At age 70, I thought my tree-planting days were behind me.
Actuarial tables say I can expect to live another 13.7 years — not time enough, from my selfish perspective, for a seedling of my favorite tree, the bur oak, to attain the strength, height and beauty for which it is widely admired.
But a recent presentation by nature champion Doug Tallamy, an entomologist at the University of Delaware, impressed upon me the wisdom of the old saw: The best time to plant a tree was 20 years ago. The second-best time is now.
While the proverb emphasizes tree plantings’ benefit to our descendants, Tallamy urges the planting of trees and other native plants to restore the specialized relationships of nature that help sustain us all.
After hearing Tallamy’s Sept. 29 presentation at the Linn County Landowners Forum, I realized that, even if planting a tree would add little enjoyment to the rest of my life, I should do it for the baby birds.
Baby birds get most of their nourishment from caterpillars, which feed on specific plant hosts, and the oak tree tops Tallamy’s lepidoptera index, which ranks plants by the number of butterfly and moth species they support.
“No caterpillars, no baby birds,” said Tallamy, whose research found 15 of the 20 most common families of birds feed their nestlings caterpillars.
Large, soft, nutritious, easily digestible, easy to catch and widely available during nesting season, caterpillars transfer more energy up the food chain than any other animal, he said.
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Likewise, without insects, the foundation of the food webs on which all life on earth depends, “humans are doomed,” Tallamy said.
Tallamy explained plants and animals, evolving together, have established specialized relationships. A classic example, he said, is the monarch butterfly, whose larva can eat only milkweed plants.
While plants have evolved to defend their tissue with distasteful or toxic chemicals, the monarch has evolved to tolerate milkweed’s cardiac glycosides, Tallamy said.
“Ninety percent of insects that eat plants can reproduce and develop only on plants with a shared evolutionary history,” he said, but those relationships have been threatened and in some cases destroyed by such relatively recent phenomena as habitat loss, climate change, pesticides and the introduction of non-native plants.
For our own health and that of the planet, Tallamy urges we restore those specialized relationships by creating on our own little parcels of private property landscapes where nature thrives. If each of us halved our turf grass lawns and replaced them with native plants, we would create 20 million acres of natural habitat, he said.
Tallamy also advised removing non-native and invasive species and replacing them with “keystone” natives such as oak, black cherry, willow, birch and poplar trees and flowers such as goldenrod, aster, sunflower and Joe Pye.
As he talked, I thought of all the little oak seedlings I rip out of my lawn and garden each year — squirrel-planted offspring of the beloved ancient bur oak that shades my favorite resting spot — and thought: Why don’t I let a couple of them grow for the baby birds?
And maybe, 100 years from now, when I and my ancient tree are long gone, someone else will enjoy the shade, security and 365-days-a-year beauty of a mature bur oak.