Turbulence and phytoplankton diversity: A general model of the “paradox of plankton”

The principle of “competitive exclusion” predicts that no two species can occupy the same ecological niche at the same time and place (Hardin, 1960). Hutchinson (1953, 1961) suggested that the vast diversity of phytoplankton observed in many aquatic environments presents an apparent contradiction to this principle. Since all phytoplankton compete for the same basic resources, and since the euphotic zones of most natural waters are relatively homogeneous, such coexisting plankters appear to be simultaneously occupying the same niche. In this paper we present simulation results from a mathematical model wherein we examine the hypothesis that physical turbulence in an aquatic system can mollify interactive pressures between plankton populations and allow coexistence of species competing for the same resources. Using Bella's (1972) highly simplified model as a point of departure, we develop a new model, explicitly incorporating gross physiological mechanisms, to investigate the effects of both advective and turbulent components of water movement on the growth of three competing phytoplankton species. We observed that, in the absence of water motion, no two species were able to coexist, while under the hypothetical conditions of advection without turbulence (laminar flow), just two species were able to occur contemporaneously. Coexistence of all three species was achieved only with the addition of a random turbulent component to the model's hydrodynamic function. Moreover, this general coexistence was observed only when the major turbulent frequency approached the turnover rate of phytoplankton populations. We suggest that there is a limited region of periodicities and magnitudes for hydrodynamic energy in which phytoplankton can coexist, and that most natural aquatic environments fall within this region. We further speculate that, in general, the coupling of physical and biological processes in nature may be influenced by the relative frequency characteristics of those processes.     

Time,affluence and pollution in the theory of consumer's behavior

This paper extends Becker's analysis on the allocation of time to provide a theoretical basis for the phrase “affluence breeds effluence.” Many environmentalists fear that a pollutant tax is merely a license to pollute. Their fears are well-founded if we consider the effect of increased affluence of the society on the pollutant stock. Assuming that relatively pollutant intensive “commodities” are also relatively less time intensive, an assumption applicable to most of the affluent societies, it is shown that the pollutant tax policy will be ineffective if the effect of increased wage rate on pollutant stock is ignored in spite of the efficiency of such a tax as a policy tool.     

Relating environmental modeling to policy issues and decisions

This paper describes a linear program-based computer model which has been developed to identify the most effective spending patterns for environmental cleanup based on public preferences and spending limitations. The inputs to the model include the costs of removing each residual studied from its various sources. The objective function is the total “value of removal”. The factor added for each residual consists of a value for the residual multiplied by the quantity or fraction removed.Results of the analysis relate to and support current and projected policy decisions by the U.S. Environmental Protection Agency (EPA) for air and water programs. In addition, the results of the analysis suggest that EPA undertake a redirection of the Nation's resources among residual control programs.     

Optimal quasi-market choice in the presence of pollution externalities

When the relationship between emissions and ambient pollution is known, it is possible to implement a program to achieve economically efficient pollution levels, even when the control agency knows nothing about the victim's valuation of pollution damages or about emission abatement costs. Unlike a Pigouvian tax, the program provides the correct incentives for entry and exit whether or not marginal damages from a firm's emissions vary over the range of these emissions. Through the provision of “missing” markets, sizable revenues are raised while allocative distortions are corrected.     

The economic theory of species extinction: Comment on smith

A widely recognized article by Smith suggests that harvesting leading to species extinction may be socially optimal, provided that the species growth-potential is sufficiently low. It is shown that this conclusion hinges on special assumptions about harvest technology which, despite a superficial compatibility with neoclassical production theory, contradict a basic postulate of a pioneering article by Gordon. As soon as Gordon's postulate is taken into account, while all other aspects of Smith's model are maintained, it turns out that even a species with a very low growth potential should not become extinct.     

Energy and Depletable Resources: Economics and Policy, 1973–1998

This paper reviews the impact of the literature in depletable resources and energy economics over the period 1973–1998, particularly the initial period of publication of the Journal of Environmental Economics and Management, 1974–1998. A discussion of prominent policy issues in this arena is provided, along with an indication of what academic economics papers have contributed to that debate. This is followed by a citation analysis of contributions in the fields of energy and exhaustible resource economics. For each of these two fields, a list of the top papers in each five-year period from 1974 to 1998 is presented, along with a list of the top journals in each decade, based on average citations per article. The top ten cited articles in the fields in the Journal of Environmental Economics and Management are also presented.     

