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Estimates of the Potential Cost of Emerald Ash Borer (Agrilus planipennis Fairmaire) in Canadian Municipalities


Abstract and Figures

Emerald ash borer (EAB) is an invasive phloem-feeding insect causing extensive mortality to ash (Fraxinus sp.) in North America. Economic costs associated with EAB-related mortality of street and backyard trees in Canadian urban areas were estimated over a 30-year time horizon. The approach employed a simple spread model to approximate EAB arrival times at each community based on three maximum spread rates: slow (∼10 km/year), medium (∼30 km/year), and fast (∼50 km/year). Costs are estimated for four discount rates (0%, 2%, 4%, and 10%) and three treatment rates (0%, 10%, and 50% of trees treated with an insecticide). Ash density along urban roads was estimated from a variety of sources, including a recently developed survey that allows for rapid assessment of street tree compositions. Based on the 30 km/year spread rate, a 4% discount rate, and a 10% treatment rate, the present value of the costs is estimated to be approximately CAD $524 million (2010 currency rate); this value increases to roughly $890 million when costs associated with backyard trees are included. These estimates are conservative because they focus only on damage to street (and backyard) trees; nonetheless, their magnitude suggests considerable justifcation for investments to slow the spread of EAB in Canada.
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Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
Daniel W. McKenney, John H. Pedlar, Denys Yemshanov, D. Barry Lyons, Kathy L. Campbell,
and Kevin Lawrence
Estimates of the Potential Cost of Emerald Ash Borer (Agrilus
planipennis Fairmaire) in Canadian Municipalities
Arboriculture & Urban Forestry 2012. 38(3): 81–91
Abstract. Emerald ash borer (EAB) is an invasive phloem-feeding insect causing extensive mortality to ash (Fraxinus sp.) in North America. Eco-
nomic costs associated with EAB-related mortality of street and backyard trees in Canadian urban areas were estimated over a 30-year time horizon.
The approach employed a simple spread model to approximate EAB arrival times at each community based on three maximum spread rates: slow
(~10 km/year), medium (~30 km/year), and fast (~50 km/year). Costs are estimated for four discount rates (0%, 2%, 4%, and 10%) and three treat-
ment rates (0%, 10%, and 50% of trees treated with an insecticide). Ash density along urban roads was estimated from a variety of sources, including
a recently developed survey that allows for rapid assessment of street tree compositions. Based on the 30 km/year spread rate, a 4% discount rate, and
a 10% treatment rate, the present value of the costs is estimated to be approximately CAD $524 million (2010 currency rate); this value increases to
roughly $890 million when costs associated with backyard trees are included. These estimates are conservative because they focus only on damage
to street (and backyard) trees; nonetheless, their magnitude suggests considerable justification for investments to slow the spread of EAB in Canada.
Key Words. Agrilus planipennis; Canada; Cost-benefit Analysis; EAB Spread Model; Fraxinus; Urban Forest Management.
Emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Bu-
prestidae), is a metallic wood-boring beetle, native to Asia, that
has destroyed millions of ash trees since being accidentally in-
troduced to North America (Smith et al. 2009). During its larval
stage, EAB feeds on the inner phloem and outer xylem of ash
trees, leading to disrupted vascular flow and ultimately tree death
(Cappaert et al. 2005). Once EAB becomes established in an area,
about 30% of ash trees are killed each year (Herms et al. 2009a);
very few host trees have shown any natural resistance, though
blue ash (Fraxinus quadrangulata Michx.) and Asian ash spe-
cies may be less susceptible (Anulewicz et al. 2007; Rebek et al.
2008). A number of insecticides have proven effective in protect-
ing trees against EAB attack (Herms et al. 2009b; McKenzie et al.
2010); however, they are not likely to be widely applied because
of considerations around cost, efficacy, and safety. Furthermore,
EAB infestations are often difficult to detect until host trees show
obvious signs of stress (McCullough et al. 2009), at which point
it may be too late to reverse the damage (Herms et al. 2009b).
Since being introduced into southern Michigan in the early
1990s (Cappaert et al. 2005), EAB has spread rapidly across east-
ern and central North America, with outbreaks currently reported
from 15 U.S. states and two Canadian provinces (USDA-APHIS
2011). Though a small percentage of mated females are capable
of flying more than 20 km in 24 hours (Taylor et al. 2010), most
larvae that originate from point source introductions are found
within 100 m of adult emergence sites (Mercader et al. 2009).
Thus, human-assisted dispersal via transport of infested ash
material (Cappaert et al. 2005) and/or hitchhiking on vehicles
(Buck and Marshall 2008) is likely the main cause of the ob-
served EAB expansion (Prasad et al. 2010). Over time, EAB is
expected to continue its advance across Canada and the United
States, decimating ash in urban and rural settings along the way.
Given its rapid rate of spread and the prevalence of ash in
both natural and urban forests across much of eastern and cen-
tral North America (Burns and Honkala 1990; Woodall et al.
2009), EAB clearly has the potential to bring about significant
economic and ecological impacts. Several studies have produced
regional economic impact estimates in the U.S. (Kovacs et al.
2010; Sydnor et al. 2007; Sydnor et al. 2011). The objective
of the current study was to report on efforts to generate EAB-
related cost estimates for Canadian urban areas. The approach
employs a relatively simple spread model to coarsely simulate
EAB expansion to Canadian communities over a 30-year period.
For each community in the study area, costs related to ash
removal, replacement, and treatment are estimated and then
discounted according to the timelines projected by the spread
model. The lack of spatial data on ash distribution and abun-
dance in Canada presents a significant challenge for this type
of study. A variety of sources were used to estimate ash abun-
dance along urban streets, including early results from a sur-
vey that allows rapid assessments of street tree composition.
This research focused on street trees because they can be reli-
ably and rapidly surveyed and are almost certain to require
management action (i.e., removal/replacement or treatment)
if attacked. This is an underestimation of total EAB impact.
Regulatory efforts to prevent the introduction of alien species
to Canada and associated research are federal responsibilities,
while long term management of established pests requires strong
McKenney et al.: Cost of EAB in Canadian Municipalities
©2012 International Society of Arboriculture
involvement of provincial ministries and municipalities. The Ca-
nadian Food Inspection Agency has regulatory authority over any
new species entering the country, including the development of
quarantine measures. The Canadian Forest Service is the federal
government’s lead in forest research with a strong capacity in
forest insects and diseases. Provincial and territorial governments
manage most of the forestlands in the country and therefore have
a strong interest in alien species threats. Because of this the Ca-
nadian Forest Service is often engaged in monitoring and survey-
ing efforts. Municipalities (and homeowners) manage removal,
replacement, and treatment efforts in the urban setting—often
bearing the financial burden of these frontline activities. All of
these stakeholders have expressed the desire for more quan-
titative damage estimates to help justify mitigation activities.
Study Area and Associated Data
This study was carried out for Canadian urban centers that fall within
the natural geographic range of native ash (Fraxinus sp.) as defined
by Little (1971) (Figure 1). Urban centers were identified using a
digital version of Canada’s urban areas cartographic boundary file
(Statistics Canada 2007). For this coverage, an urban area is defined
as having a population of at least 1,000 persons and a density of not
fewer than 400 persons per square kilometer. There are 895 urban
areas across Canada in this database; 641 of these fall within the
native range of ash (Figure 1). The study is road based, so a digital
version of the national road network was intersected with the urban
areas boundary file to provide an estimate of the kilometers of road
in each of these communities. A summary of the human popula-
tion and road network in these communities is provided in Table 1.
Estimating Urban Ash Component in Eastern
For estimating EAB impacts, the primary focus of the study
authors was ash trees within 10 m of urban roadways (“street
trees”) as these trees would almost certainly require action (i.e.,
removal/replacement or treatment) if attacked. The cost for
these actions would be borne by the municipality, utility com-
pany, or property owner depending on the specific location and/
or ownership of a given tree. The number of ash street trees
were estimated using a variety of methods and data sources for
both eastern and western Canada. Potential impacts to back-
yard trees were also included as an additional focus. There are
other trees in the urban setting, such as those in parks and ri-
parian areas, which could also have direct financial costs if at-
tacked. Reliable data on these urban forest components are
difficult to find, hence, not further considered at this stage.
The primary data source on ash abundance in eastern Canada
is a survey that was developed to help rapidly assess the compo-
sition of street trees. Data currently exists for 16 urban centers
in Ontario and New Brunswick, Canada (Table 2). Briefly, the
survey protocol involves participants walking or driving routes
(0.5 km in length) randomly located throughout an urban center.
Trees within 10 m of the road edge are identified and placed in
coarse height classes (small = 1.5 to 5.0 m; medium = 5.0 to 10.0
m; large = >10 m). In total, the routes covered approximately
10% of the total length of roads in each urban center. While de-
veloping the survey, this level of coverage yielded reasonably ac-
curate estimates of percent cover for major street tree species.
From this data, the total number of trees per km of road was
calculated, the percentage of those trees that were ash, and the
percentage of ash in each size class (Table 2). The survey was
web-based and random survey routes were generated for all 895
urban areas in Canada (contact the authors for further details).
Surveys are ongoing that will enable further refinements to the re-
sults presented here and support other alien species risk analyses.
These tree survey data were augmented with information
from existing tree inventories for Canadian urban centers, for
example, information for three cities in eastern Canada (Table
2) from the Urban Forest Effects model (Nowak et al. 2010).
This program was designed to collect forest composition data
from urban areas in the U.S., but has been applied to several
Canadian communities as well. Information for the city of St.
Johns, Newfoundland, Canada (Table 2) (Environmental De-
sign and Management, Ltd. 2006) was also obtained. All of
these surveys were carried out to estimate tree species composi-
tion for the entire urban landscape. For this analysis it was as-
sumed that the relative composition values were representative
of trees within 10 m of city streets (i.e., definition of street trees).
A final source of information came from high resolution sat-
ellite imagery available through Google Maps. It was not pos-
sible to identify trees to the species level with this approach,
but it was possible to count the total number of trees within 10
Figure 1. Geographical range of Fraxinus spp. (shaded) and lo-
cations of urban centers (dots) in Canada; urban centers falling
within the shaded area were included in the current study.
Table 1. The number of urban areas, the human population, road length, and estimated number of street ash found within the
Canadian range of Fraxinus spp.
Region Urban Human Road Estimated number of ash trees
areas (N) population length (km) Small Medium Large Total
Eastern Canada 545 17,282,389 86,477 138,363 216,193 190,250 544,806
Western Canada 96 1,510,706 11,074 96,348 223,704 364,350 684,401
Total 641 18,793,095 97,552 234,711 439,897 554,599 1,229,207
Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
m of city streets. This was done for a total of 150 randomly lo-
cated 0.5-km street segments across six Ontario cities (Table 2).
