Historical floods in the Dutch Rhine Delta

International audienceHistorical records provide direct information about the climatic impact on society. Especially great natural disasters such as river floods have been for long attracting the attention of humankind. Time series for flood development on the Rhine branches Waal, Nederrijn/Lek and IJssel in the Dutch Rhine Delta are presented in this paper. In the case of the Waal it is even possible to compare historical flood frequencies based on documentary data with the recent development reconstructed from standardized instrumental measurements. In brief, we will also discuss various parameters concerning the structure of the flood series and the "human dimension" of natural disaster, i.e. the vulnerability of society when facing natural disasters

Sunflecks in the upper canopy: dynamics of light-use efficiency in sun and shade leaves of Fagus sylvatica

Sunflecks are transient patches of direct radiation that provide a substantial proportion of the daily irradiance to leaves in the lower canopy. In this position, faster photosynthetic induction would allow for higher sunfleck-use efficiency, as is commonly reported in the literature. Yet, when sunflecks are too few and far between, it may be more beneficial for shade leaves to prioritize efficient photosynthesis under shade. We investigated the temporal dynamics of photosynthetic induction, recovery under shade, and stomatal movement during a sunfleck, in sun and shade leaves of Fagus sylvatica from three provenances of contrasting origin. We found that shade leaves complete full induction in a shorter time than sun leaves, but that sun leaves respond faster than shade leaves due to their much larger amplitude of induction. The core-range provenance achieved faster stomatal opening in shade leaves, which may allow for better sunfleck-use efficiency in denser canopies and lower canopy positions. Our findings represent a paradigm shift for future research into light fluctuations in canopies, drawing attention to the ubiquitous importance of sunflecks for photosynthesis, not only in lower-canopy leaves where shade is prevalent, but particularly in the upper canopy where longer sunflecks are more common due to canopy openness

Sunflecks in the upper canopy : dynamics of light-use efficiency in sun and shade leaves of Fagus sylvatica

Sunflecks are transient patches of direct radiation that provide a substantial proportion of the daily irradiance to leaves in the lower canopy. In this position, faster photosynthetic induction would allow for higher sunfleck-use efficiency, as is commonly reported in the literature. Yet, when sunflecks are too few and far between, it may be more beneficial for shade leaves to prioritize efficient photosynthesis under shade. We investigated the temporal dynamics of photosynthetic induction, recovery under shade, and stomatal movement during a sunfleck, in sun and shade leaves of Fagus sylvatica from three provenances of contrasting origin. We found that shade leaves complete full induction in a shorter time than sun leaves, but that sun leaves respond faster than shade leaves due to their much larger amplitude of induction. The core-range provenance achieved faster stomatal opening in shade leaves, which may allow for better sunfleck-use efficiency in denser canopies and lower canopy positions. Our findings represent a paradigm shift for future research into light fluctuations in canopies, drawing attention to the ubiquitous importance of sunflecks for photosynthesis, not only in lower-canopy leaves where shade is prevalent, but particularly in the upper canopy where longer sunflecks are more common due to canopy openness.Peer reviewe

Mammals of Fort Leavenworth, Kansas: a 60-year followup to Brumwell (1951)

More than 60 years have elapsed since Brumwell\u27s (1951) comprehensive assessment during 193911940 of resident terrestrial vertebrates from Fort Leavenworth Military Rooervation in northeastern Kansas. Subsequent studies have been accomplished for the amphibians, reptiles, and birds. Our study is the first to assess intervening changes in the mammalian composition of this diverse local fauna. Notable observations include: the decline or extirpation of the black-tailed jackrabbit (Lepus californicus), Franklin\u27s ground squirrel (Spermophilus franklinii), muskrat (Ondatra zibethicus), long-tailed weasel (Mustela frenata) and eastern spotted skunk (Spilogale putorius); the return or recovery of locally extirpated gray fox (Urocyon cinereoargenteus), puma (Puma concolor), and white-tailed deer (Odocoileus virginianus), the increases of the once uncommon eastern chipmunk (Tamias striatus) and striped skunk (Mephitis mephitis), the invasion and establishment of the hispid cotton rat (Sigmodon hispidus), and the displacement of the eastern fox squirrel (Sciurus niger) by the eastern gray squirrel (S. carolinensis) as the most common squirrel. Documented species either not mentioned by Brumwell (1951) or listed by him as hypothetically occurring on the post, included northern myotis (Myotis septentrionalis), eastern pipistrelle (Pipistrellus subflavus), evening bat (Nycticeius humeralis), southern bog lemming (Synaptomys cooperi), and meadow jumping mouse (Zapus hudsonius)

Metatranscriptomics captures dynamic shifts in mycorrhizal coordination in boreal forests

Carbon storage and cycling in boreal forests—the largest terrestrial carbon store—ismoderated by complex interactions between trees and soil microorganisms. However,existing methods limit our ability to predict how changes in environmental conditionswill alter these associations and the essential ecosystem services they provide. To addressthis, we developed a metatranscriptomic approach to analyze the impact of nutrientenrichment on Norway sprucefine roots and the community structure, function, andtree–microbe coordination of over 350 root-associated fungal species. In response toaltered nutrient status, host trees redefined their relationship with the fungal commu-nity by reducing sugar efflux carriers and enhancing defense processes. This resulted ina profound restructuring of the fungal community and a collapse in functional coordi-nation between the tree and the dominant Basidiomycete species, and an increase infunctional coordination with versatile Ascomycete species. As such, there was a func-tional  shift  in  community  dominance  from  Basidiomycetes  species,  with  importantroles in enzymatically cycling recalcitrant carbon, to Ascomycete species that have mela-nized cell walls that are highly resistant to degradation. These changes were accompa-nied  by  prominent  shifts  in  transcriptional  coordination  between  over  60  predictedfungal effectors, with more than 5,000 Norway spruce transcripts, providing mechanis-tic insight into the complex molecular dialogue coordinating host trees and their fungalpartners. The host–microbe dynamics captured by this study functionally inform howthese complex and  sensitive biological  relationships may mediate  the carbon  storagepotential of boreal soils under changing nutrient conditions

A New Combined European Permanent Network Station Coordinates Solution

The EUREF (International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe) network of continuously operating GPS stations (EPN) was primarily established for reference frame maintenance, and also plays an important role for geodynamical research in Europe. The main goal of this paper is to obtain an independent homogeneous time-series of the EPN station coordinates, which is also available in SINEX format. A new combined solution of the EPN station coordinates was computed. The combination was performed independently for every week, in three steps: 1. the stated constraints on the coordinates were removed from the individual solutions of the Analysis Centers; 2. the de-constrained solutions were aligned to ITRF2000; 3. the resulting solutions were combined using the Helmert block-ing technique. All the data from GPS week 900 to week 1302 (April 1997 - December 2004) were used. We investigated in detail the behavior of the transformation parameters aligning the new combined solution to ITRF2000. In general, the time-series of the transformation parameters show a good stability in time although small systematic effects can be seen, most likely caused by station instabilities. A comparison of the new combined solution to the official EUREF weekly combined solution is also presented

Collective dynamics of liquid aluminum probed by Inelastic X-ray Scattering

An inelastic X-ray scattering experiment has been performed in liquid aluminum with the purpose of studying the collective excitations at wavevectors below the first sharp diffraction peak. The high instrumental resolution (up to 1.5 meV) allows an accurate investigation of the dynamical processes in this liquid metal on the basis of a generalized hydrodynamics framework. The outcoming results confirm the presence of a viscosity relaxation scenario ruled by a two timescale mechanism, as recently found in liquid lithium.Comment: 8 pages, 7 figure