Research Institute for Nature and Forest

Abstract Rivers are increasingly fragmented and degraded, yet the European Union Nature Restoration Regulation calls for restoring at least 25,000 kilometres of free-flowing rivers by 2030. Translating this ambition into effective implementation remains challenging because restoration priorities differ across ecological, social, economic, and governance contexts. Here, we synthesize expert knowledge from 45 countries through a structured, multi-step prioritization process to identify research priorities for restoring free-flowing rivers in Europe. We identified 27 priorities and analysed how expert background and spatial context influenced their ranking. Restoration priorities differed systematically depending on whether experts emphasized ecological integrity, community engagement, economic considerations, or governance capacity, revealing clear patterns in how disciplinary and professional perspectives shape implementation pathways. This demonstrates that restoration strategies cannot be universal but must be adapted to local and regional political, institutional, and ecological conditions. Building on these findings, we propose a structured prioritisation framework that links barrier removal, connectivity restoration, governance mechanisms, and policy instruments to context-specific needs. Together, our results provide an empirically grounded and implementation-oriented roadmap to support European Union Member States in delivering ambitious river restoration targets in a context-sensitive and socially robust manner.

Digital Twins (DTs) are virtual representations of real-world physical objects, products, systems, or processes, and can be used for simulations and monitoring for decision support or research. DTs are rapidly gaining momentum by offering a powerful framework to assess the state of natural systems in the past, present, and future. In the marine domain, Digital Twins of the Ocean (DTOs) can be used to monitor changes in marine ecosystems, evaluate the impacts of climate change, and support sustainable use and long-term management. However, most existing DTOs remain heavily focused on oceanographic and physical components and have not yet fully integrated animal-movement data. Within the European Digital Twin Ocean (EDITO), launched by the European Commission, ocean knowledge is made readily available to everyone. EDITO integrates data from satellites, sensors, computer models, and personal device, including all EMODnet (European Marine Observations and Data Network) and Copernicus Marine data, among other sources. Since November 2025, aquatic animal tracking data from the European Tracking Network (ETN) is incorporated. The ETN database host tracking data of a wide variety of aquatic animals - such as teleost fish, elasmobranchs and molluscs - with a focus on acoustic telemetry and data storage tags. These data contribute to studies on movement ecology, species distribution modelling, wildlife management and conservation. By contributing its tracking data to EDITO, ETN strengthens its commitment to open, interoperable, and accessible data. Securing the continuous update of data to the EDITO requires the establishment of reliable pipelines between data sources and the EDITO Data Lakes. To achieve this, ETN has developed pipelines that deliver down-sampled data in Darwin Core format via EMODnet, and full-resolution data in Parquet format via SpatioTemporal Asset Catalog (STAC) standard. The harmonized ETN data streams ensure that researchers, managers, and developers can readily access animal-movement information for modelling, forecasting, and visualization within the EDITO platform.In this presentation, we outline our best practices for integrating bio-logging and tracking data into Digital Twin initiatives, highlighting lessons learned and presenting how these data streams can enhance evidence-based decision-making in marine management and policy.

Population genetic diversity (GD) is essential for long-term adaptation of wild species to changing environments. Humans have eroded ~10% of global GD, a silent crisis undermining food security, health and climate resilience. Effective population size Ne is a genetic parameter crucial for monitoring GD, understanding evolutionary processes and designing conservation strategies as it impacts the rate of random genetic drift, inbreeding, and adaptive potential. The “proportion of populations within species with Ne above 500” (Ne500) is an indicator endorsed by the Kunming-Montreal Global Biodiversity Framework that can be calculated from DNA-based or proxy data. Our aims are (1) to develop best practices for estimating Ne when genetic data is available, and (2) to operationalize this indicator via FAIR workflows to facilitate its reporting to the CBD. We intend to improve the estimation of Ne by accounting for life-history traits (LHT) such as longevity and reproductive strategies. We implemented an existing LHT-based categorization framework based on demographic matrices across a wide range of taxa. This allowed us to select DNA datasets from a subset of 18 European species across the main categories of the LHT framework, thus covering a large range of evolutionary histories and biological characteristics. We estimated genetic Ne and other population genetic metrics for 195 populations across the 18 species, and explored their variation across the LHT framework. We observed a large variation of Ne estimates across LHT categories, including populations with Ne below and above 500. We showed a negative relationship between Ne and population-specific divergence across a large proportion of LHT categories. We discuss situations where genetic or genomic data offer clear advantages over proxy data for reporting the Ne500 indicator, and we highlight the practical challenges of reliably estimating Ne in natural populations, particularly when spatial and age structures interact.We are currently implementing operational workflows for end-users to compute Ne500 from a representative set of populations on the Galaxy-Ecology platform. These workflows infer genetic clusters to help with delimiting populations and control the effect of genomic data quality on Ne estimates.

