bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions of ferricyanide with humic soils and charred straw
Authors: Rennert T. , Kaufhold S. , Brodowski S. , Mansfeldt T. 
Published: February 2008

SummaryThe iron‐cyanide complexes ferricyanide, [FeIII(CN)6]3−, and ferrocyanide, [FeII(CN)6]4−, are anthropogenic contaminants in soil. We studied the interactions of ferricyanide with humic soils and charred straw (maize and rye, both charred at 300, 400 and 500°C) by batch experiments and Fourier transform infrared (FTIR) spectroscopy. All soil samples sorbed ferricyanide (up to 8.4 g kg−1). Precipitation of a manganese ferrocyanide after reduction of ferricyanide in the moderately acidic to neutral soils was deduced from both FTIR spectroscopy (CN absorption bands at 2069–2065 cm−1) and geochemical modelling. Ferricyanide was also adsorbed onto the charred straw. The amounts of iron‐cyanide complexes adsorbed increased with increasing charring temperature, with a maximum of 1.71 g kg−1. An absorption band at 2083 cm−1 indicated weakly adsorbed intermediates of the reduction of ferricyanide to ferrocyanide. This band disappeared in the samples charred at higher temperature, whereas a band at 2026 cm−1 was present in all spectra and became intensified in the high‐temperature straw. We attribute this band to ferrocyanide forming inner‐sphere complexes, presumably with quinone species of the organic matter. The band at 2026 cm−1 was also present in the spectra of the soils, indicating that soil organic matter also adsorbs ferrocyanide. However, in humic soils the main processes of ferricyanide interaction include reduction to ferrocyanide and precipitation as manganese ferrocyanide. Quantitatively, adsorption on highly aromatic substances plays only a less important role as compared with precipitation.
How do elevated CO2 and O3 affect the interception and utilization of radiation by a soybean canopy?
Authors: DERMODY ORLA , LONG STEPHEN P. , McCONNAUGHAY KELLY , DeLUCIA EVAN H. 
Published: February 2008

AbstractNet productivity of vegetation is determined by the product of the efficiencies with which it intercepts light (ɛi) and converts that intercepted energy into biomass (ɛc). Elevated carbon dioxide (CO2) increases photosynthesis and leaf area index (LAI) of soybeans and thus may increase ɛi and ɛc; elevated O3 may have the opposite effect. Knowing if elevated CO2 and O3 differentially affect physiological more than structural components of the ecosystem may reveal how these elements of global change will ultimately alter productivity. The effects of elevated CO2 and O3 on an intact soybean ecosystem were examined with Soybean Free Air Concentration Enrichment (SoyFACE) technology where large field plots (20‐m diameter) were exposed to elevated CO2 (∼550 μmol mol−1) and elevated O3 (1.2 × ambient) in a factorial design. Aboveground biomass, LAI and light interception were measured during the growing seasons of 2002, 2003 and 2004 to calculate ɛi and ɛc. A 15% increase in yield (averaged over 3 years) under elevated CO2 was caused primarily by a 12% stimulation in ɛc , as ɛi increased by only 3%. Though accelerated canopy senescence under elevated O3 caused a 3% decrease in ɛi, the primary effect of O3 on biomass was through an 11% reduction in ɛc. When CO2 and O3 were elevated in combination, CO2 partially reduced the negative effects of elevated O3. Knowing that changes in productivity in elevated CO2 and O3 were influenced strongly by the efficiency of conversion of light energy into energy in plant biomass will aid in optimizing soybean yields in the future. Future modeling efforts that rely on ɛc for calculating regional and global plant productivity will need to accommodate the effects of global change on this important ecosystem attribute.
Potential effects of climate change on DOC release from three different soil types on the Northern Pennines UK: examination using field manipulation experiments
Authors: HARRISON ANTHONY F. , TAYLOR KENNETH , SCOTT ANDY , POSKITT JAN , BENHAM DAVID , GRACE JOHN , CHAPLOW JACKY , ROWLAND PHILIP 
Published: February 2008

