Improving Diversity in our Urban Forests


One of the best ways to make our properties and our cities more beautiful and more healthy is to add to the diversity of tree species that we plant over time.  Healthy trees help make the air cleaner and cooler, provide pleasant shade.  They slow down winds, offer nesting sites, food and places of refuge to birds and other wildlife, create privacy, and produce lovely flowers, beautiful form, color and texture in cities where life seems to be getting ever more hectic.  BY planting a wider variety of tree species, we make our urban forests less vulnerable to the next widespread tree disease/epidemic.

Our urban forests used to have far too high a percentage of Elm trees.  Dutch Elm Disease killed hundreds of millions of American Elms, and the unfortunate response was to plant far too many Ash trees.  With the over planting of Ash trees over a period of 40 years, the arrival of Emerald Ash Borer insects is now killing millions of Ash trees, and devastating both urban and wild forests.  It’s a predictable and sad result of once again planting too many of one kind of tree variety  We need to plant a wider range of tree genuses and varied species within each genus to regain a better balance.

Going forward, we would be wise to plant fewer maples (but not none) and more Oaks, the new Elm varieties that are resistant to Dutch Elm Disease, and also more trees from the following list:

Hackberry, Catalpa, Horsechestnut, Honeylocust, Willow, Buckeye, Yellowwood, Showy Mtn. Ash, Ginkgo, Birch, Plum, Bald Cypress, Quaking Aspen, Cherry, Korean Maple, Big Tooth Asppen, Apple, Hydrangea trees, Oak hybrids, Crabapple, Lilac trees, ‘Sentry’ American Linden,  and Redbuds.

Some of my current favorite tree varieties for adding diversity are Ancestry Oak, Heritage Oak, New Harmony Am. Elm, Prairie Expedition American Elm, Catalpa, Ginkgo, Yellowwood, Sh

owy Mtn. Ash, and ‘Select’ Quaking Aspen, and Rugged Ridge Miyabei Maple.

As you add diversity to your part of our urban forests, I suspect you will enjoy the new and unusual varieties enough to keep planting more diversity into the landscape.