PD Dr. Janine Bolliger

Maintaining ecological connectivity is crucial for biodiversity, yet effectively managing interconnected areas through actor collaboration is challenging. This study examines collaboration through social–ecological fit in interconnected aquatic "blue" and terrestrial "green" areas, encompassing natural and semi-natural elements, in human-dominated landscapes. Combining species distribution models and connectivity analyses focused on declining amphibians and survey data on actors' area management and collaboration within interconnected areas, we create a spatially explicit social–ecological network that we analyze using network models. Results highlight diverse ecological dependencies shaping actor interactions. Strong collaboration is observed in interconnected blue-rural-green areas, whereas blue-urban-green areas lack collaboration, with minor rivers and urban-green spaces at the network's core plagued by social–ecological misfit. Strengthening collaboration in these areas is essential to prevent further ecological network degradation. Incorporating a spatially explicit social–ecological perspective covering diverse blue and green areas guides targeted interventions and fosters effective conservation policy and practice.

Angesichts der schnellen Landschaftsveränderungen, insbesondere im urbanen Raum, haben innovative, gemeinsam erarbeitete Ideen zu einer verbesserten Umsetzung von ökologischer Infrastruktur höchste Priorität. Zwei Workshops mit unterschiedlichen Teilnehmenden haben eine Plattform geboten, um sich über die Herausforderungen und Herangehensweisen rund um die ökologische Infrastruktur auszutauschen. Es scheinen besonders Hürden in Bezug auf Koordination über die verschiedenen Sektoren hinweg, Ausbildung als auch Finanzierung zu bestehen. Es wird auch klar, dass alle Akteure aus verschiedenen Bereichen der Praxis und Wissenschaft gefragt sind, um gemeinsam das Ziel einer ökologischen Infrastruktur zur Förderung und Erhaltung der Biodiversität langfristig zu realisieren.

Eu égard aux modifications rapides du paysage, en particulier dans l'espace urbain, il est urgent de produire des idées collaboratives et innovantes afin d'améliorer la mise en oeuvre de l'infrastructure écologique. Deux ateliers accueillant des profils différents ont servi de plateforme d'échange sur le thème des difficultés et des approches en lien avec l'infrastructure écologique. Les obstacles rencontrés concernent principalement la coordination intersectorielle, la formation et le financement. Tous les acteurs des différents domaines de la pratique et de la recherche sont appelés à conjuguer leurs efforts afin de concrétiser en commun l'objectif durable d'une infrastructure écologique capable de promouvoir et de préserver la biodiversité.

Im Rahmen der Forschungsinitiative «Blau-grüne Biodiversität» von Eawag und WSL diskutierten an zwei Workshops verschiedenste Interessenvertretende über die Herausforderungen rund um die ökologische Infrastruktur. Die Teilnehmenden betonten die Notwendigkeit, die interdisziplinäre Zusammenarbeit zu verbessern, und erkundeten Hindernisse wie Interessenkonflikte, politische Trägheit und wenig genutztes Potenzial. Der an den Workshops vielfach geäusserte Wunsch nach verstärkter Zusammenarbeit unterstreicht die Bedeutung solcher Veranstaltungen für die Umweltpolitik und eine nachhaltige Entwicklung.

Europe's semi-natural grasslands support notably high levels of temperate biodiversity across multiple taxonomic groups. However, these ecosystems face unique conservation challenges. Contemporary agricultural practices have replaced historical traditional low-intensity agriculture in many regions, resulting in a spectrum of management intensities within these ecosystems, ranging from highly intensive methods to complete abandonment. Paradoxically, both extremes along this spectrum of management intensity can be detrimental to biodiversity of semi-natural grasslands. Moreover, while anthropogenic climate change is an overarching threat to these ecosystems, rapid changes in land use and its intensity often present more immediate pressures. Often occurring at a faster rate than climate change itself, these land-use changes have the potential to rapidly impact the biodiversity of these grasslands. Here, we divide the ecological processes, threats, and developments to semi-natural grasslands into three sections. First, we examine the different impacts of agricultural intensification and abandonment on these ecosystems, considering their different consequences for biodiversity. Second, we review seminal works on various evidence-based management practices and offer a concise summary that provides support for various conservation and management strategies. However, the socio-economic factors that drive both abandonment and intensification in semi-natural grasslands can also be used to develop solutions through strategic governmental and non-governmental interventions. Accordingly, we conclude with a way forward by providing several key policy recommendations. By synthesizing existing knowledge and identifying research gaps, this essay aims to provide valuable insights for advancing the sustainable management of semi-natural grasslands.