AbstractThree field manipulation experiments were carried out during 1993–1995 on the Northern Pennines to investigate the influences of temperature, solar radiation and rainfall on the release of dissolved organic carbon (DOC) from vegetated soil cores using zero‐tension lysimeters. The cores were manipulated by being translocated to four sites down a climatic gradient, by artificial soil heating or being exposed to double normal rainfall. In each experiment three soil types, a brown earth, a micropodzol and a peaty gley, with differing organic matter content and distribution within the profile, were studied. DOC data, expressed as mg C m−2 day−1, were analysed following log10 transformation, by a repeated measures analysis of variance procedure, using climatic variables measured concurrently with sampling, and 1 and 2 months before sampling. DOC release was dominated by rainfall but was also associated with solar radiation and temperature. With each of the three climatic variables, rainfall, solar radiation and temperature, both positive and negative effects on DOC release have been found significant, indicating that the concurrent and delayed effects of the same variable may be different. DOC release was positively related with all three soils to concurrent rainfall, indicating rainfall's primary leaching action. DOC release was also negatively related to rainfall of the previous month indicating that its action depletes the leachable pool of DOC in the soil. DOC release was positively associated with solar radiation 2 months earlier, indicating that DOC's main source is that of primary production; DOC peaks closely followed peaks of annual primary production. DOC release was linked with temperature, the strongest association being with temperature 2 months earlier, indicating that temperature effects both primary production and DOC regeneration via organic matter decomposition. A conceptual model, relating our findings to those processes known to govern DOC release from soils, has been presented.
Carbon dioxide exchange above a Mediterranean C3/C4 grassland during two climatologically contrasting years
Authors: AIRES LUIS MIGUEL IGREJA , PIO CASIMIRO ADRIÃO , PEREIRA JOÃO SANTOS 
Published: February 2008

AbstractEddy‐covariance measurements of net ecosystem carbon exchange (NEE) were carried out above a grazed Mediterranean C3/C4 grassland in southern Portugal, during two hydrological years, 2004–2005 and 2005–2006, of contrasting rainfall. Here, we examine the seasonal and interannual variation in NEE and its major components, gross primary production (GPP) and ecosystem respiration (Reco), in terms of the relevant biophysical controls. The first hydrological year was dry, with total precipitation 45% below the long‐term mean (669 mm) and the second was normal, with total precipitation only 12% above the long‐term mean. The drought conditions during the winter and early spring of the dry year limited grass production and the leaf area index (LAI) was very low. Hence, during the peak of the growth period, the maximum daily rate of NEE and the light‐use and water‐use efficiencies were approximately half of those observed in the normal year. In the summer of 2006, the warm‐season C4 grass, Cynodon dactylon L., exerted an evident positive effect on NEE by converting the ecosystem into a carbon sink after strong rain events and extending the carbon sequestration for several days, after the end of senescence of the C3 grasses. On an annual basis, the GPP and NEE were 524 and 49 g C m−2, respectively, for the dry year, and 1261 and −190 g C m−2 for the normal year. Therefore, the grassland was a moderate net source of carbon to the atmosphere, in the dry year, and a considerable net carbon sink, in the normal year. In these 2 years of experiment the total amount of precipitation was the main factor determining the interannual variation in NEE. In terms of relevant controls, GPP and NEE were strongly related to incident photosynthetic photon flux density on short‐term time scales. Changes in LAI explained 84% and 77% of the variation found in GPP and NEE, respectively. Variations in Reco were mainly controlled by canopy photosynthesis. After each grazing event, the reduction in LAI affected negatively the NEE.
Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions
Authors: BELNAP JAYNE , PHILLIPS SUSAN L. , FLINT STEPHAN , MONEY JOHN , CALDWELL MARTYN 
Published: February 2008

AbstractBiological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring–fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV‐protective pigments, nitrogenase activity, and extracellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, β‐carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV‐protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute to the stability and fertility of soils in dryland regions.
Shrub encroachment in North American grasslands: shifts in growth form dominance rapidly alters control of ecosystem carbon inputs
Authors: KNAPP ALAN K. , BRIGGS JOHN M. , COLLINS SCOTT L. , ARCHER STEVEN R. , BRET‐HARTE M. SYNDONIA , EWERS BRENT E. , PETERS DEBRA P. , YOUNG DONALD R. , SHAVER GAIUS R. , PENDALL ELISE , CLEARY MEAGAN B. 
Published: February 2008

