Ten Good Things about Trees

by Mike Weilbacher, Executive Director

I’ve been thinking about trees a lot these last few weeks, in part because the leaves are turning color and falling to the ground, something I look forward to every year. But also because the Schuylkill Center just found evidence of emerald ash borers on our massive property, something that is deeply troubling, as we are now faced with hundreds of dead and dying trees.

And because not far from the Schuylkill Center, a sister nonprofit cleared about an acre of trees to make room for a playground. Playgrounds, of course, are wonderful things, but losing a whole acre of trees is, for me, the director of an environmental center, hard to stomach.

Because we just lost an acre of ecosystem services, something tough to come by in this environmentally challenged world.

And because, at day’s end, there are 10 great things trees do for us.

First, trees are natural air conditioners. Walking into the Schuylkill Center forest on a hot summer’s day, the temperature immediately drops. The ground is shaded by trees, and that umbrella of leaves protects the soil from the sun’s scorching rays. Trees are literally cool.

Trees also filter air pollution, pulling bad stuff out of the leaves—urban smog, say—and putting fresh air back into the world.

Those same leaves are air fresheners; when they pull pollution out of the air, they replace it with oxygen, one of the requirements for life. So leaves are oxygen factories, renewing our air. Two mature trees, it is frequently said, provide the oxygen needs of a family of four. That acre of trees that just came down? That’s the oxygen needed for about 18 people to breathe. They’ll have to get it elsewhere.

But while making oxygen, those leaves are also pulling in carbon dioxide, a greenhouse gas, the stuff that flows out of our tailpipes in car exhaust and is supercharging our atmosphere. Trees mitigate climate change: the more trees we have, the better our chances of surviving and beating climate change. Philadelphia hopes to plant a million trees in the next few years, and the Schuylkill Center has been doing its part in planting new trees on our property. This will not only improve the city’s smog but help us address the scourge of climate change.

Everyone in Roxborough has been talking about stormwater in recent years, how the climate’s larger storms flood our streets with too much rainwater. Manayunk has a lot to say about climate change’s impact on flooding, as Manayunk too frequently receives Roxborough’s stormwater. A tree, amazingly, addresses stormwater—a mature tree’s large umbrella of thousands if not millions of leaves slow down rainfall, allowing water to trickle to the ground slowly long after the storm has moved on. And tree roots act like sponges to mop up water, the tree’s dead leaves on the ground underneath the tree also sopping up stormwater. Cool beans: the more trees in our landscape, the better we can address the increasingly intractable problem of stormwater.

Trees provide food for all kinds of creatures. A dogwood tree’s bright-red berries are eaten by some 90 species of creatures, including many birds who crave it in the nutrient-starved winter months when the berry is smartly ready. Black cherry fruits are craved by many kinds of birds; acorns are eaten by thousands of species of animals, not just squirrels.

A tree is also habitat, home to millions of living things. A woodpecker digs out a home in a trunk; that hole is later co-opted by a screech owl or raccoon. Squirrels are nesting high in the branches, chipmunks in the roots underneath, bats are behind the peeling bark (and those bats are eating the mosquitoes in your yard; trust me—you love bats.)

Winter’s coming, and trees can also help you address the cold north winds. Planting evergreen trees on your northern exposure can reduce that wind—trees lower your heating bill. (Yes, trees cool your house in the summer and warm it in the winter!)

Trees, of course, are aesthetically pleasing, lovely to look at—and healing. Evidence indicates that we are hardwired to relax when looking at greenery, so sitting in your yard surrounded by trees can actually lower your blood pressure and calm and soothe you. Trees are healing.

And the 10th good thing about trees: money actually grows on trees. According to the USDA, a large tree in front of a house increases that home’s sales price by about $7,130, and if that tree is part of a beautiful, well-kept landscape, your home’s value increases by about 10 percent. Plant trees and your home gets a higher resale value.

So, Roxborough, plant away!