As earth stewards of our amazing planet, we can appreciate the potential importance of all species to the continued existence of a complex ecosystem. But there are some that stand out and do the heavy lifting. Specific integral species are more important than others to the sustainability of an ecosystem and are called ‘Keystone Species’ – organisms that support the entire ecosystem and stabilize complex, highly connected food webs.

According to Douglas Tallamy, famed ecologist/entomologist, just 5% of our native plant genera host roughly 75% of our caterpillar species, which sustain our native bird populations. For example, a chickadee must catch 6,240 to 9,120 caterpillars to rear one clutch of hatchlings, according to him. And amazingly, caterpillars transfer more energy from plants to other animals than any other insect. 

Keystone Plants – Trees & Perennials

Likewise, with the plant kingdom, there are keystone plants that play an outsize role in supporting other species. In the mid-Atlantic region, native Oaks (Quercus), Willows (Salix), Birches (Betula), Black Cherries (Prunus) Pines, (Pinus), and Poplars (Populus) are at the top of the list that supports the greatest number of Lepidoptera (butterflies and moths), which in turn feed the birds and other wildlife. And for herbaceous plants – Goldenrods (Solidago), Asters (Aster), perennial Sunflowers (Helianthus), Bee Balm (Monarda) and Joe Pye Weed (Eupatorium), are significant to the food web in supporting many different kinds of insects.  As a homeowner and gardener, these are a great starting point to transform your backyard into a conservation oasis that provides wildlife habitat.

Wise Plant Choices

I live in the mid-Atlantic state of Maryland and the natives that I plant would be different from other parts of the country, such as California. A Red Oak planted in my area would support many more insects than if it were planted in a non-native area, like the Pacific Northwest. So research before you plant, the local natives that are indigenous to your area.

Wise plant choices will support insects that maintain plant diversity and support insects that contribute the most energy to the food web. Intentional plant choices should be informed by the plants that are native to your particular eco-region. Check out The National Wildlife Federation website, determine your eco-region, and plant the things that will benefit the most species.

Plant an Oak

According to Douglas Tallamy, author of Bringing Nature Home, Oaks (Quercus) are the number one tree in the United States that supports the most insect biodiversity, supporting up to 557 Lepidoptera species. There are a variety of Oaks native to different parts of the country that you could choose from. A handy reference is Field Guide to Native Oaks in Eastern North America. Oaks are also called ‘mast trees’ which is simply a tree that forms acorns or other nuts and these further sustain wildlife as an essential food.

Working as a landscape designer, when a client wants a tree planted, they usually focus on a showy spring flowering one, such as a Japanese Weeping Cherry (Prunus sp.) or Bradford Pear (Pyrus calleryana), which support a fraction of insect species that an Oak does.  But an Oak tree is a hard sell, because of the insignificant flowers and the belief that they grow slowly.

And in the case of the Bradford Pear, it has invaded wild areas and taken over to the detriment of native species. Instead, I always suggest for longevity and wildlife importance, one of the native oaks, like a White Oak (Quercus alba), Willow Oak (Quercus phellos), Red Oak (Quercus rubra) or Pin Oak (Quercus palustris). Extended fall colors are a plus for these trees, long after the maples have dropped their colorful leaves.

Another beautiful large tree that is important to insects are Maples (Acer) at supporting 285 Lepidoptera (butterfly) species. Sugar Maple (Acer saccharum), one of my favorites, has a blazing red, yellow, burnt orange fall color and is the iconic tree used for collecting sap for maple syrup. Needing plenty of room, Sugar Maples light up the fall landscape. Another good choice  is Birch (Betula)trees support 413 Lepidoptera species and the River Birch (Betula nigra) which I grow, has wonderful exfoliating bark for all season interest.

If You Plant, They Will Come

Many of us have only a small piece of property or maybe just some containers on a patio. Perennials are the solution to provide the most benefit to wildlife and provide keystone attributes in a smaller space. Small shrubs will work also, like Blueberries (Vaccinium) or Chokeberries (Aronia). Black Eyed Susan (Rudbeckia), Aster (Aster), Phlox (Phlox), Milkweed (Asclepias), and Bee Balm (Monarda) plantings would create a long blooming oasis in pots that can attract and nourish a host of insects. Many people only plant annuals, ignoring perennial choices, in their containers, but perennials will come back every year with little care in pots. Not blooming as long as annuals, choose perennials with different blooming times so you have something flowering all season long. Anise Hyssop (Agastache) blooms for weeks in a container and I watch a constant parade of butterflies and other natives visit the blooms for weeks in mid to late summer from my patio.

Diversity & Mass

Diversity is the key here. Include a broad array of plants to attract beneficial insects and pollinators to your garden, preferably planted in blocks or groups. A mass of same species of about 3’ by 3’ provide a target for pollinators to head to. Food, shelter, and water are important to create a welcoming and healthy ecosystem to your yard and keystone species give you the most ‘bang for the buck’.

Should you continue to plant and enjoy non-natives? Yes!! Non-natives, such as butterfly bushes, still provide nectar and pollen to pollinators, but don’t act as a host plant to caterpillars. There are sterile species of these that won’t seed around and they can provide a valuable role in the garden. This is a controversial position, but I believe if you plant at least 70-75% native species, you can add some fun non-natives for interest and even more diversity. There are so many non-natives that provide valuable food for wildlife, but make sure it isn’t on the invasive list. Check out this article – Natives Vs. Non-Natives & Invasives for a good explanation of this. Don’t rip out all your non-native plants! Gradually add new native ones to your garden as plants die and beef up your keystone native choices.

Transforming a Non-Native Landscape

I am in the process of converting a totally non-native landscape to a mostly native landscape for a client. What was once full of liriope, pachysandra, and shrubs such as azaleas and nandinas, is gradually being transitioned to native plantings. We tore out some failing Rhododendrons and Nandinas and replaced them with Service Berries, Eastern Red Cedar, Aronias, Clethra, WinterBerry, and the native Pachysandra ground cover (Pachysandra procumbens). It has been a gradual process and now my client has 70% native species, instead of 100% all non-natives. It can be done, but tackle each area separately, to keep within your budget.

Also HOA’s have to be informed and dealt with. Sometimes they aren’t receptive to change in the form of native plants which aren’t as familiar to them. But education is key here. Inform your neighbors as to what your are planting and more importantly, ‘why’, so you can get them on board with what you are trying to accomplish.