Reduced risk for positive soil-feedback on seedling regeneration by invasive trees on a very nutrient-poor soil in Seychelles

Invasive plants sometimes alter habitat conditions so as to promote further invasion, either by the same or by other non-native species. Such positive feedbacks often occur because the non-native species increases soil fertility, thereby favouring recruitment of non-native seedlings. This has been demonstrated in nitrogen-poor habitats invaded by nitrogen-fixing species, but it is unclear whether similar processes operate in habitats limited by phosphorus and other nutrients. I compared the growth of seedlings of Cinnamomum verum, an abundant invasive tree on phosphorus-poor soils in the Seychelles, in soils taken from beneath different tree species. I expected that soil phosphorus availability would be higher beneath stands of C. verum than beneath stands of either the native Northea hornei or the non-native nitrogen-fixing species, Falcataria moluccana. I therefore predicted that C. verum seedlings would grow faster in soil taken from beneath C. verum trees than in soil taken from beneath either of the other two species. To test this hypothesis, I performed a bioassay experiment with seedlings of C. verum grown in soils from stands of C. verum, F. moluccana and N. hornei. Different nutrient treatments (control, plus phosphorus (P), plus nitrogen (N), plus N and P, and plus complete fertilizer) were applied to investigate how nutrient availabilities modulate the effects of the trees. In the control treatment without added nutrients, there was a weak tendency for seedlings to perform better in the soils from beneath invasive than native trees. However, seedling growth in soils from beneath invasive species was markedly higher following the addition of phosphorus in the case of the F. moluccana soil, and complete fertilizer in the case of the C. verum soil. These results indicate that on very nutrient-poor soils, a low supply of nutrients other than N may reduce the risk of a soil-feedback by invasive trees on seedling regeneratio

Neophyten in Gebirgen - Wissensstand und Handlungsbedarf

Zusammenfassung: In Gebirgen wurden bisher im Gegensatz zu Flachlandökosystemen nur wenige Neophyten beobachtet und nur selten gravierende Veränderungen durch invasive Arten dokumentiert. Seit 2005 untersucht das Mountain Invasion Research Network (MIREN, www.miren.ethz.ch) das Risiko von Pflanzeninvasionen in Gebirgen und erarbeitet präventive Management-Maßnahmen. Eine von MIREN erstellte Datenbank von nicht-einheimischen und invasiven Pflanzenarten in Gebirgen weltweit umfasst im Moment etwa 1500 Arten. Als problematisch in Gebirgen eingestuft werden zurzeit insbesondere Gehölzpflanzen und Arten, welche als Zierpflanzen eingeführt wurden und an ein Bergklima vorangepasst sind. Es ist zu erwarten, dass Pflanzeninvasionen in Gebirgen in naher Zukunft stark zunehmen werden. Klimawandel wird invasiven Pflanzen aus dem Tiefland ermöglichen, sich auch in Gebirgen zu etablieren. Durch die Veränderung der Landnutzung in Gebirgen von Weidewirtschaft hin zu mehr Tourismus kann eine Veränderung nicht-einheimischer Floren erwartet werden und damit ein erhöhtes Invasionsrisiko. Auch zunehmende anthropogene Nutzung und Störung von höheren Gebirgslagen können das Invasionsrisiko erhöhen. Gebirge, insbesondere die europäischen Alpen, sind bislang von Pflanzeninvasionen noch nicht gravierend betroffen. Dadurch ergibt sich die einmalige Möglichkeit, rechtzeitig auf eine zukünftige Bedrohung zu reagieren. Prävention im Sinne des Vorsorgeprinzips ist die effektivste und kostengünstigste Möglichkeit. Dazu müssen potentiell invasive Arten identifiziert und ihr Transport reglementiert werden. Mit dem Klimawandel werden sich in Zukunft auch vermehrt einheimische Tieflandpflanzen in Gebirge ausbreiten. Es bedarf daher einer breiteren Diskussion zur Bewertung und dem Management von Florenveränderungen in Gebirgen. Neben Pflanzen werden sich in Zukunft auch andere Organismengruppen verstärkt in höhere Lagen ausbreiten, zum Beispiel Schädlinge von Tieren und Pflanze

Urban Agriculture: Passing Fad or New Prospects for Agriculture and Cities?

While urban agriculture might be considered a passing fad, we argue that it is a vehicle to deal with many urgent topics of societal transformation towards a sustainable future. We discuss the potential of urban agriculture to change agriculture and urban life

Problemorientierte inter- und transdisziplinäre und transformative Nachhaltigkeitsforschung: Welche Schnittstellen ergeben sich für die Geistes- und Sozialwissenschaften?

