This is a book that all ecologists and economists interested in bioeconomics should read. The master narrative encompassing a bi-disciplinary framework and endogenous risk makes it intuitively and logically appealing. A narrative that can be generalized in such a straightforward manner constitutes a forceful principle for organizing research and for informing policy. The work here should leave even the disciplinary isolationist interested in studying more about what a joint determination framework can offer.
Invasive species are a major environmental policy challenge. They continue to alter, often in undesirable ways, the workings of ecosystems around the globe. This book provides general and species-specific overviews of ecological and economic tools and also consensus propositions for studying interactions of the determinants and behaviors of invasive species. It treats lessons from past attempts to understand and to manage invasive species. It also suggests strategies for understanding and combating the threats to environmental and economic well-being that nonindigenous species pose. Readers will get a thorough treatment of the relevant scientific issues as well as a comprehensive review of the analytical and the empirical tools used by ecologists and economists to research invasive aquatic and terrestrial flora and fauna in North America and around the world.
Pleas for collaboration between ecologists and economists to advance understanding and resolution of environmental problems are so commonplace as to be almost hackneyed. When adherents of each disciplinary personality try to work together, they usually lapse into discord, followed by retreat into remote if not totally separated intellectual pursuits. Most ecologists and economists see only dimly how to clarify assumptions about their respective disciplines. The book provides a master narrative in which ecological and economic expertise complement and make each area more robust than were it to stand alone.
Ecological and economic systems each mediate the behaviors of the opposite system. The appropriate focus is the decision maker working in her or his environment, for in reality, neat separation of natural and human activities does not exist. A species’ initial invasion, establishment, spatial spread, and temporal persistence influences and is influenced by abiotic and biotic processes and by individual and institutionalized human decisions. Decision makers adapt to environmental change by changing their personal behaviors as well as by directly changing a particular environment. Interactions and feedback between and among systems and system scales influence the structure, resilience, and dynamics of respective systems. Thus, jointly determined vision encourages individuals from each discipline to consider and understand what the other brings to the table. Each discipline is thereby forced to better scrutinize and document the information needs of the other. Such a vision supplies a framework for fostering sharper questions as well as sharper and smarter answers. This volume makes better-informed outcomes possible.
The focus of this book is on the bioeconomic behavioral roots of invasive species. Evaluation techniques (e.g., energy analysis, benefit–cost analysis) take a secondary role. The authors primarily address what does happen rather than what should happen. They present empirical illustrations demonstrating that the joint determination vision produces different answers from those arising from a framework based solely on either the ecological or the economic system.
Framing the causal relations between the ecology and the economics of invasive species as reciprocating systems does not imply that researchers should reform their entire set of ecological and economic tools or the tenets these tools have uncovered. Similar tools will likely be employed to develop propositions and to extract empirical results, whatever framework is used.
It is possible for model components to become so entangled in a web of interconnectedness, especially when some components are ill defined, that explanatory power is lost rather than gained. Parsimony can trump completeness, implying that there has to be some limit to the reciprocal coupling of the ecological and the economic components of an environmental model. Some intellectual separation is necessary to mark distinctions in system integration and to assure empirical content. This book acknowledges the parsimony–completeness tradeoff. Given limited research budgets and policy goals, this tradeoff immediately brings up the question of those facets of an invasive species model for which accuracy (unbiasedness) and precision (low variability across independent measurements) are especially important. Though the authors offer no firm answers to this question, the background they provide on invasive species will help formulate answers. A key extension of joint determination runs throughout the book. Uncertainty, irreversibilities, and timing issues almost always characterize invasive species problems. Uncertainty about causes or consequences shifts the focus to endogenous risk, a scenario in which decision makers can try to alter the risks (the product of probability and severity, if realized) of the establishment, spread, and persistence of an invasive species. An endogenous-risk focus has the potential to make less costly the tradeoff between model parsimony and completeness. A careful reading of this book strongly conveys this impression.
Whatever the issue, complexity and ambiguity tempt policy makers and even scientific experts to wrap themselves in a cloak of objectivity by picking and choosing the scientific results they deem relevant. The authors are alert to this temptation. Policy makers and experts must often transfer findings from existing original studies to new areas of scientific or policy interest. Several chapters here consider the transfer question. They ponder both the theoretical underpinnings of the question and its statistical and computational treatment. In particular, the authors recognize that combining information from multiple sources and models of a common phenomenon can produce parameter estimates corresponding more closely to a new setting than can any single source.
The book concludes with an appealing human touch. The editors recall and reflect upon the successes and failures of their research and their attempts to communicate and to convince the public and policy makers about the causes and likely consequences of invasive species problems. They view their records of success as mixed. This tentativeness is leavened by the cheery optimism of a young ecologist recounting what inspires him about invasive species research. He nevertheless expresses bewilderment at the frequent reluctance of policy makers and the public to learn about and to accept scientific results.
Thomas D. Crocker
Department of Economics and Finance
University of Wyoming