Native landscaping

Landscaping with native plants (also called indigenous plants) can help improve the environment in several ways. North America is home to thousands of indigenous plants that over many thousands of years have evolved and adapted to specific North American habitats such as prairies, deciduous forests, deserts, or coastal plains. However, many plants that are common today were brought to North America from different biogeographic areas by European and Asian immigrants. Some of the most common landscaping plants used in North America today, such as zinnias (Zinnia elegans ) or Kentucky bluegrass (Poa pratensis ), are not native to areas where they now thrive.

Plants brought from their native habitat to another ecosystem are called non-native or alien plants. For example, early colonists brought with them seeds from their homes in Europe to plant for food or use for landscaping. Likewise, some native North American plants, such as tobacco Nicotiana sp.), were taken back to Europe. Many of these plants thrived in their new homes.

While new plants were being imported, increased colonization altered the character of the land in North America. Forests were felled and prairies plowed under to convert large swatches of land to farming. Some of the newly introduced plants grew better under these altered conditions than did native North American plants. Some species of non-native plants begin to take over the habitat of native plants, forcing the native plants out. Sometimes this was intentional, as when a non-native plant was grown for food or planted for landscaping. Other times, it was accidental, as when a non-native plant used in landscaping escaped the garden and began to grow uncontrolled in the wild.

One way to maintain native plants is to set aside large nature preserves and protected parks where native plants can grow undisturbed. Native landscaping hopes to protect our plant heritage in another way, by planting native species in home gardens and landscaped areas such as the grounds around corporate headquarters, on college campuses, and in city parks. Native landscaping in many cases saves water, reduces pesticide use, and maintains unique systems of indigenous plants and animals.

Landscaping around urban and suburban homes usually employs only several dozen kinds of plants, from turf grass to evergreens for foundation plantings to decorative flowers. This typical landscape supports little variety in insect and animal life. Lawns and evergreen hedges offer little protective cover for small mammals, and streams or ponds that provide water and a home for animals are often diverted or drained to make way for development. Gardeners may plant beds of decorative annual flowers, but these are usually not adequate for feeding bees, butterflies, and other insects that depend on nectar.

Native plants, on the other hand, have evolved in complex communities. Often the land can support a greater variety of native plant species. In some cases these plant communities naturally enrich the soil to make it fertile enough to support still more species. These communities shelter a variety of animals and insects that in turn help plant species thrive by pollinating the plants and distributing their seeds. The plants and animals are tied together in ecosystems where all have evolved to live with specific natural conditions (for example, high soil acidity, low rainfall, or high mineral content of the soil).

The number of different species of plants and animals that form an ecological community determines the biodiversity of that community. Many urban and suburban landscapes have low biodiversity, because they support only a few different species. Even landscaped lawns and gardens that support a high level of biodiversity are considered of low value by ecologists when the plants are almost entirely alien.

Native landscaping helps to develop biocommunities that improve the ecological integrity of the land. The biodiversity of the area returns more closely to its original state. This is considered a desirable goal by ecologists. Often when native plants are grown in their natural habitat, they require fewer resources (water, fertilizer ) than alien species because they have evolved to suit the natural conditions of the area. For example, the turf grass that covers most American yards evolved in the cool, rainy summers of Northern Europe. Consequently, in many parts of the United States there is inadequate natural rainfall in the summer for this grass to thrive and, people must water their lawns to keep the non-native grass green and healthy. Alien flowers and non-native ornamental trees may also be more susceptible to disease and pests. Native landscaping is a valuable way to cut back on the use of chemical pesticides and fertilizers, as well as water, because native plants in the proper site can support themselves without this supplemental care.

In some cases, plants introduced from other places have become pests, growing abundantly and choking off native growth. These plants are called invasive plants, because they invade or take over the habitat of native plants. One example is purple loosestrife (Lythrum salicaria ), an ornamental plant brought from Europe in the 1800s. It has grown so well in some areas of North America that it is now a significant threat to the biodiversity of wetland habitats. Alien insects that arrive on introduced plants can also threaten native plants with extinction . Native landscapers help root out invasive plants and restore the original plant communities.

The trend toward landscaping with native plants emerged in the United States in the 1980s and 1990s. Some communities (for example in the San Francisco Bay area) now have local native plant societies that hold annual sales of native plants to help the gardener interested in native landscaping. The first step towards native landscaping is usually to reduce the amount of lawn. Some gardeners have replaced traditional turf lawn with a meadow or prairie planting of native grasses. Some environments, such as desert , do not naturally support any kind of grass. Native landscapers in these regions tend to favor drought-tolerant perennials. In dry areas, landscaping with native plants can be an important element in landscaping for water conservation (called xeriscaping).

Another move toward native landscaping is to border a turf lawn with plantings of native perennials, shrubs, and trees. Many native plants are quite ornamental, but the native landscaper may also select plants based on kind of ecological community they support. Native planting might include shrubs that bear fruits eaten by local birds and mammals, early spring wildflowers that provide nectar for insects just emerging from winter dormancy, or nut trees to feed squirrels through the winter. A native landscape might also include flowers that will attract local butterflies. The resulting landscape may prove to easier and cheaper to maintain than a traditional planting, need few or no pesticides or fertilizers, use less water, and provide food and habitat for a diverse animal population.

[Angela Woodward ]

RESOURCES

BOOKS

Stein, Sara. Noah's Garden. New York: Houghton Mifflin, 1993.

Stein, Sara. Planting Noah's Garden. New York: Houghton Mifflin, 1997.

Wasowski, Andy, and Sally Wasowski. The Landscaping Revolution. Chicago: Contemporary Books, 2000.

PERIODICALS

"Going Native: Biodiversity in Our Own Backyards." Brooklyn Botanic Garden Handbook 140 (1994).

"Native Perennials." Brooklyn Botanic Garden Handbook 146 (1996).

Orecklin, Michele, and David Schwartz. "Say Goodbye to Grass" Time (July 2, 2001): 56.

OTHER

Environmental Protection Agency. Landscaping with Native Plants. January 24, 2000 [cited July 2002]. http://www.epa.gov/glnpo/native plants/index.html.