Assessing risks of uncertain but potentially damaging events, such as environmental disturbances,... more Assessing risks of uncertain but potentially damaging events, such as environmental disturbances, disease outbreaks and pest invasions, is a key analytical step that informs subsequent decisions about how to respond to these events. We present a continuous risk measure that can be used to assess and prioritize environmental risks from uncertain data in a geographical domain. The metric is influenced by both the expected magnitude of risk and its uncertainty. We demonstrate the approach by assessing risks of human-mediated spread of Asian longhorned beetle (ALB, Anoplophora glabripennis) in Greater Toronto (Ontario, Canada). Information about the human-mediated spread of ALB through this urban environment to individual geographical locations is uncertain, so each location was characterized by a set of probabilistic rates of spread, derived in this case using a network model. We represented the sets of spread rates for the locations by their cumulative distribution functions (CDFs) an...
Long-distance introductions of new invasive species have often been driven by socioeconomic facto... more Long-distance introductions of new invasive species have often been driven by socioeconomic factors, such that traditional ‘‘biological’ ’ invasion models may not be capable of estimating spread fully and reliably. In this study we present a new methodology to characterize and predict pathways of humanassisted entries of alien forest insects. We have developed a stochastic quantitative model of how these species may be moved with commodity flow through a network of international marine ports and Electronic supplementary material The online version of this article (doi:10.1007/s10530-011-0117-5) contains supplementary material, which is available to authorized users.
Pest risk maps are an important source of decision support when devising strategies to minimize i... more Pest risk maps are an important source of decision support when devising strategies to minimize introductions of invasive organisms and mitigate their impacts. When possible management responses to an invader include costly or socially sensitive activities, decision makers tend to follow a more certain (i.e. risk-averse) course of action. We present a new mapping technique that assesses pest invasion risk from the perspective of a risk-averse decision maker. We demonstrate the approach by evaluating the likelihood that an invasive forest pest will be transported to one of the continental US states or Canadian provinces in infested firewood that may be carried by visitors to US federal campgrounds. We test the impact of the risk aversion assumption using distributions of plausible pest arrival scenarios generated with a geographically explicit model developed from data documenting camper travel across the study area. Next, we prioritize regions of high and low pest arrival risk via a...
Pest risk modelling and mapping for invasive alien species, 2015
Uncertainty is inherent in model-based forecasts of ecological invasions. In this chapter, we exp... more Uncertainty is inherent in model-based forecasts of ecological invasions. In this chapter, we explore how the perceptions of that uncertainty can be incorporated into the pest risk assessment process. Uncertainty changes a decision maker's perceptions of risk; therefore, the direct incorporation of uncertainty may provide a more appropriate depiction of risk. Our methodology borrows basic concepts from portfolio valuation theory that were originally developed for the allocation of financial investments under uncertainty. In our case, we treat the model-based estimates of a pest invasion at individual geographical locations as analogous to a set of individual investment asset types that constitute a 'portfolio'. We then estimate the highest levels of pest invasion risk by finding the subset of geographical locations with the 'worst' combinations of a high likelihood of invasion and/or high uncertainty in the likelihood estimate. We illustrate the technique using a...
ABSTRACT Geographically explicit land use change models based on net present value have been crit... more ABSTRACT Geographically explicit land use change models based on net present value have been criticized for not reflecting the breadth of economic considerations relevant to private land use decisions. An alternative approach is to econometrically estimate land allocations from historical transactions, but this approach requires extensive historical econometric data sets, which may not be available, and may be difficult to model spatially.We show that a geographically explicit net present value approach inclusive of an option value to defer land conversion can be a viable and insightful alternative to econometric approaches. The model is applied to Alberta, Canada where historical land use change data are not available. The elasticity estimates of converting agricultural land to afforestation, 0.21 to 0.37, are similar to other North American estimates from econometric studies.