Linking the concept of ecological footprint and valuation of ecosystem services: A case study of economic growth and natural carrying capacity

Human activities have become so extensive that all ecosystems on the planet have been altered to some extent. The fate of humankind will be determined by how sustainable ecosystems and the renewable resources in them are managed. The implication of this is obvious: humanity must live within nature's carrying capacity. In recent years, humans have recognised that growth of the economy depends on natural capital, and it is important that we now recognise that we are part of an international ecological economics community, so as to better integrate the economy and ecology. However, there are few successful examples of this. The aim of this paper is to show a method for integrated analysis between economic growth and natural carrying capacity by linking the concepts of ecological footprint and valuation of ecosystem services. When applied to China for the period 1987–2003, the empirical evidence suggests that the size of the Chinese economy surpassed the carrying capacity in 1992. Perhaps, we should abandon our high-growth predilection and initiate a transition to a steady-state economy.     

Biodiversity Conservation and Indigenous Land Management in the Era of Self‐Determination

Abstract: Indigenous people inhabit approximately 85% of areas designated for biodiversity conservation worldwide. They also continue to struggle for recognition and preservation of cultural identities, lifestyles, and livelihoods—a struggle contingent on control and protection of traditional lands and associated natural resources (hereafter, self‐determination). Indigenous lands and the biodiversity they support are increasingly threatened because of human population growth and per capita consumption. Application of the Endangered Species Act (ESA) to tribal lands in the United States provides a rich example of the articulation between biodiversity conservation and indigenous peoples' struggle for self‐determination. We found a paradoxical relationship whereby tribal governments are simultaneously and contradictorily sovereign nations; yet their communities depend on the U.S. government for protection through the federal‐trust doctrine. The unique legal status of tribal lands, their importance for conserving federally protected species, and federal environmental regulations' failure to define applicability to tribal lands creates conflict between tribal sovereignty, self‐determination, and constitutional authority. We reviewed Secretarial Order 3206, the U.S. policy on “American Indian tribal rights, federal–tribal trust responsibilities, and the ESA,” and evaluated how it influences ESA implementation on tribal lands. We found improved biodiversity conservation and tribal self‐determination requires revision of the fiduciary relationship between the federal government and the tribes to establish clear, legal definitions regarding land rights, applicability of environmental laws, and financial responsibilities. Such actions will allow provision of adequate funding and training to tribal leaders and resource managers, government agency personnel responsible for biodiversity conservation and land management, and environmental policy makers. Increased capacity, cooperation, and knowledge transfer among tribes and conservationists will improve biodiversity conservation and indigenous self‐determination.     

Mainstreaming the social sciences in conservation

Despite broad recognition of the value of social sciences and increasingly vocal calls for better engagement with the human element of conservation, the conservation social sciences remain misunderstood and underutilized in practice. The conservation social sciences can provide unique and important contributions to society's understanding of the relationships between humans and nature and to improving conservation practice and outcomes. There are 4 barriers—ideological, institutional, knowledge, and capacity—to meaningful integration of the social sciences into conservation. We provide practical guidance on overcoming these barriers to mainstream the social sciences in conservation science, practice, and policy. Broadly, we recommend fostering knowledge on the scope and contributions of the social sciences to conservation, including social scientists from the inception of interdisciplinary research projects, incorporating social science research and insights during all stages of conservation planning and implementation, building social science capacity at all scales in conservation organizations and agencies, and promoting engagement with the social sciences in and through global conservation policy‐influencing organizations. Conservation social scientists, too, need to be willing to engage with natural science knowledge and to communicate insights and recommendations clearly. We urge the conservation community to move beyond superficial engagement with the conservation social sciences. A more inclusive and integrative conservation science—one that includes the natural and social sciences—will enable more ecologically effective and socially just conservation. Better collaboration among social scientists, natural scientists, practitioners, and policy makers will facilitate a renewed and more robust conservation. Mainstreaming the conservation social sciences will facilitate the uptake of the full range of insights and contributions from these fields into conservation policy and practice.     

Michael Soulé (1936–2020) on spirituality,ethics, and conservation biology

Michael Soulé is best known for his scientific contributions and central role in founding the Society for Conservation Biology and its flagship journal. Less well known are his childhood experiences, his affinity for Zen Buddhism and Arne Naess’ deep ecology philosophy, and his contributions as an environmental activist to efforts to protect biodiversity and rewild ecosystems. Also less well known is the extent to which he was an interdisciplinary environmental studies scholar, struggling to understand what promotes and hinders proenvironmental behaviors. In this regard, his life and that of many other conservation scientists provide important clues, but no easy answers. By attempting to integrate the humanities, with its quest for a meaningful and fulfilling human existence, with naturalistic nature spirituality and ecocentric values, as well as the social and natural sciences, Soulé sought to solve the riddle as to why human beings seemed unable to understand, slow, and halt negative anthropogenic environmental change. He thus modeled what interdisciplinary environmental studies is at its best. Those advocating the conservation of biological diversity have much to learn from Michael Soulé, not only from his scientific findings but also from his way of seeing, the questions he asked, and his love of the living world.     

