When is a “wait and see” approach to invasive species justified?

Predictions of damages and damages that might be avoided from invasive species control policies are marred by uncertainty that has both economic and ecological roots. Public policies directed at invasive species typically lag their detection. One possible explanation is the coupling of uncertainty with political and economic commitments creates an incentive to delay a policy response in order to gain more information on how damaging the invasion will be – a “wait and see” approach. We investigate whether this rationale is justified by identifying invasion characteristics that require the wait and see approach often adopted by lawmakers and government agencies. The model shows that the source of uncertainty and degree of policy irreversibility matter and allows the classification of invasive species with a low rate of spread and low levels of uncertainty as those where policies can be optimally timed in the future.     

Modeling the human-induced spread of an aquatic invasive: The case of the zebra mussel

Ecological evidence indicates that transient recreational boating is the principal overland vector of dispersal for several freshwater invasive species. Understanding boating behavior, and how behavior responds to policy changes, is central to understanding the effectiveness of efforts to halt or slow the spread of aquatic invasives. We develop a framework that combines a recreation demand model of boating behavior with a discrete duration model describing the spatial and temporal spread of an aquatic invasive. The integrated approach allows us to link invasion risk probabilities directly to boating behavior, policy levers, and behavior changes arising from policy shocks. With an application to zebra mussels in Wisconsin we show that explicitly accounting for behavioral responses can dramatically change predictions for the effectiveness of particular policies, in some instances leading to increases in invasions risks at some sites.     

Using an integrated fuzzy set and deliberative multi-criteria evaluation approach to facilitate decision-making in invasive species management

There are two issues at the core of invasive species risk management: on the one hand, decision-makers struggle to balance environmental goals against other often competing societal goals such as economic benefits and social welfare; on the other hand, uncertainty often prevails in understanding the invasion process and in communicating invasion risks to the stakeholders. In this paper, we describe how an integrated Deliberative Multi-Criteria Evaluation (DMCE) and fuzzy set approach can tackle these two issues in the analysis of alternative risk management strategies, using the example of European House Borer (EHB, Hylotrupes bajulus Linnaeus). DMCE offers a platform for stakeholders to interact and to make a trade-off decision between multiple goals based on social learning and deliberation. The fuzzy set approach, applied within a DMCE framework, explicitly incorporates the inherent uncertainty in estimating potential EHB impacts and in evaluating participants' subjective preferences. This integrated method, therefore, provides a promising approach for tackling the dual challenges of competing goals and uncertainty in the evaluation of invasive species risk management options.     

Managing invasive alien species with professional and hobby farmers: Insights from ecological-economic modelling

Biosecurity is a great challenge to policy-makers globally. Biosecurity policies aim to either prevent invasions before they occur or to eradicate and/or effectively manage the invasive species and diseases once an invasion has occurred. Such policies have traditionally been directed towards professional producers in natural resource based sectors, including agriculture. Given the wide scope of issues threatened by invasive species and diseases, it is important to account for several types of stakeholders that are involved. We investigate the problem of an invasive insect pest feeding on an agricultural crop with heterogeneous producers: profit-oriented professional farmers and utility-oriented hobby farmers. We start from an ecological-economic model conceptually similar to the one developed by Eiswerth and Johnson [Eiswerth, M.E. and Johnson, W.S., 2002. Managing nonindigenous invasive species: insights from dynamic analysis. Environmental and Resource Economics 23, 319-342.] and extend it in three ways. First, we make explicit the relationship between the invaded state carrying capacity and farmers' planting decisions. Second, we add another producer type into the framework and hence account for the existence of both professional and hobby farmers. Third, we provide a theoretical contribution by discussing two alternative types of equilibria. We also apply the model to an empirical case to extract a number of stylised facts and in particular to assess: a) under which circumstances the invasion is likely to be not controllable; and b) how extending control policies to hobby farmers could affect both types of producers.     

