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

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

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

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

Unifying niche shift studies: insights from biological invasions.

Assessing whether the climatic niche of a species may change between different geographic areas or time periods has become increasingly important in the context of ongoing global change. However, approaches and findings have remained largely controversial so far, calling for a unification of methods. Here, we build on a review of empirical studies of invasion to formalize a unifying framework that decomposes niche change into unfilling, stability, and expansion situations, taking both a pooled range and range-specific perspective on the niche, while accounting for climatic availability and climatic analogy. This framework provides new insights into the nature of climate niche shifts and our ability to anticipate invasions, and may help in guiding the design of experiments for assessing causes of niche changes

Will climate change increase the risk of plant invasions into mountains?

Mountain ecosystems have been less adversely affected by invasions of non-native plants than most other ecosystems, partially because most invasive plants in the lowlands are limited by climate and cannot grow under harsher high-elevation conditions. However, with ongoing climate change, invasive species may rapidly move upwards and threaten mid-, and then high-elevation mountain ecosystems. We evaluated this threat by modeling the current and future habitat suitability for 48 invasive plant species in Switzerland and New South Wales, Australia. Both regions had contrasting climate interactions with elevation, resulting in possible different responses of species distributions to climate change. Using a species distribution modeling approach that combines data from two spatial scales, we built high-resolution species distribution models (≤ 250 m) that account for the global climatic niche of species and also finer variables depicting local climate and disturbances. We found that different environmental drivers limit the elevation range of invasive species in each of the two regions, leading to region-specific species responses to climate change. The optimal suitability for plant invaders is predicted to markedly shift from the lowland to the montane or subalpine zone in Switzerland, whereas the upward shift is far less pronounced in New South Wales where montane and subalpine elevations are already suitable. The results suggest that species most likely to invade high elevations in Switzerland will be cold-tolerant, whereas species with an affinity to moist soils are most likely to invade higher elevations in Australia. Other plant traits were only marginally associated with elevation limits. These results demonstrate that a more systematic consideration of future distributions of invasive species is required in conservation plans of not yet invaded mountainous ecosystems

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

Boron-Rich Nanoscale Delivery Agents for the Boron Neutron Capture Therapy of Cancer

Nanoscience Poster SessionThe translational research effort in boron neutron capture therapy (BNCT) described below and recently initiated at the University of Missouri International Institute of Nano and Molecular Medicine and the University of Missouri Research Reactor would benefit from collaboration with a research group knowledgeable in modeling human tumors using small animal hosts and cellular biology as it relates to therapeutic results and the treatment of experimental data. The boron-10 (10B) isotope is unique among light elements for its high neutron cross-section and low inherent toxicity. When subjected to relatively benign thermal neutrons, the 10B nucleus undergoes a neutron capture reaction forming an excited 11B species. This unstable nucleus subsequently undergoes essentially instantaneous fission to release 2.4 MeV of kinetic energy in the form of a pair of 7Li3+ and 4He2+ ions, which are confined to the volume of about one cell. Therefore, preferential accumulation of 10B-containing structures within cancerous cells can lead to selective destruction of these cells. This process is more commonly known as Boron Neutron Capture Therapy (BNCT) for cancer. The key to the implementation of this potentially powerful and selective therapy is the delivery of at least 30 parts per million (ppm) of 10B within the tumor tissue while minimizing superfluous 10B within the surrounding healthy tissue. This difference in 10B concentration is often denoted through the boron concentration in tumor to boron concentration in blood ratio, with a higher ratio being preferable. Herein we describe the synthesis and results of biodistribution experiments with two nano-scale boron delivery agents: liposomes and oligomeric phosphate diesters (OPDs). Liposomes, containing both amphiphilic (KC2B9H11(CH2)15CH3, MAC) and hydrophilic (Na3B20H17NH3, TAC) components and ranging in diameter from 30 to 100 nm, showed tumor boron accumulations as high as 50 ppm and tumor to blood ratios over 8. OPDs, ranging in size from 1 to 5 nm in diameter, also exhibited preferential tumor accumulations of 30 ppm at tumor to blood ratios as high as 35 to 1. In both cases, liposomes and OPDs greatly outperformed currently available small boron-containing pharmaceuticals at the same injected dose of 10B. Studies in which OPDs were fluorescently labeled proved their localization within the cellular nucleus, increasing the relative efficacy of these species due to their proximity to the DNA target. In conclusion, both liposomes and OPDs show great promise as nano-sized delivery vehicles for BNCT

Integrating ecosystem services and disservices: insights from plant invasions

There is growing interest in ecosystem disservices, i.e. the negative effects of ecosystems on humans. The focus on disservices has been controversial because of the lack of clarity on how to disentangle ecosystem services and disservices related to human wellbeing. A perspective that considers both services and disservices is needed to inform objective decision-making. We propose a comprehensive typology of ecosystem disservices, and present a framework for integrating ecosystem services and disservices for human wellbeing linked to ecosystem functioning. Our treatment is underpinned by three key assumptions: (1) ecosystem attributes and functions are value-free; (2) the perception of benefits or nuisances are however dependent on societal context, and preferences and actions by societal actors may trigger, enhance or alleviate benefits or nuisances derived from ecosystems; and (3) the notion of disservices must account for the role of human management in assessments of ecosystem values, i.e. the social and technological measures that identify, protect, promote or restore desirable levels of services, and concurrently minimise, mitigate or adapt to disservices. We illustrate our ideas with examples from plant invasions as a complex social-ecological phenomenon