bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linking individual response to biotic interactions with community structure: a trait‐based framework
Authors: Gross Nicolas , Kunstler Georges , Liancourt Pierre , De Bello Francesco , Suding Katharine Nash , Lavorel Sandra 
Published: June 2009

Summary 1.  Due to species‐specificity of the outcomes of biotic interactions, it is difficult to generalize from observed biotic interactions at the individual plant level to the effect of those interactions at the community level. To evaluate the importance of biotic interactions in shaping plant communities, it is necessary to understand how the outcomes of the complex interactions observed at the individual level can influence community structure. 2.  Here, we propose a trait‐based framework that identifies and organises mechanisms affecting community structure (here described with relative abundances of plant functional traits – i.e. the distribution of trait values at the community level). We applied our approach to a single leaf trait, specific leaf area (SLA), to link individual responses to plant interactions with community structure (SLA distribution observed at the community level) and to test whether biotic interactions can predict the functional composition of subalpine grasslands. We evaluated the generality of our model through a cross‐validation with a set of eight subalpine grasslands independent from the four fields used to build the model. 3.  We found that competition and facilitation were able to explain the functional composition of subalpine grasslands, and the relevant fitness components (survival or growth) explaining this link changed depending on the limiting resources. When soil water availability was limiting, positive plant‐plant interactions acting on survival were able to explain community structure. In contrast, when no water limitation was observed competition acting on individual growth was the main driver of community structure. 4.  Our framework enables evaluation of the consequences of biotic interactions observed at individual level on community structure, thereby indicating when and where different types of plant‐plant interactions are important.
Non‐uniqueness with refraction inversion – a syncline model study
Authors: Palmer Derecke 
Published: June 2009

ABSTRACTNon‐uniqueness occurs with the 1D parametrization of refraction traveltime graphs in the vertical dimension and with the 2D lateral resolution of individual layers in the horizontal dimension. The most common source of non‐uniqueness is the inversion algorithm used to generate the starting model. This study applies 1D, 1.5D and 2D inversion algorithms to traveltime data for a syncline (2D) model, in order to generate starting models for wave path eikonal traveltime tomography.The 1D tau‐p algorithm produced a tomogram with an anticline rather than a syncline and an artefact with a high seismic velocity. The 2D generalized reciprocal method generated tomograms that accurately reproduced the syncline, together with narrow regions at the thalweg with seismic velocities that are less than and greater than the true seismic velocities as well as the true values.It is concluded that 2D inversion algorithms, which explicitly identify forward and reverse traveltime data, are required to generate useful starting models in the near‐surface where irregular refractors are common. The most likely tomogram can be selected as either the simplest model or with a priori information, such as head wave amplitudes.The determination of vertical velocity functions within individual layers is also subject to non‐uniqueness. Depths computed with vertical velocity gradients, which are the default with many tomography programs, are generally 50% greater than those computed with constant velocities for the same traveltime data. The average vertical velocity provides a more accurate measure of depth estimates, where it can be derived.Non‐uniqueness is a fundamental reality with the inversion of all near‐surface seismic refraction data. Unless specific measures are taken to explicitly address non‐uniqueness, then the production of a single refraction tomogram, which fits the traveltime data to sufficient accuracy, does not necessarily demonstrate that the result is either ‘correct’ or the most probable.
Plant–soil interactions in the expansion and native range of a poleward shifting plant species
Authors: Van GRUNSVEN ROY H. A. , Van Der PUTTEN WIM H. , MARTIJN BEZEMER T. , BERENDSE FRANK , VEENENDAAL ELMAR M. 
Published: June 2009

