Thursday, April 22, 2021

Saving biodiversity one backyard at a time -- April 22, 2021 column


Joni Mitchell got it right.

“They paved paradise and put up a parking lot,” she sang in “Big Yellow Taxi.”

Mitchell wrote the song in 1969 during her first trip to Hawaii. More than half a century later, we’re still paving paradise, or what’s left of it.

Most people don’t think of it this way, but some “paving” is not even hardscape. It’s green.

Our well-manicured lawns are the equivalent of parking lots – dead space – to most insects, entomologist Douglas W. Tallamy and other ecologists say. And insects, as naturalist E.O. Wilson memorably observed, are “the little things that run the world.”

Insects pollinate more than 80% of all plants and 90% of all flowering plants. Without insects, the “food web” that support humans and other mammals, reptiles, amphibians, birds, and freshwater fishes would disappear.

But Americans love their lawns – 40 million acres’ worth. Homeowners east of the Mississippi typically have 90% of their yards in lawn, and only 10% in the tree biomass that was there previously, Tallamy writes in “Nature’s Best Hope,” his 2019 book about a backyard conservation approach he calls “Homegrown National Park.”

With insects and birds in decline around the world, Tallamy and other ecologists say it’s time to end our love affair with our lawns. To save insects and birds and our food supply: Mow less.

He challenges us not only to let our grass grow to 3 inches before mowing – tall enough to protect box turtles -- but to shrink our lawns by half. Then, put in native plants to restore biodiversity.

Doing so would create a network of homegrown parks to supplement the national parks that alone cannot preserve species to the levels needed. There are far more lawns and they are closer to each other.

Native plants are critical because insects tend to shun our common non-native plants. But not all native plants are created equal. You need “keystone” plants to create conditions for successful food webs. Native oaks are the top keystone plant, and white oaks are “superstars,” says Tallamy, whose new book is “The Nature of Oaks.”

Native cherries, willows and birches are also keystones. The top herbaceous plants, those that do not have woody stems, are goldenrods, asters and sunflowers.

Homegrown National Park is a grassroots campaign to restore habitat one window box, balcony, rooftop garden, backyard and city park at a time. An interactive map shows where people have planted natives. You can type in your state to see what others have done by county.

Of course, shrinking one’s lawn in half or planting a mighty oak isn’t practical for everyone. Tallamy suggests replacing non-native ornamental plants, many of which are invasive, with natives and using motion detector lights at night (to save moths).

Check out “Eight simple actions that individuals cantake to save insects from global declines” by four academics.

The team suggests even a partial conversion of lawns – a 10% reduction – could significantly help insect conservation – and cut costs of watering as well as herbicide, pesticide and fertilizer applications.

“If every home, school and local park in the United States converted 10% of their lawn space into natural habitat, this would increase usable habitat for insects by more than 4 million acres,” the authors say.

State-specific groups like the Virginia Native Plant Society and Virginia Cooperative Extension Master Gardeners are good resources for information on local native plants. Or put in your Zip Code on the National Wildlife Federation’s plant finder page for a list of suitable natives. 

Public gardens offer a wealth of free videos online and webinars. Researching this piece, I watched an excellent symposium on native plants sponsored by the Smithsonian Gardens and a native plant nursery in Winchester.

While President Joe Biden’s efforts to reassert the United States’ leadership in the fight against climate change may ignite political fights, taking personal action to save insects need not be a political statement.

Homegrown National Park says in a website disclaimer it “has no political, religious, cultural or geographical boundaries because everyone – every human being on this planet – needs diverse, highly productive ecosystems to survive,” Tallamy says.

Amen. Not everyone can cut their own carbon emissions, but most of us can plant a native plant. We each can do something to help save the insects.

©2021 Marsha Mercer. All rights reserved.


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