In pest risk assessment it is frequently necessary to make time-critical decisions regarding mana... more In pest risk assessment it is frequently necessary to make time-critical decisions regarding management of expanding pest populations. When an invasive pest outbreak is expanding rapidly, preemptive quarantine of areas that are under imminent threat of infestation is one of only a few available management tools that can be implemented quickly to help control the expansion. The preemptive quarantine of locations that surround an infested area also acts as a safeguard to counteract the risk of failed detections of the pest in field surveys. In this paper, we present a method that assesses the suitability of preemptive quarantine measures at the level of small geographical subdivisions (U.S. counties). The cost of a preemptive quarantine in a given county is weighed against the protective benefit of delaying the spread of an outbreak to other neighboring counties. We demonstrate the approach with a decision support model that estimates the suitability of preemptive quarantine across mu...
Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spr... more Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spread of alien species. One pathway of concern in North America is the possible spread of forest pests in firewood carried by visitors to campgrounds or recreational facilities. We present a network model depicting the movement of campers and, by extension, potentially infested firewood. We constructed the model from US National Recreation Reservation Service data documenting more than seven million visitor reservations (including visitors from Canada) at campgrounds nationwide. This bi-directional model can be used to identify likely origin and destination locations for a camper-transported pest. To support broad-scale decision making, we used the model to generate summary maps for 48 US states and seven Canadian provinces that depict the most likely origins of campers traveling from outside the target state or province. The maps generally showed one of two basic spatial patterns of out-o...
... SUPPLY AND HARVESTS IN EASTERN CANADA Denys Yemshanov1, Daniel W. McKenney1, Peter de Groot1,... more ... SUPPLY AND HARVESTS IN EASTERN CANADA Denys Yemshanov1, Daniel W. McKenney1, Peter de Groot1, Dennis Haugen2, Derek Sidders3, and Brent ... Edmonton, AB T6H 3S5 Canada ABSTRACT This study focuses on an emerging threat, Sirex noctilio Fabricius, a pine ...
Assessing risks of uncertain but potentially damaging events, such as environmental disturbances,... more Assessing risks of uncertain but potentially damaging events, such as environmental disturbances, disease outbreaks and pest invasions, is a key analytical step that informs subsequent decisions about how to respond to these events. We present a continuous risk measure that can be used to assess and prioritize environmental risks from uncertain data in a geographical domain. The metric is influenced by both the expected magnitude of risk and its uncertainty. We demonstrate the approach by assessing risks of human-mediated spread of Asian longhorned beetle (ALB, Anoplophora glabripennis) in Greater Toronto (Ontario, Canada). Information about the human-mediated spread of ALB through this urban environment to individual geographical locations is uncertain, so each location was characterized by a set of probabilistic rates of spread, derived in this case using a network model. We represented the sets of spread rates for the locations by their cumulative distribution functions (CDFs) an...
Long-distance introductions of new invasive species have often been driven by socioeconomic facto... more Long-distance introductions of new invasive species have often been driven by socioeconomic factors, such that traditional ‘‘biological’ ’ invasion models may not be capable of estimating spread fully and reliably. In this study we present a new methodology to characterize and predict pathways of humanassisted entries of alien forest insects. We have developed a stochastic quantitative model of how these species may be moved with commodity flow through a network of international marine ports and Electronic supplementary material The online version of this article (doi:10.1007/s10530-011-0117-5) contains supplementary material, which is available to authorized users.
Pest risk maps are an important source of decision support when devising strategies to minimize i... more Pest risk maps are an important source of decision support when devising strategies to minimize introductions of invasive organisms and mitigate their impacts. When possible management responses to an invader include costly or socially sensitive activities, decision makers tend to follow a more certain (i.e. risk-averse) course of action. We present a new mapping technique that assesses pest invasion risk from the perspective of a risk-averse decision maker. We demonstrate the approach by evaluating the likelihood that an invasive forest pest will be transported to one of the continental US states or Canadian provinces in infested firewood that may be carried by visitors to US federal campgrounds. We test the impact of the risk aversion assumption using distributions of plausible pest arrival scenarios generated with a geographically explicit model developed from data documenting camper travel across the study area. Next, we prioritize regions of high and low pest arrival risk via a...
