Earth Day Starts at Home: Plant Layers for Habitat Structure

By Carol Heiser, DWR Habitat Education Coordinator

Finding everyday connections with nature in our own surroundings can be very restorative and comforting in these extraordinary times of stress and uncertainty. Although the in-person spring festivals and gatherings that were being planned to celebrate the 50^th anniversary of Earth Day have been canceled, there are still many ways we can get involved to make our environment healthier for people and for wildlife.

We can be mindful of how our landscape choices impact living systems around us, and we can do our part to restore habitat for birds, butterflies, bees and other wildlife species that need ecologically balanced and sustainable landscapes to survive. Consider adding some beautiful native plants to your yard! The first step towards creating an eco-friendly yard is figuring out whether or not you have good habitat quality for a diversity of wildlife species, including mammals, birds, and pollinators.

Quality Habitat

The easiest way to assess the habitat “quality” of your yard is to take a look at the existing plants and see if you can answer “yes” to these three questions:

• Are a wide variety of native plant species represented?
• Are there at least three layers of different types of plants growing at different heights—that is, a mixture of trees, shrubs and herbaceous plants or perennial flowers?
• Is there a fairly balanced distribution of evergreen and deciduous plants?

These questions will help you determine the vegetative structure of your existing habitat. Good structure is the single most important ingredient for supporting a variety of wildlife species. Birds, mammals, reptiles, and amphibians each key-in on the various layers present. If one or more of the basic plant layers is missing, the wildlife species associated with those plants will not occur there.

A diverse, functional wildlife habitat is said to have good structure when it contains an herbaceous layer of green-stemmed plants, a layer of shrubs and small trees, and a canopy of large trees overhead. The ground layer should not be overlooked, either: below the taller plants is an important carpet of organic matter called the leaf layer, where the annual fall of dead leaves and stems continually replenishes soil nutrients.

The Bones of Your Yard

Think of structure as the “bones” of your yard. This is the skeleton or scaffolding on which you’ll build a flower bed here, or a shrub bed there.

The uppermost layer that provides a canopy over the habitat are the large tree species that are so invaluable to wildlife. If you’re missing this layer, then start your habitat make-over by planting a tree! This is the domain of powerhouse species like white oak (Quercus alba), black cherry (Prunus serotina) and black gum (Nyssa sylvatica). Evergreens such as American holly (Ilex opaca), Eastern red cedar (Juniperus virginiana) and Virginia pine (Pinus virginiana) will help to round out this layer and also provide protective winter cover, too.

However, if your yard is mostly lawn that’s already dotted with a few large trees, then you’ll likely need to add more “bones” to the middle layer, often referred to as the “understory,” because it grows under the tree canopy.

Building up the structure in the understory can be done with several of the smaller, native tree species such as the following: dogwood (Cornus florida); serviceberry (Amelanchier arborea); sweetbay magnolia (Magnolia virginiana); sassafras (Sassafras albidum); American holly (Ilex opaca); river birch (Betula nigra); persimmon (Diospyros virginiana); fringetree (Chionanthus virginicus); paw-paw (Asimina triloba); or redbud (Cercis canadensis).

Structure can also be improved by planting clusters of native shrubs in large beds adjacent to the tree layer. Some native shrub species favored by birds and other wildlife include the following: elderberry (Sambucus canadensis); inkberry (Ilex glabra); sweetspire (Itea virginica); silky dogwood (Cornus amomum); beautyberry (Callicarpa americana); chokeberry (Aronia melanocarpa); pepperbush (Clethra alnifolia); New Jersey tea (Ceanothus americanus); ninebark (Physocarpus opulifolius); waxmyrtle (Myrica cerifera); and several viburnums (Viburnum dentatum, V. nudum, V. prunifolium).

When it’s time to purchase your plants, be aware that using the scientific plant name will ensure you get the right plant, because scientific names are universal identifiers that will be recognized wherever you go.

Adding Height with Vines

Using vines in the landscape is another way to add vertical structure to the existing plant composition, especially if the size or layout of your yard is not conducive to planting trees and shrubs. We tend to overlook vines when shopping around for plants, but they can be equally effective at providing cover to birds and insects. For example, trumpet honeysuckle (Lonicera sempervirens) is a native vine that produces red tubular flowers attractive to hummingbirds. Some other good choices that look attractive on sturdy trellises or arbors include the following: crossvine (Bignonia capreolata); trumpetvine (Campsis radicans); American bittersweet (Celastrus scandens); passionflower (Passiflora incarnata); Virginia creeper (Parthenocissus quinquefolia); and virgin’s bower (Clematis virginiana).

