Ministry of Controversy

The best possible case for native plants

by Susan
I recently attended an all-day conference put on by the Chesapeake Conservation Landscaping Council. Over 200 landscape professionals were taught sustainable landscaping practices like organic lawn care and site-specific stormwater management techniques.  The organizer who urged me to attend recommended the closing talk by Doug Tallamy above all, so I stayed to hear it and I’m glad I did.  I found his talk the most compelling case I’d ever heard or read for the use of native plants, and here’s why:

  • Studies have shown that American dogwood (Cornus florida) supports 117 species of moths and butterflies while the Asian C. Kousa only supports one.   He cited similar results for other native-nonnative pairs.  That got my attention, as it would anyone who loves nature.
  • I was open to what he had to say because, as Elizabeth noted, he isn’t preachy, and he acknowledges the difficulties.  So I appreciate his bringing a bit of fresh air to what’s become a very contentious argument between nativists and people in the gardening world.

More surprising facts
Trees
and woodies are the most important plants for sustaining wildlife because they support the most biodiversity.  The surprising part is that in the East, 82 percent of the plants that grew here were oak trees, so it’s no wonder there are comparatively few nonwoody native plants.

He urged landscapers to

  • Create corridors connecting natural areas,
  • Reduce the total area now used for lawn, and
  • Transition to native ornamentals, especially in habitat corridors that run through our backyards and connect them.

Tallamy did a masterful job of making the case that a great number of insects need native plants for their survival.  But during the Q&A when he was asked how contractors might convince their clients that they should landscape for insects, he had no answer. 

Which brings us back to the question in Elizabeth’s post, whether the "battle for natives has been won."  Judging from the reaction of these boots-on-the-ground professional gardeners and designers, not by a long shot and that’s because it’s still homeowners who make these decisions, not entomologists and wildlife ecologists.  And because homeowners want plants that look good and are low-maintenance, they’re choosing Cornus Kousa in ever-increasing numbers, especially when advised by professionals in the hort biz, because it’s more drought-tolerant and less vulnerable to disease than our native dogwood.  So which plant is more sustainable?   

My full report on the conference and the larger questions it raised – especially that unanswered one about how to change clients’ minds – is coming soon.

Posted by on December 2, 2007 at 12:02 pm, in the category Ministry of Controversy.
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9 responses to “The best possible case for native plants”

  1. chuck b. says:

    INSECTS ATTRACT BIRDS!!!

  2. susan harris says:

    Chuck, are you suggesting that homeowners would go for it if their landscapers made the case for birds, rather than insects?

  3. Amy Stewart says:

    I think the important point from Tallamy’s book is that insects need native plants because they (often in their larval form) eat the leaves of native plants. They can’t digest the compounds in an exotic azalea any more than you and I can. In fact, a lot of our cherished ornamentals were imported specifically because they are “pest resistant,” meaning that all that leafy green matter is unpalatable to bugs.

    I’ve spoken to Tallamy myself a few times lately, and the important points he makes are:

    1. Bugs need native plants so they can eat their leaves.

    2. Birds need bugs because that’s what they feed their young. Baby birds don’t eat seeds and berries, they eat bugs.

    That’s a pretty significant link to break in the food chain. Back in the good ol’ days when there was plenty of wild, open space, gardeners could simply plant whatever looked pretty. Now that we’ve destroyed so much open space, gardeners have a different role to play. We can (should?) replace some lost habitat and plant some of what bugs, birds, amphibians, etc. need to survive.

  4. CJ says:

    So, 82% of my landscape should be oak trees?

    We do have several large oaks (red & white), and I’ve planted four more (pin & willow). We have Sassafras. and have added tulip poplar, ash, redbud, dogwood (C. florida) and river birch. There are hedgerows of natives ringing most of our lawn – yes, we have a lawn. We’ve finally found someone who does completely organic lawn care.

    All of this said, I won’t give up the exotics I grow, shrubs and perennials alike. Why should I?

  5. chuck b. says:

    Yes, sorry for shouting. Who doesn’t like birds? Where there’s insects, there’s birds. Birds need more to eat than seed, and insects don’t grow weeds in your garden like birdseed does. Insects also feed spiders, and studies indicate spiders are huge part of the hummingbird diet. Of course, I don’t know anything about gardening on the east coast. I can only say what I’ve learned gardening on the west coast.

  6. Tibs says:

    Corridors of native growth? Brings the deer deeper and deeper into suburban settings. And they eat anything and everything.

  7. Diana says:

    Out here in Corvallis (Oregon!) we’re trying to have both natives and everything else – perennials, annuals, and edible landscaping (strawberries, grapes, vegetable garden, raspberries) and all completely organic. In our 1/4 acre suburban lot, our native shrub section is along the back fence, and in a center ‘oasis’ a big leaf maple, incense cedar, oregon ash, and volunteer nut trees. So far, everything is co-habitating great; even the slugs! We’re hoping to maintain a balance in which everything has a place, including insects, garter snakes, and birds.

  8. Common Weeder says:

    Balance is all, isn’t it. I have also been reading about wildlife corridors and my first reponse was – Oh, so the deer can move unimpeded. The deer are a problem, a big problem, but other creatures move through those corridors. I welcome the hunters to my 60 acres, but since deer are becoming a more severe suburban problem we have to look for more answers to deer population control.

  9. bev says:

    I too have heard Dr. Tallamy’s inspiring lecture, although it was last year at another event. Aside from the leaves/larvae/birds connection so aptly quoted by Amy, the take home point I remember is that he said it’s now up to US – the suburban gardeners – to recreate the ecosystem. That’s how totally destroyed it has been. A scary thought and a big responsibility. I don’t remember him saying that one could not grow exotics, however – just don’t let them push out the natives. And who needs grass anyway??! Remember, guys, we need pollination in order to eat too!

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