Ecosystems

The concept of an ecological niche (econiche) has been used in a variety of ways, some of which are incompatible with a relational or functional interpretation of the term. This essay seeks to standardize usage by limiting the concept to functional relations between organisms and their surroundings, and to revise the concept to include epistemic relations. For most organisms, epistemics are a vital aspect of their functional relationships to their surroundings and, hence, a major determinant of their econiche. Rejecting the (...) traditional dualism of organism and environment, an econiche is defined as the reciprocal (dual) of a functionally specified class of organisms (FSTU). From this perspective, an econiche necessarily implies a certain type of organism, and a class of functionally similar organisms implies a special econiche.The econiche concept is also discussed in relation to other ecological terms that reflect the distributional patterns of organisms, such as habitat, and the concept of an empty niche is criticized. (shrink)

Sustainable ecosystem management often requires setting goals despite uncertainty regarding the achievability and desirability of the intended state of affairs. Coming to doubt the achievability or desirability of a previously set goal might sometimes, but not always, require reconsidering that goal. There is, however, a need to strike a balance between responsiveness to new information and knowing when to retain goals despite doubts. By critically engaging with adaptive ecosystem management, as advocated by environmental pragmatist Bryan G. Norton, criteria for warranted (...) reconsideration of long-term goals are investigated. (shrink)

The importance of ecosystem services to human welfare and economic livelihoods in low-income countries is now well recognized. Poor people in developing regions are particularly vulnerable to the deteriorating ecological values resulting from the loss of tropical forests, coral reefs, mangroves, and other ecosystems. Current efforts to reconcile development pressures with maintaining key ecosystem benefits focus on payment for environmental services and other incentives to protect critical ecosystems and habitat in developing countries. But geographical targeting and other means of tackling (...) poverty more directly should be considered also. (shrink)

The immune system does not just fight pathogens but also engages in interactions with beneficial microbes and non-immune cells of the body to harmonize their behavior by means of cytokines, antibodies and effector cells (Dinarello, 2007; Moticka, 2015, pp. 217e226, 261e267). However, the importance of these “housekeeping” functions has not been fully appreciated (Cohen, 2000). In his new book Immunity: The Evolution of an Idea Alfred I. Tauber traces the history of fundamental ideas in immunology and refers to recent advances (...) in the field to overturn the notion that immunity is the ability of an autonomous organism to protect itself against pathogens. Indeed, as suggested by the author, the autonomy of the organism is illusive because individuals develop as holobionts: functionally integrated multispecies consortia (p. 98). Similarly, he suggests that pathogenicity also emerges from the lack of subordination of a microbe to social welfare of the holobiont rather than from context-independent properties of this organism (pp. 165, 181). Emphasizing the contextual character of the parasite and the host, Tauber redefines immunity as an active process of coordination of a cellular ecosystem, which allows this collective to navigate through challenges of the environment and to face demands of the communal living (pp. 10e16). From this point of view, the failure to modulate intercellular interactions by the immune system entails mitigating immunity and impairing resistance to infection and disease (pp. 103e104). Immunity is a groundbreaking work establishing a new framework for understanding the function and activity of the immune system. Its value also lies in the fact that it serves as an important stepping-stone towards an integrated philosophical, ecological and immunological study of our embedment in the microbial world. (shrink)

A mass balance based model has been derived to represent the dynamical behavior of the ecosystem contained in an anaerobic digester. The model considers two bacterial populations: acidogenic and methanogenic bacteria. It forms the basis for the design of a software sensor considering both a model of the biological system and on-line gaseous measurements. The software sensor computes the concentration of inorganic carbon and volatile fatty acids (VFA) in the digester. Another software sensor is dedicated to the estimation of the (...) bacterial biomasses. The predictions of the software sensors for a real experiment are very close to the actual off-line measurements. The software sensors monitor the accumulation of VFA and thus very early detect a destabilization of the digester due to overloading. The presented methodology demonstrates the usefulness of advanced monitoring techniques for an improved understanding of the internal working of a biological system. (shrink)

