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AbstractAlthough the role that Pleistocene glacial cycles have played in shaping the present biota of oceanic islands world‐wide has long been recognized, their geographical, biogeographical and ecological implications have not yet been fully incorporated within existing biogeographical models. Here we summarize the different types of impacts that glacial cycles may have had on oceanic islands, including cyclic changes in climate, shifts in marine currents and wind regimes and, especially, cycles of sea level change. The latter have affected geographical parameters such as island area, isolation and elevation. They have also influenced the configurations of archipelagos via island fusion and fission, and cycles of seamount emergence and submergence. We hypothesize that these sea level cycles have had significant impacts on the biogeographical processes shaping oceanic island biotas, influencing the rates and patterns of immigration and extinction and hence species richness. Here we provide a first step toward the development of a glacial‐sensitive model of island biogeography, representing the tentative temporal evolution of those biogeographical parameters during the last glacial cycle. From this reasoning we attempt to derive predictions regarding the imprint of sea level cycles on genetic, demographic or biogeographical patterns within remote island biotas.

Abstract. Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5–12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr)) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean, max and range pHNBS and max and range ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced max and min ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. Max and range ΩAr within the meadow showed a positive trend with the calcium carbonate load of the leaves, pointing to a possible link between structural parameters, ΩAr and carbonate deposition. Calcifying organisms, e.g. epiphytes with carbonate skeletons, may benefit from the modification of the carbonate system by the meadow. There is, however, concern for the ability of seagrasses to provide modifications of similar importance in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, on which LAI is based. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

Monthly Notices of the Royal Astronomical Society, 472 (3) ISSN:0035-8711 ISSN:1365-2966

AbstractResearch into the formation of InAs quantum dots (QDs) in GaAs using the metalorganic vapor phase epitaxy technique is presented. This technique is deemed to be cheaper than the more often used and studied molecular beam epitaxy. The best conditions for obtaining a high photoluminescence response, indicating a good material quality, have been found among a wide range of possibilities. Solar cells with an excellent quantum efficiency have been obtained, with a sub‐bandgap photo‐response of 0.07 mA/cm2 per QD layer, the highest achieved so far with the InAs/GaAs system, proving the potential of this technology to be able to increase the efficiency of lattice‐matched multi‐junction solar cells and contributing to a better understanding of QD technology toward the achievement of practical intermediate‐band solar cells. Copyright © 2016 John Wiley & Sons, Ltd.

AbstractAt extremely low reaction times (0.02 s), cellulose was hydrolyzed in supercritical water (T=400 °C and P=25 MPa) to obtain a sugar yield higher than 95 wt %, whereas the 5‐hydroxymethylfurfural (5‐HMF) yield was lower than 0.01 wt %. If the reaction time was increased to 1 s, the main product was glycolaldehyde (60 wt %). Independently of the reaction time, the yield of 5‐HMF was always lower than 0.01 wt %. To evaluate the reaction mechanism of biomass hydrolysis in pressurized water, several parameters (temperature, pressure, reaction time, and reaction medium) were studied for different biomasses (cellulose, glucose, fructose, and wheat bran). It was found that the H+ and OH− ion concentration in the reaction medium as a result of water dissociation is the determining factor in the selectivity. The reaction of glucose isomerization to fructose and the further dehydration to 5‐HMF are highly dependent on the ion concentration. By an increase in the pOH/pH value, these reactions were minimized to allow control of 5‐HMF production. Under these conditions, the retroaldol condensation pathway was enhanced, instead of the isomerization/dehydration pathway.

AbstractQuestionsHow do thermal migration distance and extreme cold events affect seedling emergence and survival in assisted migration schemes in the sub‐Mediterranean context? What role does plant provenance play? Can biotic interactions such as nurse effect of the overstorey and shrub layer buffer the negative responses to plant translocation? Are any of these effects species‐specific?LocationThree pinewoods in the Catalan Pre‐Pyrenees, northeast Iberian Peninsula.MethodsWe used a replicated field trial to test the early years establishment of two contrasted provenances of four Quercus species (Q. coccifera, Q. ilex, Q. faginea and Q. pubescens) that were sown and planted along gradients of elevation and understorey microsite conditions in sub‐Mediterranean pinewoods. Seedling responses to translocation were evaluated through seedling emergence, seedling survival and re‐sprouting after dieback events according to seedling provenance, thermal migration distance, extreme cold events and microenvironment.ResultsThe study reports high success of both the planting (with an overall 76.3% of initial 3‐yr survival) and sowing (with an overall 50% of seedling emergence) experiments. The results show that: (1) the thermal migration distance and the occurrence of extreme cold events have strong effects on the responses of the translocated species (particularly the evergreen oaks); (2) the forest overstorey plays an important role in attenuating the negative effects of thermal migration distance on seedling survival; and (3) these responses are species‐specific. The evergreen Quercus species showed more evidence of high ecotypic differentiation in terms of cold tolerance, enabling local provenances to respond better to translocation. In contrast, marcescent species, showed high phenotypic plasticity that led to a better overall establishment success.ConclusionThe implementation of assisted migration is a feasible option to increase the diversity and resilience of the sub‐Mediterranean pinewoods. Assisted migration programmes should manage risks by thoroughly considering thermal migration distances and the occurrence of extreme cold events when selecting species and seed sources, since Mediterranean tree species show different strategies regarding adaptation to cold. Programme managers should also consider the advantage of planting/sowing under relatively closed canopy to buffer some of the negative responses associated with translocation.