Sudbury Valley TrusteesConservation, Collaboration, and Community since 1953

Some autumns our streets and trails roll with acorns, but not this season. Oak trees produce more of their jauntily-capped nuts some years than others; this year they’ve made very few.

How does a scarcity of acorns affect the forest? It poses no threat to the population of oak trees. In fact, a feast-or-famine pattern might help ensure new seedlings. If oaks produced the same quantity of acorns every year, the population of acorn eaters would, in the reasoning of ecologists, become ever more efficient in converting those calories and proteins into chipmunks, flying squirrels, wood ducks, and white-tailed deer, all on the oaks’ biological nickel. Each year the fraction of acorns that sprouted into young trees would be smaller, because a higher and higher percentage of acorns would be consumed by animals. By failing, periodically, to supply the forest with this rich source of food, oaks reduce populations of acorn eaters.

The payoff, for the oaks, comes in the years when each mature tree drops a couple thousand acorns. Those years spread a feast for creatures in the oak forest. Embarrassed by their wealth, squirrels and blue jays hide more acorns than they can eat. In the process, they disperse and plant the seeds of future trees.

Acorns, chestnuts, beechnuts, and hickory nuts make up the forest’s crop of mast, critical food for black bears, wild turkeys, and many other animals. Years of mast failure impose a hardship. Species survive the ups and downs of natural cycles, but individual animals go hungry. Lean years result from spring weather that prevents seeds from setting, defoliation by gypsy moth caterpillars, or other causes. Mast failures can occur over a wide area and across numerous species; the mechanisms that produce this result are not fully understood.

Acorns were of less importance when our New England forest had as many chestnut trees as oaks. Equally numerous and higher in protein, chestnuts covered the forest floor more reliably than acorns. Their relatively stable supply, palatability, and nutritional value made chestnuts hugely important to two- and four-legged foragers. Alas, they are gone, eliminated by a fungus that appeared in New York City a century ago and by 1950 affected American chestnuts throughout their Maine-to-Mississippi range. Young chestnut trees grow vigorously and look healthy, but as they begin to mature, the blight kills them. Adult American chestnuts are few and far between.

Where I walk, acorns are absent, which means a tough winter for white-tailed deer, wild turkeys, mice, and squirrels. How widespread is this situation? Are you seeing many acorns this fall? Please let me know at rmcadow@sudburyvalleytrustees.org.

The American Chestnut Foundation works to restore that important tree to its native range. To learn more about their efforts at breeding disease-resistant American chestnuts, visit their website at www.acf.org.