As biological and biomedical research increasingly reference the environmental context of the biological entities under study, the need for formalisation and standardisation of environment descriptors is growing. The Environment Ontology (ENVO; www.environmentontology.org) is a community-led, open project which seeks to provide an ontology for specifying a wide range of environments relevant to multiple life science disciplines and, through an open participation model, to accommodate the terminological requirements of all those needing to annotate data using ontology classes. This paper summarises ENVO’s (...) motivation, content, structure, adoption, and governance approach. (shrink)

Are ecosystems morally considerable-that is, do we owe it to them to protect their “interests”? Many environmental ethicists, impressed by the way that individual nonsentient organisms such as plants tenaciously pursue their own biological goals, have concluded that we should extend moral considerability far enough to include such organisms. There is a pitfall in the ecosystem-to-organism analogy, however. We must distinguish a system’s genuine goals from the incidental effects, or byproducts, of the behavior of that system’s parts. Goals seem capable (...) of giving rise to interests; byproducts do not. It is hard to see how whole ecosystems can be genuinely goal-directed unless group selection occurs at the community level. Currently, mainstream ecological and evolutionary theory is individualistic. From such a theory it follows that the apparent goals of ecosystems are mere byproducts and, as such, cannot ground moral considerability. (shrink)

Wilderness, for seventeenth-century Puritan colonists in America, was hideous and howling. In the eighteenth century, Puritan preacher and theologian, Jonathan Edwards, began the process of transforming the American wilderness into an aesthetic and spiritual resource, a process completed in the nineteenth century by Ralph Waldo Emerson. Henry David. Thoreau was the first American to recommend wilderness preservation for purposes of transcendental recreation (solitude, and aesthetic and spiritual experience). In the twentieth century, Theodore Roosevelt and Aldo Leopold advocated wilderness preservation for (...) a different kind of recreation (hunting, fishing, and primitive travel) in order to preserve the putatively unique American character and institutions. Of these three historic conceptions of wilderness preservation, the third is the best model for frontier ecosystems at the austral tip of the Americas. (shrink)

There are many different kinds of model and scientists do all kind of things with them. This diversity of model type and model use is a good thing for science. Indeed, it is crucial especially for the biological and cognitive sciences, which have to solve many different problems at many different scales, ranging from the most concrete of the structural details of a DNA molecule to the most abstract and generic principles of self-organization in networks. Getting a grip (or more (...) likely many separate grips) on this range of topics calls for a teeming forest of techniques, including many different modeling techniques. Barbara Webb’s target article strikes us as a proposal for clear-cutting the forest. We think clear-cutting here would be as good for science as it is for non-metaphorical forests. Our argument for this is primarily a recitation of a few of the ways that diversity has been useful. Recently, looking at the actual practice of artificial life modelers, one of us distinguished four uses of simulation models classified in terms of the position the models take up between theory and data (see Figure 1). The classification is not exhaustive, and the barriers between kinds are not absolute. Rather, the purpose of the taxonomy is to open up the view for an epistemic ecology of modeling practices. First, and closest to the empirical domain, there are mechanistic models, in which there is an almost one-to-one correspondence between variables in the model and observables in the target system and its environment. Webb’s.. (shrink)