Tradeable risk permits to prevent future introductions of invasive alien species into the Great Lakes

Commercial shipping has been implicated in over 60% of new introductions of invasive alien species (IAS) in the Great Lakes since 1960, with ballast water being the primary pathway. Recent policies have shifted the focus from postinvasion controls to prevention, with the regulation of oceanic ballast exchange as the primary approach. But this approach is not very effective, and it is often unsafe. We investigate whether an IAS tradeable permit program could provide an efficient alternative, keeping in mind that: (1) not every vessel will actually emit a species, yet ex ante each vessel is a potential emitter; (2) biological emissions are highly stochastic and essentially unobservable given current monitoring technologies. Theoretical issues in the design of a trading program are considered. We then compare the cost-effectiveness of trading versus command and control to reduce the likelihood of invasion by three classes of Ponto–Caspian species that are considered potential invaders capable of causing economic damage in the Great Lakes.     

The Control of Invasive Species on Private Property with Neighbor-to-Neighbor Spillovers

Invasive pests cross property boundaries. Property managers may have private incentives to control invasive species despite not having sufficient incentive to fully internalize the external costs of their role in spreading the invasion. Each property manager has a right to future use of his own property, but his property may abut others’ properties enabling spread of an invasive species. The incentives for a foresighted property manager to control invasive species have received little attention. We consider the efforts of a foresighted property manager who has rights to future use of a property and has the ability to engage in repeated, discrete control activities. We find that higher rates of dispersal, associated with proximity to neighboring properties, reduce the private incentives for control. Controlling species at one location provides incentives to control at a neighboring location. Control at neighboring locations are strategic complements and coupled with spatial heterogeneity lead to a weaker-link public good problem, in which each property owner is unable to fully appropriate the benefits of his own control activity. Future-use rights and private costs suggest that there is scope for a series of Coase-like exchanges to internalize much of the costs associated with species invasion. Pigouvian taxes on invasive species potentially have qualitatively perverse behavioral effects. A tax with a strong income effect (e.g., failure of effective revenue recycling) can reduce the value of property assets and diminish the incentive to manage insects on one’s own property.     

Economic Valuation of the Threat Posed by the Establishment of the Asian Tiger Mosquito in Australia

Invasive species policy could be better informed if we understood how much people value reductions in the risks posed by these organisms. This study investigates the public’s willingness to pay (WTP) for additional measures to reduce the risk of invasion of the Australian mainland by the Asian tiger mosquito (ATM). The study contributes to the literature by applying a stated preference method to estimate the public’s WTP to reduce the risk of an ATM invasion, expressed as a change in probability. It is the first ex ante invasive species analysis to test over two discrete invasion reduction probabilities based on management effort. Further, to overcome the challenges in valuing changes in probabilities, the study presented respondents with a well-defined discrete difference in the final probability, with one scenario reducing risk from 50 to 25% and the other from 50 to 5%. We find a significant difference in the mean WTP values between these two scenarios (A$67 vs. A$90). The overall conclusion is that estimated benefits of reducing the probability of an ATM incursion outweigh the costs.     

How trade politics affect invasive species control

Trade has become the main mode of transport for many invasive species, including diseases and agricultural pests. Most species are brought to their new homes unintentionally, which constitutes a market failure rooted in international trade. Unless it is practical to drive invasion risk to zero, the external costs may justify a tariff. In this paper, we analyze the political process likely to govern the formation of tariffs so justified using a straightforward incorporation of an invasive species externality into Grossman and Helpman's (GH) well-known political economy model. We show that our measure of disguised protectionism—the gap between the optimal tariff and that set in the equilibrium of the political economy game—is equal to the tariff that would be set if there were no invasive species and no international disciplines on trade policy. The informational needs required to distinguish disguised protectionism from legitimate public-goods protection are formidable.     

Importing exotic plants and the risk of invasion: are market-based instruments adequate?

Exotic plant species are often intentionally imported into regions outside of their normal range as ornamental plants or as breeding stock, thereby generating benefits for consumers and producers. However, one of the unintended side effects of such introductions is that the exotic plant species may become invasive. Prohibiting sale of this type of exotic plant species, on the basis that it may become invasive, will have social costs in the form of foregone consumer benefits and nursery profits. We develop a model of a private commercial plant breeding industry that imports an exotic plant species into a region. The risk associated with invasion is modeled using a probabilistic ‘hazard function’, the key determinants of which are the characteristics of the exotic plant and the number of commercial nurseries contributing to its dispersal. We consider the possibility of employing market-based instruments (e.g., Pigovian tax) consistent with the concept of ‘introducers pay’, to regulate the nursery industry. We then provide an empirical illustration using the historical introduction of saltcedar (Tamarisk spp.) into the United States. Our results indicate that the mere presence of a risk of invasion does not mean that it is socially optimal to prevent commercial sales of an exotic plant species. Indeed, there appear to be plausible forms of the functional relationships involved that require only a modest reduction in the private industry optimum. In contrast, no sales of the exotic plant should occur at all under several sets of assumptions about the level of invasion risk and the linkage between dispersal sites and invasion hazard.     

