The Beekeeper’s Companion Since 1861
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The Curious Beekeeper

Vertically Verdant: Trees to Save the Planet, the Bees, and Ourselves

- May 1, 2023 - Rusty Burlew - (excerpt)

When we consider planting for pollinators, we often focus on crop plants or garden flowers that bloom at eye level or below. These range from tiny forget-me-nots to swaths of clover to prickly jungles of raspberries.

For whatever reason, we rarely consider trees for our pollinator gardens. We may think trees are slow to grow, deposit messy litter on the lawn, or shed shade where we don’t want it. Or perhaps we overestimate the danger of a tree that grows close to the house.

But if there is one thing our planet needs more of, it’s trees. And lucky for us beekeepers, honey bees thrive on flowering trees. And so do we.


Square-foot gardening

A few years ago, so-called square-foot gardening was all the rage, especially in urban areas. The goal was to plant many species within neatly divided square-foot plots, usually in raised beds. Compared to planting in rows, aficionados touted this practice as more efficient and less wasteful of water and soil amendments.

But if you want to plant for honey bees, so much variety in a small space is counterproductive. At the very least, honey bees prefer to collect from a single species for the duration of a foraging trip. And a full day of trips is even better. When feeding honey bees, a bigger plot is better.

A variation on square-foot planting

Although I never got into checkerboard gardening, I think of it whenever I plant a tree. After clearing a little patch of soil — not much bigger than a square foot — I sink a hole in the center and plant my itsy-bitsy seedling. I tend it for a year or two, deleting weeds and adding water until it looks happy.

Afterward, I forget about it, sometimes for years. Then one day, I walk by and realize my twig is as big as a house — well, taller than a house, anyway. If only my bank account had the same vigor.

I’ve always been a tree planter. Each spring, I’ve purchased trees from my conservation district, usually in bundles of ten or twenty-five. Those trees are the reason my house is chilly on the sweatiest summer days (no air conditioning needed). They’re also the reason the paint lasts so long (no UV light to ruin it), and the reason my hives are in constant shade, something the bees don’t seem to mind at all.


A life strung together with trees

One day last summer, beneath an azure Midwestern sky, I sat in the grass contemplating the biggest cottonwoods I’ve ever seen. The trees were iconic, rough-barked giants, with beefy branches as thick as full-grown sycamores with the kind of roots that tilt sidewalks and crack driveways. Their stately presence and look-at-me attitude unleashed a wash of tree memories.

Trees have been a lifetime source of happiness and contentment. I see my life as a string of beads where each bead is a different tree. I’ve simply gone from one to the next, admiring every one of them.


Trees for a healthy life

Is anything more magical than a fragrant manila rope hanging from a shady oak loud with chattering squirrels and squawking jays? My third-grade rope — coarse, shaggy, and redolent of rotting grass — ended in a fat knot that kept me from sliding to the ground. Despite calloused hands and ragged fingers, I spent lazy summers swinging in great arcs, hoping I would never grow up.


Besides providing wood and fruit and piles of musky leaves, trees in our neighborhoods purify the air, reduce road noise, provide privacy, lower our exposure to UV radiation, and keep us cooler. Trees lure us to the outdoors and introduce us to wildlife and sounds we remember for a lifetime: the squawking of birds, the chatter of chipmunks, and the cacophony of busy insects.

Playgrounds with shade are more popular than those in bright sun, and picnickers like a table under a tree despite bird droppings, seeds, pollen, and leaves that land there. Trees provide comfort like a well-worn security blanket. Nothing lures humanity like a tree.

Study after study confirms that green spaces promote emotional health and happiness. They ease anxiety and depression and can lessen anger. Studies have shown that inner-city crime and violence diminish in areas with shade trees, and kids are more likely to play outside.

Then too, trees provide private places. Even with people all around, trees help us collect our thoughts and sort through problems. People seek trees as places to read, talk to friends, or simply watch the world pass by. And since wildlife loves trees as much as we do, tree lovers are never truly alone but surrounded by companions of every size and disposition.


Trees can cut your energy bill

Years ago, while hiking with family members in the Anza-Borrego desert east of San Diego, we came across a stand of mortero palms. Entering the stand was physically shocking, like stepping into a walk-in freezer. But instead of dry, the air among the trees felt thick and damp and smelled like aging hay bales. Those astonishing trees grew straight and tall amid boulder piles in the scorching desert heat, yet wore layers of dead fronds like frilly petticoats that shaded the ground beneath.


Buildings shaded by trees can easily escape the huge energy loads of air conditioning. My home is a good example. Over the past thirty years, untold numbers of visitors have gushed. “Oh my, it’s so cool in here!” Or, “You must have heavy-duty air conditioning.”

Yet we have no air conditioning and never did. And even with warmer daytime temperatures, I still wear a hoody at my desk all summer long. One by one, our surrounding neighbors cut down their trees, and each expressed surprise when they could no longer bear the summer heat without air conditioning. Homes can be 10-15 degrees cooler just by leaving trees in place.

And if the trees are deciduous, you get a double benefit: cool shade in summer, and sunny warmth in winter. You couldn’t design a better system, no matter how much money you poured into it.


Trees thrive on carbon dioxide

With all the environmental problems we have, I’m surprised we continue to cut trees and clear the land just because we can. Now more than ever before, we need to give trees the respect they deserve.

Like all plants, trees take up carbon dioxide (CO2) and water (H2O) during the day. When we add sunlight, the chlorophyll in plants produces sugar (glucose) and oxygen (O2) through photosynthesis. The oxygen enriches the atmosphere and the carbon-containing glucose gets stored in the plant.

But like animals, plants respire 24/7, using O2 and giving off CO2. During the day when photosynthesis occurs, plants use only some of the O2 for respiration and release the rest into the air. During darkness, however, photosynthesis stops so plants must use O2 from the air and give off CO2. Despite this reversal, plants release less CO2 at night than they use during the day. That means trees are carbon sinks: storage vaults for carbon.

In trees, most of the carbon gets stored in the wood. Later, if we burn that tree as firewood, the carbon dioxide goes back into the atmosphere, turning the wood into a carbon dioxide source.

Trees have a short carbon cycle

For many trees, such as Douglas-fir, the carbon cycle takes about 60 years. The tree lives and stores carbon for roughly 60 years before we cut it. If we build a house with it, the carbon remains in the wood. If we burn the wood, the CO2 goes back into the atmosphere.

This cycle of collection and release is short in geologic terms. Before people began burning fossil fuels, the CO2 regularly cycled between plants and the atmosphere, such that the atmospheric levels of CO2 remained very constant. But burning fossil fuels yields a very different result because it takes millions of years to recycle the CO2 back into the ground and make coal or oil. As a result, our atmospheric CO2 is rising quickly.

Recent research shows that trees release more carbon dioxide during respiration when temperatures are higher. But even in a warming atmosphere, trees will ….