Martha Nussbaum has expanded the capabilities approach to defend positive duties of justice to individuals who fall below Rawls’ standard for fully cooperating members of society, including sentient nonhuman animals. Building on this, David Schlosberg has defended the extension of capabilities justice not only to individual animals but also to entire species and ecosystems. This is an attractive vision: a happy marriage of social, environmental and ecological justice, which also respects the claims of individual animals. This paper asks whether it (...) is one that the capabilities approach can really deliver. Serious obstacles are highlighted. The potential for conflict between the capability-based entitlements of humans and those of nonhuman animals or ‘nature’ is noted, but it is argued that this does not constitute a decisive objection to the expanded capabilities approach. However, intra-nature conflicts are so widespread as to do so: the situation is outside the circumstances of justice as they are standardly understood. Schlosberg attempts to reconcile such conflicts by re-examining what it means to flourish as a sentient nonhuman animal. This fails, because of the distinction between flourishing as a species, which often requires predation, and flourishing as an individual, which is as frequently incompatible with it. Finally, the paper considers how a capabilities theorist might move beyond such conflicts, identifying two possible strategies (which are not themselves unproblematic) for reconciling the demands of humans, animals and ecosystems. (shrink)

In 1935, A. G. Tansley, who was knighted later, proposed the ecosystem concept. Nevertheless, this concept was not without predecessors. Why did Tansley’s ecosystem prevail and not one of its competitors? The purpose of this article is to pin the distinguishing features of Tansley’s ecosystem down, as far as the published record allows. It is an exercise in finding the difference that made a difference. Besides being a pioneering ecologist, Tansley was an adept of psychoanalysis. His interest even led him (...) to visit Sigmund Freud in Vienna for a while. Psychologists had to regard the mind as an entity in its own right, while knowing that it truly was part of a larger whole (body + mind), because the causal relation between body and mind was unknown. This lead Tansley to conclude that psychologists must not objectify the system under study, have to search for causes within their own field, and must not speculate unless this serves a scientific purpose. In 1925, Tansley defended psychoanalysis in a prolonged controversy against a concerted attack criticizing its speculative content and poor scientific standing. This could have been the reason why Tansley kept his ecosystem free of speculative content and unscientific connotation. The competing ecosystem-like concepts, however, have contained philosophical speculation, non-deterministic properties like vitalism or entelechy, or have been burdened with unscientific connotations. Hence, rigorous restraint distinguished the ecosystem concept and made it ready for use by later researchers. (shrink)

The most pressing problems facing humanity today - over-population, energy shortages, climate change, soil erosion, species extinctions, the risk of epidemic disease, the threat of warfare that could destroy all the hard-won gains of civilization, and even the recent fibrillations of the stock market - are all ecological or have a large ecological component. in this volume philosophers turn their attention to understanding the science of ecology and its huge implications for the human project. To get the application of ecology (...) to policy or other practical concerns right, humanity needs a clear and disinterested philosophical understanding of ecology which can help identify the practical lessons of science. Conversely, the urgent practical demands humanity faces today cannot help but direct scientific and philosophical investigation toward the basis of those ecological challenges that threaten human survival. This book will help to fuel the timely renaissance of interest in philosophy of ecology that is now occurring in the philosophical profession. Provides a bridge between philosophy and current scientific findings Covers theory and applications Encourages multi-disciplinary dialogue. (shrink)

Protopolybia sedula is a social swarming wasp, widely spread throughout many countries in the Americas, including most of Brazil. Despite its distribution, studies of its behavioral ecology are scarce. This study aimed to describe its foraging activity and relation to climatic variables in the city of Juiz de Fora in southeastern Brazil. Three colonies were under observation between 07:00 and 18:00 during April 2012, January 2013, and March 2013. Every 30 minutes, the number of foragers leaving and returning to the (...) colony was registered along with air temperature and relative humidity. Activity began around 07:30¸ increased between 10:30 and 14:30, and ended around 18:30. A mean of 52.7 exits and 54 returns were measured every 30 minutes. The daily mean values were 1,107 ± 510.6 exits and 1,135 ± 854.8 returns. Only one colony showed a significant correlation between forager exits and temperature (rs = 0.8055; P < 0.0001) and between exits and relative humidity (rs = -0.7441; P = 0.0001). This paper shows that climatic variables are likely to have little control on the foraging rhythm of P. sedula when compared to other species, suggesting the interaction of other external and internal factors as stimuli of species foraging behavior. (shrink)

Environmental ethics is generally searching for the intrinsic value in natural beings. However, there are very few holistic models trying to reflect the various dimensions of the experience-to-be a natural being. We are searching for that intrinsic value, in order to determine which species are holders of rights. In this article, I suggest a set of moral and rational principles to be used for identifying the intrinsic value of a given species and for comparing it to that of other species.