Pest risk modelling and mapping for invasive alien species, 2015
Uncertainty is inherent in model-based forecasts of ecological invasions. In this chapter, we exp... more Uncertainty is inherent in model-based forecasts of ecological invasions. In this chapter, we explore how the perceptions of that uncertainty can be incorporated into the pest risk assessment process. Uncertainty changes a decision maker's perceptions of risk; therefore, the direct incorporation of uncertainty may provide a more appropriate depiction of risk. Our methodology borrows basic concepts from portfolio valuation theory that were originally developed for the allocation of financial investments under uncertainty. In our case, we treat the model-based estimates of a pest invasion at individual geographical locations as analogous to a set of individual investment asset types that constitute a 'portfolio'. We then estimate the highest levels of pest invasion risk by finding the subset of geographical locations with the 'worst' combinations of a high likelihood of invasion and/or high uncertainty in the likelihood estimate. We illustrate the technique using a...
ABSTRACT Geographically explicit land use change models based on net present value have been crit... more ABSTRACT Geographically explicit land use change models based on net present value have been criticized for not reflecting the breadth of economic considerations relevant to private land use decisions. An alternative approach is to econometrically estimate land allocations from historical transactions, but this approach requires extensive historical econometric data sets, which may not be available, and may be difficult to model spatially.We show that a geographically explicit net present value approach inclusive of an option value to defer land conversion can be a viable and insightful alternative to econometric approaches. The model is applied to Alberta, Canada where historical land use change data are not available. The elasticity estimates of converting agricultural land to afforestation, 0.21 to 0.37, are similar to other North American estimates from econometric studies.
In pest risk assessment it is frequently necessary to make time-critical decisions regarding mana... more In pest risk assessment it is frequently necessary to make time-critical decisions regarding management of expanding pest populations. When an invasive pest outbreak is expanding rapidly, preemptive quarantine of areas that are under imminent threat of infestation is one of only a few available management tools that can be implemented quickly to help control the expansion. The preemptive quarantine of locations that surround an infested area also acts as a safeguard to counteract the risk of failed detections of the pest in field surveys. In this paper, we present a method that assesses the suitability of preemptive quarantine measures at the level of small geographical subdivisions (U.S. counties). The cost of a preemptive quarantine in a given county is weighed against the protective benefit of delaying the spread of an outbreak to other neighboring counties. We demonstrate the approach with a decision support model that estimates the suitability of preemptive quarantine across mu...
Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spr... more Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spread of alien species. One pathway of concern in North America is the possible spread of forest pests in firewood carried by visitors to campgrounds or recreational facilities. We present a network model depicting the movement of campers and, by extension, potentially infested firewood. We constructed the model from US National Recreation Reservation Service data documenting more than seven million visitor reservations (including visitors from Canada) at campgrounds nationwide. This bi-directional model can be used to identify likely origin and destination locations for a camper-transported pest. To support broad-scale decision making, we used the model to generate summary maps for 48 US states and seven Canadian provinces that depict the most likely origins of campers traveling from outside the target state or province. The maps generally showed one of two basic spatial patterns of out-o...
... SUPPLY AND HARVESTS IN EASTERN CANADA Denys Yemshanov1, Daniel W. McKenney1, Peter de Groot1,... more ... SUPPLY AND HARVESTS IN EASTERN CANADA Denys Yemshanov1, Daniel W. McKenney1, Peter de Groot1, Dennis Haugen2, Derek Sidders3, and Brent ... Edmonton, AB T6H 3S5 Canada ABSTRACT This study focuses on an emerging threat, Sirex noctilio Fabricius, a pine ...
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