Natural rewilding of abandoned agricultural land and proforestation (the practice of leaving existing, mature forests to grow undisturbed and unmanaged) are increasingly promoted as low-cost nature-based solutions for biodiversity conservation and climate mitigation. Yet their outcomes remain debated across scientific, policy, and societal domains. In particular, Europe lacks harmonized, large-scale evidence on how rewilding influences soil biodiversity and its relationship to forest recovery and carbon sequestration. Existing studies are fragmented across regions, methods, and disciplines, leaving, especially, belowground responses insufficiently understood and poorly integrated into environmental monitoring frameworks.The WILDCARD project, an EU Horizon 2020 initiative, addresses these gaps through a coordinated, cross-European assessment of forest ecosystems undergoing natural succession and proforestation. Using high-throughput DNA metabarcoding of bacterial and fungal ribosomal markers, we characterize soil microbial communities along rewilding gradients spanning from managed croplands to old secondary and primeval forests. Microbial datasets are combined with measurements of forest structure, soil properties, and carbon accumulation trajectories to identify microbial indicators that reflect ecosystem recovery processes.Among others, we expect to observe belowground recovery patterns along the rewilding gradient, including increases in microbial diversity and network connectivity, which are associated with higher functional complexity and overall ecosystem resilience. Reductions in agroecosystem-associated pathogens and increases in symbiotic and saprotrophic microorganisms are anticipated to enhance nutrient cycling, support forest regeneration capacity, and influence carbon persistence. Exploring these patterns will help determine whether and how rewilding shapes belowground biodiversity, and what implications this may have for long-term ecosystem functioning and carbon stabilization.By identifying robust microbial indicators linked to forest rewilding and soil carbon dynamics, this work provides a foundation for developing soil health metrics suitable for large-scale monitoring. The resulting bioindicators will strengthen the scientific basis needed to evaluate the contribution of rewilding to EU climate and biodiversity goals and further support evidence-based decision-making in ecological restoration.

Accurate biodiversity indicators are essential to track ecosystem health, detect early signs of degradation, and guide effective conservation policy. Within the EU Water Framework Directive (WFD), ecological indices such as the fish-based Index of Biotic Integrity (IBI) serve as key tools to translate monitoring data into management-relevant scores. However, conventional electrofishing, though well established, faces limitations including restricted spatial coverage, seasonal and detection biases, and increasing ethical concerns. Environmental DNA (eDNA) metabarcoding has emerged as a promising alternative, yet its integration into standardized policy frameworks requires robust validation.We present the results of a large-scale case study across 59 Flemish lowland river sites, where eDNA metabarcoding was benchmarked against electrofishing. By comparing biodiversity detection, seasonal consistency, and resulting ecological quality ratios (EQRs), we demonstrate that eDNA consistently detects higher species richness, including rare and cryptic taxa overlooked by traditional surveys. At the same time, electrofishing provides unique insights into population structure and recruitment, underscoring the complementarity of both approaches. Importantly, eDNA-derived ecological indices proved highly comparable to abundance-based WFD assessments, and they responded sensitively to habitat pressures across the landscape.Building on these findings, we outline two pathways for embedding molecular methods into biodiversity policy metrics: (1) recalibration of existing IBI metrics per detection method to ensure methodological fairness, and (2) development of dedicated eDNA-based indices underpinned by standardized quality controls and transparent reporting. Such approaches enable eDNA to significantly upscale monitoring networks in both spatial coverage and temporal resolution, while targeted electrofishing continues to safeguard demographic information critical for management.This hybrid monitoring framework demonstrates how molecular biodiversity measurements can be translated into robust ecological indicators. Beyond the WFD, the approach offers a blueprint for integrating eDNA into global biodiversity observation systems and emerging legislative frameworks such as the EU Nature Restoration Law. By combining sensitivity, scalability, and policy relevance, eDNA-based indicators can help accelerate biodiversity assessment and support evidence-based decision-making in freshwater conservation.