Sagoff (2016) criticizes widely used “theoretical” methods in ecology; arguing that those methods employ models that rely on problematic metaphysical assumptions and are therefore uninformative and useless for practical decision-making. In this paper, I show that Sagoff misconstrues how such model-based methods work in practice, that the main threads of his argument are problematic, and that his substantive conclusions are consequently unfounded. Along the way, I illuminate several ways the model-based inferential methods he criticizes can be, and have been, usefully (...) informative. (shrink)

Value claims about ecological entities, their functionality, and properties take center stage in so-called “ecological” ethical and aesthetic theories. For example, the claim that the biodiversity in an old-growth forest imbues it with “value in and for itself” is an explicit value claim about an ecological property. And the claim that one can study “the aesthetics of nature, including natural objects...such as ecosystems” presupposes that natural instances of a type of ecological entity exist and can be regarded as more or (...) less aesthetically valuable. My discussion below will bear wide implications for how claims like... (shrink)

This dissertation addresses two questions at the center of critical debate about ecology’s ability to provide scientific guidance in efforts to address mounting environmental problems. The first concerns whether and, if so, how theoretical ecological models (TEMs) can usefully inform environmental policy and resource management decision-making. The second concerns whether and, if so, in what manner the entities such models characterize (i.e., ecological populations, communities, and systems) exist. Throughout this work, I clarify how these questions are, and are not, related (...) and infer answers to each by analyzing the arguments of critics of theoretical, TEM-based, ecological research and analyzing ecologist’s practices of using TEMs in landmark research studies. My analyses illuminate numerous ways in which theoretical ecological research can aid in environmental policy and resource management decision-making, and show that modern ecologists embrace a largely ontology-neutral metaphysics and instrumentalist epistemology (contrary to the received view among critics of ecology). I defuse a number of popular criticisms of theoretical ecological research by showing that they rely on confusions about ecology’s conceptual foundations and the reasoning processes employed in theoretical ecological research. At the same time, I take pains to isolate the substantive point about the limitations of such research that critics can reasonably make. Accordingly, the overarching structure of this dissertation sees it as an effort to, first, isolate the substantive point critics make about the limitations of theoretical ecological research and then identify ways in which such research can aid in practical decision-making despite those limitations. This dissertation pushes forward the philosophical and broader crossdisciplinary dialogue concerning ecology’s conceptual foundations and practical value, while at once directly addressing the ever more urgent practical need to make plain how theoretical ecological research can usefully inform crucially important political, ethical, and management decisions about how best to cope with mounting environmental problems. It contributes to multiple disciplines as such, and students and professionals of all stripes interested in ecology and its practical applications should find resources to extend their own investigations in it. (shrink)

While many recognize that rigid historical and compositional goals are inadequate in a world where climate and other global systems are undergoing unprecedented changes, others contend that promoting ecosystem services and functions encourages practices that can ultimately lower the bar of ecological management. These worries are foregrounded in discussions about Novel Ecosystems (NEs); where some researchers and conservationists claim that NEs provide a license to trash nature as long as some ecosystem services are provided. This criticism arises from what we (...) call the " anything goes " problem created by the release of historical conditions. After explaining the notion of NE, we identify numerous substantive motivations for worrying about the anything-goes-problem and then go on to show the problem can be solved by correcting two mistaken assumptions. In short, we argue that the problem is a product of adopting an overly sparse functional perspective and one that assumes an unrealistically high degree of convergence in the trajectories of natural processes. Our analysis illuminates why such assumptions are unwarranted. Finally, we further argue that adopting an appropriate ethical framework is essential to overcoming the anything-goes-problem and suggest that a certain virtue ethics conception of ecological management provides useful resources for framing and resolving the problem. (shrink)