During this process, several other pieces of information were
gathered. First, to estimate impacts in residential backyards,
the number of trees in backyards were counted along the same
150 random street segments used to count street trees (Table
2). In cases where houses backed onto woodlots, making prop-
erty lines difficult to distinguish, only trees within 10 m of the
woodlot edge were counted, as these would have a higher likeli-
hood of being treated or removed in the case of an EAB attack.
The ratio of street trees to backyard trees was 1:1, suggesting
that street tree costs could be doubled to include the backyard
component. However, not all streets are fronted by dwell-
ings with backyards (i.e., some are fronted by parks, industrial
parks), thus the percentage of urban roads fronted by residen-
tial dwellings at the same 150 road segments was also estimated.
Based on these estimates, backyard tree impacts are expected
to be about 68% of those associated with street trees (Table 2).
Estimating Urban Ash Component in Western
Different data sources were available for provinces in western
Canada (e.g., Manitoba, Saskatchewan, and Alberta). The For-
estry Branch of Manitoba Conservation provided a GIS database
of an ash inventory that had been carried out for 16 urban cen-
ters in Manitoba. To make these data comparable to the street
tree data for eastern Canada, the study authors selected only trees
within a 10 m buffer of the road system in each community. Each
tree in the database had a height attribute, and so were classi-
fied into the same height classes as those outlined for eastern
Canada. The number of street ash per kilometer of road was cal-
culated for each of the 16 communities by summing the number
of street trees in each size class and then dividing each total by
the length of the urban road system in that community (Table 3).
Due to a lack of comparable data from other western provinces,
these values were applied to Saskatchewan and Alberta as well.
There were notable differences in the relative abundance of
ash in eastern and western Canada. In western Canada, there was
an average of 8.7, 20.2, and 32.9 street ash/km in the small, me-
dium, and large size classes, respectively (Table 3); comparable
numbers for eastern Canada were 1.6, 2.5, and 2.2 street ash/km
(calculated from Table 2). This approximately 8× higher inci-
Table 2. Street tree parameters used to estimate impact of EAB in eastern Canada.
City Provincez Data Trees/km % Ash % Ash % Ash % Ash Ratio of %
sourcey road <5 m 5–10 m >10 m backyard to house
tall tall tall front yard trees frontage
Bathurst NB S 84.4 4.0 0 100 0 - -
Barrie ON G 100.4 - - - - 0.95 60.3
Bracebridge ON S 185.7 0.0 - - - - -
Chatham ON S, G 115.9 - - - - 0.75 62.7
Fredericton NB S 123.0 0.0 - - - - -
Guelph ON S, G 112.7 6.3 8.1 16.2 75.7 1.21 82.7
Halifax NS P - 0.4 - - -
Huntsville ON S 164.4 1.5 0 0 100 - -
Kitchener ON G 95.7 - - - - 0.98 74.1
London ON S 97.1 3.3 - - -
Meaford ON S 120.8 8.2 12.5 25.0 62.5
Moncton NB S 72.1 0.1 - - - - -
Oakville ON P - 9.2 - - -
Ottawa - Gatineau ON G 115.5 - - - - 1.05 68.6
Oromocto NB S 149.3 0.4 - - - - -
Owen Sound ON S 106.2 6.7 23.1 46.2 30.8
Parry Sound ON S 50.5 19.8 35 25 40 - -
Sault Ste Marie ON S 91.4 2.2 5.9 28.2 65.9
St. Johns NFLD P - 7.8 - - -
South Porcupine ON S - 1.7 0 36.3 63.6
Sudbury ON S 59.0 4.9 - - -
Thunder Bay ON G 76.8 - - - - 1.08 54.4
Timmins ON S 124.0 0.4 - - - - -
Toronto ON P - 7.8 - - -
Averagex 107.6 6.0 10.4 34.6 54.8 1.0 67.5
z NB = New Brunswick; ON = Ontario; NS = Nova Scotia; NFLD = Newfoundland.
y S = street tree survey; G = Google Maps; P = published values. See text for complete details.
x Average is weighted by population size of urban areas.
Table 3. Number of small, medium, and large ash trees per
kilometer of urban road for 16 communities in western Canada.
Urban area Province Ash trees per km of urban road
<5 m tall 5–10 m tall >10 m tall
Manitou Manitoba 0.1 36.3 38.0
Treherne Manitoba 11.1 31.2 46.6
Altona Manitoba 10.6 35.6 51.2
Beausejour Manitoba 6.3 8.7 16.1
Carberry Manitoba 6.7 22.3 36.5
Carman Manitoba 21.6 19.3 49.2
Dauphin Manitoba 2.6 13.6 18.4
Deloraine Manitoba 26.4 30.7 66.8
Rivers Manitoba 8.8 4.2 16.6
Selkirk Manitoba 3.9 10.0 15.1
Souris Manitoba 11.5 27.7 44.7
Steinbach Manitoba 9.5 24.3 39.8
Stonewall Manitoba 7.6 7.7 16.3
Virden Manitoba 9.0 11.2 23.0
Winkler Manitoba 23.0 48.7 79.6
Portage La Prairie Manitoba 2.8 13.6 19.0
Averagez 8.7 20.2 32.9
z Average is weighted by population size of urban areas.
McKenney et al.: Cost of EAB in Canadian Municipalities
©2012 International Society of Arboriculture
dence of ash in western Canada was supported by two sources:
1) Google Maps counts of street trees at 16 random locations
in four Manitoba communities indicated that there were about
twice as many street trees in Manitoba than Ontario, and 2) street
tree composition data for the city of Saskatoon, Saskatchewan
(Geoff McLeod, pers. obs.) indicated that about 25% of street
trees were ash, approximately 4× that of eastern Canada. This
pattern is perhaps not surprising given the more limited num-
ber of tree species that can tolerate the somewhat more extreme
climate found in the prairies region (McKenney et al. 2007).
Predicting EAB Spread
The Canadian Forest Service Forest Bioeconomic Model (CFS-
FBM) was used as the basic modeling framework for projecting
EAB spread over time. The model shares conceptual similarities
with the spread model described by Yemshanov et al. (2009a),
Yemshanov et al. (2009b), and Koch et al. (2009). Briefly, CFS-
FBM provides a grid-based modeling framework for simulating
a variety of processes in a spatial setting, including the spread,
establishment, and impact of alien species. For example, the
model has been used to examine potential wood supply im-
pacts from Sirex noctilio, an invasive alien wasp species (Koch
et al. 2009; Yemshanov et al. 2009a; Yemshanov et al. 2009b).
A simplified version of CFS-FBM was used to obtain a
coarse depiction of how EAB might spread across the country.
The approach required a spread probability-density function,
or ‘kernel,’ which determined the probability of EAB spread as
a function of the geographic distance to locations with known
EAB infestations. Published EAB spread rates vary by more
than two orders of magnitude, reflecting the highly variable
spread of EAB under different conditions. The smallest report-
ed value (30 m/yr) was for a new infestation starting from a
single source (a pile of infested logs) with many ash trees in
the near vicinity (Mercader et al. 2009). In contrast, Kovacs et
al. (2010) reported an average spread rate of 16 km/yr based
on spread data in Michigan, U.S., over the period 1994–2009.
Similarly, Smitley et al. (2008) reported a rate of 10.6 km/yr
for the spread rate of detectable symptoms for an outbreak
in southeastern Michigan over the period 2003–2006. These
larger estimates are based on data that include natural long
distance dispersal events that may be induced by high popula-
tion density and/or low host availability, as well as regional-
scale, human-assisted movements (such as trade and trans-
portation). Based on comparison to observed rates of spread
in southern Ontario, the spread rate reported by Smitley et al.
(2008) was adopted as a baseline value for the current study.
The spread model simulations covered an area extend-
ing from maritime Canada in the east to Alberta in west-
ern Canada with a map cell resolution of ~1 km2. The
model employed a negative exponential function to deter-
mine the probability, p that a cell would become infested as
a function of its distance, d from the nearest infested cell:
[1] p = e-0.0943d
The value of the exponent in Equation 1 (i.e., 0.0934) was
determined such that the mean distance defined by the equation
is 10.6 km (i.e., the desired average spread rate as previously
outlined). To address the wide variation in potential spread rate,
the model was run with three different maximum spread values
to represent slow, medium, and fast linear rates of spread cor-
responding to approximately 10, 30, and 50 km/year. The maxi-
mum spread value truncates the negative exponential probabili-
ty-density function, thus placing an upper limit on the extent of
annual spread – a key factor controlling overall spread rates and
patterns (Koch et al. 2009; Yemshanov et al. 2009a; Yemshanov
et al. 2009b). This approach produced a uniform spread pattern
that predicted consistent arrival times that were not influenced
by rare (and highly uncertain) long-distance dispersal events.
The model was run over a 30-year time horizon to generate
expected arrival times for EAB at each map cell in the study area.
The model was initiated from known Canadian and U.S. EAB
occurrence locations as of 2009 (USDA-APHIS 2011). An im-
plicit assumption was that any cell that fell within the study area
contained at least some ash that could be a host (and hence path-
way) for colonization. This assumption was necessary because,
as previously noted, detailed spatial data of ash abundance were
not available in Canada; furthermore, ash is considered relatively
common throughout its native Canadian range (Farrar 1995).
Unit Cost Estimates for EAB Damage
Four types of costs were explicitly incorporated into this
study: removal costs, replacement costs, treatment costs,
and what were termed as community overhead costs (Ta-
ble 4). All cost estimates are in year 2010 Canadian dol-
lars and based on a combination of published values from the
United States. (Kovacs et al. 2010) and personal communi-
cations with City Foresters in Windsor, Toronto, Oakville,
London, Ottawa, and Thunder Bay, Ontario; and Saskatoon.
It was assumed that all ash street trees, as defined in this
study, required either removal or treatment. Removal costs
vary widely according to tree size (height and diameter), lo-
cation (e.g., proximity to buildings, and power and telephone
lines), and contractor rate; the cost estimates attempted to de-
scribe an average cost for small, medium, and large trees (Ta-
ble 4). Replacement costs are also highly variable and depend
on the size and source of the planting stock; the estimate of
CAD $400 is representative of the per tree costs incurred by
municipalities when planting well established (i.e., ~ 4 cm in
diameter) saplings. It was posited that only a certain percent-
age of removed trees would actually be replaced; in lieu of
data on this subject, a 50% replacement rate was assumed.
Insecticide treatments were incorporated into the model
as an alternative to cutting large and medium sized trees.
Three plausible treatment scenarios were considered: 1) no
treatments; 2) a modest treatment rate, where 10% of large
and medium trees were treated; and 3) a high treatment rate,
where 50% of large and medium trees were treated. Cur-
rently, the main product used in Canada for protecting trees
against EAB attack is TreeAzin (McKenzie et al. 2010).