Abstract Parental care can shape post-fledging behaviour through provisioning, guidance and social information, yet its absence may alter how young birds establish space use and habitat preferences. We tested the consequences of absent parental care by comparing, hand-reared juvenile herring gulls released without parents with wild, parent-reared conspecifics, focusing on the first two months after fledging. Wild juveniles frequently revisited their natal nest during the first month, whereas hand-reared birds rarely returned to the release site; revisits declined in both groups by the second month but remained more common in wild birds. Wild juveniles used smaller ranges that subsequently expanded, while hand-reared birds began with larger ranges that later contracted, leading to convergence. Contrary to expectation, wild juveniles occurred in areas with higher human population density than hand-reared birds. Habitat use also differed between groups and changed over time. Early on, wild juveniles concentrated activity in anthropogenic and marine habitats, whereas hand-reared birds used rural green habitats more. Later, both groups shifted away from marine areas towards rural green habitats, reducing but not eliminating between-group differences. Short-term survival, did not differ between hand-reared and wild juveniles, indicating that parental care primarily reshaped early space use and habitat choice rather than immediate survival.

ABSTRACT Aim To examine how butterfly population trends respond to climate change and urbanisation at a continental scale, and whether responses differ between urban and rural environments. Location 869 sites across 12 European countries, spanning six bioclimatic zones. Time Period 1976–2021. Major Taxa Studied Butterflies (Lepidoptera). Methods We analysed long‐term monitoring data from > 8400 populations of 145 species representing a wide range of ecological and life‐history traits. Population trends were modelled in relation to climate variables (temperature, precipitation and aridity), urbanisation (built‐up surface), and their interactions with urban context (urban vs. rural) and species traits (trophic specialisation, body size, reproductive rate and thermal adaptation). Results Climate warming and aridification were consistently linked to population declines in both rural and urban contexts, while precipitation effects varied by location and species. Urbanisation alone did not predict trends, but the urban–rural context strongly modulated species' responses to warming, indicating potential synergies between climate change and urbanisation. The stronger impact of warming in urban populations likely reflects elevated baseline temperatures and reduced habitat suitability and connectivity in urban landscapes, limiting thermal buffering. Species with colder thermal niches and lower reproductive rates were most vulnerable to warming, as warming exceeds the thermal optima of cold‐adapted species and lower reproductive rates limit their capacity to buffer climate‐driven population declines. Under aridification, which can reduce host‐plant availability, trophic specialists declined more in urban areas, whereas generalists unexpectedly declined more in rural sites, suggesting context‐dependent constraints under increasing water limitation. Main Conclusions Our findings highlight the complex interplay between climate change, urban context, and species traits in driving population dynamics. Importantly, our results suggest that urbanisation generally amplifies the negative impact of climate change on insect population trends.

Soil biodiversity monitoring requires standardized and practical sample storage methods, particularly for large-scale surveys. Yet, the influence of the soil storage conditions on eDNA-based assessments of microbial and faunal communities remains a key concern. Here, we assessed whether air-drying of soils at room temperature alters microbial (prokaryotes, fungi, micro-eukaryotes) and faunal (nematodes, annelids, micro-arthropods) abundance and diversity compared to freezing at –20 °C across different land-use types and management intensities through quantitative polymerase chain reaction (qPCR) and multi-marker DNA metabarcoding. We sampled topsoil (0 – 10 cm) from 42 sites of the Swiss Central Plateau spanning forests, grasslands, arable lands, orchards, wetlands, and urban areas. Forests, grasslands and arable lands were sampled in sites varying in management intensities. Across land-use types and management intensities, air-drying of soil followed by four to eight weeks of storage at room temperature or at –20 °C and freezing soil directly yielded comparable gene abundances, alpha-diversity, and community structure for all microbial and faunal groups. Moreover, microbial and faunal community structure were consistently shaped by land-use types and soil physicochemical variables regardless of the soil storage method used. These findings demonstrate that air-drying is a cost-effective and reliable method for short-term storing soil samples in large-scale biodiversity monitoring without compromising data quality. • Air-dried and frozen soils were compared from lands with management intensities. • Both soils yielded comparable microbial and faunal eDNA abundance and diversity. • Microbial and faunal communities were consistently shaped by environmental factors.