We adopted a landscape-scale approach to analyze the genetic patterns (diversity, structure, and differentiation) of the Marbled White (Melanargia galathea). This butterfly species is characteristic of semi-dry grasslands, which have substantially declined in Switzerland during past decades. We sampled individuals on a regular grid of the established Biodiversity Monitoring program of Switzerland over five consecutive years, obtaining 1639 genotyped individuals from 185 locations. Results showed that M. galathea populations cluster into five spatially aggregated clusters that largely coincide with the biogeographic regions of Switzerland. Genetic diversity (allelic richness) was higher in the South of the Alps, likely related to immigration dynamics that suggest recolonisation from the South after the last glaciation. Demographic history resulted in distinct isolation by distance (IBD) and by cumulative elevational difference (isolation by altitude, IBA) at large scale, while regional IBD and IBA were less pronounced. This pattern was likely induced by the barrier effect of the high mountains of the Alps impeding continuous northward migration after the last glacial maximum. A temporal analysis revealed that regional genetic diversity did not change strongly during the five sampling years. This result indicates that the genetic diversity pattern in M. galathea has not been noticeably affected by historical land-use change or that the sampling period of five years is too short to detect any changes. Our findings highlight the regionally, topography-induced distinct genetic clusters, relevant for consideration as conservation units and likely reflecting genetic structures similar to those found in other butterfly species of conservation concern.

Lichtverschmutzung durch künstliches Licht in der Nacht ist ein ernstzunehmendes Umweltproblem. Innovationen in der LED-Technologie können dabei zur Lösung beitragen. Die technischen Eigenschaften von LEDs umfassen z.B. eine präzise Lichtsteuerung, eine Reduktion des Lichtniveaus (Dimmbarkeit) und unterschiedliche spektrale Zusammensetzungen des Lichts (z. B. bernsteinfarben, neutral- oder warmweiss). Kombinationen dieser Eigenschaften können
optimiert werden, um negative Auswirkungen der Lichtverschmutzung auf die Umwelt zu verringern. Das Projekt ALANeX der WSL zeigt, dass gut fokussierte und gedimmte Leuchten einen wichtigen Beitrag zur Reduktion der Auswirkungen des künstlichen Lichts auf die nächtliche Biodiversität leisten können, während der Einfluss der LED-Farben unklar bleibt.

La pollution lumineuse due à l'éclairage artificiel pendant la nuit est un problème environnemental à prendre au sérieux. Les innovations dans la technologie LED peuvent aider à le résoudre. Les propriétés techniques des LED permettent notamment de diriger précisément la lumière, de réduire le niveau de luminosité (gradation de l'intensité) et d'opter pour différentes compositions spectrales de la lumière (par ex. couleurs ambrées, blanc neutre ou blanc chaud).
Les combinaisons de ces propriétés peuvent être optimisées pour réduire les effets néfastes de la pollution lumineuse sur l'environnement. Le projet ALANeX du WSL montre qu'un éclairage ciblé et gradué peut fortement contribuer à la réduction des effets de la lumière artificielle sur la
biodiversité nocturne. Par contre, on ne sait toujours pas très bien quel est l'effet des couleurs LED.