Treated trees were tracked in a separate cost stream that re-
ceived ongoing biannual treatments for the remainder of the
simulation; cost estimates were based on reported costs as-
sociated with TreeAzin for large and medium trees (Table 4).
Community overhead costs are intended to represent consider-
ations such as staff time to manage and coordinate the response,
communication costs, monitoring and surveillance costs, and dis-
posal operations for tree waste. Based on discussions with city
Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
foresters, it was estimated that these costs would be approximately
$0.40/household – applied in each year that an outbreak was on-
going in a given city. The number of households in each commun-
ity was obtained from Statistics Canada (Statistics Canada 2007).
Three different positive discount rates were employed: 2%,
4%, and 10%. These rates reflect different perspectives on the
value of delaying payment for incurred costs. In addition, re-
sults are presented with no discounting (a zero discount rate),
to demonstrate the effect of discounting. Some economists
provide theoretical arguments that very low discount rates are
justifiable when significant intergenerational outcomes are at
stake; species losses could arguably be taken as one such out-
come (Weitzman 1994; Portney and Weyant 1999). For the
positive discount rates, the authors also report the cost esti-
mates in equivalent annual dollars (see Boardman et al. 2001).
Model Scenarios and Sensitivity Analysis
The model was run for 36 different combinations of spread rate
(slow, medium, and fast), treatment rate (0%, 10%, and 50%),
and discount rate (0%, 2%, 4%, and 10%). As with any model,
there was uncertainty in the input parameters; to address this, 100
Monte Carlo simulations were run for each of the 36 scenario
combinations using the @Risk software package (Pallisade Cor-
poration 2002). During each simulation, the value for each input
parameter was drawn from a user-defined distribution of possible
values. Since there were multiple estimates of the tree composi-
tion parameters for eastern and western Canada, a Gaussian dis-
tribution for each parameter was defined using mean and standard
deviation values calculated from the data (Table 4). Due to the rel-
atively small amount of empirical data behind the remaining input
parameters, they were assigned a triangular distribution for the
Monte Carlo simulations. This distribution requires knowledge of
mean, min, and max values, and assumes only a simple triangular
shape. Plots of cumulative mean cost against simulation number
indicated that 100 replications were adequate for this analysis.
The influence of each input parameter listed in Table 4 on
regional and total EAB economic impact was estimated us-
ing a regression approach (Pallisade Corporation 2002). For
this analysis, each iteration of the simulation produced an ob-
servation for a multiple regression model with cost as the de-
pendent variable and the input parameters as the independent
variables. The standardized slope coefficient associated with
each input parameter was taken as its measure of influence.
Overall Economic Impact
Approximately 545,000 and 684,000 ash street trees were esti-
mated in eastern and western Canada, respectively, for a total of
~1.2 million ash street trees across the 641 communities included
in the study area (Table 1). Estimated impacts for the 30-year time
horizon ranged from $265 million to $1,177 million depending
on the combination of spread, treatment, and discount rates (Ta-
ble 5). The low estimate resulted from the slow spread rate, 10%
discount rate, and 50% treatment rate; the high estimate resulted
from the fast spread rate, 0% discount rate and 50% treatment
rate. Figure 2 shows cost accumulation through time for selected
spread and treatment rates. These estimates are for street trees
only; the inclusion of expenses associated with backyard trees
can be roughly estimated by multiplying the values in Table 5 by
a factor of 1.7, bringing the range to $451 million to $2,001 mil-
lion. Total costs associated with a "middle-of-the-road" scenario
(i.e., medium spread rate, 10% treatment rate, and 4% discount
rate) were $524 million; this would increase to roughly $890.8
million if expenses related to backyard trees were included.
As would be expected, faster spread rates were associated
with higher economic impacts (Table 5). For example, total street
tree costs ranged from $265 million to $506 million (at posi-
tive discount rates) for the slow spread rate compared, to $371
million to $820 million for the fast spread rate (Table 5). These
Table 4. Model parameters and probability distributions used in the sensitivity analysis of EAB economic impacts. Currency is
expressed in 2010 Canadian dollars.
Parameter name Region Distribution Distribution
type parameters
Total trees/km Eastern Gaussian Mean = 108; S.D. = 30
% Ash Eastern Gaussian Mean = 0.06; S.D. = 0.04
% Ash - small Eastern Gaussian Mean = 0.1; S.D. = 0.1
% Ash - medium Eastern Gaussian Mean = 0.35; S.D. = 0.3
% Ash - large Eastern Gaussian Mean = 0.6; S.D. = 0.3
Small ash/km Western Gaussian Mean = 9; S.D. = 7
Medium ash/km Western Gaussian Mean = 20; S.D. = 12
Large ash/km Western Gaussian Mean = 33; S.D. = 19
Removal - small ($) Canada Triangular Mean = 150; Min = 50; Max = 250
Removal - medium ($) Canada Triangular Mean = 500; Min = 300; Max = 700
Removal - large ($) Canada Triangular Mean = 1000; Min = 700; Max = 1300
Replacement ($) Canada Triangular Mean = 400; Min = 250; Max = 550
Replacement rate (%) Canada Triangular Mean = 0.5; Min = 0.2; Max = 0.8
Treatment - large ($) Canada Triangular Mean = 165; Min = 115; Max = 215
Treatment - medium ($) Canada Triangular Mean = 110; Min = 60; Max = 160
Community cost ($ per Canada Triangular Mean = 0.4; Min = 0.2; Max = 0.6
Detection lag (years) Canada Discrete Uniform (2,3,4)
McKenney et al.: Cost of EAB in Canadian Municipalities
©2012 International Society of Arboriculture
differences stemmed from the number of communities attacked
over the 30-year time horizon under the fast (634 communities
attacked) and slow (386 communities attacked) spread scenarios.
In fact, based on the slow spread rate, the infestation had not
reached western Canada by the end of the simulation period
(Table 5). This is evident in Figure 2, where there is an obvi-
ous rise in costs mid-to-late in the simulation under the me-
dium and fast spread rates due to the arrival of EAB at cities
in western Canada (particularly Winnipeg, Manitoba); a simi-
lar pattern does not appear under the slow dispersal rate. This
result is largely driven by the high ash abundance in western
communities. There is, of course, an inverse relationship be-
tween the present value of the cost estimates and the discount
rate. For example, a 2% discount rate resulted in costs rang-
ing from $413 million to $870 million, while a 10% discount
rate produced costs ranging from $265 million to $422 mil-
lion (Table 5). Higher discount rates effectively reduce the
present value of future costs. The influence of discount rate
was also apparent in Figure 2 where the low discount rate
was associated with higher costs, particularly under the fast
spread rate and 50% treatment rate; conversely, the high dis-
count rate resulted in considerably lower costs and relatively
little difference in cost projections between scenarios. Note
however that the equivalent annual cost estimates in Table 5
increase as the discount rate increases. While this may seem
counterintuitive, it is a standard result because present val-
ues of annuities decrease as interest rates increase and in-
crease when interest rates decline (see Boardman et al. 2001).
As might be expected, increased treatment rates had higher
overall costs for the 0%, 2%, and 4% discount rates; however,
this pattern was reversed under the 10% discount rate (Table 5).
This result is particularly sensitive to the time horizon of the
simulation and the spatiotemporal pattern of the spread. Many
large urban centers in eastern Canada (e.g., Toronto, Ontario;
Montreal, Quebec) were attacked very early in the simulation,
thus a large pool of trees accumulated substantial treatment costs
by the end of the 30-year period. Since treatment costs are ac-
cumulated through time, they are also strongly influenced by
the discount rate. For example, under a medium spread rate and
0% discount rate, treating 50% of trees resulted in a total cost of
$914 million; for the same spread and treatment rates, this value
dropped to $318 million under a 10% discount rate (Table 5).
Sensitivity Analysis
Table 5 also presents standard deviations of the cost distribu-
tions for each scenario based on the Monte Carlo simulations.
Standard deviation values were generally within 40% of the
mean, indicating that the impact estimates are relatively robust
to plausible changes in the input parameter values. In eastern
Canada, estimated costs were strongly affected by the proportion
of ash and the number of trees per unit of road length (Figure
3a). Costs associated with removal, replacement, and treatment
of large and/or medium trees made up most of the remaining sig-
nificant input parameters. Detection lag had a relatively minor,
negative impact on cost estimates in eastern Canada. Higher lag
values meant that EAB attacks were detected later, resulting in
lower discounted costs or, for grid cells attacked very late in the
simulation, costs being pushed outside the 30-year time horizon.
In western Canada, the most influential parameter on final
cost estimates was the number of large trees/km (Figure 3b).
Detection lag had a much stronger influence in the west; since
many western communities were attacked very late in the simu-
lation, any increase in the detection lag resulted in a significant
number of grid cells being excluded from the 30-year analysis.
Costs associated with removal, replacement, and treatment of
large and/or medium trees made up most of the remaining sig-
Figure 2. Mean economic impact of EAB over time, based on
three scenarios: a) slow spread rate and 0% of ash trees treated,
b) medium spread rate and 10% of ash trees treated, and c) fast
spread rate and 50% of ash trees treated.
Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
nificant input parameters. For all of Canada, the percentage of
ash street trees and the number of street trees per kilometer of
road were the most influential input parameters (Figure 3c).
Impacts on Specific Urban Areas
The 10 cities showing the greatest EAB-related impacts differed
depending on the spread and discount rates (Table 6). Toronto,
Ontario; Montreal, Ottawa-Gatineau, and Quebec City, Quebec;
and Hamilton, Ontario, were consistently among the most heavily
affected cities with losses of roughly $100 million predicted for
Toronto and Montreal under each of the scenarios shown in Table
6. As noted, under the slow spread rate, no western communities
were attacked within the simulation timeframe. However, under
the faster spread rates, Winnipeg, Manitoba, was projected to ex-
perience some of the heaviest EAB-related losses – nearly $200
million in undiscounted cashflow equivalent. Other cities in west-
ern Canada, such as Brandon, Manitoba, and Regina and Moose
Jaw, Saskatchewan, also make the list when costs are not discount-
ed. These western communities are much smaller than some of the
eastern communities that appear in Table 6, but involve comparable
costs due to the considerably higher abundance of ash along urban
streets. The impact of discounting is large in western communities
because they are generally attacked late in the simulation period.