AbstractShrub encroachment into grass‐dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid‐dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (>1000 g m−2) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being nonlinear in grasslands to linear in shrublands. Thus, relatively abrupt (<50 years) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental‐scale pattern of C inputs and their control by MAP in ways that exceed the direct effects of climate change alone.
Climate warming, dispersal inhibition and extinction risk
Authors: MASSOT MANUEL , CLOBERT JEAN , FERRIÈRE RÉGIS 
Published: February 2008

AbstractGlobal warming impels species to track their shifting habitats or adapt to new conditions. Both processes are critically influenced by individual dispersal. In many animals, dispersal behaviour is plastic, but how organisms with plastic dispersal respond to climate change is basically unknown. Here, we report the analysis of interannual dispersal change from 16 years of monitoring a wild population of the common lizard, and a 12‐year manipulation of lizards' diet intended to disentangle the direct effect of temperature rise on dispersal from its effects on resource availability. We show that juvenile dispersal has declined dramatically over the last 16 years, paralleling the rise of spring temperatures during embryogenesis. A mesoscale model of metapopulation dynamics predicts that in general dispersal inhibition will elevate the extinction risk of metapopulations exposed to contrasting effects of climate warming.
Climate induced increases in species richness of marine fishes
Authors: HIDDINK J. G. , Ter HOFSTEDE R. 
Published: February 2008

AbstractClimate change has been predicted to lead to changes in local and regional species richness through species extinctions and latitudinal ranges shifts. Here, we show that species richness of fish in the North Sea, a group of ecological and socio‐economical importance, has increased over a 22‐year period and that this rise is related to higher water temperatures. Over eight times more fish species displayed increased distribution ranges in the North Sea (mainly small‐sized species of southerly origin) compared with those whose range decreased (primarily large and northerly species). This increase in species richness can be explained from the fact that fish species richness in general decreases with latitude. This observation confirms that the interaction between large‐scale biogeographical patterns and climate change may lead to increasing species richness at temperate latitudes.
Declining coral calcification in massive Porites in two nearshore regions of the northern Great Barrier Reef
Authors: COOPER TIMOTHY F. , DE'ATH GLENN , FABRICIUS KATHARINA E. , LOUGH JANICE M. 
Published: February 2008

AbstractTemporal and spatial variation in the growth parameters skeletal density, linear extension and calcification rate in massive Porites from two nearshore regions of the northern Great Barrier Reef (GBR) were examined over a 16‐year study period. Calcification rates in massive Porites have declined by approximately 21% in two regions on the GBR ∼450 km apart. This is a function primarily of a decrease in linear extension (∼16%) with a smaller decline in skeletal density (∼6%) and contrasts with previous studies on the environmental controls on growth of massive Porites on the GBR. Changes in the growth parameters were linear over time. Averaged across colonies, skeletal density declined over time from 1.32 g cm−3 (SE = 0.017) in 1988 to 1.25 g cm−3 (0.013) in 2003, equivalent to 0.36% yr−1 (0.13). Annual extension declined from 1.52 cm yr−1 (0.035) to 1.28 cm yr−1 (0.026), equivalent to 1.02% yr−1 (0.39). Calcification rates (the product of skeletal density and annual extension) declined from 1.96 g cm−2 yr−1 (0.049) to 1.59 g cm−2 yr−1 (0.041), equivalent to 1.29% yr−1 (0.30). Mean annual seawater temperatures had no effect on skeletal density, but a modal effect on annual extension and calcification with maxima at ∼26.7 °C. There were minor differences in the growth parameters between regions. A decline in coral calcification of this magnitude with increasing seawater temperatures is unprecedented in recent centuries based on analysis of growth records from long cores of massive Porites. We discuss the decline in calcification within the context of known environmental controls on coral growth. Although our findings are consistent with studies of the synergistic effect of elevated seawater temperatures and pCO2 on coral calcification, we conclude that further data on seawater chemistry of the GBR are required to better understand the links between environmental change and effects on coral growth.
Voltinism flexibility of a riverine dragonfly along thermal gradients
Authors: BRAUNE ERIK , RICHTER OTTO , SÖNDGERATH DAGMAR , SUHLING FRANK 
Published: February 2008

