Saving Species in the Garden

Fourteen years ago, when I moved into my Brooklyn brownstone, I was hip deep in what I now call my "Sissinghurst Phase." I had just returned from writer Vita Sackville-West's Sissinghurst Castle in England, and I wanted my Brooklyn cottage garden to be a white garden, like one heavenly corner of Sissinghurst, full of luminous, fragrant flowers to attract hovering moths in the smoggy urban moonlight.

For me, as for many gardeners, a beautiful backyard meant combining just the right shades of gold and blue, or placing the taller plants at the back of a flower border and the smaller ones in front.

But I've since learned that aesthetics is not all. As I've worked with botanists around the world, it has become breathtakingly clear how many species are imperiled. According to scientists at the Center for Plant Conservation, an umbrella group of botanical gardens across the country, one-fifth of all plant species in this country are of conservation concern. And 581 plant species are listed as endangered by the U.S. Fish and Wildlife Service. These plants are also critical habitat for countless other creatures. As wilderness shrinks and yard acreage increases, the home gardener can play a significant role: By transforming our yards into beautiful habitat gardens, we can improve the lot of a surprisingly large number of plants and animals.

As backyards and front lawns increase with suburban sprawl, natural areas are not only growing smaller but also more isolated from each other. This habitat fragmentation threatens genetic diversity; when populations of a species are cut off from one another, inbreeding occurs. One likely result is that future generations will lack the genetic variation that would help them cope with changing conditions, from climate change to an imported insect pest. A growing number of scientists are convinced that we are already in the midst of an age of extinction. In the words of Peter Raven, director of the Missouri Botanical Garden and one of the greatest botanists of our time, "By the middle of the [21st] century, as many as 100,000 of the estimated 300,000 [plant] species could be gone or on the way to extinction."

In this age of accelerating extinctions, we need to create gardens that are not just beautiful but also promote biodiversity. By helping to stitch together remaining fragments of natural landscape through cultivating our region's native plants and those that attract pollinating birds and insects, we can help recharge diminishing gene pools.

In my little urban backyard, I recreated a tiny pocket of the primeval oak forest that Henry Hudson and his crew found when they landed here in 1609. I planted shadbush, an understory tree, under the overhanging canopy of neighboring trees. Its evanescent white flowers appear in early spring; later cedar waxwings and other birds dine on its dark purple fruits. Sweet pepperbush, a native shrub with fragrant summer flowers to which butterflies, bees, and other pollinators flock, makes a charming backdrop for the cinnamon fern and yellow bellwort on my woodland garden's floor.

My tiny wild garden reflects a national trend. Gardeners in the Midwest are reseeding native tallgrass prairie. In midsummer, four-foot-tall rattlesnake master and purple coneflower form a dramatic display against a canvas of airy, midheight prairie grasses. In a final burst of flowering, the tawny seedheads of the grasses set off purple asters and bright yellow goldenrods in the fall. Gardeners in Arizona are making desert gardens, with giant saguaro, prickly pear, and barrel cacti. Blue palo verde and other native trees provide shade, and native wildflowers such as the bright red chuparosa add splashes of color.

Someday, thousands of biodiverse gardens may form a network of green corridors crisscrossing the country, allowing animal populations to merge and seeds to more widely disperse. With such land bridges, we may in effect be able to enlarge parks and nature preserves, transforming an archipelago of lonely islands of wilderness into a functional unit big enough to ensure the survival of thousands of species.

If I can create a biodiverse garden in my miniature inner-city yard, then you can, too. If you live in a yardless apartment, window and rooftop container plantings can provide habitat for native plants and their pollinators. Remember: If native habitats once found on your site are long gone, they can be restored.

Janet Marinelli, director of publishing at the Brooklyn Botanic Garden, is the author of Stalking the Wild Amaranth: Gardening in the Age of Extinction (Henry Holt and Co., 1998, $25).