This is the first collection of essays in which European and American philosophers explicitly think out their respective contributions and identities as environmental thinkers in the analytic and continental traditions. The American/European, as well as Analytic/Continental collaboration here bears fruit helpful for further theorizing and research. The essays group around three well-defined areas of questioning all focusing on the amelioration/management of environmentally, historically and traditionally diminished landscapes. The first part deals with differences between New World and the Old World perspectives (...) on nature and landscape restoration in general, the second focuses on the meaning of ecological restoration of cultural landscapes, and the third on the meaning of the wolf and of wildness. It does so in a way that the strengths of each philosophical school—continental and analytic—comes to the fore in order to supplement the other’s approach. This text is open to educated readers across all disciplines, particularly those interested in restoration/adaptation ecology, the cultural construction of place and landscape, the ongoing conversation about wilderness, the challenges posed to global environmental change. The text may also be a gold mine for doctoral students looking for dissertation projects in environmental philosophy that are inclusive of continental and analytic traditions. This text is rich in innovative approaches to the questions they raise that are reasonably well thought out. The fact that the essays in each section really do resonate with one another directly is also intellectually exciting and very helpful in working out the full dimensions of each question raised in the volume. (shrink)

This chapter aims to support non-selectionist elucidations of the notion of ecological role and of the idea of ecosystem-level functional organization associated with it. It does so, first, by noting how non-selectionist elucidations of ecological roles, such as those that appeal to the causal role theory of function, better accord with the context-based (rather than evolutionary-historical) understanding of ecological roles adopted in functional ecology. The chapter then discusses a serious challenge raised by the seeming accidentality of context-based ecological roles, and (...) their apparent conflict with the requirement, widely acknowledged among philosophers of biology, that accounts of function provide a principled way of distinguishing between functions and mere effects. It is argued that the perspectivalist stance on the function/mere effect distinction adopted by causal role theorists does not satisfactorily meet this challenge. It is proposed that this challenge can more satisfactorily be met through drawing the appropriate connection between the notion of ecosystem-level functional organization and a phenomenon which is fundamental to the makeup of the ecological world: the association of organisms from different species with one another into more or less resilient webs of use and service interactions, which undergird cycles of nutrients and flows of energy between those organisms. (shrink)

Following Kenya’s independence in 1963, scientists converged on an ecologically sensitive area in southern Kenya on the northern slope of Mt. Kilimanjaro called Amboseli. This region is the homeland of the Ilkisongo Maasai who grazed this ecosystem along with the wildlife of interest to the scientists. Biologists saw opportunities to study this complex community, an environment rich in biological diversity. The Amboseli landscape proved to be fertile ground for testing new methods and lines of inquiry in the biological sciences that (...) were generalizable and important for shaping natural resource management policies in Kenya. However, the local community was in the midst of its own transformation from a primarily transhumant lifestyle to a largely sedentary one, a complex political situation between local and national authorities, and the introduction of a newly educated generation. This article examines the intersection of African history and field science through the post-colonial Africanization of Kenyan politics, the broadening of scientific practices in Amboseli in previously Western-occupied spaces to include Kenyan participants, and an increasing awareness of the role of local African contexts in the results, methods, and implications of biological research. “Africanization” as an idea in the history of science is multifaceted encompassing not just Africans in the scientific process, but it needs an examination of the larger political and social context on both a local and national level. (shrink)