It was estimated that, over a 30-year time horizon, the discount-
ed financial costs of EAB on urban street trees in Canada may
range from about $0.3 to $0.9 billion; when backyard trees are
included, the range of projected impacts increases to approxi-
mately $0.5 to $1.5 billion. Kovacs et al. (2010) estimated an
economic impact of $10.7 billion (using a 2% discount rate) for
EAB in urban areas of 25 eastern U.S. states. There are a number
of differences between the studies that help explain the disparity
in the magnitude of these estimates. The population base cov-
ered by the Kovacs et al. (2010) study is about 8× that of the
current study; and since urban costs are closely related to popu-
lation size, this explains much of the difference. Furthermore,
Kovacs et al. (2010) estimated the economic impacts associat-
ed with all ash trees in communities, as opposed to only street
(and backyard) trees in the current study. When these factors
are taken into consideration, the estimates are very comparable.
Using a different approach, Sydnor et al. (2007) estimat-
ed removal and replacement costs of $1 to $4.2 billion for the
state of Ohio alone, with costs increasing to $1.8–$7.6 billion
when tree-related benefits such as shading, stormwater mitiga-
tion, pollution abatement, and property values were included
in the calculation. In a related study, Sydnor et al. (2011) esti-
mated removal and replacement costs of $5.7–$11 billion for
Table 5. Estimated economic impacts (mean and standard deviation) of EAB on street trees in Canada over a 30-year time
horizon. Equivalent annual values are shown in parentheses. Currency is expressed in 2010 Canadian dollars.
Max. spread rate Treatment rate Discount Eastern Canada Western Canada Total
(km/year) (% ash treated) rate (%) Mean S.D. Mean S.D. Mean S.D.
($, millions) ($, millions) ($, millions) ($, millions) ($, millions) ($, millions)
10 (slow) 0 0 468 221 0 0 468 221
2 413 (18) 195 (9) 0 0 413 (18) 195 (9)
4 372 (22) 176 (10) 0 0 372 (22) 176 (10)
10 292 (31) 138 (15) 0 0 292 (31) 138 (15)
10 0 513 251 0 0 513 251
2 440 (20) 216 (10) 0 0 440 (20) 216 (10)
4 388 (22) 190 (11) 0 0 388 (22) 190 (11)
10 292 (31) 143 (15) 0 0 292 (31) 143 (15)
50 0 642 281 0 0 642 281
2 506 (23) 220 (10) 0 0 506 (23) 220 (10)
4 414 (24) 179 (10) 0 0 414 (24) 179 (10)
10 265 (28) 114 (12) 0 0 265 (28) 114 (12)
30 (medium) 0 0 543 270 250 43 793 277
2 482 (22) 240 (11) 149 (7) 26 (1) 630 (28) 244 (11)
4 435 (25) 217 (13) 89 (5) 16 (1) 524 (30) 219 (13)
10 343 (36) 170 (18) 20 (2) 4 (0) 363 (39) 171 (18)
10 0 579 273 235 41 814 283
2 499 (22) 235 (10) 139 (6) 25 (1) 638 (29) 240 (11)
4 441 (25) 207 (12) 83 (5) 15 (1) 524 (30) 210 (12)
10 333 (36) 156 (17) 19 (2) 4 (0) 352 (37) 157 (17)
50 0 741 349 173 32 914 353
2 584 (26) 273 (12) 102 (5) 19 (1) 686 (31) 276 (12)
4 477 (28) 222 (13) 61 (4) 12 (1) 538 (31) 223 (13)
10 305 (32) 140 (15) 14 (1) 3 (0) 318 (34) 140 (15)
50 (fast) 0 0 554 269 467 77 1021 294
2 497 (22) 241 (11) 305 (14) 50 (2) 802 (36) 256 (11)
4 452 26) 218 (13) 202 (12) 34 (2) 654 (38) 228 (13)
10 358 (38) 173 (18) 65 (7) 11 (1) 422 (45) 175 (19)
10 0 602 283 455 83 1058 312
2 524 (23) 246 (11) 296 (13) 55(2) 820 (37) 264 (12)
4 465 (27) 219 (13) 196 (11) 37 (2) 661 (38) 230(13)
10 353 (37) 167 (18) 62 (7) 12 (1) 415 (44) 170 (18)
50 0 778 367 399 61 1177 367
2 615 (27) 290 (13) 255 (11) 39 (2) 870 (39) 289 (13)
4 503 (29) 236 (14) 166 (10) 26 (1) 669 (39) 236 (14)
10 321 (34) 151 (16) 50 (5) 8 (1) 371 (39) 150 (16)
McKenney et al.: Cost of EAB in Canadian Municipalities
©2012 International Society of Arboriculture
communities in four midwestern states, with costs increasing to
$13.4–$26 billion when the extended benefits were considered.
Even after accounting for population size differences, their re-
moval and replacement estimates are about three times higher than
those reported here. Again, this is partly explained by the inclusion
of all street, private, and park trees in their estimates. Another ma-
jor difference is that Sydnor et al. (2007; 2011) did not incorporate
spread dynamics, and hence economic discounting considerations,
into their estimates. As demonstrated here, discounting can have
a major impact on cost estimates. This variation demonstrates the
wide range in projected costs that can result from (sometimes subtle)
methodological differences between impact studies and underlines
the importance of exploring multiple approaches to such work.
The estimates provided here are conservative in a number of
ways, focusing on direct financial costs associated with street (and
backyard) tree management. While this represents an important and
more readily quantifiable portion of EAB impacts, there are a number
of other direct financial considerations that warrant mention. These
estimates do not include costs related to trees in parks and urban
woodlands. Though the number of ash in these land use categories
can be substantial (Nowak et al. 2010), there is significant difficulty
finding reliable estimates of ash density for them. Furthermore, it
is not clear what percentage of ash trees in the park\woodland set-
ting would pose safety risks and thus require management action.
These estimates also ignore costs associated with ash trees in smaller
towns and rural residential settings—again, due to data availability.
Finally, it should be recognized that ash trees do exist in urban cen-
ters outside the native range of ash, which could significantly add
to the cost of EAB in Canada [e.g., 5.3% of municipal trees in Van-
couver, British Columbia, are ash (McManus, pers. comm.)]. How-
ever, pathways and spread rates into these areas are highly uncertain.
Many other benefits have been attributed to urban trees, including
home value premiums, energy savings, pollution and runoff reduc-
tion, and human health benefits (Dwyer et al. 1992). These benefits
have been quantified for various locations, allowing approximate
economic values to be attached to urban trees (e.g., McPherson et
al. 2007). Including the loss of these benefits would clearly increase
the economic impact attributed to EAB. In fact, EAB cost estimates
provided by Sydnor et al. (2007) and Sydnor et al. (2011) approxi-
mately doubled when these “landscape values” were included in
their calculations. These benefits were not incorporated here because
widely accepted values do not exist for Canada and published values
are situation dependent (McPherson et al. 2007). Nevertheless, the
incorporation of such values could be the subject of future efforts.
Losses in timber sales would also be expected as a result of an
EAB invasion (Schwan and Elliott 2010). However, detailed spatial
data on ash volumes are not available for much of Canada, making
it very challenging to estimate potential harvest losses in the natural
forest setting. Ash also plays an important ecological role in many
southern Canadian ecosystems. For instance, ash is a common ripari-
an species and its loss will likely effect water quality for both wildlife
and humans (Kreutzweiser 2010). Furthermore, the loss of ash could
have a major impact on biodiversity in agricultural landscapes of
southern Ontario, where it is often a key component of remnant for-
est woodlots (Schwan and Elliott 2010). While these ecosystem ser-
vices are extremely challenging to include in an economic analysis,
they are mentioned here to emphasize the extent to which this assess-
ment underestimates the full impact of this invasive alien species.
For the three lower discount rates, costs increased as treatment
rate increased; this pattern was reversed at the 10% discount rate.
This finding suggests, for example, municipalities/homeowners
that have high borrowing costs should consider treating a portion
of their trees because this results in a series of smaller, delayed
payments compared to large scale removal and replacement ef-
forts (McKenney and Pedlar 2012). Even at lower discount rates,
the opportunity to spread removal costs over time through the use
of treatments may be appealing to some municipalities. These re-
sults provide a simple approximation of how overall costs may
vary under different treatment rates. However, it is important to
note that decisions to treat versus remove trees can be complex
and involve not only relatively straightforward considerations such
as treatment, removal, and replacement costs, but also more subtle
factors like the influence of tree cover on property values, energy
budgets, and pollution control. Recent studies have examined this
topic from the perspective of both individual homeowners (McK-
enney and Pedlar 2012) and municipalities (Sadof et al. 2011).
Additionally, these results may be roughly interpreted to sup-
port slow-the-spread efforts against EAB. If the medium or fast
spread rate models are deemed to be more indicative of likely
outcomes, then the cost differences between the slow versus me-
Figure 3. Sensitivity of EAB economic impact estimates to model
parameter values for: a) eastern Canada, b) western Canada, and
c) the entire study area. The sensitivity coefcients were gener-
ated using a regression approach; larger values indicate more
inuence on the impact estimates.
Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
dium and fast spread models are suggestive of potential benefits
for slowing the spread of EAB. The difference in annual costs
between the slow and medium spread rate models are between
$6 million/year and $10 million/year (derived from the differ-
ences in the annuity values shown in Table 5). Cost differences
are of course higher for the slow versus fast rate models ($11–
$18 million/year). Notably in slow rate models, western Canada
has not been affected in the 30-year simulation period. Clearly
the arbitrary cut-off of a 30-year time horizon does affect these
results but with higher discount rates (e.g., 10%), this effect is
lessened simply because of the strong effect of discounting over
that length of time. At the 10% discount rate, the differences
between the fast and slow spread rate models range from about
$11 to $14 million/year ($3 to $7 million/year for the medium
versus slow spread rate). Annual expenditures up to these lev-
els to slow the spread of EAB would be justified on economic
efficiency grounds if indeed they were judged to be effective.
EAB-related street tree damage was estimated in the study area
over a 30-year time horizon to range from $265 million to $1,177
million depending on the combination of spread, treatment, and
discount rates (~$451 million to $2,001 million with backyard
trees included). Based on a medium spread rate, 10% treatment
rate, and 4% discount rate, estimated costs were $524 million;
this value increased to $891 million when costs were extended
to include backyard trees. Cast in equivalent annual values,
these estimates range from $18 million/year (2% discount rate,
Table 6. Canadian cities projected to show the greatest economic impact from EAB invasion over the next 30 years; ten cities
are listed for each of three spread rates and two discount rates. Currency is expressed in Canadian dollars.
