bluuebunny/crossref_metadata_2025 huggingface dataset:
A 10‐year study of phosphorus balances and the impact of grazed grassland on total P redistribution within the soil profile
Authors: Watson C. J. , Matthews D. I.
Published: November 2008

Phosphorus (P) inputs (wet deposition and fertilizer P) and outputs (animal product and drainflow) were studied on reseeded grazed grassland swards receiving different nitrogen (N) inputs (100–500 kg N ha−1 year−1) for 10 years (March 1989–February 1999), at an experimental site in Northern Ireland. All plots received the same maintenance application of P fertilizer (8.5 kg P ha−1 year−1) to meet grass requirements, to minimize the P surplus and to quantify the impact on P losses to land drainage water. The annual flow weighted mean total P concentrations in drainflow ranged from 187 to 273 μg P litre−1and were well above the concentrations believed to trigger eutrophication. Annual total P lost to drainage water ranged from 0.28 to 1.73 kg P ha−1, but was unaffected by N input. As the average annual P balance was zero, there was no significant change in total P in the top 15 cm of soil. However, there was a highly significant redistribution of P to the soil surface from the 10–15 cm depth, possibly as a result of root acquisition and earthworm activity. Total P in the top 5 cm of soil increased from 0.85 g kg−1to 1.04 g kg−1, over the 10 years of the study, despite there being no net P input. This P accumulation in the top few cm of soil is likely to exacerbate P losses in overland flow and make improvements in water quality difficult to achieve.
Micromorphological evidence of black carbon in colluvial soils from NW Spain
Authors: Kaal J. , Van Mourik J. M.
Published: November 2008

Biomass burning produces a residue called black carbon (BC). Black C is generally considered to be highly resistant against biodegradation and has a potential role in the global C cycle, but is difficult to identify and quantify when subjected to prolonged degradation in terrestrial sediments. The colluvial soils from Campo Lameiro (NW Spain), also known as ‘Atlantic rankers’, are rich in organic matter (up to 140 g C kg−1 soil). A micromorphological study was undertaken to test the hypothesis that a large proportion of the organic matter was derived from BC formed during Holocene wildfires (up to > 6000 years ago).

As roughly estimated from image analysis of 12 thin sections, the volumetric BC contribution ranged between 10 and 60% (26% on average) of the organic matter. This is a conservative estimate as additional morphologically unrecognizable BC was present in the microgranular matrix of coalesced excrement. We conclude that (i) currently unknown quantities of BC are stored in Atlantic rankers and (ii) analysis of thin sections is an effective tool to identify BC.
The behaviour of soil process models of ammonia volatilization at contrasting spatial scales
Authors: Corstanje R. , Kirk G. J. D , Lark R. M.
Published: November 2008

Process models are commonly used in soil science to obtain predictions at a spatial scale that is different from the scale at which the model was developed, or the scale at which information on model inputs is available. When this happens, the model and its inputs require aggregation or disaggregation to the application scale, and this is a complex problem. Furthermore, the validity of the aggregated model predictions depends on whether the model describes the key processes that determine the process outcome at the target scale. Different models may therefore be required at different spatial scales. In this paper we develop a diagnostic framework which allows us to judge whether a model is appropriate for use at one or more spatial scales both with respect to the prediction of variations at those scale and in the requirement for disaggregation of the inputs. We show that spatially nested analysis of the covariance of predictions with measured process outcomes is an efficient way to do this. This is applied to models of the processes that lead to ammonia volatilization from soil after the application of urea.

We identify the component correlations at different scales of a nested scheme as the diagnostic with which to evaluate model behaviour. These correlations show how well the model emulates components of spatial variation of the target process at the scales of the sampling scheme. Aggregate correlations were identified as the most pertinent to evaluate models for prediction at particular scales since they measure how well aggregated predictions at some scale correlate with aggregated values of the measured outcome. There are two circumstances under which models are used to make predictions. In the first case only the model is used to predict, and the most useful diagnostic is the concordance aggregate correlation. In the second case model predictions are assimilated with observations which should correct bias in the prediction, and errors in the variance; the aggregate correlations would be the most suitable diagnostic.
Spatial variation of ammonia volatilization from soil and its scale‐dependent correlation with soil properties
Authors: Corstanje R. , Kirk G. J. D. , Pawlett M. , Read R. , Lark R. M.
Published: November 2008

