by Erin O’Hara
Science shows us that biodiversity leads to a more productive ecosystem in which more oxygen is produced, more carbon dioxide stored, more water purified, and more energy from the sun transformed into food and biomass. The key to maximizing biodiversity in our gardens and landscapes is native plants.
If we focus on butterflies and birds, we can see how planting natives can pay huge dividends. It turns out that the majority of butterfly species are plant specialists, particularly in the larval stage. This means that the average caterpillar has the ability to eat, and not be poisoned by, a limited number of indigenous plants with which it has coevolved. An example of this is the monarch butterfly, whose caterpillars rely exclusively on native milkweed species such as common milkweed and rose milkweed. In recent decades, millions of acres of milkweed habitat have been eradicated to make way for bigger farms and for development, particularly in the Midwest. In that time, we have seen a corresponding plummet in the numbers of monarchs.
The story doesn’t end there, as the widespread destruction of native plant communities has not only led to huge decreases in insect biomass but also to decreases in the numbers of all the creatures in the food web that rely on insects for food and other services. Birds have been especially hard hit. Over 90 percent of terrestrial birds feed their young almost exclusively on insects. Studies have shown significant losses in bird numbers in recent decades.
The realities that our ecosystems face are indeed disturbing, and we should all be forgiven for feeling depressed. However, there is much we can do to start repairing the damage, and there is no better place to start than our own backyards.
As stated earlier, native plants are key because of their connection to insect numbers but also because birds and other animals are more likely to benefit from the berries, nuts, and shelter that native trees, shrubs, and perennials provide.
When looking to acquire plant stock, it is important to look for the “straight” species. Many of our indigenous plants have been altered by plant breeders—these plants are known as “nativars,” which is short for “native cultivar.” For instance, purple coneflower (Echinacea purpurea) has seen its flower petals changed from pink to lime green for novelty’s sake. It has been shown that changing plants in this way usually makes them less attractive to wildlife.
Straight-species natives can be purchased locally through nurseries such as Arcana Perennials in Jericho and Perennial Pleasures in East Hardwick. They will often be sold alongside non-native plants and nativars, so be sure to ask for assistance if you are not sure what is what. Turtle Hill Native Plants is a small landscaping business and nursery that I started last year. You can visit turtlehillnativeplants.com/sales-events/ to see the schedule of plant sales this year.
Gardening for wildlife involves more than just replacing cultivars and non-natives with native species, although that is an excellent place to start. Birds and pollinators need a clean, safe water source, nesting sights, and shelter from weather and predators. There are many simple steps we can take to achieve this when designing our landscapes.
It is popular to widely space plants in a garden bed and fill in the gaps with bark mulch. However, a denser planting scheme will provide superior shelter for small birds and insects, keep more water in the soil through shading, capture more carbon, and reduce weed pressure. This will have the side benefit of cutting down on the labor and expense involved in watering, weeding, and mulching the garden.
Shrubs and small trees can make excellent habitats for nesting and shelter, but birds are more likely to benefit if shrubs are massed instead of grown as isolated specimens. Eight feet or more in width is considered ideal. This can be achieved through planting two parallel rows of shrubs instead of one to make a hedge or windbreak, or through massing shrubs in the back corner of the garden. Important native species include highbush cranberry (Viburnum trilobum), winterberry (Ilex verticillata), serviceberry (Amelanchier laevis), and black elderberry (Sambucus canadensis). I mainly acquire my shrubs through Fedco Trees in Maine and Easthill Tree Farm in Plainfield, Vermont.
As a stand-in, or in addition to shrubs, brush piles can also provide excellent shelter for insects and birds. Start with a base of leaves and dead plant stalks. Pile branches on top of that. Build it six feet tall and at least eight feet wide. Most people will want to put a brush pile in a hidden part of the garden.
Providing one or more water sources for drinking and bathing will bring more birds onto your property. Birdbaths are a cheap and easy way to achieve this. Different species of birds prefer water of varying depths, so choose a birdbath with a bowl that is ½- to 1-inch deep at the edge and slopes to a maximum of 3 inches at the center. Get a birdbath mounted on a pedestal to protect against cat predation. Larger birds such as robins and blue jays will drink and bathe in the depths, while little goldfinches, song sparrows, and chickadees will use the shallows.
Gardening for wildlife does not and should not mean sacrificing aesthetics. The pallet of flowers, leaf textures, and form is immense among native plants. However, you may find your definition of beauty is expanding, along with the number and variety of new species showing up on your property. In addition to attractive foliage and blossoms, you will have more bird song, colorful butterflies, and all manner of buzzing, slithering, jumping, and soaring creatures to add drama and beauty to your homestead.
Learn more about Gardening for Pollinators, Birds & Beauty with Erin O’Hara at his workshop at Hunger Mountain Co-op on April 21, 10:30 am–12 pm Preregistration is required