Impacts of cutting frequency and position to tree line on herbage accumulation in silvopastoral grassland reveal potential for grassland conservation based on land use and cover information

In agricultural grassland, high herbage utilisation efficiency (HEFF), which is the proportion of gross live-green herbage production that is utilised before entering senescence, is ensured by frequent defoliation. The decision upon which defoliation frequency to apply depends on the farming intensity. Assuming a reduced total herbage accumulation near trees in silvopastoral systems, frequent defoliations with high HEFF become less worthwhile—at least in specific spatial configurations. This makes an extensive management near trees an interesting option because it promotes other grassland-related ecosystem services such as biodiversity. The present study first analysed the interaction between defoliation frequency and position to trees on the total, dead and live herbage accumulation and the HEFF at two silvopastoral sites with short-rotation coppices in Germany. In addition, the total grassland–tree interface in Germany was assessed from land use and land cover maps of Germany based on satellite data to approximate the potential of grassland extensification near trees. The total herbage accumulation near trees declined by up to 41% but the HEFF was not affected by the position. Consequently, any intensification is not paid-off by adequate productivity and herbage quality in terms of HEFF and tree-related losses in herbage accumulation are expected up to a distance of 4.5–6 m. Applying a 4.5 m border on satellite data, we found that up to 4.4% (approximately 2200 km2) of the total grassland area in Germany is at a tree interface and potentially suitable for extensification. These findings indicate substantial potential for biodiversity conservation in grasslands with low trade-off for high-quality yield.Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Peer Reviewe

Auf elektronischem Wege nach Bologna

Der Bologna-Prozess ist in seinen strukturellen Auswirkungen eng verbunden mit der Nutzung digitaler Technologien. Die damit verbundenen Fragen werden unter dem Stichwort E-Bologna diskutiert. Zwei Themen stehen dabei im Vordergrund: Wie müssen die vorhandenen Systeme an Hochschulen aus einer organisatorischen und administrativen Perspektive integriert und erweitert werden und welche Möglichkeiten bieten digitale Technologien in der Lehre, die Förderung von Mobilität, lebenslangem Lernen und Aufbau von Schlüsselkompetenzen zu unterstützen? Der Beitrag zeigt praxisnahe Beispiele, wie an den Instituten der Humboldt-Universität flexibel mit den neuen Herausforderungen umgegangen wird. Die präsentierten Lösungen sind eng an konkreten Herausforderungen entwickelt worden und haben nicht den Anspruch eine umfassende Lösung zu erarbeiten. Sie sind vielmehr strikt pragmatisch angelegt und damit alltagstauglich im fachlichen Kontext. Der Beitrag will Anregungen und Beispiele geben, wie die mit Bologna verbundenen Herausforderungen mit Hilfe digitaler Technologien gemeistert werden

Undecidability of Dyadic First-Order Logic in Coq

We develop and mechanize compact proofs of the undecidability of various problems for dyadic first-order logic over a small logical fragment. In this fragment, formulas are restricted to only a single binary relation, and a minimal set of logical connectives. We show that validity, satisfiability, and provability, along with finite satisfiability and finite validity are undecidable, by directly reducing from a suitable binary variant of Diophantine constraints satisfiability. Our results improve upon existing work in two ways: First, the reductions are direct and significantly more compact than existing ones. Secondly, the undecidability of the small logic fragment of dyadic first-order logic was not mechanized before. We contribute our mechanization to the Coq Library of Undecidability Proofs, utilizing its synthetic approach to computability theory

Melocoton: A Program Logic for Verified Interoperability Between OCaml and C

International audienceIn recent years, there has been tremendous progress on developing program logics for verifying the correctness of programs in a rich and diverse array of languages. Thus far, however, such logics have assumed that programs are written entirely in a single programming language. In practice, this assumption rarely holds since programs are often composed of components written in different programming languages, which interact with one another via some kind of foreign function interface (FFI). In this paper, we take the first steps towards the goal of developing program logics for multi-language verification. Specifically, we present Melocoton, a multi-language program verification system for reasoning about OCaml, C, and their interactions through the OCaml FFI. Melocoton consists of the first formal semantics of (a large subset of) the OCaml FFI-previously only described in prose in the OCaml manual-as well as the first program logic to reason about the interactions of program components written in OCaml and C. Melocoton is fully mechanized in Coq on top of the Iris separation logic framework