Quantitative predictions of ammonia volatilization from soil are useful to environmental managers and policy makers and empirical models have been used with some success. Spatial analysis of the soil properties and their relationship to the ammonia volatilization process is important as predictions will be required at disparate scales from the field to the catchment and beyond. These relationships are known to change across scales and this may affect the performance of an empirical model. This study is concerned with the variation of ammonia volatilization and some controlling soil properties: bulk density, volumetric water content, pH, CEC, soil pH buffer power, and urease activity, over distances of 2, 50, 500, and >2000 m. We sampled a 16 km × 16 km region in eastern England and analyzed the results by a nested analysis of (co)variance, from which variance components and correlations for each scale were obtained. The overall correlations between ammonia volatilization and the soil properties were generally weak: –0.09 for bulk density, 0.04 for volumetric water content, –0.22 for CEC, –0.08 for urease activity, –0.22 for pH and 0.18 for the soil pH buffer power. Variation in ammonia volatilization was scale‐dependent, with substantial variance components at the 2‐ and 500‐m scales. The results from the analysis of covariance show that the relationships between ammonia volatilization and soil properties are complex. At the >2000 m scale, ammonia volatilization was strongly correlated with pH (–0.82) and CEC (–0.55), which is probably the result of differences in parent material. We also observed weaker correlations at the 500‐m scale with bulk density (–0.61), volumetric water content (0.48), urease activity (–0.42), pH (–0.55) and soil pH buffer power (0.38). Nested analysis showed that overall correlations may mask relationships at scales of interest and the effect of soil variables on these soil processes is scale‐dependent.
Exploring the relationship between sampling efficiency and short‐range endemism for groundwater fauna in the Pilbara region, Western Australia
Authors: EBERHARD STEFAN M. , HALSE STUART A. , WILLIAMS MATTHEW R. , SCANLON MICHAEL D. , COCKING JAMES , BARRON HARLEY J.
Published: November 2008

1. Identifying the existence of short or narrow range endemic species is an important issue when planning for conservation of groundwater fauna in the face of threats to groundwater quantity and quality.

2. Fourteen bores were sampled six times over 3 or 4 years to assess the reliability of net‐hauling sampling in broad‐scale survey to collect the groundwater fauna present at a site and to identify short‐range endemic (SRE) species.

3. Species accumulation curves suggested that one sample from a bore collected 23% and 46% of species occurring in low and high abundance, respectively, and two samples collected 38% and 65% of such species. False‐negative rates provided a slightly higher estimate of the collection probability of species with low abundances.

4. The frequent failure to collect species present at a site means that some apparent short‐range endemism was probably an artefact of low sampling effort. Nevertheless, as is typical for subterranean fauna, a high proportion of the known species in the Pilbara region appeared to be SREs. About 55% had probable ranges <10 000 km2, the criterion proposed byHarvey (2002)for short‐range endemism.

5. Consideration of species occurrence patterns, natural barriers and the scale of most disturbances suggest that 1000 km2is a more satisfactory threshold for short‐range endemism than 10 000 km2but, as the threshold is reduced, more intensive sampling is required to determine whether a species qualifies as an SRE.

6. Extrapolation of the results of regional sampling suggested the Pilbara contains about 500–550 species of groundwater fauna, with the density of species being relatively uniform across the region. Attempts to use a T‐S curve approach (sensuUgland & Gray, 2004) highlighted the lack of information about within‐population dispersal of these species and the area of an aquifer that is effectively sampled by a bore.
Crassulacean acid metabolism contributes significantly to the in situ carbon budget in a population of the invasive aquatic macrophyte Crassula helmsii
Authors: KLAVSEN SIGNE KOCH , MABERLY STEPHEN C.
Published: November 2008

1. The ecophysiological significance of Crassulacean acid metabolism (CAM) in the invasive aquatic macrophyte Crassula helmsii was studied in an English soft‐water lake. The extent and the contribution of CAM to the carbon budget was examined in spring (April) and summer (July) along a depth gradient (0.5–2.2 m), covering the growth range of C. helmsii in the lake.

2. Significant in situ CAM activity (30–80 meq kg−1 FW) was present in all specimens, although it decreased with depth and hence correlated with the decline in photon irradiance. Potential CAM activity (60–161 meq kg−1 FW), measured after exposure to low concentrations of CO2 in the day and high concentrations at night, were on average 2.7‐times greater than in situ CAM activity. Overall CAM activity increased from April to July, which is consistent with higher potential carbon limitation caused by increased temperature and light availability.

3. CAM activity in C. helmsii appeared to be carbon‐limited at night because night‐time carbon‐fixation increased at raised, compared to ambient, concentrations of CO2.

4. The high in situ CAM activity in C. helmsii was reflected in the contribution of CAM to the total carbon budget which, independent of depth and season, ranged from 18% to 42%. The amount of CO2 taken up in the night via CAM was 0.74 to 2.94 times the amount of CO2 lost in respiration, thus emphasizing the importance of CAM in refixation of potentially lost respiratory CO2.

5. The onset of decarboxylation in the morning appeared to be under circadian control as there was a delay of up to 5.5 h between the start of the light period and a decline in cell acidity level.

6. There was little variation in δ13C content (−21.69 to 23.49‰) with season or depth suggesting, along with the estimated contribution to the carbon‐budget, that CAM is important for the whole population of C. helmsii. CAM may confer a competitive advantage in relation to growth, which may be one of the reasons for the invasiveness of this species.
Waterborne metals impair inducible defences in Daphnia pulex: morphology, life‐history traits and encounters with predators
Authors: MIRZA R. S. , PYLE G. G.
Published: November 2008

1. Inducible defences may be temporary and favoured where predation is intermittent and have been demonstrated in several invertebrates and vertebrates when prey detect chemical cues (kairomones) released by predators. Daphnia pulex (a water flea) exposed to Chaoborus (midge larvae) kairomones produce small neckteeth on the dorsal surface of the head as a defence against this gape‐limited predator and survive better in the presence of Chaoborus. Recent studies have shown that waterborne copper (Cu) impairs the induction of neckteeth which could lead to lower survival.