AbstractClimate warming causes range shifts of many species toward higher latitudes and altitudes. However, range shifts of host species do not necessarily proceed at the same rates as those of their enemies and symbionts. Here, we examined how a range shifting plant species performs in soil from its original range in comparison with soil from the expansion range. Tragopogon dubius is currently expanding from southern into north‐western Europe and we examined how this plant species responds to soil communities from its original and expansion ranges. We compared the performance of T. dubius with that of the closely related Tragopogon pratensis, which has a natural occurrence along the entire latitudinal gradient. Inoculation with the rhizosphere soil from T. dubius populations of the original range had a more negative effect on plant biomass production than inoculation with rhizosphere soil from the expansion range. Interestingly, the nonrange expander T. pratensis experienced a net negative soil effect throughout this entire range. The effects observed in this species pair may be due to release from soil born enemies or accumulation of beneficial soil born organisms. If this phenomenon applies broadly to other species, then range expansion may enable plants species to show enhanced performance.
Carbon stored in human settlements: the conterminous United States
Authors: CHURKINA GALINA , BROWN DANIEL G. , KEOLEIAN GREGORY 
Published: June 2009

AbstractUrban areas are home to more than half of the world's people, responsible for >70% of anthropogenic release of carbon dioxide and 76% of wood used for industrial purposes. By 2050 the proportion of the urban population is expected to increase to 70% worldwide. Despite fast rates of change and potential value for mitigation of carbon dioxide emissions, the organic carbon storage in human settlements has not been well quantified. Here, we show that human settlements can store as much carbon per unit area (23–42 kg C m−2urban areas and 7–16 kg C m−2exurban areas) as tropical forests, which have the highest carbon density of natural ecosystems (4–25 kg C m−2). By the year 2000 carbon storage attributed to human settlements of the conterminous United States was 18 Pg of carbon or 10% of its total land carbon storage. Sixty‐four percent of this carbon was attributed to soil, 20% to vegetation, 11% to landfills, and 5% to buildings. To offset rising urban emissions of carbon, regional and national governments should consider how to protect or even to increase carbon storage of human‐dominated landscapes. Rigorous studies addressing carbon budgets of human settlements and vulnerability of their carbon storage are needed.
Exposure to preindustrial, current and future atmospheric CO2 and temperature differentially affects growth and photosynthesis in Eucalyptus
Authors: GHANNOUM OULA , PHILLIPS NATHAN G. , CONROY JANN P. , SMITH RENEE A. , ATTARD RENEE D. , WOODFIELD ROSLYN , LOGAN BARRY A. , LEWIS JAMES D. , TISSUE DAVID T. 
Published: June 2009

AbstractTo investigate if Eucalyptus species have responded to industrial‐age climate change, and how they may respond to a future climate, we measured growth and physiology of fast‐ (E. saligna) and slow‐growing (E. sideroxylon) seedlings exposed to preindustrial (290), current (400) or projected (650 μL L−1) CO2 concentration ([CO2]) and to current or projected (current +4 °C) temperature. To evaluate maximum potential treatment responses, plants were grown with nonlimiting soil moisture. We found that: (1) E. sideroxylon responded more strongly to elevated [CO2] than to elevated temperature, while E. saligna responded similarly to elevated [CO2] and elevated temperature; (2) the transition from preindustrial to current [CO2] did not enhance eucalypt plant growth under ambient temperature, despite enhancing photosynthesis; (3) the transition from current to future [CO2] stimulated both photosynthesis and growth of eucalypts, independent of temperature; and (4) warming enhanced eucalypt growth, independent of future [CO2], despite not affecting photosynthesis. These results suggest large potential carbon sequestration by eucalypts in a future world, and highlight the need to evaluate how future water availability may affect such responses.
Annual wood production in a tropical rain forest in NE Costa Rica linked to climatic variation but not to increasing CO2
Authors: CLARK DAVID B. , CLARK DEBORAH A. , OBERBAUER STEVEN F. 
Published: June 2009