Die Umwelt- und Nachhaltigkeitswissenschaften haben in den letzten Jahrzehnten ein Forschungsverständnis entwickelt, welches als «problemorientierte inter- und transdisziplinäre Forschung zu komplexen gesellschaftlichen Herausforderungen» bezeichnet werden kann; zunehmend wird auch von Transformationsforschung oder transformativer Forschung gesprochen. Dieser Beitrag stellt diese Forschungsverständnisse der Nachhaltigkeitsforschung vor und lädt dazu ein, Schnittstellen mit den Geistes- und Sozialwissenschaften (SSH) auszuloten.Cite as: Kueffer, Christoph (2023): Problemorientierte inter- und transdisziplinäre und transformative Nachhal-tigkeitsforschung: Welche Schnittstellen ergeben sich für die Geistes- und Sozialwissenschaften?, in: Schweizerische Akademie der Geistes- und Sozialwissenschaften: Wege zu einem nachhaltigen Konsum | Vers une consommation durable, (Swiss Academies Communications, 18, 5), S. 118-125. https://doi.org/10.5281/zenodo.817718

L’importance de la collaboration entre conservationnistes des différentes îles océaniques pour l’enseignement et la recherche sur la biodiversité

I argue in this essay that conservationists on islands should engage more regularly in systematic cross-island learning and capitalise on the research opportunity provided by replicated islands around the world that are faced with similar nature conservation problems. In a rapidly changing anthropogenic world in particular learning across multiple sites is important to ensure that conservationists are not blind to unexpected future changes and novel ecological patterns and processes. There are increasingly opportunities for conservationists from different islands to interact but knowledge exchange remains often informal or piecemeal. One reason why cross-island learning is relatively rare may be the difficulty to generalise knowledge about real-world systems that are often highly idiosyncratic. It is thus often not clear how the insights gained in one place can be applied in another. However, medical doctors for instance are also faced with the challenge of building up a body of knowledge that is transferable from one patient to the next despite the uniqueness of each patient. Like doctors conservationists need to better learn how to form a shared pool of knowledge and expertise that is context-sensitive but still transferable between management cases. To indicate the range of conservation issues on islands that await a more systematic cross-island learning approach I discuss four examples: (i) predicting plant invasion risks, (ii) impacts of alien rats on native flora and fauna, (iii) mutualistic plant-animal interactions, and (iv) habitat restoration. I end the article by emphasising that successful cross-island research and learning depends on long-term continuous collaborations. Unique island biodiversity is rapidly disappearing. Island conservationists are confronted with the taunting task of devising and implementing new conservation strategies that address at once and in a very short time span many different interacting and rapidly changing threat factors, which affect thousands of threatened island species. To save much island biodiversity from extinction a global and concerted learning and action effort is urgently neededDans cet essai, je plaide pour que les conservationnistes de la biodiversité dans les îles s’engagent plus régulièrement dans un processus d’enseignement inter-îles et tirent profit des opportunités de recherches apportées par des îles confrontées à des problèmes similaires de conservation. En particulier, dans un monde évoluant rapidement, les enseignements à partir de nombreux sites sont importants pour s’assurer que les conservationnistes prennent bien en compte des changements imprévus et l’évolution vers de nouveaux écosystèmes. Les occasions d’interactions entre conservationnistes de différentes îles sont croissantes, mais les échanges de connaissances restent souvent informels et faibles. Une des raisons tient peut-être dans les difficultés de généralisation des connaissances à propos de systèmes qui sont souvent très particuliers. Il n’est de ce fait pas facile d’extrapoler des résultats obtenus sur un site à un autre site. Cependant, les médecins par exemple sont aussi confrontés à ce problème de construction d’un corpus de connaissances pouvant être transférable d’un patient au suivant malgré l’unicité de chaque patient. Comme les médecins, les conservationnistes doivent apprendre comment partager un ensemble de connaissances et d’expertises relatives à des cas particuliers mais tout de même transférables entre les modes de gestion. Quatre exemples de sujets illustrant les enjeux de conservation et nécessitant une approche systématique inter-îles sont présentés: (1) la prévision des risques d’invasions par les plantes, (2) les impacts des rats introduits sur la flore et la faune indigènes, (3) les interactions mutualistes entre plantes et animaux, (4) la restauration des habitats. Je termine l’article en insistant sur le fait que le succès de la recherche et de l’enseignement inter-îles dépend de collaborations continues sur le long terme. Une biodiversité insulaire unique est en train de disparaître rapidement. Les conservationnistes insulaires sont confrontés à la tâche difficile d’inventer et de mettre en oeuvre de manière simultanée et sur une période très courte de nouvelles stratégies concernant de nombreuses menaces en interaction et évolution rapide, qui affectent des milliers d’espèces insulaires menacées. Pour sauver cette biodiversité insulaire de l’extinction, un effort global d’échanges de connaissances et d’actions entreprises doit être réalisé de manière urgent

