The politics of national SDG indicator systems: A comparison of four European countries.

The sustainable development goals (SDGs) constitute an ambitious comprehensive global framework including monitoring mechanisms and indicators to evaluate progress towards precise targets of sustainable development. Most European countries have adapted their national sustainability indicator systems to conform to the UN Agenda 2030 for sustainable development, introducing new indicators and monitoring frameworks and governance processes in which these are embedded. What do we know about the political processes and struggles of implementing this important global framework? How does the politics of indicators differ in national contexts? We propose a classification of national indicator systems along dimensions of indicator selection, appraisal landscape, participatory nature, and political communication. We empirically explore these dimensions for four European national sustainability indicator systems through a comparative analysis based on national policy documents, indicator databases, and web portals as well as inputs from workshops and expert interviews. Given the considerable variation with respect to the trajectory of national sustainability indicator systems, we posit that these differences correspond to different national interpretations of sustainability.

Sustainable Development Goals and risks: The Yin and the Yang of the paths towards sustainability.

The United Nations 2030 Agenda and Sustainable Development Goals (SDGs) define a path towards a sustainable future, but given that uncertainty characterises the outcomes of any SDG-related actions, risks in the implementation of the Agenda need to be addressed. At the same time, most risk assessments are narrowed to sectoral approaches and do not refer to SDGs. Here, on the basis of a literature review and workshops, it is analysed how SDGs and risks relate to each other's in different communities. Then, it is formally demonstrated that, as soon as the mathematical definition of risks is broadened to embrace a more systemic perspective, acting to maintain socio-environmental systems within their sustainability domain can be done by risk minimisation. This makes Sustainable Development Goals and risks "the Yin and the Yang of the paths towards sustainability". Eventually, the usefulness of the SDG-risk nexus for both sustainability and risk management is emphasized.

The Hierarchy-of-Hypotheses Approach: A Synthesis Method for Enhancing Theory Development in Ecology and Evolution.

In the current era of Big Data, existing synthesis tools such as formal meta-analyses are critical means to handle the deluge of information. However, there is a need for complementary tools that help to (a) organize evidence, (b) organize theory, and (c) closely connect evidence to theory. We present the hierarchy-of-hypotheses (HoH) approach to address these issues. In an HoH, hypotheses are conceptually and visually structured in a hierarchically nested way where the lower branches can be directly connected to empirical results. Used for organizing evidence, this tool allows researchers to conceptually connect empirical results derived through diverse approaches and to reveal under which circumstances hypotheses are applicable. Used for organizing theory, it allows researchers to uncover mechanistic components of hypotheses and previously neglected conceptual connections. In the present article, we offer guidance on how to build an HoH, provide examples from population and evolutionary biology and propose terminological clarifications.

"Organismic" positions in early German-speaking ecology and its (almost) forgotten dissidents.

In early German ecology, the key concept used to refer to a synecological unit was Biozönose (biocoenosis). Taken together with the concept of the Biotop (biotope), it was also understood as an integrated higher-order unit of life, sometimes called a "Holozön" (holocoen). These units were often perceived as having properties similar to those of individual organisms, and they informed the mainstream of German ecology until at least the late 1960s. Here I ask how "organismic" these concepts really were and what conceptual problems they entailed. To do so, I focus on some almost forgotten dissident positions, especially those of (German-born) Friedrich Simon Bodenheimer and Fritz Peus, which I contrast with the mainstream German ecology of the time. In a radical paper published in 1954 that postulated the "dissolution of the concepts of biocoenosis and biotope", Peus in particular elicited a forceful response from many prominent German ecologists. An analysis of the ensuing debate, including especially a colloquium held in 1959 that was partly inspired by Peus' paper, is helpful for sifting the various arguments proffered with respect to a quasi-organismic perception of the biocoenosis in German speaking ecology. Although German mainstream ecologists rejected the notion of the biocoenosis as a superorganism, ontological holism was quite common among them. Additionally, the mainstream concept of the biocoenosis was plagued by several methodological problems and much conceptual confusion, to which the "dissidents" rightly pointed. Some of these problems are still pertinent today, e.g. in connection with more modern concepts such as "ecosystem".

Conceptual frameworks and methods for advancing invasion ecology.

Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology.

Can we define ecosystems? On the confusion between definition and description of ecological concepts.

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.

Ecological units: definitions and application.

Concepts of ecological units, such as population, community, and ecosystem, are at the basis of ecological theory and research and have increasingly become the focus of conservation strategies. Concepts of these units still suffer from inconsistencies and confusions over terminology. The different concepts are treated here together as a common "conceptual cluster," with similar ecological functions (roles) and similar problems in their definition and use. An analysis of the multitude of existing terms and concepts that have been developed for these units reveals that they differ with respect to at least four basic criteria: (i) the questions as to whether they are defined statistically or via a network of interactions; (ii) if their boundaries are drawn by topographical or process-related criteria; (iii) how high the required internal relationships are; and (iv) if they are perceived as "real" entities or abstractions by an observer The various definitions cannot be easily sorted into just a few types, but they can be characterized by several independent criteria. I argue that serious problems arise if the different possibilities of defining ecological units are not recognized and if the concepts are perceived as self-evident. The different concepts of ecological units should be defined and used in a philosophically informed manner I propose a dual approach to the use of ecological units. Generic meanings of the main concepts (especially population, community, and ecosystem) should be retained only as heuristically useful perspectives, while specific and "operational" definitions of the concepts as units should be developed, depending on specific purposes of their use. Some thoughts on the basic requirements for such definitions and the domains of their uses are briefly explained.