Artificial Light at Night (ALAN) has been identified as a primary driver of environmental change in the 21st century with key impacts on ecosystems. At the same time, developments of LED lighting systems with adjustable parameters—such as color temperature and light intensity—may provide an opportunity to mitigate the negative effects of ALAN. To test the potential effects of LED properties, we conducted a comprehensive field study over two summers at three forest sites in Switzerland. We investigated the impact of three key attributes of LED lights (color temperature, brightness, and luminaire shape) on the abundance and community structure of ground-dwelling invertebrate functional groups (predators, omnivores, and detritivores). We found a significantly increased nocturnal attraction of omnivores (+275%) and predators (+70%), but not detritivores, to ALAN, altering arthropod community composition and trophic interactions in forests. LED color temperature and luminaire shape showed minimal effects on all three functional groups, while reducing light level from 100% to 50% attracted fewer individuals in all groups with a significant effect in omnivores (−57%). In addition, we observed significant interactions of color temperatures and luminaire shapes with light intensity, with a decrease in numbers when dimming the light to 50% intensity combined with a color temperature of 3700 K for predators (−53%), with diffusing luminaire shapes for omnivores (−77%) and with standard luminaire shape for detritivores (−27%). The predator-detritivore ratio showed a significant color temperature – light level interaction, with increased numbers of predators around streetlights with 3700 K and 100% intensity, resulting in an elevated top-down pressure on detritivores. These results suggest the importance of considering combined light characteristics in future outdoor lighting designs.

Der Aufbau einer blau-grünen Infrastruktur erfordert die Koordination zwischen ganz verschiedenen gesellschaftlichen Akteurinnen und Akteuren. Es ist daher essenziell, die sozio-ökologischen Netzwerke zu analysieren sowie die Herausforderungen für alle Beteiligten bei der Planung und Umsetzung zu verstehen.

Künstliches Licht in der Nacht (artificial light at night – ALAN) ist eng mit modernen Gesellschaften verbunden und nimmt weltweit drastisch zu. Wissenschaftliche Erkenntnisse zeigen jedoch, dass ALAN eine ernsthafte Bedrohung für alle Ebenen der biologischen Vielfalt darstellen kann – von Genen bis hin zu Ökosystemen. Bevor wir die Auswirkungen von ALAN auf die biologische Vielfalt vollständig verstehen und wirksame Maßnahmen zur Abmilderung der Auswirkungen von Lichtverschmutzung entwickeln können, gibt es noch viele offene Fragen zu klären. Hier haben wir die dringendsten wissenschaftlichen Forschungsfragen zusammengetragen, die geklärt werden müssen, um die Auswirkungen von ALAN auf die Biodiversität besser reduzieren zu können, angefangen bei grundlegenden Herausforderungen in der Standardisierung von Lichtmessungen über die vielschichtigen Auswirkungen auf die biologische Vielfalt bis hin zu Möglichkeiten und Herausforderungen für eine nachhaltigere Beleuchtung in der Nacht.

Artificial light at night (ALAN) is closely associated with modern societies and is rapidly increasing worldwide. A dynamically growing body of scientific literature shows that ALAN poses a serious threat to all levels of biodiversity – from genes to ecosystems. Many “unknowns” remain to be addressed, however, before we fully understand the impact of ALAN on biodiversity and can design effective mitigation measures against light pollution. Here, we summarise the most pressing research questions that have to be answered to find ways to reduce the impact of ALAN on biodiversity. The questions address fundamental knowledge gaps, ranging from basic challenges on how to standardise light measurements, through the multi-level impacts on biodiversity, to opportunities and challenges for more sustainable use of ALAN.

Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrative approach to explain these differences by linking impacts to four fundamental processes that structure communities: dispersal, speciation, species-level selection and ecological drift. Our goal is to provide process-based insights into why human impacts, and responses to impacts, may differ across ecosystem types using a mechanistic, eco-evolutionary comparative framework. To enable these insights, we review and synthesise (i) how the four processes influence diversity and dynamics in terrestrial versus freshwater communities, specifically whether the relative importance of each process differs among ecosystems, and (ii) the pathways by which human impacts can produce divergent responses across ecosystems, due to differences in the strength of processes among ecosystems we identify. Finally, we highlight research gaps and next steps, and discuss how this approach can provide new insights for conservation. By focusing on the processes that shape diversity in communities, we aim to mechanistically link human impacts to ongoing and future changes in ecosystems.