2. Here, we examined the effects of Cu on morphological changes and shifts in life‐history traits in D. pulex exposed to kairomone from Chaoborus americanus. We exposed D. pulex mothers to chemical cues of C. americanus fed on either D. pulex neonates or on brine shrimp Artemia salina, the same Chaoborus cues combined with an environmentally relevant concentration of copper (10 μg L−1), or dechlorinated tap water. We examined several morphological characteristics of neonates and life‐historical characteristics of adults as well as assessing survival of neonates by staging encounters with predators.

3. Neonates from mothers exposed to kairomone plus copper had fewer and shorter neckteeth than neonates from mothers exposed to kairomone alone. Moreover, neonates exposed to Cu had lower survival during encounters with predators than neonates exposed to kairomone without Cu.

4. Adult female Daphnia exposed to kairomones released more neonates within the first 24 h of brood release and emptied their brood pouches quicker than mothers not exposed to kairomones, irrespective of the presence of Cu.

5. Impairment by metals of morphological defences in zooplankton could lead to a decline in population density and alter community structure.
Contribution of N2O to the greenhouse gas balance of first‐generation biofuels
Authors: SMEETS EDWARD M. W. , BOUWMAN LEX F. , STEHFEST ELKE , Van VUUREN DETLEF P. , POSTHUMA ADAM
Published: November 2008

In this study, we analyze the impact of fertilizer‐ and manure‐induced N2O emissions due to energy crop production on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first‐generation biofuels (also taking account of other GHG emissions during the entire life cycle). We calculate the nitrous oxide (N2O) emissions by applying a statistical model that uses spatial data on climate and soil. For the land use that is assumed to be replaced by energy crop production (the ‘reference land‐use system’), we explore a variety of options, the most important of which are cropland for food production, grassland, and natural vegetation. Calculations are also done in the case that emissions due to energy crop production are fully additional and thus no reference is considered. The results are combined with data on other emissions due to biofuels production that are derived from existing studies, resulting in total GHG emission reduction potentials for major biofuels compared with conventional fuels. The results show that N2O emissions can have an important impact on the overall GHG balance of biofuels, though there are large uncertainties. The most important ones are those in the statistical model and the GHG emissions not related to land use. Ethanol produced from sugar cane and sugar beet are relatively robust GHG savers: these biofuels change the GHG emissions by −103% to −60% (sugar cane) and −58% to −17% (sugar beet), compared with conventional transportation fuels and depending on the reference land‐use system that is considered. The use of diesel from palm fruit also results in a relatively constant and substantial change of the GHG emissions by −75% to −39%. For corn and wheat ethanol, the figures are −38% to 11% and −107% to 53%, respectively. Rapeseed diesel changes the GHG emissions by −81% to 72% and soybean diesel by −111% to 44%. Optimized crop management, which involves the use of state‐of‐the‐art agricultural technologies combined with an optimized fertilization regime and the use of nitrification inhibitors, can reduce N2O emissions substantially and change the GHG emissions by up to −135 percent points (pp) compared with conventional management. However, the uncertainties in the statistical N2O emission model and in the data on non‐land‐use GHG emissions due to biofuels production are large; they can change the GHG emission reduction by between −152 and 87 pp.
Forest–flood relation still tenuous – comment on ‘Global evidence that deforestation amplifies flood risk and severity in the developing world’ by C. J. A. Bradshaw, N.S. Sodi, K. S.‐H. Peh and B.W. Brook
Authors: Van DIJK ALBERT I. J. M. , Van NOORDWIJK MEINE , CALDER IAN R. , BRUIJNZEEL SAMPURNO L. A. , SCHELLEKENS JAAP , CHAPPELL NICK A.
Published: November 2008

In a recent paper in this journal, Bradshaw and colleagues analyse country statistics on flood characteristics, land cover and land cover change, and conclude that deforestation amplifies flood risk and severity in the developing world. The study addresses an important and long‐standing question, but we identify important flaws. Principal among these are difficulties in interpreting country statistics and the correlation between population and floods. We review current knowledge, which suggests that the removal of trees does not affect large flood events, although associated landscape changes can under some circumstances. Reanalysis of the data analysed by Bradshaw and colleagues shows that population density alone already explains up to 83% of the variation in reported flood occurrences, considerably more than forest cover or deforestation (<10%). Feasible explanations for this statistical finding – whether spurious or causative – are not difficult to conceive. We, therefore, consider the conclusion of Bradshaw and colleagues to be unsupported. However, their study is a valuable first step to show how these or similar flood data might be used to further explore the relationship between land cover and flooding.
Regional analysis of the impacts of climate change on cheatgrass invasion shows potential risk and opportunity
Authors: BRADLEY BETHANY A.
Published: November 2008

