by Jeanne McRight
Keystone species are amazing. These are the relatively few wildlife species who sustain their much larger community, named after the final, carefully fitted top stone in an arch. It's essential in preventing the arch's collapse. Our keystone species have the same function: they are essential to the survival of our ecosystems. Removing a keystone species from an ecological community is like removing the wrong block from a Jenga game - it all comes tumbling down.
There are two types of keystone plants:
Host plants that feed the young caterpillars of approximately 90% of butterflies and moths (Lepidoptera).
Plants that feed specialist bees who only eat pollen from specific plants. Keystone plants for native bees feed both specialist and generalist bees.
Native oak trees support more than 430 insect species that are essential to their ecological community's well-being. 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.
Each of Ontario's top 5 native keystone tree species support hundreds of caterpillar species
Oaks (Quercus spp. such as Northern red oak, white oak, and bur oak) - support 436 species
Cherries and plums (Prunus spp. such as black cherry, chokecherry, and wild plum) support 340 species
Willows (Salix spp. such as pussy willow and black willow) support 289 species
Birch (Betula spp. such as paper birch, white birch, and yellow birch) support 284 species
Maple (Acer spp. such as red maple and sugar maple) support 238 species
Did you know?
Only about 5% of our locally native plant species hosts 70–75% of our local butterfly and moth species! And butterfly and moth caterpillars are used by 96% of bird species to feed their nestlings. Without those keystone plants, we don't have birds.
Learn more from the National Wildlife Federation: Keystone Native Plants - Eastern Temperate Forests
The beautiful river birch is more tolerant of summer heat than other native birch, and it attracts many birds such as American Goldfinch, Black-Capped Chickadee, Blue Jay, Crossbill, Dark-Eyed Junco, Eastern Towhee, Northern Cardinal, Pine Siskin, Purple Finch, Tufted Titmouse, White-Breasted Nuthatch, and Yellow-Bellied Sapsucker. Photo: Jeanne McRight
Now is a great time to plant native trees and shrubs. There are lots of native beauties to choose from, but make sure you include some keystone species too.
Sources
KEYSTONE TREES & SHRUBS Homegrown National Park
Narango, D.L., Tallamy, D.W. & Shropshire, K.J. Few keystone plant genera support the majority of Lepidoptera species. Nat Commun 11, 5751 (2020). https://doi.org/10.1038/s41467-020-19565-4
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