Oak Park is fortunate to have its canopy of trees, arching green over our streets, shading our parks, gracing our yards and gardens. Because they are usually so long-lived, it is always a shock when a tree comes down, whether uprooted by a strong windstorm or the end of its natural life.
Although the long life spans of most trees lead us to think they’ll be there forever, trees do die of old age. In our parkways and parks, lost trees are promptly replaced, necessarily with younger specimens that will need years of growth to fill the void left by their forebear.
Trees die of disease, too. The effects of Dutch Elm disease on our green canopy continue to be felt, decades after this plague first appeared. And now there is the Emerald Ash Borer, a shiny green beetle that is decimating ash trees as it moves across the country. (What happens is that the larval [caterpillar] stage of the insect’s life cycle chews galleries under the bark, which clog the channels that carry food and water throughout the tree.)
We have many ash trees in our community. As was the case with Dutch Elm disease, there are no natural predators at hand to unleash on the Emerald Ash Borer. What makes matters worse is that infestation with the borer does not usually become visible until a tree is fatally damaged. The first sign of this damage is dead or dying branches high in the tree, called “flagging.” By this time, the few treatments available have not proved to do much more than delay the inevitable,* while being prohibitively expensive, especially where there are both many ash trees on public land and tight public budgets.
So, painfully, Oak Park’s ash trees are coming down. There are communities that have decided to simply remove all their ash trees, regardless of their current state of health, simply because, eventually, they will all become infested and die. We are not taking such drastic action. Nonetheless, in our parks, dying ash trees are being removed. New trees are being planted in our parks at a ratio substantially higher than that which would be dictated by 1:1 replacement of those lost to whatever cause.
It is sad. But as we understand that trees do have life cycles, and that devastating pests and diseases arrive, often from faraway places, we, as a community, will use the most effective and economical means to meet these challenges.
Section 3.4 of the Park District’s Tree Management Policy provides the guide: “A healthy tree population in our parks is as critical as safe playground equipment and well-maintained athletic fields.”
*The most current research information may be found at “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer,” prepared by entomologists from Ohio State, Michigan State, Purdue, and the universities of Wisconsin and Illinois, June 2009, www.emeraldashborer.info/files/multistate_eab_insecticide_fact_sheet.pdf.
Sandy Lentz, an Oak Park resident, is a member of the Park District Greening Advisory Committee.
