Human Health and Economic Benefits of Native Plants and Native Wildlife
(Excerpted from Ecoscaping Back to the Future…Restoring Chesapeake Landscapes.)
“Short of Aphrodite, there is nothing lovelier on this planet than a flower, nor more essential than a plant. The true matrix of human life is the greensward covering mother earth. Without green plants we would neither breathe nor eat. On the undersurface of every leaf a million movable lips are engaged in devouring carbon dioxide and expelling oxygen. All together, 25 million square miles of leaf surface are daily engaged in this miracle of photosynthesis, producing oxygen and food for man and beast.” –Peter Tompkins and Christopher Bird, The Secret Life Of Plants
Aside from all of the excellent reasons for planting native plants, such as their beauty, low maintenance, and promotion of a sense of place, native plants should be the norm in the landscape for a host of very pragmatic reasons. A wide diversity of native plants and wildlife is absolutely essential, not only to our health, but to our survival. One of the most vital reasons is that native plants provide valuable pollinators with food and places to reproduce. We need these pollinators to help us produce food crops.
Many examples of the close relationship of plants and animals exist in this geographic area, such as the host-plant relationship between various butterflies and the plants on which their caterpillars must feed. The monarch butterfly is famous for its dependence on milkweed; and the Maryland state insect—the Baltimore checkerspot butterfly—must lay her eggs on one of only a few select plants, including turtleheads; and the zebra swallowtail butterfly feeds almost exclusively on pawpaw trees during its larval (caterpillar) stage. Examples of native milkweed, turtlehead, and pawpaw can be seen at the Chesapeake Ecology Center. As with the classic monarch butterfly and milkweed example, native insects and other pollinators have developed complex relationships with numerous plant species, so that they depend on them for the survival of healthy populations.
The next time you bite into your lunch, think about this. According to the Johns Hopkins Bloomberg School of Public Health, experts calculate that “over 90 percent of all flowering plants and over 75 percent of food crops require fertilization by animal pollinators in order to produce fruit and seed.” The domestic honeybee population is in decline, due to several factors, including pesticide use. Therefore, we now need to depend, even more than at other times in history, on the benefits of native pollinator animals to help provide the foods we eat.
The NBII (National Biological Information Infrastructure, part of the U.S. Geological Survey) reports, for example, that “More than half the world’s diet of fats and oils comes from oilseed crops. Many of these, including cotton, oil palm, canola, and sunflowers, are pollinated by animals.” Without pollination, these plants would not produce the viable seeds or plant parts on which we rely so heavily. Now add the grains, fruits, vegetables, fibers, and other products which need pollinators, and you get a picture of their essential role in our lives.
Our food supply and many products we use are dependent on animals, including the native bees, wasps, butterflies, moths, beetles, flies, birds, bats, and other pollinators. Native plants provide habitat requirements which make them essential for many of these animals.
Native plants also attract a variety of wildlife species which help with the control of mosquitoes, flies, and other annoying and disease-causing insects. With the arrival of West Nile virus, and the existence of many other mosquito-borne illnesses, the public health value of natural controls for mosquitoes is significant. Many types of birds eat flying insects like mosquitoes; and wildlife such as bats, dragonflies, frogs, toads, and others help control them as well. Creating and restoring native habitat areas helps to attract these useful animals and keep them near to where we live, so that they can do the job of reducing nuisance insects around our homes. Reducing or eliminating pesticide use also helps protect and enhance populations of birds, amphibians, and other animals.
Another pragmatic argument for landscaping with native plants, especially as an alternative to lawn only, is that it can increase property values. According to the National Wildlife Federation, planting even a few trees in a yard adds to its potential value. Property owners have also found that a thoughtfully landscaped yard with low-maintenance native plants can be a big selling point.
Although many people agree that there is an intrinsic value to supporting native plants and wildlife, and many wish to enjoy the pleasure of seeing birds and butterflies and other wildlife close to where they live and work, there are documented economic reasons to support these populations as well.
In 2001, close to 22 million people took trips for the purpose of watching non-game wildlife. They spent $8.2 billion on travel related expenses, including $4.8 billion on food and lodging. Most of these, 18 million Americans, took trips for the express purpose of watching wild birds. The total amount spent that year on travel, equipment, and related supplies and materials to observe wildlife is estimated at $38.4 billion. This includes participation by 31 percent of the adult population over the age of 16, or 66.1 million people.
A final self-serving reason to protect and restore wildlife habitat in our landscapes is that the decline of certain species can be seen as a harbinger of the decline of an entire ecosystem. The status of wildlife as “canaries in a coal mine” indicators of trouble ahead for us should not be underestimated. If, on the other hand, we can maintain populations of local wildlife by landscaping with native plants, providing enough diverse habitats, and eliminating or greatly reducing the use of toxic chemicals, we can be fairly certain that our health will be better protected as well. Rachel Carson’s book Silent Spring was a startling wake up call regarding the importance to humanity of caring for our environment and deciding what we really want to put, or not put, into it. Her example of pesticide use (especially DDT which causes bird eggs to break) potentially causing a “silent” spring with no bird song, caused many people to think hard about how we want to treat our world.