Knowing But Not Doing: Selecting Priority Conservation Areas and the Research–Implementation Gap

Abstract: Conservation assessment is a rapidly evolving discipline whose stated goal is the design of networks of protected areas that represent and ensure the persistence of nature (i.e., species, habitats, and environmental processes) by separating priority areas from the activities that degrade or destroy them. Nevertheless, despite a burgeoning scientific literature that ever refines these techniques for allocating conservation resources, it is widely believed that conservation assessments are rarely translated into actions that actually conserve nature. We reviewed the conservation assessment literature in peer‐reviewed journals and conducted survey questionnaires of the authors of these studies. Two‐thirds of conservation assessments published in the peer‐reviewed scientific literature do not deliver conservation action, primarily because most researchers never plan for implementation. This research–implementation gap between conservation science and real‐world action is a genuine phenomenon and is a specific example of the “knowing–doing gap” that is widely recognized in management science. Given the woefully inadequate resources allocated for conservation, our findings raise questions over the utility of conservation assessment science, as currently practiced, to provide useful, pragmatic solutions to conservation planning problems. A reevaluation of the conceptual and operational basis of conservation planning research is urgently required. We recommend the following actions for beginning a process for bridging the research–implementation gap in conservation planning: (1) acknowledge the research–implementation gap is real, (2) source research questions from practitioners, (3) situate research within a broader conservation planning model, (4) expand the social dimension of conservation assessments, (5) support conservation plans with transdisciplinary social learning institutions, (6) reward academics for societal engagement and implementation, and (7) train students in skills for “doing” conservation.     

What Every Conservation Biologist Should Know about Economic Theory

Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.     

Individual versus community level processes and pattern formation in a model of sand dune plant succession

A cellular automata model of a sand dune plant community on Galveston Island, Texas, USA was utilized to test hypotheses regarding individual plant interactions and their impact upon community organization. Simulations demonstrated that both an environmental gradient and facilitative succession resulted in the formation of characteristic sand dune patterns. The results showed that the plant patterns were due to individual plant responses to their environment within their local neighborhood, yet these responses were constrained by the global history of the community. The local neighborhood was related to the “zone of influence” concept, “field of neighborhood” models, and “ecological field” theory. It is proposed that plants responded individualistically to environmental conditions within the local neighborhood and that plants were constrained by the community-unit beyond the local neighborhood. The ratio of the scale of environmental variability versus the scale of a plant's local neighborhood determined the relative importance of the individual and the community in forming pattern. This work makes important contributions to the Gleasonian–Clementsian debate, sand dune successional theory, and in pattern-based, deductive hypothesis testing with cellular automata models.     

Geography and Recovery under the U.S. Endangered Species Act

Abstract: The U.S. Endangered Species Act (ESA) defines an endangered species as one “at risk of extinction throughout all or a significant portion of its range.” The prevailing interpretation of this phrase, which focuses exclusively on the overall viability of listed species without regard to their geographic distribution, has led to development of listing and recovery criteria with fundamental conceptual, legal, and practical shortcomings. The ESA's concept of endangerment is broader than the biological concept of extinction risk in that the “esthetic, ecological, educational, historical, recreational, and scientific” values provided by species are not necessarily furthered by a species mere existence, but rather by a species presence across much of its former range. The concept of “significant portion of range” thus implies an additional geographic component to recovery that may enhance viability, but also offers independent benefits that Congress intended the act to achieve. Although the ESA differs from other major endangered‐species protection laws because it acknowledges the distinct contribution of geography to recovery, it resembles the “representation, resiliency, and redundancy” conservation‐planning framework commonly referenced in recovery plans. To address representation, listing and recovery standards should consider not only what proportion of its former range a species inhabits, but the types of habitats a species occupies and the ecological role it plays there. Recovery planning for formerly widely distributed species (e.g., the gray wolf [Canis lupus]) exemplifies how the geographic component implicit in the ESA's definition of endangerment should be considered in determining recovery goals through identification of ecologically significant types or niche variation within the extent of listed species, subspecies, or “distinct population segments.” By linking listing and recovery standards to niche and ecosystem concepts, the concept of ecologically significant type offers a scientific framework that promotes more coherent dialogue concerning the societal decisions surrounding recovery of endangered species.     

