"Acorns, which are literally forest food, are critically important to many wildlife species."

Forest Stewardship News
August 30, 2007

“Great oaks from little acorns grow.” But acorns, the fruit of oaks, are an important bounty provided by our woodlands.

In the fall, hunters begin to scout the landscape for acorns, which are mast – literally, forest food – and critically important to many wildlife species. Every squirrel, turkey, deer, and bear hunter and many bird watchers know that finding acorns may increase their chances of finding wildlife.

Oak trees form two general groups: red and white. Trees in the red oak group take two growing seasons to produce a mature acorn. The white oak group trees produce a fully grown nut in one growing season. These asynchronous fruit producing characteristics, along with the season when acorns germinate, are quite useful for meeting wildlife mast needs.

The red oak group species flower in the spring. Sometimes red oaks will miss one or more years, as frost can kill the flowers or drought or insect damage stress the tree and it aborts fruit.

Species in the white oak group germinate in the fall. When they fall, they quickly extend a root from the acorn’s point. This allows them to move some of their nutrients into a more protected place – under the ground. This strategy is really important, as these white oaks produce seeds lower in bitter tannic acid and, although slightly less nutritious than red oaks, much preferred by wildlife. They have to make sure that some of their acorns escape the hungry acorn eaters.

Acorns from species in the red oak group spend the winter lying on the forest floor, often under the leaves that the parent tree scattered over them after they dropped. Only after the white oak acorns are eaten, many species go looking for red oaks – you will frequently see heavy scratching and searching through the snow as various species search for these acorns later in the year.

Acorns do produce mighty oaks. However, across the oak’s range, fewer mighty oaks are growing from acorns. USDA Forest Service periodic inventories document the decline in oak as a forest component in its traditional range. At one time, chestnut was the mast species of choice, but with its loss, oak took on an increasingly important role as the leading forest food producer. The decline in oak will be sorely felt by many wildlife species and you.

There are many reasons for declining oak regeneration.
Research finds that deer browsing is important in that fewer acorns survive to germinate. Management strategies that reduce fire occurrence have given the advantage to plant species that fire would normally kill and oaks, which are fire adapted, cannot compete. Poorly planned harvesting decisions often focus on cutting oak, thus removing the seed source. And acid rain and introduced pests are other threats to the future oak forest.

The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management. For a list of free publications, call 800 234-9473 (toll free), send an e-mail to RNRext@psu.edu, or write to Forest Stewardship Program, Forest Resources Extension, The Pennsylvania State University, 320 Forest Resources Building, University Park, PA 16802. The Pennsylvania Bureau of Forestry and USDA forest Service, in Partnership with Penn State’s Forest Resource Extension, sponsor the Forest Stewardship Program in Pennsylvania.