Interactions between climate change and non‐native invasive species may combine to increase invasion risk to native ecosystems. Changing climate creates risk as new terrain becomes climatically suitable for invasion. However, climate change may also create opportunities for ecosystem restoration on invaded lands that become climatically unsuitable for invasive species. Here, I develop a bioclimatic envelope model for cheatgrass (Bromus tectorum), a non‐native invasive grass in the western US, based on its invaded distribution. The bioclimatic envelope model is based on the Mahalanobis distance using the climate variables that best constrain the species' distribution. Of the precipitation and temperature variables measured, the best predictors of cheatgrass are summer, annual, and spring precipitation, followed by winter temperature. I perform a sensitivity analysis on potential cheatgrass distributions using the projections of 10 commonly used atmosphere–ocean general circulation models (AOGCMs) for 2100. The AOGCM projections for precipitation vary considerably, increasing uncertainty in the assessment of invasion risk. Decreased precipitation, particularly in the summer, causes an expansion of suitable land area by up to 45%, elevating invasion risk in parts of Montana, Wyoming, Utah, and Colorado. Conversely, increased precipitation reduces habitat by as much as 70%, decreasing invasion risk. The strong influence of precipitation conditions on this species' distribution suggests that relying on temperature change alone to project future change in plant distributions may be inadequate. A sensitivity analysis provides a framework for identifying key climate variables that may limit invasion, and for assessing invasion risk and restoration opportunities with climate change.
Forest fine‐root production and nitrogen use under elevated CO2: contrasting responses in evergreen and deciduous trees explained by a common principle
Authors: FRANKLIN OSKAR , McMURTRIE ROSS E. , IVERSEN COLLEEN M. , CROUS KRISTINE Y. , FINZI ADRIEN C. , TISSUE DAVID T. , ELLSWORTH DAVID S. , OREN RAM , NORBY RICHARD J.
Published: November 2008

Despite the importance of nitrogen (N) limitation of forest carbon (C) sequestration at rising atmospheric CO2concentration, the mechanisms responsible are not well understood. To elucidate the interactive effects of elevated CO2(eCO2) and soil N availability on forest productivity and C allocation, we hypothesized that (1) trees maximize fitness by allocating N and C to maximize their net growth and (2) that N uptake is controlled by soil N availability and root exploration for soil N. We tested this model using data collected in Free‐Air CO2Enrichment sites dominated by evergreen (Pinus taeda; Duke Forest) and deciduous [Liquidambar styraciflua; Oak Ridge National Laboratory (ORNL)] trees. The model explained 80–95% of variation in productivity and N‐uptake data among eCO2, N fertilization and control treatments over 6 years. The model explains why fine‐root production increased, and why N uptake increased despite reduced soil N availability under eCO2at ORNL and Duke. In agreement with observations at other sites, the model predicts that soil N availability reduced below a critical level diminishes all eCO2responses. At Duke, a negative feedback between reduced soil N availability and N uptake prevented progressive reduction in soil N availability at eCO2. At ORNL, soil N availability progressively decreased because it did not trigger reductions in N uptake; N uptake was maintained at ORNL through a large increase in the production of fast turnover fine roots. This implies that species with fast root turnover could be more prone to progressive N limitation of carbon sequestration in woody biomass than species with slow root turnover, such as evergreens. However, longer term data are necessary for a thorough evaluation of this hypothesis. The success of the model suggests that the principle of maximization of net growth to control growth and allocation could serve as a basis for simplification and generalization of larger scale forest and ecosystem models, for example by removing the need to specify parameters for relative foliage/stem/root allocation.
New coupled model used inversely for reconstructing past terrestrial carbon storage from pollen data: validation of model using modern data
Authors: WU HAIBIN , GUIOT JOËL , PENG CHANGHUI , GUO ZHENGTANG
Published: November 2008

The knowledge of potential impacts of climate change on terrestrial vegetation is crucial to understand long‐term global carbon cycle development. Discrepancy in data has long existed between past carbon storage reconstructions since the Last Glacial Maximum by way of pollen, carbon isotopes, and general circulation model (GCM) analysis. This may be due to the fact that these methods do not synthetically take into account significant differences in climate distribution between modern and past conditions, as well as the effects of atmospheric CO2 concentrations on vegetation. In this study, a new method to estimate past biospheric carbon stocks is reported, utilizing a new integrated ecosystem model (PCM) built on a physiological process vegetation model (BIOME4) coupled with a process‐based biospheric carbon model (DEMETER). The PCM was constrained to fit pollen data to obtain realistic estimates. It was estimated that the probability distribution of climatic parameters, as simulated by BIOME4 in an inverse process, was compatible with pollen data while DEMETER successfully simulated carbon storage values with corresponding outputs of BIOME4. The carbon model was validated with present‐day observations of vegetation biomes and soil carbon, and the inversion scheme was tested against 1491 surface pollen spectra sample sites procured in Africa and Eurasia. Results show that this method can successfully simulate biomes and related climates at most selected pollen sites, providing a coefficient of determination (R) of 0.83–0.97 between the observed and reconstructed climates, while also showing a consensus with an R‐value of 0.90–0.96 between the simulated biome average terrestrial carbon variables and the available observations. The results demonstrate the reliability and feasibility of the climate reconstruction method and its potential efficiency in reconstructing past terrestrial carbon storage.
Global climate patterns explain range‐wide synchronicity in survival of a migratory seabird
Authors: JENOUVRIER STEPHANIE , THIBAULT JEAN‐CLAUDE , VIALLEFONT ANNE , VIDAL PATRICK , RISTOW DIETRICH , MOUGIN JEAN‐LOUIS , BRICHETTI PIERANDREA , BORG JOHN J. , BRETAGNOLLE VINCENT
Published: November 2008