The world is an untidy place, and the sciences—all of them—reflect this. One source of this untidiness is the relationship between levels of organization. Reducing macrolevels to microlevels—explaining the former in terms of the latter—has met with successes but has never been the whole story. In the biological sciences, there has been much attention lately to the shortcomings of reductionism on the grounds that (i) it changes the subject rather than explaining, (ii) it leads to a myopically molecular view of (...) the biological world, and (iii) the behavior or behaviors of complex systems are often very poorly predicted based solely on their microproperties. It is just for these reasons that biologists of many stripes have called for a move away from reductionism and toward a new kind of biology for the 21st century. But what shape might this new biology take? (shrink)

In “What Does Environmental Protection Protect?” Mark Sagoff argues that there is no ecological way to test the claim that natural ecosystems are complex adaptive systems. In this critical commentary, I recreate that argument, object to it, and attempt to clarify its normative upshot. I show that Sagoff relies on substantive assumptions about (1) the tools and methods of ecological science, (2) what can be done with those tools and methods, and (3) ecology’s being separable from other disciplines, all of (...) which are controversial and in need of defense. I also identify five different ways that one might interpret the action-guiding recommendation that Sagoff wants to make on the basis of that argument, and I explain why all five are somewhat problematic. (shrink)

The influence of many factors on ecological success in common pool resource management is still unclear. This may be due to methodological issues. These include causal complexity, a lack of large-N-studies and nonlinear relationships between factors. We address all three issues with a new methodological approach, artificial neural networks, which is discussed in detail. It allows us to develop a model with comparably high predictive power. In addition, two success factors are analyzed: legal security and institutional fairness. Both factors show (...) a positive impact on success in irrigation and fisheries supporting the view that there are sector-independent success factors. (shrink)

The development of ecological thinking in North America has been conditioned by the imperative aiming at a valuation of the biotic community. Since the end of WWII, the US population was warned against the dangerous and violent alterations of nature. Many then found in theology an unforeseen ally. I review the roots of the tension which led to debates involving radical ecologism or its denial, and I aim at analyzing it philosophically.

Conservationists have two types of arguments for why we should conserve ecosystems: instrumental and intrinsic value arguments. Instrumental arguments contend that we ought to conserve ecosystems because of the benefits that humans, or other morally relevant individuals, derive from ecosystems. Conservationists are often loath to rely too heavily on the instrumental argument because it could potentially force them to admit that some ecosystems are not at all useful to humans, or that if they are, they are not more useful than (...) alternative configurations of those ecosystems. Consequently, conservationists often resort to an intrinsic value argument, contending that ecosystems are objectively valuable as ends in themselves, rather than merely as means to an end. If ecosystems have intrinsic value, then they have moral standing, which means that we must consider their needs and interests in any decisions we make about them. This paper concerns the significance of this move for... (shrink)

In this article, I will discuss possible differences between ecosystems and organisms on the basis of their intrinsic complexity. As the concept of complexity still remains highly debated, I propose here a practical and original way to measure the complexity of an ecosystem or an organism. For this purpose, I suggest using the concept of logical depth (LD) in a specific manner, in order to take into account the difficulty as well as the time needed to generate the studied object. (...) I illustrate this method with fully controlled Daisyworld simulations (i.e., simulations based on the Gaia hypothesis) that have often been proposed to mimic living systems. The method consists of the following sequential stages: (1) identification of the shortest program able to numerically model the studied system (also called the Kolmogorov–Solomonoff complexity); (2) running the program, once if there are no stochastic components in the system, several times if stochastic components are there; and (3) computing the time needed to generate the system with LD complexity. This measure is supposed to estimate the system complexity. It appears in this study that LD estimations fit well with the intuition we have of complex systems, with higher complexities being found for more realistic Daisyworlds. With such a method of capturing the time needed to build a system, we expect to detect in future studies any quantified differences between complex ecosystems and organisms. (shrink)