Primary considerations for urban blue-green infrastructure (BGI) encompass sustainable stormwater/urban heat management while biodiversity conservation is often considered an inherent benefit rather than a core planning requirement. However, ecological function of BGI as 'stepping stones' or linear corridors for otherwise fragmented habitats is undisputed. While quantitative approaches for modelling ecological connectivity in conservation planning are well established, mismatches in scope and scale with models that support the planning of BGI makes their adoption and integration difficult across disciplines. Technical complexities have led to ambiguity around circuit and network-based approaches, focal node placement, spatial extents, and resolution. Furthermore, these approaches are often computationally intensive, and considerable gaps remain in their use for identifying local-scale critical "pinch-points" that urban planners may respond to with the integration of BGI interventions that address biodiversity enhancement among other ecosystem services. Here, we present a framework that simplifies and integrates the merits of regional connectivity assessments with a focus on urban areas to prioritise BGI planning interventions while reducing computational demands. Our framework facilitates: (1) modelling potential ecological corridors at a coarse regional scale, (2) prioritising local-scale BGI interventions based on the relative contribution of individual nodes in this regional network, and (3) inferring connectivity hot- and cold-spots for local-scale BGI interventions. We illustrate this in the Swiss lowlands, demonstrating how, compared to previous work, we are able to identify and rank different priority locations across the region for BGI interventions in support of biodiversity enhancement and how their local-scale functional design may be benefited by addressing specific environmental variables.

Street lights are important light sources that contribute to artificial light at night (ALAN). To date, ecological impacts of individual LED properties (color temperature, dimmability) have been studied, while interactions between light properties or aspects of luminaire design have not been addressed. However, the design of luminaires can influence ALAN impacts as the shape determines the spatial distribution of light and its visibility in the environment. This may cause amplifying or mitigating effects. We assessed the relative individual and interacting effects of two LED luminaire designs and three LED color temperatures (1750 K, 3000 K, 4000 K) on nocturnal insect abundance, bat foraging and feeding activity. We considered a standard LED luminaire shape with focused light emission and a luminaire shape with a diffusor to scatter the light spatially, leading to increased visibility of the light in the environment. During 104 nights, we trapped 51263 nocturnal insects of which 97% were caught at lights and 3% at dark sites. For bats, up to 44.8% fewer acoustic signals were recorded at dark sites. We caught 31% insects at LEDs with1750 K, 34% and 35% at 3000 K and 4000 K, respectively. Thus, color temperatures of 1750 K proved less detrimental than 3000/4000 K. Effects of luminaire shape led to an increase (16%) of trapped insects for luminaires with diffusors compared to the standard shape. In addition, luminaires with diffusors amplified the effects of LED color (+12% insects at 1750 K/3000 K; +25.6% at 4000 K). In contrast, bat foraging activity was independent of the light treatments while bat feeding activity was increased by 21.5% at standard luminaire shapes. Likely, intense straylight at diffused lights negatively affects the target-focused echolocation by deterring the bats. We concluded that ecological impacts of luminaire shape are an important, yet underestimated variable in light-pollution impact research.

Increasing urbanization degrades quantity, quality, and the functionality of spatial cohesion of natural areas essential to biodiversity and ecosystem functioning worldwide. The uncontrolled pace of building activity and the erosion of blue (i.e., aquatic) and green (i.e., terrestrial) landscape elements threaten existing habitat ranges and movability of wildlife. Local scale measures, such as nature-inspired engineered Blue-Green Infrastructure (BGI) are emerging mitigation solutions. Originally planned to promote sustainable stormwater management, adaptation to climate change and improved human livability in cities, such instruments offer interesting synergies for biodiversity in support of existing ecological infrastructure. BGI are especially appealing for globally declining amphibians, a rich and diverse vertebrate assemblage sensitive to urbanization. We integrated biological and highly resolved urban-rural land-cover data, ensemble models of habitat suitability, and connectivity models based on circuit theory to improve multi-scale and multi-species protection of core habitats and ecological corridors in the Swiss lowlands. Considering a broad spectrum of amphibian biodiversity, we identified distributions of amphibian biodiversity hotspots and four landscape elements essential to amphibian movability at the regional scale, namely i) forest edges, ii) wet-forest habitats, iii) soils with variable moisture and iv) riparian zones. Our work shows that cities can make a substantial contribution (e.g., up to 15% of urban space in the study area) to wider landscape habitat connectivity. We highlight the importance of planning BGI locally in strategic locations across urban and peri-urban areas to promote the permeability and availability of ‘stepping stone’ habitats in densely populated landscapes, essential to the maintenance of regional habitat connectivity and thereby enhancing biodiversity and ecosystem functioning.