WHAT YOU CAN DO
Conservation landscaping can be a positive solution to lessen the impacts of development. As an alternative to outdated, damaging cultural fashions in landscaping, try these methods to begin restoring and protecting your own backyard and our Chesapeake Bay watershed. As Dr. Maya Angelou tells us, “We did what we knew; when we knew better, we did better.” Imagine the difference it would make if we all did what we now know is the better thing to do.
Principles of Conservation Landscaping are summarized here and examined in greater detail on the Conservation Landscaping page
- Avoid the use of and remove and replace invasive plants.
- Use regionally native plants.
- Place plants in appropriate growing conditions.
- Minimize the use of supplemental watering.
- Minimize the amount of lawn.
- Reduce or eliminate the use of chemical fertilizers and pesticides.
- Compost to reduce yard waste and to use as a soil amendment.
- Reduce the use of power landscape equipment.
- Utilize native trees to reduce heating and cooling needs.
- Purify the air and water by planting native trees, shrubs, and perennials.
- Reduce the amount of impervious surface and install rain gardens to recharge groundwater and reduce runoff.
- Reduce runoff and soil erosion and stabilize slopes by planting native trees, shrubs, and perennial ground covers in swales and on terraces, in addition to level and raised areas.
- Provide wildlife habitat by planting native species.
- Mulch to conserve water, suppress weeds, improve soil structure, and to lessen erosion.
- Learn to appreciate nature and tolerate some imperfection in the garden.
- Protect existing natural areas and the watershed’s “sense of place.”
- Maintain native plant gardens and plan for the long term.
Conservation landscaping—using native plants, removing invasive plants, conserving water, eliminating or reducing chemical fertilizers and pesticides to reduce pollution and conserve resources, shaping the ground for better infiltration and to control erosion, and enhancing aesthetics and wildlife habitat—is beginning to be implemented on a regional basis nationwide.
Tips to Benefit Wildlife
Local wildlife, such as birds, insects, and mammals are critically dependent on native plant communities. The value of native plants to wildlife cannot be over-emphasized. The plants that evolved here over thousands of years are associated closely with the native animals and other simple forms of life, such as fungi and invertebrates, which evolved together with them. This means that native plants support the inner workings of the whole ecosystem, if we give them the chance.
A few simple changes in how we landscape can make a big difference to wildlife species. Consider these tips for increasing the wildlife-friendly character of your yard, campus, or public space.
- Plant native plants appropriate to the soils for your site: wet, dry, salty.
- Plant a variety of trees, shrubs, grasses and other herbaceous plants for food, shelter, nesting, and habitat.
- Provide clean water sources for as much of the year as possible. We often think of providing food for wildlife, however, water can be an even more critical need.
- Choose plants that will grow to varying heights to reproduce overstory, understory, and herbaceous layers found in nature.
- Reduce or eliminate deadheading of flowers. Although meticulous gardeners tend to remove some types of flower heads to force them to bloom again and cut back grasses, consider leaving them intact until late winter or early spring. Leaving plants uncut over the winter provides seeds, shelter, and nesting sites for wildlife.
- Leave logs and snags (standing dead trees), as long as safety allows, for habitat.
- Provide brush piles of fallen branches, rock piles, and evergreen shrubs and trees for cover.
- Consider adding nesting boxes and bird feeding stations if they can be properly maintained.
- Add plants that provide winter food.
- Plant native plants with berries and other fruits such as blueberry, blackberry, black chokeberry, winterberry, American holly, dogwoods, paw- paw, persimmon, sumacs, inkberry, cranberry.
- Plant native plants that produce nuts, such as oaks, hickories, American beech, and American hazelnut.
- Plant composites and grasses with seeds enjoyed by wildlife, such as switchgrass, broomsedge, orange coneflower, and other composite flowers.
- Plant nectar flowers for pollinators like butterflies, bees, and hummingbirds. (Hummingbirds especially like red and orange flowers such as cardinal flower, native honeysuckle, wild columbine, and trumpet vine.)
- Include host plants for caterpillars, such as turtlehead (Baltimore checkerspot butterfly), milkweed (monarch butterfly), and pawpaw (zebra swal lowtail butterfly).
- Consider planting a series of early-, mid-, and late-season bloomers to provide nectar, and then fruit and seed, throughout the year.
- Consider leaving a sandy patch unplanted, in which solitary bees may nest.
- Don’t plant the exotic butterfly bush (Buddleia sp.) which is spreading to wild areas by seeds.
- Avoid the use of pesticides, which often kill much more than the intended pests.