If there is one genus that carries the forest system on its shoulders, it is Quercus, the oaks. This photo encapsulates a story about oaks, bears, parasitism, and systems thinking.
This diorama represents the two most important sources of calories for black bears of the Blue Ridge. The emerging plant -- yes, to many people’s surprise, it is a plant! -- is bear corn, Conopholis americana. It’s a plant with no leaves and no chlorophyll -- the green chemicals that give plants the superpower of making food out of sunlight. Bear corn relinquished this ability eons ago because it found an easier source of energy -- oak trees. Bear corn taps directly into the roots of oak trees, some of the most powerful producers of carbohydrate energy in the entire forest.
Many biologists consider bear corn’s relationship with oaks to be parasitism. As E.O. Wilson defines them, parasites are “predators that eat prey in units of less than one.” By definition, parasites bring some amount of harm to their host. Though sometimes called “cancer root,” it is unknown whether bear corn brings harm to their massive oak hosts. As an observer of the forest as a system, I’m highly skeptical of many relationships that are traditionally considered parasitic.
It’s well known by biologists and hunters that Appalachian black bears’ primary food, as they fatten for their winter sleep, is acorns. A study conducted in the Smokies in 1995 determined that acorns made up 71% of plant-based calories available to bears. In the fall, bears (along with deer, squirrels, and numerous other critters) simply vacuum oak-calories from the forest floor. But acorns have a narrow 6-week season of abundance. Bears sleep all winter, and in the spring and summer they scrounge whatever grubs and berries they can get with their paws and jaws. I’ve long been told that bear corn is a laxative, and bears use it as a tonic to release the fecal plug that forms during hibernation, and to get their bowels moving in the spring. It’s their springtime cup of coffee after their winter of sleep -- Doug Elliot calls it bearlax.
But guess what food source was shown by the Smokies study as the second most available after acorns? Bear corn, with a whopping 16%. It’s likely that bear corn is the most abundant source of calories for lactating bear mothers during the crucial period of late spring and early summer. From the bears’ point of view, bear corn is the means by which oaks provide for them before the acorns are ripe. Ask the bears whether they think bear corn is a parasite. The oaks are the true lactating mother in this scenario. In all likelihood, the oaks have a stake in the bears’ survival. Perhaps the bears’ presence intimidates herbivores who would devour oak seedlings. Maybe the bears’ feces fertilizes the oaks. Maybe the bears’ hair is an essential ingredient in the nests of songbirds who spend all spring and summer grooming the oaks of caterpillars and other voracious insects. The mind of the human explodes while contemplating the mind of the forest.