University of Koblenz and Landau

Abstract. Carbon emission estimates from riverine ecosystems at high northern latitudes are rarely assessed, resulting in significant uncertainty in the carbon budgets of this region. To close this gap, we determined chamber-derived carbon dioxide (CO2) and methane (CH4) fluxes alongside surface partial pressure measurements within the Teno river catchment. The Teno river represents an undisturbed, natural ecosystem at the border between northern Finland and Norway. Chamber measurements were conducted on the water and at river banks (i.e. vegetation-free parafluvial and partially vegetated areas) and yielded predominantly low fluxes. Water-air CO2 fluxes amounted to 0.25 ± 0.27 μmol m−2 s−1 (mean ± standard deviation), and water-air CH4 fluxes to 1.77 ± 3.19 nmol m−2 s−1. Soil-air CO2 fluxes from banks reached 1.45 ± 1.38 μmol m−2 s−1 for ecosystem respiration (Reco), and 0.55 ± 1.34 μmol m−2 s−1 for net ecosystem exchange (NEE), while corresponding CH4 fluxes were 1.03 ± 3.14 nmol m−2 s−1. Using hydrographic datasets, we upscaled our observations for water-air fluxes from the river channel and for soil-air fluxes from the banks. Accordingly, the total vertical carbon emissions amounted to 3,017 tC yr−1 for CO2 and 3.3 tC yr−1 for CH4, while banks overall were estimated to emit more than four times the amount of CO2 than the river channel. Furthermore, we determined the lateral carbon export of the river towards the ocean and estimated a total annual export of roughly 70,000 tC yr−1 from Teno river, mostly in the form of dissolved organic carbon and bicarbonates. As a result, the river network acted as a small carbon source to the atmosphere and the ocean. Carbon dioxide dominated the net carbon balance of the river, while CH4 emissions were minimal. Although the measured fluxes and the carbon balance of the river network were small in comparison with the landscape-scale carbon balance, the study provides important baseline data for pristine, subarctic rivers, a data-poor ecosystem in current literature. As previous flux measurement sites may be biased towards high-emission ecosystems, it is important to highlight the significance of carbon dynamics for low-emitting sites in order to achieve a balanced understanding. In addition, this study provides insight into the land-water-atmosphere carbon dynamics of northern rivers, and can be used as benchmark for Earth System and process-based models.

Understanding and sustaining biodiversity futures requires approaches that integrate ecological and social dimensions over the long term. The Kili-SES (Kilimanjaro social-ecological system) platform in Tanzania illustrates how Long-Term Social-Ecological Research (LTSER) can generate such integrative knowledge. Building on more than a decade of interdisciplinary collaboration, Kili-SES combines ecological monitoring, social research, and participatory scenario work within a shared conceptual framework inspired by the IPBES approach. A systematic plot design that captures both an elevation and a land-use gradient enables consistent long-term data collection and supports analyses linking biodiversity, ecosystem functions, and nature’s contributions to people (NCP). This framework allows the project to trace connections from biodiversity through NCP to human well-being and governance, while continually refining methods and insights through long-term engagement with people and place.Recent work in Kili-SES has advanced this integration in several ways. A novel conceptual framework connects ecological network analysis with NCP supply, revealing how species interactions and human demand jointly shape the importance of biodiversity for NCP. Applying this framework to the extensive ecological and social datasets accumulated since the project’s inception allows us to identify keystone species for NCP provision and to anticipate how network changes may alter local livelihoods under future land-use or climate scenarios.Scenario-building workshops conducted in the project allowed different local social actors to jointly identify key drivers of change and to co-develop contrasting future scenarios for the Kilimanjaro region. In the upcoming phase, these participatory dialogues will expand toward co-developing pathways for resilient and just human–wildlife coexistence—illustrated by a case study on fruit bats that integrates ecological, epidemiological, and social perspectives on both beneficial and detrimental NCP.Together, these examples demonstrate how sustained, place-based, and interdisciplinary research can bridge ecological processes and societal aspirations. LTSER platforms like Kili-SES provide the scientific continuity and participatory grounding needed to envision and navigate toward sustainable biodiversity futures.

Abstract The 13th Young Environmental Scientists (YES) Meeting, held in York, United Kingdom, from the 11-15th August 2025, continued the tradition of fostering interdisciplinary collaboration and professional development among early-career researchers in environmental sciences. Organised by the SETAC Europe Student Advisory Council (SAC), this student-led conference brought together 111 participants from 22 countries, offering a dynamic platform for scientific exchange across all different disciplines that exist within SETAC. Under the theme, “Between Grinding Gears—Students and Early Career Scientists Under Pressure ”, the meeting featured over 100 scientific contributions, four interactive workshops and three keynote lectures that addressed scientific challenges as well as personal- and professional realities faced by students and early career scientists. Beside the academic program, there were also social events to bolster networking among peers, strengthening the community that defines the YES meetings and securing its role as a cornerstone for early-career engagement within SETAC. This commentary highlights the scientific and social achievements of the 2025 edition, the financial support that made it possible, and the collaborative spirit that brought it to life. As we look to the future, the continued success of the YES Meeting depends on the passion and voluntary engagement of students and early-career researchers, whose energy and commitment will continue to advance this unique, student-driven platform thriving as a space for growth, collaboration, and lasting friendships.