To predict the impact of climate change over the whole species distribution range, comparison of adult survival variations over large spatial scale is of primary concern for long‐lived species populations that are particularly susceptible to decline if adult survival is reduced. In this study, we estimated and compared adult survival rates between 1989 and 1997 of six populations of Cory's shearwater (Calonectris diomedea) spread across 4600 km using capture–recapture models. We showed that mean annual adult survival rates are different among populations along a longitudinal gradient and between sexes. Variation in adult survival is synchronized among populations, with three distinct groups: (1) both females and males of Corsica, Tremiti, and Selvagem (annual survival range 0.88–0.96); (2) both females and males of Frioul and females from Crete (0.82–0.92); and (3) both females and males of Malta and males from Crete (0.74–0.88). The total variation accounted for by the common pattern of variation is on average 71%, suggesting strong environmental forcing. At least 61% of the variation in survival is explained by the Southern Oscillation Index fluctuations. We suggested that Atlantic hurricanes and storms during La Niña years may increase adult mortality for Cory's shearwater during winter months. For long‐lived seabird species, variation in adult survival is buffered against environmental variability, although extreme climate conditions such as storms significantly affect adult survival. The effect of climate at large spatial scales on adult survival during the nonbreeding period may lead to synchronization of variation in adult survival over the species' range and has large effects on the meta‐population trends. One can thus worry about the future of such long‐lived seabirds species under the predictions of higher frequency of extreme large‐scale climatic events.
Effect of sowing date of triticale on seasonal herbage production in the central Appalachian Highlands of the United States
Authors: Clapham W. M. , Fedders J. M.
Published: November 2008

Triticale (X Triticosecale Wittmack) was evaluated as a complementary pasture to buffer those periods when herbage production from mixed perennial pasture is marginal in the central Appalachian Highlands of the United States. Triticale was sown every month from May to October for five consecutive years from 1999 to 2003. Plant population structure and herbage production were evaluated at intervals until May of the year following establishment. Triticale established quickly at all times of sowing except late October. Wet summers resulted in foliar disease and a rapid decline in plant density when triticale was sown in May and June. In contrast, during the relatively dry summer of 1999, triticale stands exhibited minimal decline. Triticale sown in August had a herbage yield of 1580 kg DM ha−1 when harvested in October which was over twice the herbage yield of triticale sown in May, June and July. Average herbage yield in the following April of triticale sown in September was higher (1750 kg DM ha−1) and less variable than herbage yields from other sowing dates. Plant and tiller populations declined throughout the following April but herbage yields in May were high due to stem and seed head development associated with reproductive growth. Incorporating areas of triticale into mixed‐species perennial pasture systems could buffer herbage production during hot and dry summer periods as well as during cool periods of late autumn and early spring.
The effects of clipping height and frequency on net primary production ofAndropogon gerardii(C4grass) andBromus inermis(C3grass) in greenhouse experiments
Authors: Woodis J. E. , Jackson R. D.
Published: November 2008

There are potential agronomic and environmental benefits from incorporating warm‐season (C4) grasses into temperate pasture systems, usually dominated by cool‐season (C3) grasses, but there is a lack of information on how frequency and height of defoliation affects C4grasses. Three greenhouse experiments were conducted under (i) spring, (ii) summer and (iii) spring + summer clipping regimes. In each experiment, the effects of clipping frequency (weekly and monthly) and clipping height (clipped to 5 and 10 cm) were determined on above‐ and below‐ground net primary production (ANPP and BNPP) and total and seasonal dry matter (DM) yield forAndropogon gerardiiVitman (big bluestem, C4grass) andBromus inermisLeyss (smooth brome, C3grass). Six replicates per treatment were used. In all experiments, ANPP and BNPP of smooth brome was greater than that of big bluestem although during late summer months big bluestem had higher DM yields of herbage than smooth brome. There were different effects of frequency and height of clipping for both species on two similar measurements: total annual DM yield and ANPP, indicating that the ability to generalize about the effects of defoliation from ecological and agronomic grassland standpoints is questionable. Clipping effects on ANPP and BNPP were different for summer‐clipped pots than for spring, and spring + summer‐clipped pots, indicating that management could be tailored to meet specific agronomic or conservation goals.
Potential of the indigenous desert grasses of the Arabian Peninsula for forage production in a water‐scarce region
Authors: Osman A. E. , Makawi M. , Ahmed R.
Published: November 2008

