If you haven’t been thinking much about maple sugaring these past few months, well, who can blame you. This is the season of McIntosh apples, golden pumpkins, and venison stew – not the time when people usually pause to consider the liquid gold of springtime. Yet for sugarmakers, autumn is the second-busiest season, and the work being done now is far more significant, from an ecological perspective, than tapping and boiling.
First of all, there’s the gathering of firewood for the evaporator. Most sugarmakers burn softwood – pine, hemlock, spruce, and fir – because, with its oils and resins, it burns hotter and faster than hardwood, which in turn makes for a faster boil. Slabs from sawmills – the bark-covered outer slices of logs – are great for firing an evaporator, and many sawmill operators depend on sugarmakers to take this otherwise waste wood off their hands. Firewood processors know the same thing – sugarmakers will happily take any softwood that is harvested as a byproduct of cutting hardwood for indoor fireplaces and woodstoves.
This division between hardwood and softwood works perfectly in the sugarbush, too, where sugarmakers try to remove as much softwood as possible so that the warm sun of springtime can reach the roots of the trees as early as possible, while the nights are still cool. Anyone who has walked in the woods on a spring morning and come across pockets of cold air beneath clumps of softwoods knows that this is exactly the opposite of the warm days, cold nights pattern that sugarmakers prefer.
There is a downside to removing softwood and other competitors from a sugarbush, however, which is that insect infestations become more likely as species diversity declines. About one tree in four is a sugar maple in the woods of Vermont (and the Connecticut River valley of New Hampshire), but that rises to nearly four trees in four in a sugarbush. The sugar maple borer thrives in pure stands of the species, scarring the trunks of sugar maples as if someone had used a penknife to carve a crooked smile or half-moon into the bark. Though these wounds rarely kill a tree, they can reduce its health and ability to supply sap.
Some sugarmakers attempt to limit damage from the maple borer by thinning out the sugar maples, too, not just the softwood. Sugar maples growing with full, vigorous crowns produce more sap and are better able to overwhelm the borer with chemical defenses. Especially if the cut trees are left in the woods to rot, returning organic matter to the soil, sugarmakers can mitigate the problems associated with growing trees in a monoculture.
Another task of autumn is to cut back the brush in the sugarbush, which is also a double-edged sword. Removing brush from around the trunks of the sugar maples makes it easier to move around the sugarbush in the spring, often on snowshoes, to tap the trees and either tighten up pipelines or collect buckets. But the park-like appearance of a sugarbush, much as it seems to delight our human sense of order and propriety, makes life tough for many species of wildlife, most of which like a certain amount of the cover and protection provided by shrubs, small trees, and brush.
Some sugarmakers spend October spreading lime around their maples, at least those trees that are easily accessible with a lime truck from a roadway. Acid rain is the prime suspect in sugar maple decline, a widespread phenomenon in the Northeast in which sugar maples are losing some of their ability to withstand insect outbreaks, harsh winters, and the stresses of everyday life. Spreading lime enriches the soil with calcium, the element most easily stripped by acid rain. Unfortunately, while acid rain is a regional problem, spreading lime is only a local solution, and most sugarbushes are too large and too far from roadways to make spreading lime economically or logistically feasible.
As sugarmakers cruise their woods at this time of year, there is one easy way for them to tell at a glance how each tree is doing: have last spring’s tap holes closed up? When a tree has the strength and energy reserves to completely bark over a tap hole in six months, that’s a healthy tree. Holes that never grow over are a sure sign of a tree that is growing very slowly, so slowly that decay around the hole is outpacing the tree’s ability to put new wood over the wound.
Whether you are a sugarmaker yourself or simply enjoy the fruits of their labor, raise a glass of freshly pressed apple cider to toast our maple sugarmakers, now hard at work in the woods of Vermont and New Hampshire, insuring that all of our lives will be that much sweeter come springtime.