Max. spread rate 0% Discount rate 4% Discount rate
(km/year) City Impact City Impact
($, millions) ($, millions)
10 (slow) Toronto 96 Toronto 85
Montréal 95 Montréal 76
Ottawa - Gatineau 27 Ottawa - Gatineau 24
Québec 23 Hamilton 18
Hamilton 20 St. Catherines - Niagara 13
St. Catherines - Niagara 15 Kitchener 9
Kitchener 13 Windsor 9
Windsor 10 London 9
London 10 Québec 8
Oshawa 8 Oshawa 7
30 (medium) Winnipeg 161 Toronto 85
Toronto 97 Montréal 78
Montréal 93 Winnipeg 58
Ottawa - Gatineau 27 Ottawa - Gatineau 24
Québec 25 Hamilton 18
Hamilton 20 Québec 15
Brandon 16 St. Catherines - Niagara 13
St. Catherines - Niagara 15 Kitchener 10
Kitchener 13 Windsor 9
Windsor 10 London 9
50 (fast) Winnipeg 172 Toronto 85
Toronto 96 Winnipeg 84
Montréal 92 Montréal 78
Regina 53 Ottawa - Gatineau 24
Ottawa - Gatineau 27 Regina 19
Québec 25 Hamilton 18
Moose Jaw 23 Québec 17
Brandon 22 St. Catherines - Niagara 13
Hamilton 20 Brandon 10
St. Catherines - Niagara 15 Kitchener 10
slow spread, and no treatments) to $45 million/year (10% dis-
count rate, fast spread, and no treatments). Including backyard
trees would increase these annual equivalents to ~$31 million
and $77 million per year. Though conservative, these estimates
are comparable to a similar study carried out in the U.S. (Ko-
vacs et al. 2010), once differences in population size and study
scope are taken into account. Community-specific cost esti-
mates can be obtained by contacting the corresponding author.
These findings can provide some justification for slow-the-
spread initiatives, such as early detection surveys and wood
movement laws. However, the net value of a slow-the-spread
program depends on two major considerations: 1) the ex-
tent to which it delays EAB arrival at a given urban centre,
and 2) the perceived time value of expenditures as influenced
by the discount rate. Nevertheless, even just the simple no-
tion of preserving ash in communities for future generations
may be an important consideration for some decisionmak-
ers, especially if EAB proves to be as devastating as some be-
lieve. Given the magnitude of the damage estimates provided
here, there is also considerable economic justification for on-
going research efforts to better understand and manage EAB.
Acknowledgements. We thank: Irene Pines, Robert McMahon, and oth-
ers at Manitoba Conservation for generously sharing their ash survey data;
the Ontario Stewardship Rangers and all other volunteers who have helped
to collect street tree data in eastern Canada; and Geoff McLeod, Bill Roe-
sel, Jason Pollard, John McNeil, and Richard Ubbens for feedback on tree
removal and replacement costs. We also thank two anonymous reviewers
for their comments. Any errors remain the responsibility of the authors.
McKenney et al.: Cost of EAB in Canadian Municipalities
©2012 International Society of Arboriculture
Anulewicz, A.C., D.G. McCullough, and D.L. Cappaert. 2007. Emer-
ald ash borer (Agrilus planipennis) density and canopy dieback in
three North American ash species. Arboriculture & Urban Forestry
Buck, J.H., and J.M. Marshall. 2008. Hitchhiking as a secondary disper-
sal pathway for emerald ash borer, Agrilus planipennis. The Great
Lakes Entomologist 41:197–199.
Burns, R.M., and B. H. Honkala, technical coordinators. 1990. Silvics of
North America: 2. Hardwoods. Agriculture Handbook 654. Washington
D.C.: U.S. Department of Agriculture, Forest Service. Vol. 2, 877 pp.
Cappaert, D., D.G. McCullough, T.M. Poland, and N.W. Siegert. 2005.
Emerald ash borer in North America: a research and regulatory chal-
lenge. American Entomologist 51:152–165.
Dwyer, J. F., E.G. McPherson, H.W. Schroeder, and R.A. Rowntree.
1992. Assessing the benefits and costs of the urban forest. Journal of
Arboriculture 18:227–234.
Environmental Design and Management Ltd. 2006. St. John’s urban
forest management master plan. City of St. John’s, Newfoundland,
Canada. 71 pp.
Farrar, J.L. 1995. Trees in Canada. Fitzhenry and Whiteside Lmt. 502 pp.
Herms, D.A., K.J.K. Gandhi, A. Smith, J. Cardina, K.S. Knight, C.P.
Herms, R.P. Long, and D.G. McCullough. 2009a. Ecological impacts
of emerald ash borer in forests of southeast Michigan. pp. 36–37. In:
K.A. McManus and K.W. Gottschalk. Proceedings. 20th U.S. Depart-
ment of Agriculture interagency research forum on invasive species
2009. Gen. Tech. Rep. NRS-P-51. Newtown, PA, U.S. Department of
Agriculture, Forest Service, Northern Research Station.
Herms, D.A., D.G., McCullough, D.R. Smitley, C.S. Sadof, R.C. William-
son, and P.L. Nixon. 2009b. Insecticide options for protecting ash trees
from emerald ash borer. North Central IPM Center Bulletin. 12 pp.
Koch, F.H., D. Yemshanov, D.W. McKenney, and W.D. Smith. 2009.
Evaluating critical uncertainty thresholds in a spatial model of forest
pest invasion risk. Risk Analysis 29:1227–1241.
Kovacs, K.F., R.G. Haight, D.G. McCullough, R.J. Mercader, N.W. Sieg-
ert, and A.M. Liebhold. 2010. Cost of potential emerald ash borer
damage in U.S. communities, 2009–2019. Ecological Economics
Kreutzweiser, D. 2010. Ecological implications of emerald ash borer in-
festations and management. pp. 18–21. In: D.B. Lyons and T.A. Scarr.
Workshop Proceedings: Guiding Principles for Managing the Emerald
Ash Borer in Urban Environments. Natural Resources Canada. 44 pp.
Little, E.L. Jr. 1971. Atlas of United States Trees, vol. 1: Conifers and
Important Hardwoods. Washington (D.C.): U.S. Department of Agri-
culture. Miscellaneous publication no. 1146.
McCullough, D.G., T.M. Poland, and D. Cappaert. 2009. Attraction of the
emerald ash borer to ash trees stressed by girdling, herbicide treatment
or wounding. Canadian Journal of Forest Research 39:1331–1345.
McKenney, D.W., and J.H. Pedlar. 2012. To treat or to remove: An
economic model to assist homeowners in deciding the fate of ash
trees threatened by emerald ash borer. Arboriculture & Urban For-
estry, in press.
McKenney, D., J.H.Pedlar, K. Lawrence, K. Campbell, and M. Hutchin-
son. 2007. Beyond traditional hardiness zones: Using climate enve-
lopes to map plant range limits. BioScience 57:929–937.
McKenzie, N., B. Helson, D. Thompson, G. Otis, J. McFarlane, T. Bus-
carini, and J. Meating. 2010. Azadirachtin: an effective systemic
insecticide for control of Agrilus planipennis (Coleoptera: Bupresti-
dae). Journal of Economic Entomology 103:708–717.
McPherson, G.E., J.R. Simpson, J.J. Peper, S.L. Gardner, K.E. Vargas,
and Q. Xiao. 2007. Northeast community tree guide: benefits, costs,
and strategic planting. Gen. Tech. Rep. PSW-GTR-202. Albany, CA:
U.S. Department of Agriculture, Forest Service, Pacific Southwest
Research Station. 106 pp.
Mercader, R.J., N.W. Siegert, A.M. Liebhold, and D.G. McCullough.
2009. Dispersal of the emerald ash borer, Agrilus planipennis in new-
ly-colonized sites. Agricultural and Forest Entomology 11:421–424.
Nowak, D.J., R.E. Hoehn III, D.E. Crane, J.C Stevens, and C.L. Fisher.
2010. Assessing urban forest effects and values, Chicago’s urban
forest. Resour. Bull. NRS-37. Newtown Square, PA: U.S. Department
of Agriculture, Forest Service, Northern Research Station. 27 pp.
OMNR. 2010. Annual Report on Forest Management 2008/09. Queen’s
Printer for Ontario.
Pallisade Corporation. 2002. Guide to using @Risk version 4.5: advanced
risk analysis for spreadsheets. Pallisade Corporation, Newfield, New
York, U.S.
Portney P.R., and J.P. Weyant. 1999. Discounting and intergenerational
equity. Resources for the Future. 186 pp.
Prasad, A.M., L.R. Iverson, M.P. Peters, J.M. Bossenbroek, S.N. Mat-
thews, T. Sydnor, and M.W. Schwartz. 2010. Modeling the invasive
emerald ash borer risk of spread using a spatially explicit cellular
model. Landscape Ecology, 25:353–369.
Rebek, E.J., D.A. Herms, and D.R. Smitley. 2008. Interspecific variation
in resistance to emerald ash borer (Coleoptera: Buprestidae) among
North American and Asian ash (Fraxinus spp.). Environmental Ento-
mology 37:242–246.
Sadof, C.S., L. Purcell, F.J. Bishop, C. Quesada, and Z. Zhang. 2011.
Evaluating restoration capacity and costs of managing the emerald
ash borer with a web-based cost calculator in urban forests. Arbori-
culture & Urban Forestry 37:74–83.
Schwan, T.D., and K.A. Elliott. 2010. Effects of diameter-limit by-laws
on forestry practices, economics, and regional wood supply for
private woodlands in southwestern Ontario. The Forestry Chronicle
Smitley, D.R., T. Davis, and E.J. Rebek. 2008. Progression of ash canopy
thinning and dieback outward from the initial infestation of emer-
ald ash borer (Coleoptera: Buprestidae) in southeastern Michigan.
Journal of Economic Entomology 101:1643–1650.
Smith, E. L., A.J. Storer, and B.K. Roosien. 2009. Emerald ash borer
infestation rates in Michigan, Ohio, and Indiana. p. 96. In: K.A.
McManus and K.W. Gottschalk. Proceedings. 20th U. S. Department
of Agriculture interagency research forum on invasive species 2009.
Gen. Tech. Rep. NRS-P-51. Newtown, PA, U.S. Department of Agri-
culture, Forest Service, Northern Research Station.
Statistics Canada. 2007. Community Profiles. 2006 Census. Statistics
Canada Catalogue no. 92-591-XWE. <
Sydnor, T.D., M. Bumgardner, and A. Todd. 2007. The potential eco-
nomic impacts of emerald ash borer (Agrilus planipennis) on Ohio,
U.S., communities. Arboriculture & Urban Forestry 33:48–54.
Sydnor, T.D., M. Bumgardner, and S. Subburayalu. 2011. Community
ash densities and economic impact potential of emerald ash borer
(Agrilus planipennis) in four midwestern states. Agriculture & Urban
Forestry 37:84–89.
Taylor, R.A.J., L.S. Bauer, T.M. Poland, and K.N. Windell. 2010. Flight
performance of Agrilus planipennis (Coleoptera: Buprestidae) on a
flight mill and in free flight. Journal of Insect Behavior 23:128–148.
