Monday, September 27, 2021

Majestic oaks

By Larry Cornelis – President, Sydenham Field Naturalists

Oaks are in the beech family.

That always seemed backwards to me since there are so many more oak species than beech.

Shouldn’t beeches be in the oak family?

Oh well, Linneaus must be right.

Larry Cornelis Photo

Oaks may be our most important genus of trees here in Ontario and across North America.

They have the highest ecological values of any native tree species. An oak is the most important tree you can plant.

Oaks are very long-lived trees, 300 years on average and some species, such as white oak can live to 800 years old.

They can grow to large diameters (7-8’).

Oaks have more leaves than most other trees and those leaves support more species of herbivorous larvae, especially the caterpillars of butterflies and moths.

Native oaks support over 450 species of butterflies and moths in our area.

These caterpillars are a food source for songbirds.

More importantly, they are an absolute necessity as a food source for raising baby songbirds who need to eat proteins and fats in the form of insects, mainly caterpillars (over 95%).

What better food source for them than a soft fat juicy caterpillar.

Studies by Doug Tallamy, University of Delaware professor, entomologist, and author and his students, found that a pair of chickadees with five young to raise required about 9,000 caterpillars to raise the young to fledgling age (17 days).

Native oaks are by far the best at providing this food source. Oaks also produce acorns which provide food for many creatures including birds like turkeys, woodpeckers, and blue jays and mammals such as chipmunks, squirrels and bears.

Larry Cornelis Photo

Oak acorns were a staple food of the First Nations People historically.

Oaks can also play a role in mitigating climate change because of their longevity, carbon sequestration, oxygen production and water transpiration.

A forest of oaks protects our environment and supports wildlife biodiversity bigtime.

Oaks are divided into two groups, red oak and white oak.

The red oak group species have leaves with pointed, bristly tipped lobes and acorns that take 2 years to mature and the white oak group has leaves with round lobes and the acorns mature in one year.

There are over 70 species in North America (many shrub like) and we have nine species tree size and one shrub form (Dwarf Chinquapin – Quercus prinoides) in southern Ontario.

The nine native tree oaks are, white oak (Q alba), swamp white oak (Q bicolor), burr oak (Q macrocarpa), chinquapin oak (Q muhlenburgii), pin oak (Q palustris), hill’s oak (Q ellipsoidalis), red oak (Q rubra), Shumard oak (Q shumardii), and black oak (Q velutina).

Identification can be challenging because of hybridization among species within the same group.

David Sibley (renowned author, ornithologist and biologist) suggests we should accept the fact that not all oak trees can be identified to species.

Larry Cornelis Photo

Educate yourself about trees, specifically about oaks, and focus on the long-term importance of your efforts to plant trees to benefit our environment and future generations.

Easy to grow oak species for the home landscape include burr, chinquapin, red, swamp white and white.

To quote Doug Tallamy, “if there’s only one thing you can do to help our environment it’s plant an oak.”

I’ll go one step further and suggest you plant a few oaks.

You’ll be glad you did and so will your grandchildren.

Recommended reading: ‘Natures Best Hope’ by Doug Tallamy and ‘The Sibley Guide to Trees’ by David Allen Sibley.

For more details, visit: http://www.sydenhamfieldnaturalists.ca/

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