Forest
Stewardship News Release
August
30 , 2007- For Immediate Release
Contact: Allyson
Muth, Phone: 814-865-3208, E-mail:
Acorns
Written by: Jim Finley, 814-863-0402, fj4@psu.edu
"Great oaks from little acorns grow." When it comes to acorns, this may be about as much as many of us know. 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.
Every year, as the acorns begin to fall, some urban landowners complain of the litter they leave on streets, drives, and sidewalks. The annoying clank, thud, and ping as the solid "oak nuts" strike cars, roofs, and porches, drive some homeowners to distraction. Maybe, they think, we should fell that "dirty" tree. Extension educators, nursery owners, and foresters, often hear the query "how can I stop my trees from having acorns."
Acorns are really quite interesting as they vary in their maturation rate, size, and shape. 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, which when you look at the leaves all have sharp points or bristles on the ends of their lobes, flower in the spring. The red oak flowers fertilized in spring 2007 are visible to the careful observer. Look for these tiny immature acorns on last year's twigs. They will stand out in groups of two to five acorns on their little stalks attached near where the leaves join the twig. On the current year's twig growth, you should see normal buds. Next year, when the tree again flowers, the acorns started in 2007 will begin to grow again, and if all goes well, the 2008 flowers will turn into the 2009 acorn crop. 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 lack the spurs on their leaf lobes. In this group, you will see nice rounded lobes. The 2007 flowers that bloomed on these trees are now completing their growth and will soon be full-sized mature acorns. Look for them forming on the current year's twigs.
Besides maturing at different rates, red and white oak group species have different strategies for trying to ensure that their potential offspring have a fighting chance. Species in the white oak group germinate in the fall. That is, 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 on the other hand spend the winter lying on the forest floor, often under the leaves that the parent tree scattered over them after they dropped. These acorns are generally more nutritious compared to their white oak cousins, have much more tannic acid, and logically are not preferred as highly by some wildlife species. 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.
As the saying goes, 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.
To help you learn to identify oak species and to separate them into the red and white groups. Call the PA Forest Stewardship office at Penn State and request a copy of Pennsylvania's Common Trees and the Summer Tree Key. These two resources will help you learn about your forest and help you become a better steward of our forest resources.
The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management for private landowners. For a list of free publications, call 1-800-235-WISE (toll-free), send e-mail to , 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 the Penn State's Forest Resources Extension, sponsor the Forest Stewardship Program in Pennsylvania.
# # #