USDA-APHIS. 2011. Emerald ash borer quarantine map. Accessed
06/14/2011. <
Weitzman, M. 1994. On the “environmental” discount rate. Journal of
Environmental Economics and Management 26:200–209.
Arboriculture & Urban Forestry 38(3): May 2012
©2012 International Society of Arboriculture
Woodall, C.W., C.M. Oswalt, J.A. Westfall, C.H. Perry, M.D. Nelson, and
A.O. Finley. 2009. An indicator of tree migration in forests of the east-
ern United States. Forest Ecology and Management 257:1434–1444.
Yemshanov, D., F.H. Koch, D.W. McKenney, M.C. Downing, and F.F.
Sapio. 2009a. Mapping invasive species risks with stochastic models:
A cross-border United States-Canada application for Sirex noctilio
Fabricius. Risk Analysis 29:868–884.
Yemshanov, D., D.W. McKenney, P. de Groot, D. Haugen, D. Sidders,
and B. Joss. 2009b. A bioeconomic approach to assess the impact of
an alien invasive insect on timber supply and harvesting: A case study
with Sirex noctilio in eastern Canada. Canadian Journal of Forest Re-
search 39:154–168.
Daniel W. McKenney (corresponding author)
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
John H. Pedlar
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
Denys Yemshanov
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
D. Barry Lyons
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
Kathy L. Campbell
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
Kevin Lawrence
Natural Resources Canada, Canadian Forest Service
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, ON, P6A 2E5, Canada
Résumé. L’agrile du frêne est un insecte perceur invasif qui cause
la mortalité à grande échelle des frênes (Fraxinus spp.) en Amérique du
Nord. La présente étude présente une estimation des coûts économiques
associés à la mortalité par l’agrile des frênes le long des rues et dans les
cours arrières privées en milieu urbain au Canada sur une période de 30 ans.
L’approche a fait appel un simple modèle de dispersion pour estimer le mo-
ment d’arrivée de l’agrile du frêne au sein de chaque ville en se basant sur
trois vitesse maximales de propagation: lente (~10 km/an), moyenne (~30
km/an) et rapide (~50 km/an). Les coûts sont estimés en fonction de quatre
taux d’escompte (0%, 2%, 4% et 10%) et trois niveaux de traitement (0%,
10% et 50% des arbres traités avec un insecticide). La densité en frêne le
long des rues urbaines a été estimée à partir de sources variées, incluant une
méthode d’évaluation récemment développée qui permet une évaluation
rapide de la composition en arbres des rues. En se basant sur une vitesse de
propagation de 30 km/an, un taux d’escompte de 4% et un taux de traite-
ment de 10%, les coûts sont estimés à environ 524 millions de dollars CAN
(en dollars de 2010); cette valeur s’accroît de manière brute d’environ 890
millions de dollars si on y ajoute les coûts associés aux arbres dans les cours
arrières privées. Ces estimations sont conservatrices parce qu’elles mettent
en évidence seulement les dommages associés aux arbres de rues (et dans
les cours arrières privées); quoiqu’il en soit, leur magnitude constitue une
justification majeure pour investir dans les moyens qui permettront de ral-
entir la progression de l’agrile du frêne au Canada.
Zusammenfassung. Der Asiatische Eschenprachtkäfer (EAB) ist ein
invasives, Phloem-schädigendes Insekt, welches zu flächendeckendem
Absterben von Eschen in Nordamerika führt. Die gegenwärtige Studie
bewertet die ökonomischen Kosten, die mit dem massenhaften Absterben
von Eschen als Strassenbäume durch den EAB in Kanadas besiedelten
Räumen über einen Zeitraum von 30 Jahren. Der Ansatz verwendet ein
einfaches Streumodel zur Abschätzung des Eintreffens des Käfers in der
jeweiligen Kommune, basierend auf drei maximalen Streuraten: langsam
(~10 km/ Jahr), mittel (~30 km/ Jahr), und schnell (~50 km/Jahr). Die
Kosten wurden für vier Abschlagsraten (0%, 2%, 4%, und 10%) und drei
Behandlungsraten (0%, 10%, und 50% der Bäume, die mit einem Insekti-
zid behandelt wurden). Die Eschendichte entlang der Strassen wurde an-
hand von verschiedenen Quellen geschätzt, einschließlich einer kürzlich
entwickelten Erhebung, die eine schnelle Erfassung der Baumartenzusam-
mensetzung erlaubt. Basierend auf der 30 km/Jahr-Ausbreitungsrate, einer
4 % Abschlagsrate und einer 10 % Behandlungsrate wird der gegenwärtige
Wert der Kosten mit schätzungsweise CAD$ 524 Millionen(Wechselkurs-
Stand 2010) angenommen. Dieser Wert steigt grob geschätzt auf $ 890
Millionen, wenn die Kosten der Bäume in den Hinterhöfen hinzuaddiert
werden. Die Schätzungen sind konservativ, weil sie nur auf den Schaden an
Strassen- (und Hinterhof-)bäumen fokussieren, nichtsdestotrotz gibt ihre
Höhe doch eine ernstzunehmenden Faktor bei der Berechnung von Inves-
titionen zur Eindämmung des Prachtkäfers in Kanada.
Resumen. El barrenador esmeralda del fresno (EAB) es un insecto
invasivo del floema que causa mortalidad extensiva del fresno (Fraxinus
sp) en Norte América. Este estudio estimó los costos económicos asocia-
dos con EAB-mortalidad relacionada de árboles de calles y patios en áreas
urbanas de Canadá en un periodo de 30 años. Esta aproximación empleó
un modelo simple de propagación para los tiempos de arribo de EAB a
cada comunidad con base en tres tasas máximas: lenta (~10 km/año), me-
dia (~30 km/año), y rápida (~50 km/año). Los costos son estimados para
cuatro tasas de descuento (0%, 2%, 4%, y 10%) y tres tasas de tratamiento
(0%, 10%, y 50%) de árboles tratados con un insecticida. Se estimó la den-
sidad del fresno a lo largo de las vías urbanas de una variedad de fuentes,
incluyendo una encuesta reciente que permite una evaluación rápida de la
composición de árboles. Con base en una tasa de propagación de 30 km/
año, una tasa de descuento del 4%, y una tasa de tratamiento del 10%, el
valor presente de los costos es estimado aproximadamente en CAD $524
millones (valores del 2010); este valor incrementa a $890 millones cuando
se incluyen los costos asociados con árboles de los patios. Estas estimacio-
nes son conservadoras debido a que se enfocan solamente al daño a árboles
de las calles (y patios); no obstante, su magnitud sugiere justificación con-
siderable de inversiones para reducir la propagación de EAB en Canadá.
... Assisted migration is being increasingly applied in forestry, particularly for species that may be unable to grow optimally as their local environments get drier and warmer (GC, 2014b). Most assisted migration actions and proposals have to date focused on intracontinental, single-species movements within or just beyond their native range (Pedlar et al., 2012). For example, British Columbia was the first jurisdiction in Canada to implement an explicit policy to facilitate the movement of western larch (Larix occidentalis) seed from southern to northern regions of the province (Klenk, 2015). ...
... 30-year economic impact of emerald ash borer in Canada (from 2009 to 2039) was estimated to be between $0.5 to $1.5 billion (McKenney et al., 2012). ...
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Plants sustain life on Earth, providing humans and other organisms with food, shelter, and clean air. They are foundational to the economic, cultural, physical, and spiritual well-being of people in Canada. Although plants are a constant ― often unnoticed ― presence in our lives, they are increasingly at risk and under pressure. Plants face many threats, such as rising temperatures, changing precipitation patterns, extreme weather events, disease, and new predators, all of which have been exacerbated by climate change, the global movement of people and goods, and evolutionary processes. There is still a great deal to learn about how stressors affect plants and their relationships with pests and the environment. It’s clear, however, that the risks to plant health also threaten the health of broader ecosystems, affecting climate, human and animal health, biodiversity, and food security. Addressing current and emerging risks to plant health is vital to the survival of life on Earth. Cultivating Diversity examines the existing and emerging risks to plant health in Canada and offers insights into promising practices that may help to mitigate them. The report focuses on key areas of risk, rather than specific risks, as well as strategies to reduce vulnerability and increase resilience.
... The risk of having tree monocultures in cities has been demonstrated in the United States (US) and Canada through devastating outbreaks of the chestnut blight fungus [Cryphonectria parasitica (Murrill) Barr], Dutch elm disease [Ophiostoma novo-ulmi (Buisman) Melin and Nannf.], and more recently from the emerald ash borer (Agrilus planipennis Fairmaire) (Sinclair and Campana, 1978;Schlarbaum et al., 1997;Raupp et al., 2006). Emerald ash borer, which attacks trees in the Fraxinus genus, has spread to 35 states in the US (USDA and APHIS, 2020) and is estimated to have cost North American cities over 10 billion USD (2010 currency rate) to manage (Kovacs et al., 2010;McKenney et al., 2012). In response to such losses from invasive pests and pathogens, and the recognition among urban forestry professionals that there was a historical overreliance on a limited set of species, practitioners and researchers have supported species diversification since the 1970s Roman et al., 2018). ...
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Urban forests provide critical environmental benefits, but the resilience of these socio-ecological systems to stresses like pest and disease outbreaks relies on tree health and diversity. Despite this, low species diversity continues to be a challenge in urban forest management. Using a participatory research approach in central Florida (United States), we selected and tested underutilized native tree species (Celtis laevigata Willd., Ilex vomitoria Aiton, Taxodium ascendens Brongn., Ulmus alata Michx., and Viburnum obovatum Walter) in two urban settings (streetscape and park) in four communities (total n = 200). Our collaborative process was organized into five steps, including a 2-year monitoring period to assess mortality and health through establishment. At the end of the trial, 156 trees survived with annual mortality rates differing by species and plot type. Taxodium ascendens had the highest annual mortality of the five species trialed. Overall, U. alata and V. obovatum showed the greatest potential in central Florida urban settings. Our tree selection process can guide others who want to create forward-thinking and diverse planting lists. Furthermore, this project demonstrates that co-production of knowledge involving members of local municipalities, practitioners, and researchers can be an effective strategy for selecting and testing underutilized tree species.
... We adapted the problem 1 and 2 formulations to develop optimal survey strategies for the EAB in Winnipeg, Canada. EAB has destroyed ash populations in much of the eastern United States and eastern Canada (Herms & McCullough, 2014;Kovacs et al., 2010;McKenney et al., 2012). EAB spread is assisted by vehicular transport (Buck & Marshall, 2008) and movement of infested materials (Haack, Petrice, & Wiedenhoft, 2010;Short et al., 2019). ...