Indigenous perennial grasses are widely distributed in the Arabian Peninsula. Their survival under limited rainfall and grazing suggests a potential role as grassland species and for rehabilitation of degraded rangelands. Forage productivity, seed production and water‐use efficiency (WUE) was determined over 2 years for four indigenous grasses: buffel grass (Cenchrus ciliaris L.), dakhna (Coelachyrum piercei Benth.), da’ay (Lasiurus scindicus Henr.) and tuman (Panicum turgidum Forssk.) together with one exotic species, rhodes grass (Chloris gayana Kunth) in the central region of the United Arab Emirates. Three irrigation treatments were used: R1 (1858–6758 m3 ha−1 year−1), R2 (929–3379 m3 ha−1 year−1) and R3 (464–1689 m3 ha−1 year−1). Buffel grass had the highest dry‐matter (DM) yield under all irrigation treatments. The average DM yield of buffel grass was 14·6 and 15·1 t ha−1 in the 2 years which was significantly higher than that for the other grasses with dakhna having the lowest DM yields. The WUE of 0·7 and 0·8 kg DM m−3 in the 2 years for buffel grass was significantly greater than for the other grasses. Buffel grass showed the highest increase in WUE in both years when the irrigation was reduced from treatment R1 to R3. The results suggest that the desert grasses of the Arabian Peninsula, such as buffel grass, could be useful grass species in reducing the use of scarce irrigation water provided that seed production can be increased.
Low‐ammonia‐emission application methods can increase the opportunity for application of cattle slurry to grassland in spring in Ireland
Authors: Lalor S. T. J. , Schulte R. P. O.
Published: November 2008

Application of slurry in spring to grassland in north‐west Europe increases the efficiency of nitrogen recovery compared with the application in summer. In Ireland, however, more than 0·50 of slurry is applied in the summer. The splash‐plate method of application, most commonly used in Ireland, can make application in spring difficult because of the risk of contamination of grass with slurry, affecting subsequent silage quality and grazing preferences. This study evaluated the potential of low‐emission spreading methods to increase the opportunity for spring application of slurry using an agro‐meteorological modelling approach. Weather data from two weather stations were combined with data on grass growth from two nearby sites. Using three soil‐drainage classes (well, moderate and poor), each with a typical regime of grassland management, a database of soil moisture deficits, drainage, patterns of grazing and cover of grass herbage was developed for three hypothetical management systems, one for each soil drainage class, at each site. Simulations of four slurry application methods [splash‐plate (SP), band‐spreader (BS), trailing‐shoe (TS) and shallow‐injection (SI)], subject to a series of constraints, were compared over an 8‐year period (1998–2005) in order to determine the number of days during the period from 1 January to approximately 10 May of each year, when it was considered that grassland was suitable for application of slurry. These constraints were: (i) restrictions on spreading imposed by current legislation in Ireland; (ii) the period before occurrence of drainage or overland flow; (iii) soil trafficability; (iv) the time‐lag before a subsequent grazing or harvest event; and (v) herbage mass of the pasture. On well and moderately drained soils, the model predicted that the highest number of days available for slurry spreading was found for the TS method followed by the BS, SI and SP methods. There was no difference between application methods in the number of available days on poorly drained soils.
Nitrogen flows and balances in four grassland‐based systems of dairy production on a clay‐loam soil in a moist temperate climate
Authors: Humphreys J. , O’Connell K. , Casey I. A.
Published: November 2008

This study examined productivity, nitrogen (N) flows and N balances in grassland‐based systems of dairy production in Ireland. There were four stocking densities of dairy cows on grass/white clover pastures and four inputs of N as fertilizers, concentrates and biological fixation over 2 years; 2001 and 2002. Annual stocking densities were 1·75, 2·10, 2·50 and 2·50 cows ha−1. Associated N inputs were 205, 230, 300 and 400 kg ha−1 respectively. There were eighteen cows per system. Cows calved within a 12‐week interval in spring with a mean calving date of 28 February and lactation extended until mid‐December in each year. There were no differences in annual milk yield (6337 kg cow−1; s.e.m. 106·1), live weight or body condition score. Pre‐grazing N concentrations in herbage increased (P < 0·001) with increasing N input, whereas there were no differences in N concentrations in silage reflecting optimum N inputs for silage production. Grazed herbage accounted for 0·64, silage 0·26 and concentrates 0·10 of annual dry matter consumed by the cows. Annual intakes of N ranged from 144 to 158 kg cow−1 and were mostly influenced by N concentration in grazed herbage. Annual output of N in milk and liveweight change was 38 kg cow−1 and was not different between systems. Annual N surpluses increased with increasing N inputs from 137 to 307 kg ha−1, whereas the proportion of N inputs recovered in products declined from 0·34 to 0·24. More efficient N use was associated with lower N inputs and in particular lower N concentrations in grazed herbage.
Selective induction of the Notch ligand Jagged‐1 in macrophages by soluble egg antigen from Schistosoma mansoni involves ERK signalling
Authors: Goh Felicia , Irvine Katharine M. , Lovelace Erica , Donnelly Sheila , Jones Malcolm K. , Brion Kristian , Hume David A. , Kotze Andrew C. , Dalton John P. , Ingham Aaron , Sweet Matthew J.
Published: November 2008

