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Choosing landscape plants to create an ecologically sustainable yard

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In Douglas W. Tallamy’s new book, “Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard,” he writes, “Nature has proven to be more resilient, more malleable, and more forgiving than I ever thought.” That’s good news for anyone who wants to do something productive, proactive and positive, he adds, “at the local scale – the scale that counts ecologically.”

Tallamy offers a well-written, accessible and well-argued case for using ecological considerations, particularly the food web, as the basis for choosing landscape plants. Amid declines in songbird populations and news of the “insect apocalypse,” it’s heartening to read a book about nature’s resilience that’s based on science.

A key concept is learning to appreciate insects, which Tallamy says “sustain the earth’s ecosystems by sustaining the plants and animals that run those ecosystems.”

“Insects are the animals that are best at transferring energy from plants to other animals … and most insects are very fussy about which plants they eat,” he writes.

Another key is including at least some “keystone” native plants. Tallamy defines “native plants” by their ecological function, that is, the web of “specialized relationships” they have developed with other organisms over evolutionary time. The keystone native plants host the greatest number of caterpillars, crucial food for most songbirds.

Landscape maintenance

Notably, without keystone plants, even a mostly native landscape will not be as ecologically productive, supporting “70 to 75 percent fewer caterpillar species,” according to Tallamy. One reason, he notes, is because “interaction diversity” – the number of plant-insect interactions – is a better measure of a healthy landscape than species diversity.

Also, non-native invasive plants degrade food webs not only by replacing a variety of natives with a monoculture, but also by devastating interaction diversity.

Tallamy recommends paying attention to landscape maintenance. Keeping leaf litter under trees can enable bees, butterflies and other insects to complete their life cycles. Other overwintering sites include pithy dried stems and decaying logs.

Each cluster of habitat created in suburban yards can be “one small piece of a giant puzzle, which, when assembled, has the potential to form a beautiful ecological picture,” Tallamy writes, adding that these landscapes would depart from traditional landscapes in only three ways: less lawn, more total plants and a greater percentage of habitat plants – “the powerhouse species that drive food webs and support pollinators.”

If everyone replaced half their lawn area with habitat plants, the resulting “Homegrown National Park” Tallamy proposes would comprise more land area than existing national parks. An added benefit would be the ability to observe “the seasonal progression of species in your yard,” he writes. Unlike a rushed annual visit to a national park, a lazy afternoon in your own yard would allow you to have the kind of experiences with nature that Tallamy says take “time, convenience, patience, solitude, and serendipity.”

Addressing concerns about large specimen trees that could threaten structures in small suburban lots, he notes that in forests, trees “intertwine their roots, forming a root matrix that is nearly impossible to uproot.” If trees are planted in groups of three or more on 10-foot centers, “the resulting root matrix would keep them locked in place through thick and thin.”

Tanya Kucak gardens organically. Email her at [email protected]

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