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1. Multi-day survey campaigns are critical for timely detection of biological invasions. We propose a new modelling approach that helps allocate survey inspections in a multi-day campaign aimed at detecting the presence of an invasive organism. 2. We adopt a team orienteering problem to plan daily inspections and use an acceptance sampling approach to find an optimal surveillance strategy for emerald ash borer in Winnipeg, Manitoba, Canada. The manager's problem is to select daily routes and determine the optimal number of host trees to inspect with a particular inspection method in each survey location, subject to upper bounds on the survey budget, daily inspection time, and total survey time span. 3. We compare optimal survey strategies computed with two different management objectives. The first problem minimizes the expected number of survey sites (or area) with undetected infestations. The second problem minimizes slippage-the expected number of undetected infested trees in sites that were not surveyed or where the surveys did not find infestation. 4. We also explore the impact of uncertainty about site infestation rates and detection probabilities on the surveillance strategy. Accounting for uncertainty helps address temporal and spatial variation in infestation rates and yields a more robust surveillance strategy. The approach is generalizable and can support delimiting survey programs for biological invasions at various spatial scales.
... Several economic evaluations and simulations compared costs of removing and replacing landscape ash trees with annualized costs of treating the same ash trees in alternate years with the TREE-age ® product. Results consistently demonstrated that treating trees was substantially less expensive than removing and replacing trees, either proactively or as they succumbed to EAB (Hauer and Peterson, 2017, Kovacs et al., 2014, McKenney et al., 2012, Sadof et al., 2017, Vannatta et al., 2012. More recent studies have shown that emamectin benzoate applied at low or moderate rates provided 3 years of highly effective EAB control (Bick et al., 2018;McCullough et al., 2019), further reducing costs. ...
Emerald ash borer (EAB) (Agrilus planipennis Fairmaire), discovered in southeastern Michigan, USA in 2002, has become the most destructive and costly invasive forest insect in North America. This phloem-boring beetle has also invaded Moscow, Russia and continued spread of EAB potentially threatens European ash (Fraxinus spp.) species. This review summarizes EAB life history, including interspecific variation in host preference, invasion impacts and challenges of detecting new infestations and provides an overview of available management tactics. Advances in systemic insecticides, particularly emamectin benzoate products applied via trunk injection, have yielded effective and practical options both to protect individual trees and to slow EAB population growth and ash decline on an area-wide basis without disrupting natural enemies. Economic costs of treating ash are substantially lower than removal costs, retain ecosystem services provided by the trees, reduce sociocultural impacts and conserve genetic diversity in areas invaded by EAB. Girdled ash trees are highly attractive to EAB adults in low-density populations and debarking small girdled trees to locate larval galleries is the most effective EAB detection method. An array of woodpeckers, native larval parasitoids and introduced parasitoids attack EAB life stages but mortality is highly variable. Area-wide management strategies that integrate insecticide-treated trees, girdled ash trap trees and biological control can be adapted for local conditions to slow and reduce EAB impacts.
The hardiness of Fraxinus spp. (ash) make them a common municipal tree in adverse growing conditions. In Winnipeg, Manitoba, the impacts of Dutch elm disease resulted in increased reliance on Fraxinus, resulting in a monoculture of Fraxinus across the city. Emerald ash borer (EAB) (Agrilus planipennis) poses substantial risk to Winnipeg's urban forest, forecasted to result in the total loss of Fraxinus in Winnipeg. With a lens of distributional equity, this study examines associations between Fraxinus abundance and distribution and human population demographics at the Dissemination Area and Census Tract levels. There are positive correlations with Fraxinus abundance and distribution and median household income and proportion of the population that self-identifies as a visible minority. Population density was positively associated with Fraxinus abundance and distribution at the Census Tract level. These results underscore the importance of assessing the distribution of vulnerable trees as a component of green equity. Using information on urban forest management in response to EAB, potential issues and possible opportunities are discussed.
The Emerald Ash Borer (EAB), Agrilus plaipennis (Coleoptera: Buprestidae) was introduced to North America more than two decades ago and has spread despite management efforts in both the United States and Canada. The insect kills most species of ash tree (Fraxinus sp.) and its management imposes costs to plant health protection agencies, forest industry, private landowners and municipalities. The United States Department of Agriculture – Animal and Plant Health Inspection Service (USDA-APHIS) has deemed existing regulation efforts in the United States to be ineffective and has removed federal regulations designed to limit the spread of EAB. The Canadian Food Inspection Agency (CFIA) is also trying to determine if continued regulation of EAB in Canada is worthwhile. Here we show that the benefits of slowing the spread of EAB via regulation are likely greater than the costs of implementing regulation if it is minimally effective (i.e. more than 25% effective at preventing anthropogenic spread). To evaluate the economic efficiency of existing Canadian EAB regulations, we examined trade-offs between the monetary benefits of regulation and the costs of regulation. Specifically, we simulated the spread of EAB under various levels of regulation effectiveness and estimated the timing of EAB arrival and associated ash mortality in urban and rural settings. Delaying ash mortality via regulation also delays management costs, a benefit to ash tree owners/users. Our findings suggest that an economic justification to continue regulating the insect exists based on monetary costs alone. The net present value of regulation (benefits less costs) is estimated to range between $23 million to $240 million, depending on the level of regulation effectiveness. Additional environmental and social benefits not addressed here would likely increase the value of EAB regulation but appear unneeded to justify such efforts on allocative efficiency grounds.
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en Environmental risk assessment (ERA) is an important component of risk analysis for plant pests and invasive alien species (IAS), and a standardized and consistent methodology has recently been developed for evaluating their impact on ecosystem services and biodiversity. This paper presents the application of this innovative methodology for ERA to Agrilus planipennis, the emerald ash borer, which causes significant mortality to Fraxinus (ash) species in forests and urban areas of North America (here: USA and Canada, excluding Mexico) and Russia. The methodology follows a retrospective analysis and summarizes information and observations in invaded areas in North America and Russia. Uncertainty distributions were elicited to define quantitatively a general pattern of the environmental impact in terms of reduction in ecosystem provisioning, supporting and regulating services, and biodiversity components. The environmental impacts of A. planipennis are time‐ and context‐dependent, therefore two time horizons of 5 and 20 years after introduction and two ecosystems (urban and forest) were considered. This case study shows that the quantitative assessment of environmental impacts for IAS is both possible and helpful for decision‐makers and risk managers who have to balance control costs against potential impacts of IAS. Comment l'agrile du frêne (Agrilus planipennis) affecte‐t‐il les services écosystémiques et les composantes de la biodiversité dans les zones envahies ? fr L'évaluation des risques environnementaux est une composante importante de l'analyse de risque des organismes nuisibles aux plantes et des espèces exotiques envahissantes. Une méthodologie standardisée et cohérente a récemment été mise au point afin d’évaluer leur impact sur les différents services écosystémiques et sur la biodiversité. Ce document présente l'application de cette méthodologie innovante pour l'évaluation des risques environnementaux d’Agrilus planipennis, l'agrile du frêne, causant la mortalité d’espèces de Fraxinus (frêne) dans les forêts et zones urbaines d'Amérique du Nord (ici : États‐Unis et Canada, à l'exclusion du Mexique) et de Russie. La méthodologie suit une analyse rétrospective et synthétise les informations et observations des zones envahies en Amérique du Nord et en Russie. Des distributions d'incertitude ont été établies afin de présenter une image globale etquantifiée de l'impact environnemental en termes de réduction de l'apport des services écosystémiques, des services de support et de régulation, et des composantes de la biodiversité. Les impacts environnementaux d'A. planipennis dépendent de facteurs temporaux et contextuels, c'est pourquoi deux horizons temporels (à 5 et 20 ans après introduction de l’organisme) et deux écosystèmes (urbain et forestier) ont été pris en compte. Cette étude de cas montre que l'évaluation quantitative des impacts environnementaux des espèces exotiques envahissantes est à la fois réalisable et utile pour les décideurs et gestionnaires de risques qui doivent comparer les coûts de la lutte avec les impacts potentiels de ces espèces. Как ясеневая изумрудная узкотелая златка (Agrilus planipennis) воздействует на функции экосистемные услуги и элементы биоразнообразия в зонах инвазии ? ru Oцeнкa экoлoгичecкoгo pиcкa (OЭP) являeтcя вaжным элeмeнтoм aнaлизa pиcкa для вpeдныx opгaнизмoв для pacтeний opгaнизмoв и инвaзивныx чyжepoдныx видoв (ИЧB). Heдaвнo былa paзpaбoтaнa cтaндapтизиpoвaннaя и coглacoвaннaя мeтoдoлoгия для oцeнки иx вoздeйcтвия нa фyнкции экocиcтeмныe ycлyги и биopaзнooбpaзиe. B дaннoй cтaтьe пpeдcтaвлeнo пpимeнeниe иннoвaциoннoй мeтoдики OЭP к Agrilus planipennis, яceнeвoй изyмpyднoй yзкoтeлoй злaткe, кoтopaя вызывaeт знaчитeльнyю cмepтнocтьпoтepю видoв poдa Fraxinus (яceня) в лecax и гopoдcкиx зoнaxpaйoнax Ceвepнoй Aмepики (здecь: CШA и Кaнaдa, иcключaя Meкcикy) и Poccии. Meтoдoлoгия ocнoвaнa нa peтpocпeктивнoм aнaлизe и oбoбщaeт инфopмaцию и нaблюдeния в зoнax инвaзии в Ceвepнoй Aмepикe и Poccии. Pacпpeдeлeниe нeoпpeдeлёeннocтeйи былo иcпoльзoвaнo для кoличecтвeннoгo oпpeдeлeния oбщeй тeндeнции вoздeйcтвия нa oкpyжaющyю cpeдy c тoчки зpeния coкpaщeния oбecпeчeния экocиcтeмныx ycлyг, пo cнaбжeнию, пo пoддepжкeвcпoмoгaтeльныx и пo peгyлиpoвaниюyющиx фyнкции, a тaкжe элeмeнтoв биopaзнooбpaзия. Boздeйcтвиe A. planipennis нa oкpyжaющyю cpeдy зaвиcит oт вpeмeни и кoнтeкcтa, пoэтoмy были paccмoтpeны двa вpeмeнныx интepвaлa в 5 и 20 лeт пocлe интpoдyкции и двe экocиcтeмы (гopoдcкaя и лecнaя). ДaннoeHacтoящee тeмaтичecкoe иccлeдoвaниe пoкaзывaeт, чтo кoличecтвeннaя oцeнкa вoздeйcтвия нa oкpyжaющyю cpeдy для ИЧB являeтcя вoзмoжнoй и пoлeзнoй кaк для лиц, пpинимaющиx peшeния, тaк и для cпeциaлиcтoв пo yпpaвлeнию pиcкaми, кoтopым нeoбxoдимo oбecпeчить бaлaнc мeждy зaтpaтaми нa бopьбy и пoтeнциaльным нeгaтивным вoздeйcтвиeм ИЧB.
