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Hierarchical responses of plant–soil interactions to climate change: consequences for the global carbon cycle
No full text1.Interactions between plant and soil communities play a major role in determining the impact of climate change on ecosystem functioning and the carbon cycle, and the mechanisms involved operate over a wide range of spatial and temporal scales.
2.We present a framework for understanding the consequences of climate-induced changes in plant–soil feedback for the carbon cycle. The framework describes a hierarchy of mechanisms by which changes in climate impact on ecosystem carbon dynamics at three levels of response, namely individual and community reordering and species immigration and loss.
3.For each level, we identify the mechanisms by which climate change impacts on plant–soil interactions with consequences for the carbon cycle. We also demonstrate that the potential for decoupling of plant–soil interactions increases across the three levels of response, being greatest with species immigration and/or loss, for example, if plants were to undergo a biome shift, but their associated soil communities did not. Such decoupling is a largely unrecognized, but potentially important regulator of the future global carbon cycle.
4.Synthesis. The framework presented here highlights a need for a new approach to the study of climate change impacts on plant–soil interactions and carbon cycling that integrates this hierarchy of responses, and incorporates the decoupling of above-ground and below-ground networks, across a range of temporal and spatial scales, and ecosystems.
The ACUMEN Portfolio: Accounting for Alternative Forms of Scholarly Output
No full textNew tools for measuring the impact of research (altmetrics) bring much needed attention to changing scholarly communication practices. However, alternative forms of output are still widely excluded from the evaluation of individual researchers. The ACUMEN project addresses this problem in two ways. First, by creating a researcher portfolio framework that facilitates promotion of a broad range of scholarly output. And second, by shifting the orientation of evaluations from a top-down relationship, to a dialog between the researcher and evaluation committee. The ACUMEN Portfolio facilitates negotiation of included content and the means by which researchers prepare an evidence-based argument.
Southeast Asia in the age of jazz: Locating popular culture in the colonial Philippines and Indonesia
No full textThe influence of local-and landscape-scale processes on spatial self-organization in estuarine ecosystems
No full textComplexity theory proposes that spatial self-organization, the process whereby small-scale, localized interactions among the components of a system generate complex spatial structures at large spatial scales, explains the formation of autogenic spatial patterns in ecosystems. We question this premise by reviewing three estuarine ecosystems - mussel beds, mudflats and salt marshes - where self-organization has been put forward to explain spatial patterns. Our review highlights that these self-organized estuarine systems are shaped by the combination of small-scale interactions between ecological and physical processes on the one hand, and large-scale physical forcing on the other. More specifically, local interactions generate patchiness at small spatial scales, whereas landscape forcing determines the shape and orientation of these patches in the landscape. We present a framework that illustrates how self-organized ecosystems are shaped by interactions between organisms and physical processes occurring at multiple spatial scales. Moreover, the present review of estuarine systems underlines that scale-dependent feedbacks are capable of explaining spatial patterns that are much more complex than the regular patterns to which they have been applied so far.
Habitat use throughout migration: linking individual consistency, prior breeding success and future breeding potential
No full text1. Habitat use can influence individual performance in a wide range of animals, either immediately or through carry-over effects in subsequent seasons. Given that many animal species also show consistent individual differences in reproductive success, it seems plausible that individuals may have consistent patterns of habitat use representing individual specializations, with concomitant fitness consequences.
2. Stable-carbon isotope ratios from a range of tissues were used to discern individual consistency in habitat use along a terrestrial–aquatic gradient in a long-distance migrant, the Bewick’s swan (Cygnus columbianus bewickii). These individual specialisations represented <15% of the isotopic breadth of the population for the majority of individuals and were seen to persist throughout autumn migration and overwintering until aquatic habitats were no longer available.
3. Individual foraging specialisations were then used to demonstrate two consecutive carry-over effects associated with macroscale habitat segregation: consequences of breeding season processes for autumn habitat use; and consequences of autumn habitat use for future reproductive success. Adults that were successful breeders in the year of capture used terrestrial habitats significantly more than adults that were not successful, revealing a substantial cost of reproduction and extended parental care. Use of aquatic habitats during autumn was, however, associated with increased body condition prior to spring migration; and increased subsequent breeding success in adults that had been unsuccessful the year before. Yet adults that were successful breeders in the year of capture remained the most likely to be successful the following year, despite their use of terrestrial habitats.
4. Our results uniquely demonstrate not only individual foraging specializations throughout the migration period, but also that processes during breeding and autumn migration, mediated by individual consistency, may play a fundamental role in the population dynamics of long-distance migrants. These findings, therefore, highlight the importance of long-term consistency to our understanding of habitat function, interindividual differences in fitness, population dynamics and the evolution of migratory strategies.
A comparative study on three analytical methods for the determination of the neurotoxin BMAA in cyanobacteria
No full textThe cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been considered a serious health threat because of its putative role in multiple neurodegenerative diseases. First reports on BMAA concentrations in cyanobacteria were alarming: nearly all cyanobacteria were assumed to contain high BMAA concentrations, implying ubiquitous exposure. Recent studies however question this presence of high BMAA concentrations in cyanobacteria. To assess the real risk of BMAA to human health, this discrepancy must be resolved. We therefore tested whether the differences found could be caused by the analytical methods used in different studies. Eight cyanobacterial samples and two control samples were analyzed by three commonly used methods: HPLC-FLD analysis and LC-MS/MS analysis of both derivatized and underivatized samples. In line with published results, HPLC-FLD detected relatively high BMAA concentrations in some cyanobacterial samples, while both LC-MS/MS methods only detected BMAA in the positive control (cycad seed sarcotesta). Because we could eliminate the use of different samples and treatments as causal factors, we demonstrate that the observed differences were caused by the analytical methods. We conclude that HPLC-FLD overestimated BMAA concentrations in some cyanobacterial samples due to its low selectivity and propose that BMAA might be present in (some) cyanobacteria, but in the low µg/g or ng/g range instead of the high µg/g range as sometimes reported before. We therefore recommend to use only selective and sensitive analytical methods like LC-MS/MS for BMAA analysis. Although possibly present in low concentrations in cyanobacteria, BMAA can still form a health risk. Recent evidence on BMAA accumulation in aquatic food chains suggests human exposure through consumption of fish and shellfish which expectedly exceeds exposure through cyanobacteria.
Trouwen en scheiden in tijden van voor- en tegenspoed
No full textAls het economisch goed gaat, besluiten meer mensen te trouwen, terwijl een recessie een negatief effect heeft op het aantal huwelijkssluitingen. De relatie tussen economie en echtscheiding lijkt minder eenduidig. Een recessie kan leiden tot meer echtscheidingen door financiële druk en stress. Maar, scheiden is ook duur. Als het economisch slechter gaat zou dat een rem kunnen vormen op het aantal echtscheidingen. Dit artikel laat
zien hoe de ontwikkeling van trouwen en scheiden in de afgelopen veertig jaar is beïnvloed door de economische conjunctuur.