Stepping Stones for Biological Invasion: A Bioeconomic Model of Transferable Risk

We investigate three sources of bias in valuation methods for ecosystem risk: failure to consider substitution possibilities between goods, failure to consider nonseparability of ecosystem services with market goods, and failure to consider substitution possibilities between ecosystems. The first two biases are known in the literature, and we offer insight on the size of the bias for a specific example. Our work on spatially transferable risk is novel. We develop the concept and show how it may undermine typical invasion prevention strategies. We find three key results. First, partial equilibrium estimates of welfare loss are significantly overestimated relative to general equilibrium estimates. If ecosystem services and market goods are substitutes the partial equilibrium bias is greater than if they are compliments. Second, well-intended policies do not necessarily reduce overall risk; risk reduction actions can transfer risk to another time or location, or both, which may increase total risk. Third, policies of quotas and inspections have to be extreme to improve welfare, with inspections having advantages over quotas.     

Profit risk,market power and pricing decisions of large firms

We examine the response of price-setting firms to cyclical variations in demand and establish a set of conditions under which prices are adjusted countercyclically. We consider whether firms with market power attempt to reduce risk exposure through pricing policies.     

谨防物种地理入侵维护区域经济可持续发展

人类历史上外来物种的地理引入对区系经济发展有过积极的作用,由于物种地理引入过程中的“入侵”机制,使得引入种不但不能增加原生地生物区系的物种种类,反而减少了它的生物多样性,加速了原生生物区系的物种灭绝速度,引发水土流失,恶化人类生存环境,增大难以逆转的经济损失隐患,进而制约区域经济的可持续发展,对区域经济可持续发展可能会造成严重的潜在危害。为了维护区域经济的可持续发展,必须谨防物种地理入侵。     

Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.     

An ambient tax approach to invasive species

Invasive species have become an issue of increasing concern in recent years. Invasive species are species that are not native to an area but are imported either intentionally or unintentionally and become established. A primary pathway for introduction is the ballast water of ships. Although not all imported species become invasive, those that do cause extensive damage to ecosystems and have been blamed for the endangerment of numerous native species. In many cases, release of non-native species can be prevented, either through open-ocean ballast water exchange, retention of ballast water, or other biosecurity measures. However, policies designed to encourage such actions face several specific challenges. The difficulty of linking an invasion to a specific vessel and of monitoring individual vessels' care makes using standard environmental liability plans difficult if not impossible. In this paper, we present an alternative policy option, that of an ambient tax. Building on the work of Segerson [Segerson, Kathleen, 1988. Uncertainty and incentives for nonpoint pollution control. Journal of Environmental Economics and Management, 15: 87-98.], we show that an ambient tax can ensure socially optimal behavior in both the short-run and the long-run with minimal vessel specific information.     

Species Invasion as Catastrophe: The Case of the Brown Tree Snake

This paper develops a two-stage model for the optimal management of a potential invasive species. The arrival of an invasive species is modeled as an irreversible event with an uncertain arrival time. The model is solved in two stages, beginning with the post-invasion stage. Once the arrival occurs, the optimal path of species removal is that which minimizes the present value of damage and removal costs plus the expected present value of prevention costs. An expenditure-dependent, conditional hazard rate describing species arrival is developed based on discussions with natural resource managers. We solve for the optimal sequence of prevention expenditures, given the minimum invasion penalty as just described. For the case of the Brown Tree Snake potentially invading Hawaii, we find that pre-invasion expenditures on prevention are inverse U-shaped in the hazard rate. Efficient prevention should be approximately $2.9?million today and held constant until invasion. Once invasion occurs, optimal prevention requires $3.1?million annually and $1.6?million per year on species removal to keep the population at its steady state level, due to high search costs at very small population levels.     