An experiment on the economic value of visibility

This paper reports on the development and application of an iterative bidding technique to examine proposed visibility reductions in the Four Corners Region of the southwest United States. The iterative bidding technique is a method to elicit honest bids for “goods” not priced in formal markets. Four issues associated with direct revelation of preferences for environmental goods are explored: (1) the establishment of linkages between the physical parameters of visibility and representation of the “good” called visibility to individuals for valuation purposes; (2) a systematic test for both observed and induced biases associated with the interative bidding technique; (3) replication of the results of previous experiments; and (4) reporting of empirical divergences between compensating and equivalent surplus measures of consumer surplus.     

Use of a Business Excellence Model to Improve Conservation Programs

Abstract: The current shortfall in effectiveness within conservation biology is illustrated by increasing interest in “evidence‐based conservation,” whose proponents have identified the need to benchmark conservation initiatives against actions that lead to proven positive effects. The effectiveness of conservation policies, approaches, and evaluation is under increasing scrutiny, and in these areas models of excellence used in business could prove valuable. Typically, conservation programs require years of effort and involve rigorous long‐term implementation processes. Successful balance of long‐term efforts alongside the achievement of short‐term goals is often compromised by management or budgetary constraints, a situation also common in commercial businesses. “Business excellence” is an approach many companies have used over the past 20 years to ensure continued success. Various business excellence evaluations have been promoted that include concepts that could be adapted and applied in conservation programs. We describe a conservation excellence model that shows how scientific processes and results can be aligned with financial and organizational measures of success. We applied the model to two well‐documented species conservation programs. In the first, the Po’ouli program, several aspects of improvement were identified, such as more authority for decision making in the field and better integration of habitat management and population recovery processes. The second example, the black‐footed ferret program, could have benefited from leadership effort to reduce bureaucracy and to encourage use of best‐practice species recovery approaches. The conservation excellence model enables greater clarity in goal setting, more‐effective identification of job roles within programs, better links between technical approaches and measures of biological success, and more‐effective use of resources. The model could improve evaluation of a conservation program's effectiveness and may be used to compare different programs, for example during reviews of project performance by sponsoring organizations.     

The case for policy‐relevant conservation science

Drawing on the “evidence‐based” (Sutherland et al. 2013) versus “evidence‐informed” debate (Adams & Sandbrook 2013), which has become prominent in conservation science, I argue that science can be influential if it holds a dual reference (Lentsch & Weingart 2011) that contributes to the needs of policy makers whilst maintaining technical rigor. In line with such a strategy, conservation scientists are increasingly recognizing the usefulness of constructing narratives through which to enhance the influence of their evidence (Leslie et al. 2013; Lawton & Rudd 2014). Yet telling stories alone is rarely enough to influence policy; instead, these narratives must be policy relevant. To ensure that evidence is persuasive alongside other factors in a complex policy‐making process, conservation scientists could follow 2 steps: reframe within salient political contexts and engage more productively in boundary work, which is defined as the ways in which scientists “construct, negotiate, and defend the boundary between science and policy” (Owens et al. 2006:640). These will both improve the chances of evidence‐informed conservation policy.     

Best policy response to environmental shocks: Applying a stochastic framework

The paper develops a general framework for the analysis of environmental shocks in growing economies. Endogenous capital investments allow identifying the dual role of capital as a buffer against shocks and a source of pollution. We study the effects of recurring natural disasters on optimal growth and efficient environmental policies. Emissions may cause continuous fluctuations, entail discrete and recurring jumps, or trigger so-called “tipping points” with large costs to the economy. Closed-form solutions are provided for all the model variants. We discuss possible applications in environmental economics and identify current research gaps.     

On the distribution of public program benefits between landlords and tenants

Many public programs have differential impacts on diverse parts of metropolitan areas. This fact has led analysts to use changes in land values as measures of the benefits of public programs. Using a model derived from theoretical urban economics, this paper demonstrates that changes in land values will only equal total benefits under very restrictive assumptions. Making concrete assumptions about consumer demand, the paper goes beyond previous work to consider the distributional impact of three different kinds of public programs: those which provide uniform benefits to every community, those which attempt to reduce intercommunity inequality, and those which generate improvements in only a subset of the region's towns.