Charles Perrings, Mark Williamson - Programme Leaders

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Views

Humans are the principal vector of invasives. Most introductions in the recent past have been the intended or unintended consequence of human activity. Whether new species have turned out to be boon, pest or pathogen, their introduction, establishment and spread has generally depended on the movement of people or their goods and services. The project will analyse the economic causes and consequences of biological invasions. It will consider both intentional and unintentional introductions: biological control species and accidental introduction of species damaging to ecological processes, economic production or human health.

Whereas the management of pests in agriculture and forestry has been extensively researched, there has been little systematic economic analysis of the broader problem of invasives. Agricultural pests, epidemic diseases, and the establishment of wild species in unmanaged ecosystems are all part of the same general problem. In many cases the introduction and establishment of new species is an external effect of market activities involving the public goods: public and environmental health. Such research as has been undertaken on the problem of the externalities of invasives has been largely superficial and spasmodic.

Potentially damaging biological invasions are amongst the least studied externalities of trade, transport and travel, but they are by no means the least important. While there have been some calculations of the costs of conspicuous invaders affecting agriculture and forestry (e.g. US OTA 1993), most studies have paid little attention to the external costs and benefits of either invasions or control strategies. The project will offer a systematised study of a wider set of invaders and a wider set of processes in invasions.

This section of the SCOPE programme will consider both uncontrolled and controlled introductions. Many of the latter involve threats to non-target species or habitats (Williamson, 1996). Indeed, a number involve threats to the very species they are designed to protect. For example, one common form of biological control - the use of wide-spectrum antibiotics to control bacteria affecting human health - may threaten the species it is designed to protect by reducing the scope for such control in the future (Daily and Ehrlich, 1996). Little work has so far been undertaken on either the economics of uncontrolled invasions or of controlled invasions with negative external effects of this sort.

Partly because of this, biological control has become controversial (Simberloff and Stilling, 1996). Section 7 will provide a preliminary evaluation of the options for addressing the problem of invasives, including the potential for market-based instruments such as taxes, regulations and incentives (it will be linked with a longer term research project directed by Perrings and Williamson to develop models and decision tools in this area). Since the costs of biological as compared to chemical control is uncertain, it is hard for decision-makers to evaluate the options. Both affect the ecological processes, and hence the productivity of the economic activities they support. But they do so in different ways, and with different effects over space and time. The control options are different at each stage in the process: introduction, establishment and spread (Williamson and Fitter, 1996). At importation, they include intervention through transport regulation, inspection and quarantine. At first establishment they may include eradication, but if an introduced species starts to spread, the options move to containment, to the achievement of target densities. The level and incidence of the costs and benefits of control at different stages vary substantially, not just because of the geographical scale of the problem, but because of the potential for irreversible effects.

Proposed Activities

1. To assess the current status and economic significance of invasives

2. To identify the spatio-temporal interactions between the movement of people, goods and services and that of invasive species--the economic drivers of the introduction, establishment and spread of alien species; specifically:

1. the role of invasives in disease transmission in agriculture

2. biological control, pest control and invasion externalities

3. human migration and species introductions and spread (including human diseases)

4. trade in goods and services and biological invasions

3. To characterise the uncertainties associated with the establishment and spread of invasives

4. To identify the economic consequences of invasions

5. To evaluate the options for addressing the problem of invasives, including the potential for market-based instruments such as taxes, price incentives as adjuncts to the more widely used regulations.

Section 7 will be developed with cross linkages to Sections 1 (Human dimensions), 3 (International pathways of invasives), 8 (Management of invasive species) and 10 (Legal aspects). It will comprise chapters on each of the topics specified below. Each will be prepared by an environmental/ecological economist advised by/working alongside an ecologist with specialist scientific knowledge of the aspect of the problem concerned. Where a problem has different dimensions in different economic or ecological systems, there may be a number of contributing authors.

1. Overview

2. Biodiversity
   Invaders, by homogenising the worlds biota, are seen as a serious threat to local biodiversity in many parts of the world. Indeed, some landscapes are now dominated by invaders (section 6). The controlled introduction of new species is generally reckoned to yield benefits, as crops, biological control agents and so on. However, the establishment and spread of such species also involves costs - many of them external to the market. There will be a cross link to section 8 (Waage).

3. Ecosystem functioning: the costs and benefits of invasives
   It has been argued that the main economic benefit of biodiversity is the maintenance of ecosystem function (Perrings et al. 1995). Many invaders are known to have marked effects on ecosystem functioning (Williamson 1996) but the economics of these have scarcely been evaluated. The chapter will review the results of such work as has been done.

4. Human health and epidemiology
   Invasions both by new diseases and new vectors of diseases have important economic effects. The introduction, establishment and spread of pathogens depends on the movement of people, goods and services. These are evaluated in 7.6. Chapter 7.4 will consider the economic cause and epidemiological consequences of these things. There will be a cross link to section 1 (McNeely).

5. Agriculture, forestry and fisheries
   This is the area where there has been, in the past, most evaluation of the economic effects of invaders. Nevertheless many of the external costs of invasions in agriculture, forestry and fisheries have yet to be evaluated. This chapter reports the current state of knowledge of these costs. There are many analogies that can be drawn between GMOs and invasives. The costs of developing and regulating GMOs can now be evaluated. There will be a cross link to section 8 (Waage).

6. Trade, transport and travel
   Much of the variation in the effect of invaders relates to trade, transport and travel (Williamson 1996). A detailed analysis of these phenomena is central to the evaluation of the economics of invasions. There will be a cross link to section 3 (Jenkins).

7. Distributional consequences of invasives
   The distribution of the costs and benefits of invasions has not been studied in great detail. There is considerable prima facie evidence that the incidence of costs is very variable: the beneficiaries and sufferers tend to be different. This chapter will review the evidence. There will be a cross link to section 1 (Shiva).

8. Recommendations: regulations and incentives
   This chapter will evaluate the regulations and other instruments available to deal with the problem of invasions such as legal restrictions (cross link to section 10 (Legal and Institutional Frameworks)), taxes, charges, subsidies and other market based incentives. It will also indicate the decision-tools required to determine the optimal instruments.

   The section will address the problem of capacity building through the identification of research counterparts to be attached to chapters 7.2 to 7.7. These counterparts will be responsible for drafting mini-case studies.

Proposed Products

1. A peer-reviewed assessment of the economics of biological invasions and a critical appraisal of policy options

2. The enhancement of the capacity to identify and respond to problems of biological invasions

3. A set of accessible and implementable proposals to address:

• the market failures that result in introductions as an external effect of trade in goods and services or travel.

• the policy failures that lie, in part, behind the inability to control either the introduction or spread of species with a high probability of establishment

• the implementation of the Biodiversity Convention

The impact of biological invasions on agriculture, forestry, fisheries, human health and well-being is understood to be increasing sharply. It is important to understand both the driving forces behind the invasions and the extent of their effects if we are to devise appropriate policies to deal with them. The products of this section are important building blocks to this end.