Factors determining awareness and knowledge of aquatic invasive species

Public perceptions of invasive species may influence policies and programs initiated by public and private stakeholders. We investigate the determinants of the public's awareness and knowledge of invasive species as few studies have examined this relationship. We focus on aquatic invasive species (AIS) and employ survey data from property owners in a lake district. A major contribution is that we estimate a mixed trivariate binary-ordered probit regression model that accommodates correlations among unobserved characteristics, produces statistically more efficient estimates, and allows a more proper investigation of the probability of knowledge conditional on awareness. Our results provide insights for invasive species education and management programs. We find that individuals are more likely to be aware of AIS if they participate in water-based recreation, visit lakes outside their area, have a boat, belong to a lake association, or are college educated. This has a policy implication: Given high levels of AIS awareness by those most involved in activities around lakes and those with a higher education, it may be beneficial to target informational campaigns at those who do not display these characteristics, so that they can better make informed decisions about whether to support and expend money on invasive species management programs.     

A proactive approach for assessing alternative management programs for an invasive alien pollinator species

Most evaluations of the economic impacts of invasive species are done post facto and concentrate on direct production loss caused. However, the effects of invasive species on non-market services such as biodiversity and landscapes can be considerable. A proactive approach of assessing the expected economic impact of invasive species prior to their occurrence may contribute to greater efficiency of policy makers. Here we used a stated preference method for a priori evaluating the willingness of the population to pay for different control programs of a new invasive bee species in Israel, the dwarf honey bee, Apis florea. We evaluated possible economic impacts of A. florea using two model plant species expected to be adversely affected by its invasion due to decreased pollination. The plants have no market value but they add aesthetic value to the open landscape. Using a mixed logit model we found that the mean willingness to pay (WTP) differed between the model plants, and increased with the extent of plant loss. Respondents differentiated between levels of damage to the plants and between control methods in their preferences for a specific program. Our results provide means for informed proactive decision making in preventing the continued invasion of the bee.     

Control and the management of a spreading invader

We consider the problem of management of an aquatic invader spreading in a lake system. We assume that each year the invader can be removed from a certain proportion of invaded lakes, which depends on the selected intensity of control. Control decisions are generated and compared for an optimally controlled system and for a static optimization across asymptotic steady states. Control close to eradication of the invasive species is always optimal for invasions with relatively high damages, low rates of density dependent spread and/or low chance of additional random introductions. Control to a highly invaded steady state is optimal for those invasions with low relative damages, high chances of random introduction and high levels of uncertainty in species location. In all other cases the optimal outcome depends upon initial conditions. Comparing the relative performance of the optimally controlled system and the static optimization demonstrates situations when the differences are small and when not. When invasions are acted upon in their later stages and across certain parameter combinations a static optimization provides a reasonable approximation of an optimally controlled system. The flip-side is that optimal policies directed at an invasion in its early stages tend to provide significantly savings. The savings vary across parameter combinations, yet in these situations little useful insight will be generated without consideration of a dynamically optimized system.     

外来入侵物种的法律规制

外来物种入侵已经成为世界各国面临的严峻问题,外来入侵物种对生物多样性、社会经济以及人类健康造成了严重的危害,国际上对建立预防和控制外来入侵物种的法律制度取得了许多成功的经验。我们应当在借鉴这些经验的基础上,以人与自然和谐发展的环境观和可持续发展观为指导,通过完善环境风险评估、行政许可、名录、检验检疫以及法律责任追究制度来加强外来入侵物种的法律规制。     

生物入侵对森林生态服务功能经济损失评价研究分析与展望

外来入侵物种是森林生态系统健康最大的生物威胁，通过生物入侵对森林生态服务功能经济损失评价研究，可以提高林业工作者对外来入侵物种危害程度的认识，为制定生物入侵防治的政策和制度提供科学依据。目前国内外的相关研究，在基础理论、研究方法、技术路线、计算结果敏感度分析等方面均存在缺陷和不足，严重制约了这一研究的深入开展。而资源经济学、生态经济学、灾害经济学等学科的理论研究成果，生物入侵WEB数据库的大量涌现，粗糙集、杂合粗糙集数据挖掘方法的日益成熟，3S技术在生态服务功能评价中的广泛应用，为生物入侵对森林生态服务功能经济损失评价研究提供了新的理论、方法和技术手段。从这个角度出发，本文对未来的经济损失评价研究进行了展望，探讨了经济损失评价研究的重点和需要解决的几个关键问题。