Article Figures & Data
Figures
- Figure 1.
An invasion wave model to predict borer density and the decline of ash trees and guide management intensity in different stages of the initial invasion of the emerald ash borer. Affected ash trees represent those trees that are too damaged to be saved (>30% canopy thinning) with an insecticide treatment.
- Figure 2.
Cost per 2.5 cm dbh of bids for treating ash trees with emamectin benzoate and number of trees per bid determined by surveying the public records of 27 cities in Illinois, Indiana, Minnesota, Missouri, and Ohio, U.S., from September to December of 2014. Currency is in $USD.
- Figure 3.
Ash tree decline predicted by the invasion wave model plotted with a) observed rights-of-way tree removals by the City of Fort Wayne, Indiana, U.S., b) numbers of good and fair trees declining to poor quality (>30% canopy thinning) in Indianapolis, Indiana, and c) Lafayette, Indiana. An asterisk (*) indicates years with significant difference from the predicted distribution (P < 0.05) with a Kolmogorov Smirnov test.
- Figure 4.
Annual costs of implementing selected management programs of a 1,600 ash tree forest predicted by the EAB Cost Calculator 3.0 when initiated in the a) first year of the invasion cycle (1% of ash trees beyond saving) and b) fifth year of the invasion cycle (16% of ash trees beyond saving). Cost of treatment assumes a bulk price for emamectin benzoate of $1.94/cm, and default calculator values for the cost of tree removal and replacement based on Indianapolis estimates. Currency is in $USD.
- Figure 5.
Tree growth (total dbh) of 1,600 ash forests managed under selected regimes predicted by the EAB Cost Calculator 3.0 when initiated in the a) first year of the invasion cycle (1% of ash trees beyond saving) and b) fifth year of the invasion cycle (16% of ash trees beyond saving).
Tables
- Table 1.
Strategies employed by municipalities to manage emerald ash borer and their rationales in cities found in a web search covering a 12-month period ending 04 March 2014.
Strategy Rationale Percentage of cities (n = 40) Reactively remove ash Remove dying ash to prevent hazard 20.0 Proactively removing all ash Removing ash over time to reduce annual cost 17.5 Protecting only legacy ash Only healthy trees of historic or significant landscape importance are protected 5.0 Protecting <50% of healthy ash A substantial proportion beyond legacy ash trees are protected 40.0 Protecting >50% of healthy ash Most of the healthy ash are protected 17.5 - Table 2.
Size class distribution of ash forest and cost ($USD per cm dbh) to remove and grind the stump of an ash tree of each size used in the model simulation. Costs were based on rates for the City of Indianapolis, Indiana, U.S., in 2014.
Size span (cm dbh) Ash trees in forest Removal and grinding cost 3–8 50 $14.00 8–15 200 $14.00 15–30 300 $14.75 30–46 400 $18.00 46–61 300 $21.75 61–76 200 $25.10 76–91 100 $30.50 >91 50 $36.00 - Table 3.
Management strategies used to compare costs and benefits in the EAB Cost Calculator 3.0 simulation. See text for more details about how costs were calculated.
Management strategy Detail Proactively replace ash Proactively remove and replace all ash trees before EAB has damaged them beyond the point of rescue. Reactively replace ash Remove and replace ash trees as the model of ash decline predicts that emerald ash borer will damage them beyond the point of rescue. Save 50% Treat half of the ash trees with insecticide and proactively remove and replace the rest. Save 80% Treat 80% of the ash trees with insecticide and proactively remove and replace the rest. Treat <30 cm dbh Treat ash trees with insecticides when dbh > 30 cm. Remove and replace the rest. This strategy optimizes previous municipal investment in larger trees and the benefits of ecosystem services they provide (Kovacs et al. 2010). Treat all All ash trees are protected by insecticide treatment. - Table 4.
Ratio of total discounted costs associated with emerald ash borer management per meter of trunk diameter of standing trees after implementing selected emerald ash borer management strategies for 25 years in a 1,600-tree forest. The model assumes a 3% discount rate and treating ash trees every three years through the crest of the EAB invasion wave and every five years thereafter. Reduction is the decrease in the ratio when the cost of treatment is reduced from $3.94 to $1.97 per cm dbh. Currency is in $USD.
Time step of initiation Year 1 Year 5 Cost ($USD) per cm for treatment $3.94 $1.97 Reduction (%) $3.94 $1.97 Reduction (%) Reactively replace $1,758.28 $1,758.28 0.00 $1,933.32 $1,933.32 0.00 Proactively replace $2,178.42 $2,178.42 0.00 $1,983.20 $1,983.20 0.00 Treat >30 cm dbh $973.60 $641.19 34.14 $981.56 $625.40 36.28 Treat 50% $1,176.18 $883.30 24.90 $1,148.08 $886.33 22.80 Treat 80% $1,050.47 $677.67 35.49 $962.17 $648.75 32.57 Treat all $1,056.88 $592.97 43.89 $952.74 $579.32 39.19
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