Intensiv genutzte Landschaften und Lebensraumfragmentierung sind mitverantwortlich für den Rückgang der Biodiversität, weil Lebensraumqualität und grundlegende biologische Prozesse wie z.B. die Ausbreitung gestört werden. Stetig wachsende Städte als überregionale Barrieren für die Vernetzung natürlicher Lebensräume stellen eine besondere Herausforderung dar (Abb. 1). Wir zeigen am Beispiel von Amphibien auf, wie eine gezielte Platzierung blaugrüner Infrastrukturen die Durchlässigkeit von Städten verbessern könnte und dadurch Lebensräume und Laichgebiete von regionaler Bedeutung besser vernetzt werden. Die Einrichtung blaugrüner Infrastrukturen ist eine vielversprechende Massnahme, um die Anpassung an den Klimawandel zu fördern und die Lebensqualität zu verbessern. Synergien zur Vernetzung der Biodiversität bieten sich auf lokaler und regionaler Ebene an.

L'utilisation intensive des paysages et la fragmentation des habitats sont en partie co-responsables du déclin de la biodiversité, dans la mesure où la qualité des habitats et des processus biologiques fondamentaux tels que la dispersion sont perturbés. L'urbanisation croissante constitue un défi particulier dans ce contexte, notamment en tant qu'obstacle transrégional à la connectivité des habitats naturels. En prenant l'exemple des amphibiens, nous montrons comment la planification ciblée d'infrastructures bleuesvertes pourrait améliorer la perméabilité des villes en reliant mieux les habitats naturels et les sites de reproduction d'importance régionale. L'installation d'infrastructures bleues-vertes est une mesure prometteuse qui est actuellement planifiée dans de nombreuses villes surtout pour promouvoir l'adaptation au changement climatique ainsi que pour l'amélioration de la qualité de vie. Cependant, des synergies pour la mise en réseau de la biodiversité sont aussi disponibles non seulement à niveaux local mais aussi régional.

Superblocks are an urban transformation strategy to create pedestrian-centric neighbourhoods. This study presents a methodological framework to assess the potential for urban green space (UGS) arising from superblock design. A quantitative assessment of the current state of UGS in superblocks is performed with geospatial analysis and earth observation techniques for a Swiss city. We find that UGS varies considerably across identified locations and decreases with smaller block sizes. Based on two scenarios, we illustrate how information on current UGS at the street or block level can be used to benchmark and assess urban greening potentials at superblock sites.

Begrünung des städtischen Strassenraums ist eine Chance, Grünflächen in Städten zu vergrössern, die ökologische Vernetzung oder die Erreichbarkeit von Grünflächen zu verbessern und urbane Hitzeinseln zu verhindern. Das Transformationspotential von grau zu grün wurde mit einem neuen, pragmatischen Konzept basierend auf sogenannten «Superblocks» für die Stadt Zürich untersucht. Dieser vielversprechende Ansatz
kann einen wichtigen Beitrag zu einer nachhaltigeren Stadtentwicklung leisten.

Le verdissement de l’espace routier urbain permet d’étendre la trame verte des villes, d’améliorer les liaisons écologiques et la desserte des espaces verts, et de lutter contre les îlots de chaleur urbains. Le potentiel de «transformation verte» de l’espace routier a été étudié en ville de Zurich sur la base d’une nouvelle approche pragmatique fondée sur la notion des superblocs, qui est très prometteuse et pourrait contribuer à une urbanisation plus durable.

Artificial light at night (ALAN) is closely associated with modern societies and is rapidly increasing worldwide. A dynamically growing body of literature shows that ALAN poses a serious threat to all levels of biodiversity—from genes to ecosystems. Many “unknowns” remain to be addressed however, before we fully understand the impact of ALAN on biodiversity and can design effective mitigation measures. Here, we distilled the findings of a workshop on the effects of ALAN on biodiversity at the first World Biodiversity Forum in Davos attended by several major research groups in the field from across the globe. We argue that 11 pressing research questions have to be answered to find ways to reduce the impact of ALAN on biodiversity. The questions address fundamental knowledge gaps, ranging from basic challenges on how to standardize light measurements, through the multi-level impacts on biodiversity, to opportunities and challenges for more sustainable use.