Soluble egg antigen (SEA) from the helminth Schistosoma mansoni promotes T helper type 2 (Th2) responses by modulating antigen‐presenting cell function. The Jagged/Notch pathway has recently been implicated in driving Th2 development. We show here that SEA rapidly up‐regulated mRNA and protein expression of the Notch ligand Jagged‐1 in both murine bone marrow‐derived macrophages (BMMs) and human monocyte‐derived macrophages (HMDMs). Another potential Th2‐promoting factor, interleukin (IL)‐33, was not transcriptionally induced by SEA in BMMs. Up‐regulation of Jagged‐1 mRNA by SEA was also apparent in conventional dendritic cells (DCs), although the effect was less striking than in BMMs. Conversely, SEA‐pulsed DCs, but not BMMs, promoted IL‐4 production upon T‐cell activation, suggesting that Jagged‐1 induction alone is insufficient for instructing Th2 development. A comparison of the responses initiated in BMMs by SEA and the bacterial endotoxin lipopolysaccharide (LPS) revealed common activation of extracellular signal‐regulated kinase‐1/2 (ERK‐1/2) and p38 phosphorylation, as well as induction of Jagged‐1 mRNA. However, only LPS triggered IκB degradation, phosphorylation of c‐Jun N‐terminal kinase (Jnk) and signal transducer and activator of transcription 1 (Stat1) Tyr701, and IL‐33 and IL‐12p40 mRNA up‐regulation. Inducible gene expression was modified by the presence of the macrophage growth factor colony‐stimulating factor (CSF)‐1, which inhibited Jagged‐1 induction by SEA and LPS, but enhanced LPS‐induced IL‐12p40 expression. Unlike LPS, SEA robustly activated signalling in HEK293 cells expressing either Toll‐like receptor 2 (TLR2) or TLR4/MD2. Pharmacological inhibition of the ERK‐1/2 pathway impaired SEA‐ and LPS‐inducible Jagged‐1 expression in BMMs. Taken together, our data suggest that Jagged‐1 is an ERK‐dependent target of TLR signalling that has a macrophage‐specific function in the response to SEA.
Signalling mechanisms for Toll‐like receptor‐activated neutrophil exocytosis: key roles for interleukin‐1‐receptor‐associated kinase‐4 and phosphatidylinositol 3‐kinase but not Toll/IL‐1 receptor (TIR) domain‐containing adaptor inducing IFN‐β (TRIF)
Authors: Brzezinska Agnieszka A. , Johnson Jennifer L. , Munafo Daniela B. , Ellis Beverly A. , Catz Sergio D.
Published: November 2008

Lipopolysaccharide (LPS) stimulates exocytosis in neutrophils. The signalling molecules involved in the regulation of this mechanism are currently unknown. Using neutrophils from interleukin‐1‐receptor‐associated kinase (IRAK)‐4‐ and Toll/IL‐1 receptor (TIR) domain‐containing adaptor inducing IFN‐β (TRIF)‐deficient mice, we dissected the signalling pathways that control exocytosis. We analysed exocytosis of peroxidase‐negative and azurophilic granules by following the mobilization of the β2‐integrin subunit CD11b and myeloperoxidase (MPO)‐containing granules, respectively. IRAK‐4‐null neutrophils showed marked defects in both peroxidase‐negative and azurophilic granule exocytosis in response to LPS. In contrast, the exocytic response to LPS of TRIF‐deficient neutrophils was not different from that of wild‐type cells. No differences were observed in the exocytosis of secretory organelles between IRAK‐4‐null and wild‐type neutrophils when they were stimulated with the phorbol ester phorbol 12‐myristate 13‐acetate (PMA). Electron microscopy analysis showed that no morphological abnormalities were present in the granules of IRAK‐4‐deficient neutrophils, suggesting that the lack of exocytic response to LPS is not attributable to developmental abnormalities. Using pharmacological inhibitors, we found that p38 mitogen‐activated protein kinase (p38MAPK) is essential for the exocytosis of all neutrophil secretory organelles in response to LPS. Interestingly, we found that phosphatidylinositol 3‐kinase (PI3K) is essential for azurophilic granule exocytosis but not for the mobilization of other neutrophil granules in response to LPS. Azurophilic granule exocytosis in response to Listeria monocytogenes was dependent on PI3K but not IRAK‐4 activity, suggesting that alternative signalling pathways are activated in IRAK‐4‐deficient neutrophils exposed to whole bacteria. Our results identified IRAK‐4, p38MAPK and PI3K as important regulatory components with different roles in the signalling pathways that control Toll‐like receptor ligand‐triggered neutrophil exocytosis.
Evidence for a human leucocyte antigen‐DM‐induced structural change in human leucocyte antigen‐DOβ
Authors: Deshaies Francis , Diallo Djibril A. , Fortin Jean‐Simon , O’Rourke Helen M. , Pezeshki Abdul Mohammad , Bellemare‐Pelletier Angélique , Raby Nicola , Bédard Nathalie , Brunet Alexandre , Denzin Lisa K. , Thibodeau Jacques
Published: November 2008

Human leucocyte antigen (HLA)‐DO is a non‐classical major histocompatibility complex class II molecule which modulates the function of HLA‐DM and the loading of antigenic peptides on molecules such as HLA‐DR. The bulk of HLA‐DO associates with HLA‐DM and this interaction is critical for HLA‐DO egress from the endoplasmic reticulum. HLA‐DM assists the early steps of HLA‐DO maturation presumably through the stabilization of the interactions between the N‐terminal regions of the α and β chains. To evaluate a possible role for HLA‐DM in influencing the conformation of HLA‐DO, we made use of a monoclonal antibody, Mags.DO5, that was raised against HLA‐DO/DM complexes. Using transfected cells expressing mismatched heterodimers between HLA‐DR and ‐DO chains, we found that the epitope for Mags.DO5 is located on the DOβ chain and that Mags.DO5 reactivity was increased upon cotransfection with HLA‐DM. Our results suggest that HLA‐DM influences the folding of HLA‐DO in the endoplasmic reticulum. A mutant HLA‐DO showing reduced capacity for endoplasmic reticulum egress was better recognized by Mags.DO5 in the presence of HLA‐DM. On the other hand, an HLA‐DO mutant capable of endoplasmic reticulum egress on its own was efficiently recognized by Mags.DO5, irrespective of the presence of HLA‐DM. Taken together, our results suggest that HLA‐DM acts as a private chaperone, directly assisting the folding of HLA‐DO to promote egress from the endoplasmic reticulum.
Dexamethasone/1α‐25‐dihydroxyvitamin D3‐treated dendritic cells suppress colitis in the SCID T‐cell transfer model
Authors: Pedersen Anders Elm , Schmidt Esben Gjerløff Wedebye , Gad Monika , Poulsen Steen Seier , Claesson Mogens Helweg
Published: November 2008

