A winning species: the nature of oaks
Last April, I had the opportunity to hear an online talk by University of Delaware Professor Doug Tallamy, discussing his latest book, “The Nature of Oaks.” In the program, sponsored by Reads & Company in Phoenixville and Vince Smith from the Valley Forge Audubon Society, I learned much more about oak trees than I’d known before.
The importance of oaks is something that I’d heard about years ago, when I was studying landscape design at Temple University. One of my professors observed that the two most valuable trees to plant for wildlife are oaks and white pine. The nuts of one provide food for birds, small mammals, deer, and bear. The seeds of the other provide food for a host of birds, while the evergreen foliage provides winter shelter.
A quick internet search turns up plenty of information on the variety of species that depend on acorns for survival. As noted in the National Wildlife Federation’s blog, “We all know that from tiny acorns mighty oak trees grow, but we should add that from tiny acorns also grow deer, gray squirrels, red squirrels, chipmunks, wild turkeys, crows, flying squirrels, rabbits, opossums, blue jays, quail, raccoons, wood ducks — more than 100 U.S. vertebrate species eat acorns.
“In autumn and winter, the acorn is the cheeseburger of the forest ecosystem — fairly easy to find and nicely packaged. They are one of the most valuable food resources available for wildlife.” (https://blog.nwf. org/2013/10/the-wildlife-benefits-of-acorns-and-oaks/)
That might seem like enough of a benefit, but a closer look at oaks shows how much more they contribute, and for how long. Here are some highlights from Tallamy’s talk:
“Some plants pass on the energy they make to other species. I call these ‘keystone species’ Oaks do this way more than other plants by far.”
“Oaks disperse faster and farther than any tree in the world . Almost every jay species out there has a special relationship with oaks. Jays can carry 4-5 acorns in a special pouch in their throat. They’ll tap each nut about an inch into the ground. A single jay can ‘plant’ 4,500 acorns in a year, but will remember only about a third of them. The rest remain planted. Jays will fly up to a mile from the tree, so the acorns are dispersed over a wide range.”
“Leaves contain nutrients that the oaks sucked up, and the trees can use them again. If you remove the leaves, you lose those nutrients. Our trees are adapted to low soil fertility, and you can kill trees by fertilizing/over-fertilizing. Leaf litter is the best mulch you can have.”
“Many caterpillars need soft earth to overwinter in. It’s difficult for them to get through dense, compacted lawns. This is a critically important point in maintaining diversity. Without caterpillars, there’s not enough food for birds, and you’re on the way to a dead landscape.”
“Oaks are critical in making the caterpillar biomass that migrating birds depend on. In a single night of flight, migrating birds might fly 300 miles and lose a third of their body mass. They come down to feed wherever they are. In the old days, there used to be caterpillars everywhere — maybe there’s a city there now. So, if you have space enough for a single tree, plant an oak. You can save a migrating bird.” (I learned, in Tallamy’s book, that all-told, oaks in the United States support the development of 897 species of moths.)
“Oaks can live a lot longer than we give them credit for: 300 years of growth, 300 more years in stasis, and up to 300 years in decline. Some live longer than that.”
Tallamy’s book also shows that there is an oak for every climate and for nearly ever landscape situation.
Wildlife Ecology at the University of Delaware in Newark.
Pam Baxter is an avid organic vegetable gardener who lives in Kimberton. Direct e-mail to pamelacbaxter@gmail.com, or send mail to P.O. Box 80, Kimberton, PA 19442. Share your gardening stories on Facebook at “Chester County Roots.” Pam’s book for children and families, Big Life Lessons from Nature’s Little Secrets, is available on Amazon, at Amazon.com/author/ pamelabaxter.