Biofuels have lately been indicated as a promising source of cheap and sustainable energy. In this paper we argue that some important ethical and environmental issues have also to be addressed: (1) the conflict between biofuels production and global food security, particularly in developing countries, and (2) the limits of the Human Appropriation of ecosystem services and Net Primary Productivity. We warn that large scale conversion of crops, grasslands, natural and semi-natural ecosystem, (such as the conversion of grasslands to cellulosic (...) ethanol production, or plantation of sugar cane and palm oil), may have detrimental social and ecological consequences. Social effects may concern: (1) food security, especially in developing countries, leading to an increase of the price of staple food, (2) transnational corporations and big landowners establishing larger and larger landholdings in conflict with indigenous areas and the subsistence of small farmers. Ecological effects may concern: (1) competition with grazing wild and domesticated animals (e.g., millions of grazing livestock in USA prairies), (2) an excessive appropriation of Net Primary Production from ecosystems, (3) threatening biodiversity preservation and soil fertility. We claim that is it well known how ecological and social issues are strictly interwoven and that large scale biofuels production, by putting high pressure on both fronts, may trigger dangerous feedbacks, also considering the critical fact that 9 billion people are expected to inhabit the planet by 2050. There is a need to conduct serious and deep analysis on the environmental and social impact of large scale biofuels production before important energy policies are launched at global level. Biofuels will not represent an energetic panacea and their role in the overall energy consumption will remain marginal in our present highly energivorous society, while their effect on food security and environment preservation may have detrimental results. We should also have the courage to face two key issues: (1) we cannot keep increasing resources consumption at present pace, and have to change our life style accordingly, and (2) we have to deal with population growth; we cannot expect to have 9–10 billions people inhabiting the earth by 2050, without this representing a major impact on its support system. (shrink)

In many experimental sciences, like particle physics or molecular biology, the proper place for establishing facts is the laboratory. In the sciences of population biology, however, the laboratory is often seen as a poor approximation of what occurs in nature. Results obtained in the field are usually more convincing. This raises special problems: it is much more difficult to obtain stable, repeatable results in the field, where environmental conditions vary out of the experimenter’s control, than in the laboratory. We examine (...) here how this problem affected an influential experimental research tradition in community ecology, the study of the ecology of the rocky seashores. In the 1960s, a handful of North-American ecologists, most notably Joseph Connell, Robert Paine and Paul Dayton, made the rocky seashores a model study system for experimenting in the field. Their experiments were deceptively simple: they removed species living on the seashore and described the resulting effects on the local ecology. These experiments exerted a deep influence on community ecology. They provided evidence for speculative developments concerning the theory of interspecific competition, the factors responsible for species richness and the ecology of food webs. They also stimulated novel conceptual developments. In particular, Paine developed the predation hypothesis, which states that the presence of predators can favour species richness, before introducing the keystone species concept, according to which some species exert disproportionate effects on ecological systems. More broadly, these experiments gave support to a methodological trend in favour of field experimentation. Only controlled perturbations in the field, it seemed, provided a reliable method to get insights into the structure of ecological communities. However, as experiments were continued in time and repeated in different sites, divergent results appeared. We analyse here how intertidal researchers coped with the variability of environmental conditions and tried to stabilize their results. In the process, they reconsidered not only their early conclusions, but also the exclusive status given to field experiments. Expanding on this case study, we discuss some significant differences between laboratory and field experiments. (shrink)

Sound definitions of its basic concepts are fundamental to every scientific discipline. In some instances, like in the case of the ecosystem concept, the question arises if we can define such concepts at all. And if we can define them, how should we choose from the multiple definitions available? And what are the preconditions for a scientifically sound and useful definition? On the basis of the ecosystem concept, this paper illustrates a major, often neglected distinction in the definition of ecological (...) concepts, namely that between defining criteria and additional descriptive statements connected to those definitions. As is demonstrated by examples from the literature, mixing up these categories leads to false inferences about the properties of physical objects (e.g. a particular forest) subsumed by the concept (e.g. the ecosystem). As a further consequence, this inference becomes problematic in terms of theory development and/or the application of ecological concepts for management decisions. (shrink)