The position of scientists in transformations of human-environment systems. An inquiry into IRI THESys research practices

Transformation is a multi-faceted concept with various meanings and assumptions about desired human-environment relationships and pathways towards the ideal (sustainable) society. We need a better understanding of the different positions that scientists assume when conducting research and becoming involved in transformations of human-environment systems. In this paper we begin such an analysis by exploring how researchers at the Humboldt-Universität’s Integrative Research Institute on Transformations of Human-Environment Systems (IRI THESys) position themselves within that research. Empirical work was conducted in three steps. First, a survey was carried out among the institute’s academic staff to explore the influence of ideology, their involvement in processes outside academia, the ways in which their research relates to transformations of human-environment systems, and the type of science that gives them more recognition in their peer groups or institutions. Second, the findings from the survey were used as a basis for six semi-structured interviews with a sample of respondents to further investigate the heterogeneity of positions in the institute’s research on transformations. Third, the co-authors of the paper – all of them IRI THESys staff – were asked to compare the overall findings with the notion that their scientific community has on the role of scientists in transformations of human-environment systems. In the results we systemize IRI THESys’ scientists’ positions and use them to critically reflect on the complex relationships between science and human-environment transformation. Based on our findings, we conclude that IRI THESys is a very heterogeneous epistemic environment, whose strength lies in its ability to keep people with diverse specialisations and convictions in dialogue with each other. Accountability towards different communities (scientific and beyond) and the humility of knowledge practices before the complexity of human-environment systems in transformation is key to positioning the IRI THESys in transformation research

A Review of the Application of Optical and Radar Remote Sensing Data Fusion to Land Use Mapping and Monitoring

The wealth of complementary data available from remote sensing missions can hugely aid efforts towards accurately determining land use and quantifying subtle changes in land use management or intensity. This study reviewed 112 studies on fusing optical and radar data, which offer unique spectral and structural information, for land cover and use assessments. Contrary to our expectations, only 50 studies specifically addressed land use, and five assessed land use changes, while the majority addressed land cover. The advantages of fusion for land use analysis were assessed in 32 studies, and a large majority (28 studies) concluded that fusion improved results compared to using single data sources. Study sites were small, frequently 300–3000 km 2 or individual plots, with a lack of comparison of results and accuracies across sites. Although a variety of fusion techniques were used, pre-classification fusion followed by pixel-level inputs in traditional classification algorithms (e.g., Gaussian maximum likelihood classification) was common, but often without a concrete rationale on the applicability of the method to the land use theme being studied. Progress in this field of research requires the development of robust techniques of fusion to map the intricacies of land uses and changes therein and systematic procedures to assess the benefits of fusion over larger spatial scales

A Coq Library for Mechanised First-Order Logic

International audienceWe report about an ongoing collaborative effort to consolidate several Coq developments concerning metamathematical results in first-order logic [1, 2, 11, 10, 8, 7, 6, 15, 12] into a single library. We first describe the framework regarding the representation of syntax, deduction systems, and semantics as well as its instantiation to axiom systems and tools for user-friendly interaction. Next, we summarise the included results mostly connected to completeness, undecidability, and incompleteness. Finally, we conclude by reporting on challenges experienced and anticipated during the integration. The current status of the project can be tracked in a public fork of the Coq Library of Undecidability Proofs [3]. Framework In principle, we follow ideas and suggestions present in various approaches [14, 9, 5, 4, 13] to the representation of first-order logic in CIC. Over the span of our initial projects we tried out several variants and found the final framework to be most suitable. Notably, a previous version used the Autosubst 2 tool [16] to generate the syntax, which we decided to avoid in later versions due to its use of function extensionality. The final framework, however, still follows the same design principles for binding and substitution. The syntax is represented by inductive types for terms t : T and formulas ϕ : F depending on signatures of function symbols f and relation symbols P as well as a collection of binary connectives 2 and quantifiers ∇

uds-psl/coq-library-undecidability: Coq Library of Undecidability Proofs version 1.1.1+8.18

A library of mechanised undecidability proofs in the Coq proof assistant