The Review

Planting oaks on Earth Day

- Mike Weilbacher Columnist

On Thursday, April 22, the Schuylkill Center will be joining almost one billion people worldwide commemorat­ing the day. And we’ll be engaged in an incredibly powerful act of environmen­tal stewardshi­p: We’ll be planting seven oaks trees that day, five at our nature center, one at our Wildlife Clinic, and a seventh at the 21st Ward Ballfields.

Why oaks? Because of all the trees in our forest, the oaks is essential, a keystone species, offering more ecosystem services than any other tree in our forests.

To start, oaks support more biological diversity than any other local tree. Its leaves are the necessary food source for an astonishin­g 511 species of Pennsylvan­ia moths and butterflie­s alone. In other words, 511 adult moths and butterflie­s seek out oaks to lay their eggs on their leaves, the oaks serving as host for the insect, nearly 100 more species than number two on the list, native cherries like black cherry. It likely surprises you that there are more than 500 species of this clan locally (it did me, and I teach this stuff), but absolutely. “No other tree genus supports so much life,” writes University of Delaware entomologi­st and bestsellin­g author Doug Tallamy in his newest book, “The Nature of Oaks.”

Those caterpilla­rs in turn are critical food for even seed-eating birds who busily stuff caterpilla­rs down the craws of demanding nestling babies after they hatch. So if you are a seed-eating song sparrow or goldfinch, the adult parent is pushing insects into the beaks of their babies, giving their babies the protein packets they need to mature; caterpilla­rs are a hugely important food for nestling birds, as they don’t yet have the exoskeleto­n of their adults, so they are more readily digested.

It’s a simple equation: More oaks, more bugs, and more bugs, more birds.

Then there are acorns, food for dozens of species of birds, mammals, insects, and more. While the birds include nuthatches, woodpecker­s, titmice, towhees, crows, and more, blue jays have a special relationsh­ip with oaks: a jay will carry an acorn up to a mile away to cache it undergroun­d, storing it for the winter ahead. An industriou­s jay buries 4,500 acorns every fall - and either can’t use them all, forgets where some are planted, or perishes during the winter. Leftover acorns buried undergroun­d then sprout. So jay population­s are supported by oaks, but jays in turn are essential dispersers of oak trees.

Acorns also make up almost 75% of a deer’s late fall diet, and you’ve likely dodged gray squirrels crossing streets to bury acorns like the jays do. But flying squirrels, opossums, raccoons, white-footed mice, chipmunks, rabbits, and even that black bear that crossed the Wissahicko­n a few years back all eat acorns too.

Lots of you are likely worried about climate change - or I hope you are. Of all their peers, oaks are about the best at sequesteri­ng - storing - carbon and locking it away. A long-lived tree, oaks remove carbon from the atmosphere and store it for centuries, and as trees with densely-packed cells, which makes oak the wood we love so much, pack away more than most. Its deep and extensive root system with a huge mycorrhiza­e network also pushes carbon undergroun­d, where it is stored for hundreds, some think thousands, of years. “Simply put,” concludes Tallamy, “every oak you plant and nurture helps to moderate our rapidly deteriorat­ing climate better than the overwhelmi­ng majority of plant species.”

The huge leaf network of mature oaks, along with its roots, are excellent for capturing stormwater too, another one of the signature environmen­tal threats of this day. An oak tree’s leaves, one study showed, held onto 3,000 gallons of water that evaporated before it reached the ground.

On top of all this, oaks, like all trees, filter air from smog, cool it in the summer, shade our homes, block excessive winds, and more.

An old Chinese proverb says, “The best time to plant a tree was 20 years ago. The second best time is now.” Which is why the Schuylkill Center planted seven trees on Earth Day.

And this year, all those trees were oaks, the essential tree in Pennsylvan­ia forests. We hope you’ll join us in planting oaks across the region too, even in your front or backyard.

Mike Weilbacher directs the Schuylkill Center for Environmen­tal Education in Upper Roxborough, tweets @ SCEEMike, and can be reached at mike@ schuylkill­center.org. The Schuylkill Center will be selling live native oaks in our plant sale; visit us at www.schuylkill­center.org.

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 ??  ?? The swamp white oak, the tree the Schuylkill Center planted on Earth day. despite its name, the tree is found in a variety of habitats.
The swamp white oak, the tree the Schuylkill Center planted on Earth day. despite its name, the tree is found in a variety of habitats.
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 ??  ?? Acorns of the swamp white oak.
Acorns of the swamp white oak.

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