Friday, July 31, 2015
By Bill Reichenbach, ISA Certified Arborist WI-0188A
‘Diversity’ tends to be a hot-button topic in many circles these days.Diversity is defined as ‘The quality or state of having many different forms, types, ideas, etc.’Synonyms include ‘assortment’, ‘variety’ and ‘distinct’.
So why are we talking about diversity in Wachtel’s Tree Care Blog? Having a diverse selection of trees in your landscape plays an important role in the long-term stability of your property’s ‘ecosystem’. When an area has a high diversity of tree species, it is less likely to suffer catastrophic loss from diseases or pests. Forest stewards are lucky in the sense that most tree pests are specialists, they often show a preference for a single genus and in many cases a single species.
Some examples of this include the specificity of butternut canker disease to butternut (Juglans cinerea) while not affecting the closely related black walnut (Juglans nigra). Dutch elm disease has found American elm to be a very susceptible host, yet there are several closely related varieties of elm that have characteristics that make them less susceptible to Dutch elm disease. Emerald ash borer (EAB) only attacks ash trees!
After the loss of the majority of American elms decades ago, ash was often the tree of choice when replanting. At the time, it seemed like a good choice. Ash was tough, adaptable, easy to grow and economical. Unfortunately emerald ash borer has again taught us the hard lesson of diversity. If we had planted a wider selection of tree types on our streets and in our home landscapes, we would not be dealing with as many ash trees in our fight with EAB.
It still seems we have not learned the lesson. We still see too many Colorado spruce planted as the conifer of choice in landscapes. Susceptibility to disease makes it a poor choice. Many people request maple as the tree of choice when discussing shade tree planting options. Yes, maples are wonderful trees, some better than others, however, too much of any one thing is not a good thing.
The moral of the story: plan for and plant a diversity of tree species in your landscape. Dr. James Calkins from the University of Minnesota speaks on what he has termed ‘phytobigotry’. His message is that there are many good, suitable trees for planting that have been blacklisted for one reason or another – often the reasons are based on perceived bad qualities.
Not only does a diversity of trees make for a more healthy landscape, it also makes for a more visually interesting one. Planting a variety of trees insures that you have a unique landscape with diversity in form, texture and color, preventing monotony!
So, do some research, and talk to your Wachtel Tree Science Certified Arborist to be sure you get some diversity and to plant the right tree in the right place. Here are some examples to pique your interest; Catalpa, Kentucky Coffeetree, Ginkgo, Hackberry, Katsura Tree, Oaks, Buckeyes, to name a few. Happy Planting!