Natives are Resilient

One of the main reasons ecologists encourage the use of native plants in a landscaped habitat is because native species have co-evolved with the insect communities that specialize on them. Not only do the native plant species serve as host plants for insect specialists, but the plants have also evolved adaptations to co-exist with regional insect and disease attacks, which makes them more resilient and more likely to recover from a local outbreak. Native plants are also well-adapted for the regional climate and soil conditions and more likely to endure a wider range of harsh conditions than horticulturally selected varieties or cultivars. The nutritional value of the sugars, proteins and fats found in native plants has a higher benefit for wildlife survival as well, when compared to exotic invasive plants that are often less palatable or desirable to wildlife.

When you’re deciding on plants to choose for your habitat, take your cues from the surrounding neighborhood and county. You will likely see various common native species growing in association with each other in the perennial or herbaceous layer. These native plant communities are good references, because they’re all adapted or well-suited to the same type of soil, moisture, sunlight, and other growing conditions.

For example, in low-lying wet areas that receive a lot of sun, it would be no surprise to see jewelweed (Impatiens capensis), Joe pye-weed (Eutrochium purpureum), common boneset (Eupatorium perfoliatum), cardinal flower (Lobelia cardinalis), rushes (Juncus), sedges (Carex), swamp milkweed (Asclepias incarnata), New York ironweed (Vernonia noveboracensis), buttonbush (Cephalanthus occidentalis), witch-hazel (Hamamelis virginiana), spicebush (Lindera benzoin), or winterberry holly (Ilex verticillata), all growing in relative proximity to one another.

On the other hand, if we look in areas that have poorer, drier soils—such as in the sunny, exposed, meadow-type habitat you might see near the margins of a woodland—we’d expect to see black-eyed Susans (Rudbeckia hirta), butterflyweed (Asclepias tuberosa), common milkweed (A. syriaca), asters (Symphyotricum), tickseed (Coreopsis), goldenrods (Solidago) and sumacs (Rhus).  All of these would be good native plant choices in a Habitat at Home©, too, provided you select the right species for your particular growing conditions.

How to Know if a Plant is Native to Your Area

We may not be willing or able to let our yards revert back to nature completely, but choosing plants that are representative of native communities and installing these plants in free-flowing beds is at least a good attempt at approximating a more natural environment.

For optimal success in garden planning, take a look around your neighborhood at naturally occurring plant communities and let these be your first guide. Examine the growing conditions of each location in the yard where you want to plant, and select only species that are known to tolerate those specific conditions. Install a mass of these plants, either in a large island in the middle of the lawn or along an empty edge, border or walkway.

When looking at a plant list and trying to decide what to use in your own landscape, the best way to ensure that a given species is actually native to your locality is to look it up in the Digital Atlas of the Virginia Flora, which shows species range maps by county.

Or, you can make the task even easier by using regional native plant lists. If you live in Virginia’s coastal zone, which is roughly the area along the I-95 corridor and points east, you can download regional, native plant booklets from Plant Virginia Natives to guide your plant selections. The booklets take into account the types of soils, growing conditions and plant associations unique to specific geographic regions of the coastal zone, such as Northern Virginia, the Northern Neck, Eastern Shore, Hampton Roads, the Capital Region, and others.

If you don’t live in the coastal zone, you can get regional lists for the Piedmont, Ridge and Valley, or Mountain areas of the state from the Division of Natural Heritage at the DCR website.

Be sure to also check out the U.S. Fish and Wildlife Service’s Native Plants for Wildlife Habitat and Conservation Landscaping: Chesapeake Bay Watershed booklet.  This is a wonderful companion guide, complete with full-color thumbnail pictures, a key to wildlife use, and growing requirements for each plant.  The booklet can be downloaded in PDF form or accessed as a searchable database.

Where to Buy Natives?

The popularity of native plants and continually increasing demand has brought many new nurseries into the market, and several vendors now specialize in propagating and selling native species. The Virginia Native Plant Society has a list of Virginia Nurseries where you can find one closest to you.

We are Nature’s Best Hope

What we do in our landscapes truly matters, and each of us can be a good steward. In Nature’s Best Hope, the recently published book by Dr. Douglas Tallamy (2019 Timber Press), he reminds us of our connection to nature and shares a call to action:  “We can save the natural world—and ourselves, for we are part of it and it is an inextricable and essential part of us—if we stop segregating ourselves from nature and learn to live as a part of it.”

Since we all depend on the quality of earth’s ecosystems for our own survival, we have a responsibility to restore and support these vital systems by practicing conservation in the places where we work, live, and recreate. Tallamy outlines many ways we can do this: shrink the lawn, remove invasive species, plant keystone native species, plant generously to fill in gaps and diversify habitat layers, and avoid using chemicals whenever possible, among other recommendations.

This Earth Day, show that you care about the environment and plant some natives for wildlife!

You can also find lot of information about native habitat planting, the A Habitat at Home© booklet, and the Gardening for Wildlife article at the DWR website.

• April 22, 2020