Introduction The importance of silicon for soil functioning has only recently received the attention it deserves in soil science (and ecology). To identify the actual effects of Si on ecosystem functioning, a precise knowledge about different Si soil fractions (plant-available, amorphous Si, and Si bound to organic matter, short-range ordered aluminosilicates (SROAS), or iron oxides/hydroxides) is required. Sequential extraction techniques are a common tool to quantify different soil fractions in soils of humid-temperate climates, whereas their reliability in other climatic zones or contrasting soils remains unclear. This study tested to what extend sequential extraction is applicable on soils from the High Andes and Amazon Basin, two contrasting regions with distinct soil formation processes. Methods To ensure method validity, we analyzed Si, iron (Fe), and aluminum (Al) in extracts and conducted X-ray diffraction (XRD) to detect mineral changes pre- and postextraction. Amorphous Si was more abundant in the High Andes soils, yet plantavailable Si was unexpectedly lower compared to Amazon Basin soils. Results Silicon occluded in Fe oxides/hydroxides or SROAS showed no differences between the two contrasting soils. XRD results revealed the following limitations: dithionite extraction did not completely remove Fe from hematite in Andean soils, and powder XRD lacked precision for amorphous Si quantification. Among the tested methods, CaCl2 extraction (for plant-available Si) and a two-step protocol—density separation for biogenic Si (bASi), followed by Tiron extraction for total amorphous Si (tASi)—were the most effective for these soils. Discussion These findings, with different methods not being able to characterize the soil used, underscore the need to refine Si extraction techniques for environments. Expanding methods originally developed in temperate soils is critical to understanding Si’s role in biogeochemical cycles and its broader significance for different ecosystem performance.

Abstract Aquatic emerging insects play a critical role in riparian ecosystems by supporting terrestrial consumers, particularly generalist predators like spiders. Their emergence is highly sensitive to environmental changes such as river regulation and climate change. While previous studies have demonstrated that fluctuations in aquatic insect subsidies influence spider abundance and diversity, little is known about how these changes affect spider morphology and physiology. This study aimed to investigate how flooding affects both aquatic insect emergence and morphological responses of the web‐building spider Tetragnatha extensa (Linnaeus, 1785). We conducted an experiment using a riparian stream mesocosm facility, simulating four flooding events between May and September. Aquatic insects were sampled using emergence traps during all flooding events, while spiders were collected at the beginning and end of the experiment. To assess developmental stress, we measured spider head size and fluctuating asymmetry using landmarking and geometric morphometrics. Spiders in flooded mesocosms exhibited ~15% lower fluctuating asymmetry than those in controls, suggesting reduced developmental stress. This likely reflects the 45% higher emergence of chironomids, the main prey of T. extensa . These results indicate that spider developmental stability is responsive to prey availability and that geometric morphometrics is a sensitive tool for detecting such prey‐mediated ecological effects. Climate change, water use and river regulation, through altered flooding regimes, can disrupt cross‐ecosystem fluxes by affecting the emergence of aquatic insects. Reduced prey availability may, in turn, impact spider physiology and propagate into the riparian ecosystem through altered fitness, reproductive success and population dynamics of terrestrial consumers.

The collective vibrational and magnetic response of a solid to external stimuli is encoded in the dispersion relations of phonons and magnons, respectively. Recently, the coherent drive and nonlinear manipulation of collective lattice and magnetic excitations via laser pulses has been explored, as a route to control the non-equilibrium properties of quantum materials. Device concepts that leverage coupled multiphysical dynamics must exhibit laser-induced frequency tunability controllable through external parameters. Although previous works have shown that optically driven excitations in the midinfrared can manipulate magnon frequencies, inducing deterministic red- or blue-shifts of the magnon frequency in the same material is still elusive. Here we demonstrate this concept in a nanometer-thick magnet at room temperature. Visible light pulses in combination with an external magnetic field (<200 mT) can either raise or lower the magnon frequency by up to 40% of its original value. This effect results from the interplay of the optical excitation, magnetic anisotropy and external magnetic field. Our results show how an efficient manipulation of magnons can be achieved by light and provide perspectives for the realization of logic devices optically reconfigurable on the nanosecond timescale.

Soil, as the largest terrestrial carbon sink, plays a pivotal role in the global carbon cycle. Soil microorganisms are fundamental to all biochemical processes in soil, ensuring its fertility and supporting a balanced ecosystem. Through their metabolic activities, these microorganisms drive energy and matter flows, mineralizing organic matter and releasing heat and CO 2 , which can be measured via calorespirometry. A key limitation of conventional calorimeters lies in their inability to combine high sample throughput with sufficiently large sample sizes while avoiding oxygen limitation during measurement. In order to overcome these weaknesses, we have developed a multi-channel macrocalorespirometer (CR-12) for soil analysis. To demonstrate its application, agricultural soil (Dikopshof, Luvisol) amended with 12 C (unlabeled) and 13 C (labeled) glucose was used in four experiments. Comparisons with commercial isothermal microcalorimeters confirmed the suitability of CR-12 for soil systems, providing reliable heat, CO 2 measurements and calorespirometric ratios that align with known ranges for the aerobic turnover of carbohydrates. To further investigate the incorporation of carbon into the soil organic matter (SOM), a time series of soil samples amended with 13 C-labeled glucose was subjected to mass spectrometric analysis (m/z 44 for 12 C-CO 2 ; m/z 45 for 13 C-CO 2 ) using thermogravimetry-differential scanning calorimetry-quadrupole mass spectrometry (TG-DSC-QMS). The integration of calorespirometric and mass spectrometric data demonstrated that combining these complementary techniques provides more detailed information on the fate of microbial carbon and energy turnover within SOM. • Soil microorganisms drive energy flows, mineralizing organic matter and releasing CO 2 . • Conventional techniques have limitations like low sample throughput and small sample sizes. • A multi-channel macrocalorespirometer (CR-12) was developed for improved soil analysis. • CR-12 provides reliable heat and CO 2 data, as well as calorespirometric ratios in soils. • Combining calorespirometry and mass spectrometry reveals detailed soil carbon dynamics.