since the critters aren’t reading your forestry plan. Good advice seems to be to thin as needed, but never take out too much at any one time. Leave extra to cover for unforeseen damage. Meanwhile, have fun and work safely in the woods.