Managing exotic invasive pests like emerald ash borer can strain budgets and the capacity of cities to protect their urban forest. Area-wide management approaches, like SLAM (SL.ow M.ortality), can potentially protect trees at a greatly reduced cost. We tested this strategy in three urban forests in Indiana by treating 40 % of the ash trees with insecticides. While the urban SLAM approach reduced overall mortality of untreated ash trees, survivorship varied considerably between sites. SLAM was most successful (54 % survival) where initially < 10 % of the ash trees were moribund (canopy thinning > 30 %) and 40 % of all trees were treated with emamectin benzoate every two years. The approach was less successful (38 % survival) in a site with similar initial ash morbidity but where 15 % of trees were treated with emamectin benzoate and 25 % with annual applications of imidacloprid. In the third site, where 51 % of ash forest were initially moribund and 40 % of the ash trees were treated, only 23 % survived. Overall survival of treated ash trees declined by 18–22 %, and trees that were not moribund were most likely to survive. Although many treated trees that were initially moribund regained their health by the end of the project, this was not the case for untreated ash trees. Where SLAM was most successful, both untreated and treated white ash were more likely to survive than green ash trees. Untreated ash trees at all three sites were more likely to survive when closer to trees treated with emamectin benzoate, but not to those treated with imidacloprid. Our findings suggest that the SLAM approach can protect urban ash trees, but its success is strongly influenced by initial tree condition, species composition and proximity to treated ash trees.
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The Emerald Ash Borer (EAB) was likely introduced to North America in the early 1990s and has since become a highly destructive invasive forest pest. From 2002 onwards, federal quarantines have regulated the movement of at-risk ash commodities in both Canada and the United States (U.S.). Despite these regulations, the EAB has spread rapidly from Michigan and southern Ontario to much of eastern North America, leaving millions of dead ash trees in its wake. As of 2019, the EAB was present in 36 states in the U.S. and 5 Canadian provinces, including Manitoba, Ontario, Québec, New Brunswick and Nova Scotia. The U.S. recently evaluated the effects of removing domestic EAB quarantine regulations. In this context, our study examined the costs and benefits of EAB regulations in Canada. We estimated the cost of EAB regulation by combining applicable Canadian Food Inspection Agency (CFIA) administrative costs and program compliance costs faced by participating wood product mills. The benefits of regulation were determined as the value of slowing its spread by delaying damage to high-valued street ash trees in communities and to rural trees. The model focused on the economic costs associated with the EAB and did not include an estimate of the environmental and social impacts of EAB regulation. An analysis of these non-monetary values would complement the current study and could be explored in future research but was not required to justify the regulatory efforts on allocative efficiency grounds. We assessed the economic costs and benefits of EAB regulation by simulating differences in expected damage with and without quarantine regulations in place. The actual effectiveness of regulation was uncertain and difficult to quantify. We, therefore, explored a wide range of possible effectiveness levels to ensure that we captured the true level of regulation effectiveness. We did not comment on the effectiveness of current (and past) EAB regulations since this was beyond the scope of our analysis. Estimated annual regulatory management costs to the CFIA were approximately $441,634, while estimated annual regulatory costs to industry varied between $0.39 million and $2.37 million. Street and rural tree damage cost estimates due to the EAB ranged from $1,422 million under a no regulation simulation to $1,170 million under a regulation with 95% effectiveness over this period. Results suggest if regulatory measures have even a 10% effect in slowing EAB spread to places not already affected, then the effort could be economically efficient, although the regulations as modeled did not stop EAB movement. It follows that the value of delayed damage of ash street trees and rural ash alone is large enough in most cases to justify continuing EAB regulation.
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This review summarizes current knowledge of the status and threats to the plants and fungi of Great Britain and the UK Overseas Territories (UKOTs). Although the body of knowledge is considerable, the distribution of information varies substantially, and we highlight knowledge gaps. The UK vascular flora is the most well studied and we have a relatively clear picture of its 9,001 native and alien taxa. We have seedbanked 72% of the native and archaeophyte angiosperm taxa and 78% of threatened taxa. Knowledge of the UKOTs flora varies across territories and we report a UKOTs flora comprising 4,093 native and alien taxa. We have conserved 56% of the native flora and 51% of the threatened vascular plants in Kew's Millennium Seed Bank, UK. We need a better understanding of the conservation status of plants in the wild, and progress toward completion or updating national red lists varies. Site‐based protection of key plant assemblages is outlined, and progress in identifying Important Plant Areas analyzed. Knowledge of the non‐vascular flora, especially seaweeds remains patchy, particularly in many UKOTs. The biggest gaps overall are in fungi, particularly non‐lichenized fungi. Considerable investment is needed to fill these knowledge gaps and instigate effective conservation strategies.
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Described here is the development of a web-based cost calculator for projecting management costs and restoration, during a planned response to an emerald ash borer invasion, in the City of Indianapolis, IN, U.S. Forest sizes, measured as the sum of tree diameters, and costs of managing urban ash trees were projected under various management scenarios over a 25-year period. The study authors illustrate how a city can use local, information to compare management plans. Although the simple strategy of treating all ash trees provided the lowest annual, cost and produced, the largest forest, this option was ultimately the most expensive. Simply removing ash trees and replacing them with resistant trees restored the forest to its initial size after 25 years. However, after taking five years to complete tree removal and replacement, the initial ash forest was reduced to a mere 27% of its original size. When, this management plan, was modified, by protecting trees in the median, size class with insecticides, the restoration forest was below 50% of the initial size for two years but at a discounted cost that was only 6% greater than replacing all trees. The authors of the study describe how the cost calculator can be used to address the unique local attributes of urban forests.
A survey of 586 community representatives with urban tree canopy responsibilities was conducted to provide data on ash density within four states in the Midwestern U.S., and to examine potential economic losses should emerald ash borer (EAB) become established in their communities. One hundred twenty-three responses were received from communities of various sizes. Data represented 10.5% of the population of Illinois, Indiana, Michigan, and Wisconsin, U.S., and 21% of all communities surveyed. Assuming the complete loss of ash due to EAB, losses in landscape value for ash trees within community boundaries were estimated to be between USD $7.7 (median-based) and $15 billion (mean-based). The cost to remove those trees is somewhat smaller and would be between $3 and $5.8 billion. Replacing trees lost to EAB with smaller 5 cm trees in street, park, and private plantings would cost between $2.7 and $5.2 billion. The total loss of ash for communities in the four states surveyed, including landscape losses, tree removals, and replacements are estimated to be between. $ 13.4 and $26 billion. The potential total costs per 1,000 residents in the four-state region is estimated to be between. $395,943 and $769,687. The rates per 1,000 residents estimates can be utilized by communities to begin developing contingency plans should EAB impact them.
A model is presented to assist in deciding the fate of ash trees (Fraxinus spp.) threatened by the arrival of emerald ash borer (Agrilus planipennis Fairmaire) in North America. The model tracks ongoing treatment costs versus one-time costs associated with removal and replacement. All future values are discounted following standard economic practice. For each year over a period of interest, the net treatment gain/ loss is calculated, indicating the period of time over which a homeowner would be financially ahead/behind by treating the existing ash tree. The model was populated, with values that may be expected in Canadian conditions, where treatment options are more limited than in the United States. Optional model features include property value premiums, energy savings, runoff and pollution benefits, and ongoing maintenance costs. When these extended benefits and costs are included, positive treatment gains for a medium-sized ash persist for about 17 years. Negative values can be interpreted as a "break-even existence value," an amount a homeowner would be required to pay in order to protect their ash if various other benefit flows fail to compensate the costs. An interactive version of the model is available online (
Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), a phloem-feeding insect native to Asia, was identified in 2002 as the cause of widespread ash (Fraxinus) mortality in southeast Michigan, U.S. and Windsor, Ontario, Canada. Little information about A. planipennis is available from its native range and it was not known whether this invasive pest would exhibit a preference for a particular North American ash species. We monitored A. planipennis density and canopy condition on green ash (F. pennsylvanica) and white ash (F. americana) street trees in four neighborhoods and on white and blue ash (F. quadrangulata) trees in two woodlots in southdast Michigan. Green ash street trees had significantly more canopy dieback and higher A. planipennis densities than white ash trees growing in the same neighborhood. Density increased by two- to fourfold in both species over a 3-year period. Canopy dieback increased linearly from 2002 to 2005 as A. planipennis density increased (R2 = 0.70). In each of the woodlots, A. planipennis densities were significantly higher on white ash trees than blue ash trees. Woodpecker predation occurred in all sites and accounted for 35% of the A. planipennis that developed on trees we surveyed. Results indicate that surveys for A. planipennis detection in areas with multiple ash species should focus on the relatively preferred species.
The agriculturally dominated Counties of Huron and Perth in southwestern Ontario regulate forest harvesting on private land through diameter-limit-based tree conservation by-laws. The rates of harvesting, along with the volume and value of timber sales and the type and quantity of tree marking were examined for the years 1997 to 1999. Although these harvests may form an important part of periodic farm income, at only 13% forest cover, these landscapes may be further degraded by unsustainable forest harvesting practices. Based on the three study years, the mean annual area of forest harvested was found to be 4.4% of the total private forest landbase. The mean volume harvested from upland and lowland deciduous forest was 4666 and 6148 fbm/ha, respectively. Over-harvesting under a diameter-limit or hybrid method occurred in 8% of woodlot area with removal rates in excess of 10 000 fbm/ha. The most severe over-harvesting disproportionately targeted lowland woodlots, possibly compromising the ecological health of these often sensitive areas. Sugar maple, red/silver maple and ash were most commonly harvested at 33%, 31% and 21% of total species volume, respectively.On average, for standing timber, landowners received $680/Mfbm in the upland hardwood forests and $281/Mfbm in the lowland hardwood forests. On an area basis, mean price paid was $3680/ha and $1956/ha respectively on upland and lowland forests. Only 8% of the private land was harvested using single-tree selection or stand improvement (92% harvest was diameter-limit or a hybrid of same). Using a simple model, we found that woodlot owners comprising at least 74% of private woodland area would need to participate in forest harvesting in order to maintain the 1997 to 1999 partial harvest area rate of 2349 ha/yr. This rate may not be sustainable, given poor forest conditions in some areas, past management practices and a reduction in landowners interested in forest harvesting. Improvements are needed to bring the level of good forestry practice up by 62% to meet the rates that were being performed under pre-1994, free, provincial government private land forestry programs.