Autoantigen‐presenting immunomodulatory dendritic cells (DCs) that are used for adoptive transfer have been shown to be a promising therapy for a number of autoimmune diseases. We have previously demonstrated that enteroantigen‐pulsed DCs treated with interleukin‐10 (IL‐10) can partly protect severe combined immunodeficient (SCID) mice adoptively transferred with CD4+ CD25− T cells from the development of wasting disease and colitis. We therefore established an in vitro test that could predict the in vivo function of DCs and improve strategies for the preparation of immunomodulatory DCs in this model. Based on these in vitro findings, we here evaluate three methods for DC generation including short‐term and long‐term IL‐10 exposure or DC exposure to dexamethasone in combination with vitamin D3 (Dex/D3). All DCs resulted in lower CD4+ CD25− T‐cell enteroantigen‐specific responses in vitro, but Dex/D3 DCs had the most prominent effect on T‐cell cytokine secretion. In vivo, Dex/D3 DCs most efficiently prevented weight loss and gut pathology upon CD4+ CD25− T‐cell transfer in SCID mice, although the effect on gut pathology was antigen independent. Our data in the SCID T‐cell transfer model illustrate some correlation between in vitro and in vivo DC function and document that prevention of experimental inflammatory bowel disease by transfer of immunosuppressive DCs is possible.
Primary angioplasty for heart attack: mismatch between expectations and reality?
Authors: Astin Felicity , Closs S. José , McLenachan Jim , Hunter Stacey , Priestley Claire
Published: November 2008

Title.  Primary angioplasty for heart attack: mismatch between expectations and reality?

Aim.  This paper is a report of a study to explore patients’ experiences of primary angioplasty and assess their illness perceptions during early recovery.

Background.  Primary angioplasty is recognized as the gold standard treatment for patients with ST elevation myocardial infarction, yet little is known about patients’ experiences of this treatment. Recent policy change has emphasized the need for clinical practice to be more patient‐centred. One way to achieve this is to understand patients’ experiences of treatment better.

Method.  A mixed methods exploratory study was carried out in 2006–2007 with a purposive sample of 29 patients. Data were collected 3–12 days after hospital discharge using (a) semi‐structured interviews to explore participants’ experiences and (b) The Illness Perception Questionnaire to evaluate illness perceptions. Interview data were analysed using the Framework approach. Questionnaire data were used to inform the qualitative findings.

Findings.  Participants were very positive about their treatment but experienced considerable emotional shock, which was exacerbated by the speed with which events occurred. Patients’ experiences were characterized by a mismatch between their expectations and reality. Questionnaire data supported the notion that they experienced difficulty in ‘making sense’ of their condition in a coherent way. They tended to see their condition as ‘acute’ rather than ‘chronic’ and their treatment as curative.

Conclusion.  Patient education should include focused discussions addressing the ‘mismatches’ that may occur between their expectations and reality. In this way, a more coherent understanding can be promoted, with greater awareness of heart disease as a long‐term condition requiring ongoing self‐management.
The role of technology in critical care nursing
Authors: Crocker Cheryl , Timmons Stephen
Published: November 2008

Title. The role of technology in critical care nursing.

Aim. This paper is a report of a study to identify the meaning for critical care nurses of technology related to weaning from mechanical ventilation and to explore how that technology was used in practice.

Background. The literature concerned with the development of critical care (intensive care and high dependency units) focuses mainly on innovative medical technology. Although this use of technology in critical care is portrayed as new, it actually represents a transfer of technology from operating theatres.

Method. An ethnographic study was conducted and data were collected on one critical care unit in a large teaching hospital over a 6‐month period in 2004. The methods included participant observation, interviews and the collection of field notes.

Findings. The overall theme ‘The nursing–technology relation’ was identified. This comprised three sub‐themes: definition of technology, technology transferred and technology transformed. Novice nurses took a task‐focussed approach to weaning, treating it as a ‘medical’ technology transferred to them from doctors. Expert nurses used technology differently and saw its potential to become a ‘nursing technology’.

Conclusion. Nurses need to examine how they can adapt and to ‘reconfigure’ technology so that it can be transformed into a nursing technology. Those technologies that do not fit with nursing may have no place there. Rather than simply extending and expanding their roles through technology transfer, nurses should transform those technologies that preserve the essence of nursing and can contribute to a positive outcome for patients.