GLFC e-Bulletin

On-line decision tool informs homeowners of the costs of treating versus replacing infested ash trees

Overview

Many homeowners in Ontario and Quebec are presently facing the reality that their ash trees are being infested and killed by the emerald ash borer. These homeowners can now use an online decision tool when they are trying to decide the fate of these ash trees. The tool (the Canadian Forest Service Ash Protection Model) calculates the costs associated with treating the tree to protect it versus removing and replacing it. Included in the analysis are benefits and costs that homeowners may not have been aware of.

When emerald ash borer moves into an area, homeowners with ash trees on their property will need to decide whether or not to treat their trees.  Available treatment options include a naturally derived product from neem tree seeds and a chemical control product, which must be either injected or inserted into the tree periodically to provide protection from the alien invasive insect. In making the decision to treat or remove an ash tree, salient factors include treatment, removal, and replacement costs as well as the potential loss of various benefits associated with the existing tree. Dan McKenney, John Pedlar and other staff at the Great Lakes Forestry Centre have developed an on-line tool to aid homeowners in making a decision, considering the flow of costs and benefits through time associated with the different approaches,

The homeowner enters information into the interactive tool about the existing tree, including the diameter, location relative to the house (aspect) and distance from the house. Similar details are entered for the hypothetical replacement tree. Based on this information, the model is populated with default cost parameters; these values can be overridden if better information is available about local costs. Also considered are extended benefits or costs related to the tree such as home energy effects, changes to storm water runoff and air pollution, and changes to home value, all based on information derived from experts.

Once all the values have been inputted, the tool calculates, over a 30 year period, the cost of ongoing treatment to protect the tree versus the one-time cost of removal and replacement. Results are presented in both graphical and tabular formats that show all the costs and benefits, as well as the “treatment gain” or loss for each of the coming 30 years.  The metric is calculated by summing all the benefits associated with maintaining the original ash tree and subtracting from that the sum of the benefits associated with the replacement tree.  Negative values would indicate the annual amount that a homeowner would have to be willing to pay to maintain the existing tree for a given number of years. The model assumes that treatment effectively protects the tree, which may not always be the case depending on, for example, the state of the tree when it is treated. Therefore, homeowners are advised to obtain professional advice before choosing a course of action. 

By including not only the obvious costs of treating or removing and replacing the tree, but also other costs and benefits accruing from the presence of the trees, this tool allows homeowners to make well-informed decisions about the fate of their ash trees. The tool also serves to raise awareness about the value of trees growing near our homes. An interactive version of the model is available at: Canadian Forest Service - Ash Protection Model (CFS-APM).

For more information about the Canadian Forest Service Ash Protection Model, please contact GLFC.