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The buzz on pollinators: Keystone plants create biodiversity

Native plants are important to the survival of native pollinators, but within that category are superior species that are the best for supporting native pollinators
Fallen leaves may now be covered with snow, but many caterpillars will have formed a pupa or chrysalis on the leaves, to emerge as adult butterflies or moths in the spring.

We know the importance of native plants to the survival of our native pollinators, but within the native plant category there are superior species called keystone plants that are the best for supporting native pollinators through their entire life cycle.

Simply put, pollinators facilitate the transference of pollen from the male part of the flower to the female part, which fertilizes the plant so it will produce fruit, seeds, and young plants. This transfer of pollen can happen by the wind, or on the fur of an animal, but the most effective pollination is done by insects. When an insect visits a flower in search of nectar, the pollen sticks to the hairs on its body as it moves from flower to flower causing pollination.

Native bees, bumblebees, and honey bees are the best pollinators. Their buzzing shakes the pollen loose and sticks to their hair. Butterflies, moths, hummingbirds, flies, and bats are less effective because they have smoother bodies. Nearly one-third of human food production and 75 percent of flowering plants require insect pollination. It is critical that we provide proper habitat for these creatures to thrive.

According the National Wildlife Federation, native plants have tight relationships with all wildlife. This symbiotic relationship has formed over many thousands of years, providing natural sources of food, and protection to raise their young. Approximately 95 per cent of our terrestrial birds rely on the insects supported by these plants, so without healthy native plant habitat, birds and wildlife cannot survive. The federation divides North America into ecological regions. Every ecoregion hosts unique native plant communities. Southern Ontario is located in the Eastern Temperate Forests zone.

Niagara’s location is even more unique because it is also part of the Carolinian zone, which makes Niagara one of the most biodiverse areas in Canada. Biodiversity means that we have a greater variety of flora and fauna than most other regions. Unfortunately, southern Ontario has high human population competing for land in this small area. We as landowners must share the land in a responsible way.

Professor Doug Tallamy, an American entomologist, ecologist and conservationist, stresses the importance of including keystone plants in your pollinator garden. Keystone plants are critical to the food web because they will provide all the necessary components for each stage of the pollinator’s life cycle. There are a handful of native keystone plant varieties that are superior performers when it comes the volume of beneficial insects they can support.

Biodiversity is very important, choosing keystone trees, shrubs and flowers is an easy way to provide habitat for numerous species of pollinators. One of the best keystone plants is the oak tree, which is indigenous to Ontario and thrives in Niagara. Native oak trees support more than 430 caterpillar species. Other top performers are the sugar maple, eastern cottonwood, and hickory tree. Prior to colonization, there were abundant forests of white oak, sugar maple, pine, ash, hickory and walnut trees throughout Niagara. Fine examples of these centurion trees can still be seen in the oak grove next to the commons and throughout the Chautauqua neighbourhood in Niagara-on-the-Lake.

Even if you don’t have space to plant a keystone tree, there may be one already growing nearby which you can nurture. In NOTL, a group called ‘My Chautauqua’ has put an enormous effort into counting, mapping and preserving the oak and other keystone trees in their historic neighbourhood. There is an ongoing effort to protect the old growth while continuing to replant new young progeny from the acorns that have been sprouted and reared by Niagara College’s School of Horticulture.

Just like a keystone holds an arch together, these trees and shrubs have the main components that hold the whole ecosystem together. For example, the oak tree provides branches and leaves and pollen for insects and birds plus acorns that feed deer, squirrels, jays, mice, badgers, wild turkeys and mice, which in turn feed hawks, owls, foxes and coyotes. Oak acorns are considered a foundation in their food chain.

Insect larvae is the main source of food for baby birds who cannot eat seeds. According to a study from the University of Delaware, a nest of chickadees can require up to 9,000 caterpillars to raise a single clutch.

A Lepidoptera life-cycle (butterfly or moth) begins as it lays thousands of eggs on the leaves of the host plant. When the caterpillars hatch, they eat the leaves of the host plant and grow fat, and at this stage they become prime food for birds. Many caterpillars still survive, and form a pupa or chrysalis that they attach to the underside of a branch or among the fallen leaves to over winter. In the spring they emerge as adult butterflies or moths to start the cycle again. Certain species such as monarch and spicebush swallowtail butterflies can only feed upon specific plants, so be sure to include the right plants if you want to attract them.

Think of your garden as community, with each member having a task to do. Keystone trees provide shade, leaves, food and nesting sites for birds and pollinators. Their roots protect soil from erosion, and the fallen leaves serve as a home to many insects and micro-organisms who break down the leaves into compost. Keystone shrubs provide protection from predators and the woody stems are used for bee and insect nests. Northern highbush blueberry and prairie willow support over 250 species of wildlife that feed upon their leaves, flower nectar, pollen, berries, and seeds. Native sunflowers, milkweed, black-eyed Susan, green-headed coneflower and goldenrod are prolific pollen providers and support upward of 100 insect species and 50 varieties of bees.

In comparison, imported flowers like day lilies and hostas support zero native pollinators. Use a variety of colourful keystone flowers to bring beauty to your garden and have something blooming throughout the entire growing season for a continuous nectar supply.

Start thinking of your garden as a complete ecosystem where plants and wildlife are interdependent. Becoming a more conscientious gardener will add to the biodiversity of this very special ecozone, and preserve its beauty for future generations.

To learn more about the efforts of Chautauqua tree preservation visit

For more information about keystone plants by ecoregion visit