Influence of light and nutrient conditions on seedling growth of native and invasive trees in the Seychelles

Several recent studies have shown that plant invasions can occur in resource-poor and relatively undisturbed habitats. It is, therefore, important to investigate whether and how life-history traits of species invasive in such habitats differ from those of species that are only invasive in disturbed and resource rich habitats. We compared the growth of seedlings of native and invasive tree species from nutrient-poor secondary forests in the tropical Seychelles. We hypothesised that the relative performance of the two groups would change predictably along resource gradients, with native species performing better at low levels of resource availability and invasive species performing better at higher levels. To test this hypothesis, we performed a common garden experiment using seedlings of six invasive and seven native tree species grown under three levels of light (65, 11 and 3.5% of ambient light) and two of nutrients (low and high). Due to large variation among species, differences in growth rates (RGR) were not significant among seedlings of the native and the invasive species. However, seedlings of the invasive species showed higher specific leaf areas (SLA) and higher leaf nutrient contents than seedlings of the native species. They also exhibited greater plasticity in biomass and nutrient allocation (i.e., greater plasticity in LAR, RSR and leaf nutrient contents) in response to varying resource availability. However, differences between the mean values of these parameters were generally small compared with variation within groups. We conclude that successful invaders on nutrient-poor soils in the Seychelles are either stress-tolerant, possessing growth traits similar to those of the native species, or fast-growing but adapted to nutrient-poor soils. In contrast, the more typical, fast-growing alien species with no particular adaptations to nutrient-poor soils seem to be restricted to relative nutrient-rich sites in the lowlands. The finding—that some introduced species thrive in resource-poor habitats—suggests that undisturbed habitats with low resource availability may be less resistant to plant invasions than was previously suppose

A new golden era in island biogeography

For two centuries, islands have served as rich sources of inspiration and data for biogeogra-phers, thus gaining renown as ideal natural laboratories. Their research potential continues to expand today thanks to the combined application of recent advances in several scientific fields. First, increas-ingly detailed geological and palaeoecological data are extending our understanding of the history of development of island biotas. At the same time, rapid methodological advances in molecular evolution-ary biology and systematics are revealing the pathways by which species colonized islands, evolved, and formed communities. Third, basic data on species distributions are being collected from increasing num-bers of islands and taxa, distributed widely through electronic resources, and analyzed with powerful software to reveal macroecological patterns. The pace and quality of recent advances signal a promising future in which islands will continue to play key roles in revealing how biodiversity is produced and maintained

Wissensaustausch zwischen Forschung und Praxis erfolgreich gestalten

Um die gesellschaftliche Transformation zu gestalten, wird der Austausch von Wissen zwischen Wissenschaft und Praxis immer wichtiger. Dieser Artikel benennt Prinzipien, Kompetenzen und Rahmenbedingungen für erfolgreichen Wissensaustausch

Using the ‘regime shift' concept in addressing social-ecological change : Social-ecological regime shifts

‘Regime shift’ has emerged as a key concept in the environmental sciences. The concept has roots in complexity science and its ecological applications, and is increasingly applied to intertwined social and ecological phenomena. Yet what exactly is a regime shift? We explore this question at three nested levels. First, we propose a broad, contingent, multi-perspective epistemological basis for the concept, seeking to build bridges between its complexity theory origins and critiques from science studies, political ecology, and environmental history. Second, we define the concept in a way that is consistent with this epistemology, building on previous work on speed, scale, stickiness, and interrelationships, but also emphasising human perceptions and rhetorical uses of the notion. Third, we propose a novel typology of the ways in which the regime shift concept is used in analysing social–environmental phenomena in geography and beyond. These uses are categorised along two axes. On the one side, we distinguish between description of past or present changes and normative prescriptions for the future. On the other side, we distinguish between whether the focus is on material shifts (social and ecological) or conceptual shifts (discourses and ideas). We illustrate the typology with reference to social–environmental changes in landscapes around the world that are dominated by plantations or the widespread naturalisation of Australian Acacia species. We conclude that the regime shift concept is a boundary object with value as both an analytical and communicative tool in addressing social–environmental challenges