Some species of oak trees in the Carolinas Piedmont are producing a more-abundant-than usual acorn crop this fall, say Carolinas tree experts, resulting in the phenomenon known as a “mast year.”
White oaks include a variety of species, but are most easily identified this time of year by patchy, shaggy bark. Other types of oaks common in the Charlotte area – ranging from red oaks, whose bark shows broad light-gray streaks, to the willow oaks that are the signature Myers Park tree – don’t appear to be producing greater-than-usual numbers of acorns.
“No one really knows why oak trees do it,” said Christopher Matthews, natural resources manager for the Mecklenburg park system, who noted that he’s heard from colleagues in Texas that oaks there also are producing a heavier-than-normal acorn crop. “What we have seen is the white oak group are having a mast year – and that means they are producing a bunch of acorns.”
European scientists have studied acorn production over time and still can’t account for the sudden appearance of a heavy crop, Matthews said. But theories abound, ranging from weather conditions to micro-environmental changes for a particular stand of trees.
“Oaks are one of the first trees to flower,” said Don McSween, Charlotte city arborist. “Consistently warm spring weather will produce more acorns in the fall. If you have late frost when trees are in flower, you will have lower production.”
The heavy crop of acorns plays an important role in the ecosystem, said Matt Barker, assistant district forester for the N.C. forest service. “They’re a pretty valuable wildlife mast,” said Barker, whose department collects wild acorns for the forestry service’s tree-growing operation.
- A mature oak produces over 2,000 acorns in a good year. The chances of an acorn becoming a grown tree are less than 1 in 10,000.
- 16% of Charlotte’s street trees are willow oak, and many in the Myers Park neighborhood were dug as saplings in the 1920s from riverbanks.
- Acorns contain tannins, which make them bitter. White oak acorns are the least tannic and, with roasting and blanching, can be made edible or turned into flour. They were used as winter food by many Native Americans and early settlers. Sources: City of Charlotte, Peterson Field Guide to Edible Wild Plants