AbstractPotential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonflyGomphus vulgatissimus(L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium‐sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology ofG. vulgatissimus, leading to an extension of the flight season in certain regions along the gradient.
Disregarding topographical heterogeneity biases species turnover assessments based on bioclimatic models
Authors: LUOTO M. , HEIKKINEN R. K. 
Published: February 2008

AbstractWe investigated whether the inclusion of topographical heterogeneity in bioclimatic envelope models would significantly alter predictions of climate change – induced broad‐scale butterfly species range size changes in Europe. Using generalized additive models, and data on current climate and species distributions and two different climate scenarios (HadCM3A2 and HadCM3B2) for the period 2051–2080, we developed predictions of the currently suitable area and potential range size changes of 100 European butterfly species. The inclusion of elevation range increased the predictive accuracy of climate‐only models for 86 of the 100 species. The differences in projected future distributions were most notable in mountainous areas, where the climate–topography models projected only ca. half of the species losses than the climate‐only models. By contrast, climate–topography models estimated double the losses of species than climate‐only models in the flatlands regions. Our findings suggest that disregarding topographical heterogeneity may cause a significant source of error in broad‐scale bioclimatic modelling. Mountainous regions are likely to be even more important for future conservation of species than had until now been predicted, based on bioclimatic envelope models that did not take an explicit account of elevational range of grid squares.
Seasonal and annual variation of carbon exchange in an evergreen Mediterranean forest in southern France
Authors: ALLARD V. , OURCIVAL J. M. , RAMBAL S. , JOFFRE R. , ROCHETEAU A. 
Published: February 2008

AbstractWe present 9 years of eddy covariance measurements made over an evergreen Mediterranean forest in southern France. The goal of this study was to quantify the different components of the carbon (C) cycle, gross primary production (GPP) and ecosystem respiration (Reco), and to assess the effects of climatic variables on these fluxes and on the net ecosystem exchange of carbon dioxide. The Puéchabon forest acted as a net C sink of −254 g C m−2 yr−1, with a GPP of 1275 g C m−2 yr−1 and a Reco of 1021 g C m−2 yr−1. On average, 83% of the net annual C sink occurred between March and June. The effects of exceptional events such the insect‐induced partial canopy defoliation that occurred in spring 2005, and the spring droughts of 2005 and 2006 are discussed. A high interannual variability of ecosystem C fluxes during summer and autumn was observed but the resulting effect on the annual net C budget was moderate. Increased severity and/or duration of summer drought under climate change do not appear to have the potential to negatively impact the average C budget of this ecosystem. On the contrary, factors affecting ecosystem functioning (drought and/or defoliation) during March–June period may reduce dramatically the annual C balance of evergreen Mediterranean forests.
Worst experiences of pain and conceptions of worst pain imaginable among nursing students
Authors: Bergh Ingrid , Jakobsson Eva , Sjöström Björn 
Published: February 2008

AbstractTitle.  Worst experiences of pain and conceptions of worst pain imaginable among nursing students Aim. This paper is a report of a study to explore nursing students’ own worst experiences of pain as well as their conceptions of the worst pain imaginable.Background. Pain is a personal experience, often assessed using a visual analogue scale. The endpoints of this scale are labelled with the extremes for pain experience (e.g. no pain to worst pain imaginable). People may understand the meaning of ‘no pain’, but it is unclear what meaning they assign to ‘worst pain imaginable’. This indicates that a rating along the Visual Analogue Scale‐line is dependent on the individual’s previous experiences.Methods. Data were collected during the autumn of 2002. In total, 549 nursing students completed a questionnaire focusing on two main questions: ‘What is the worst experience of hurt, ache or pain you have had?’ and ‘What is the worst pain imaginable for you?’ Content analysis was used for data analysis.Results. The students’ worst experience of pain was mostly related to acute or traumatic painful conditions, pain associated with female physiology, inflicted pain, psychological suffering and chronic painful conditions. The worst pain imaginable was described as condition‐related pain, overwhelming pain, experiences of losses, deliberately inflicted pain, psychological suffering and as vicarious pain.Conclusion. The findings imply that nursing students, when they are imagining pain, include dimensions such as hope of relief, grief, control over the situation, powerlessness and empathy for and suffer with other people’s pain. Further research is needed to explore why professional experience as a nurse diminishes the ability to imagine patients’ pain.