AbstractIncreased atmospheric [CO2] could theoretically lead to increased forest productivity (‘CO2 fertilization’). This mechanism was hypothesized as a possible explanation for biomass increases reported from tropical forests in the last 30+ years. We used unique long‐term records of annually measured stands (eighteen 0.5 ha plots, 10 years) and focal tree species (six species, 24 years) to assess the effects of rainfall, temperature, and atmospheric [CO2] on annual wood production in a neotropical rain forest. Our study area was a meso‐scale section (600 ha) of old‐growth Tropical Wet Forest in NE Costa Rica. Using the repeated remeasurements we directly assessed the relative effects of interannual climatic variation and increasing atmospheric [CO2] on wood production. A remarkably simple two‐factor model explained 91% of the interannual variance in stand‐level tree growth; the statistically independent factors were total dry season rainfall (positive effect, r2=0.85) and night‐time temperature (negative effect, r2=0.42). Stand‐level tree mortality increased significantly with night‐time temperature. After accounting for dry season rainfall and night‐time temperature, there was no effect of annual [CO2] on tree growth in either the stand or focal species data. Tree growth in this Tropical Wet Forest was surprisingly sensitive to the current range of dry season conditions and to variations in mean annual night‐time temperature of 1–2°. Our results suggest that wood production in the lowland rainforests of NE Costa Rica (and by extension in other tropical regions) may be severely reduced in future climates that are only slightly drier and/or warmer.
Oligotrophication outweighs effects of global warming in a large, deep, stratified lake ecosystem
Authors: STICH H. B. , BRINKER ALEXANDER 
Published: June 2009

AbstractBetween 1951 and 1979, total phosphorous concentrations in Lake Constance increased from 7 to 87 μg L−1. Following wastewater treatment, phosphorus levels were brought under control, returning to 7.6 μg L−1 by spring 2007. The biological and chemical data from 1980 to 2004 were first modelled by seasonal time series analyses and then used to create a general model. Excluding collinear variables allowed the data set to be condensed to six variables that could be fitted into a general linear model that explained ∼75% of the observed annual variation in chlorophyll a. A clear seasonal influence was apparent, with chlorophyll a tracking trends in temperature and the progress of spring. A nonseasonal influence was also observed in the interaction of two biological components, the proportion of phytoplankton biomass available to Daphnia (i.e. the percentage of ingestible size <30 μm) and the grazing intensity. In combination, these biotic variables had a negative impact on chlorophyll a levels. In contrast, the concentration of soluble reactive phosphorus (SRP) correlated positively with chlorophyll a. The effect of SRP showed a significant seasonal component, as it was more abundant in spring than at other times of year. In general, the model predicts a negative exponential response of chlorophyll a to further depletion of SRP in Lake Constance, while the temperature trends predicted by current global warming scenarios will result in a moderate increase in productivity. Data from 2005 to 2007 were used to verify the model. The modelled chlorophyll a values were nonbiased and showed a close match to the measured values (r2: 75%). Thus the applicability, reliability, and informative value of the model for pelagic Lake Constance was confirmed. The approach might easily be applied to other waters.
Elevated atmospheric CO2 increases microbial growth rates in soil: results of three CO2 enrichment experiments
Authors: BLAGODATSKAYA EVGENIA , BLAGODATSKY SERGEY , DORODNIKOV MAXIM , KUZYAKOV YAKOV 
Published: June 2009

AbstractIncreasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long‐term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root‐free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate‐induced respiration response after glucose and/or yeast extract addition to the soil. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ‐values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivum<Beta vulgaris<Populus deltoides. N deficiency affected microbial growth rates directly (N limitation) and indirectly (changing the quantity of fine roots). So, 50% decrease in N fertilization caused the overall increase or decrease of microbial growth rates depending on plant species. The μ‐value increase was lower for microorganisms growing on yeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). Our results clearly showed that the functional characteristics of the soil microbial community (i.e. specific growth rates) rather than total microbial biomass amount are sensitive to increased atmospheric CO2. We conclude that the more abundant available organics released by roots at elevated CO2 altered the ecological strategy of the soil microbial community specifically a shift to a higher contribution of fast‐growing r‐selected species was observed. These changes in functional structure of the soil microbial community may counterbalance higher C input into the soil under elevated atmospheric CO2 concentration.
Biotic interactions may overrule direct climate effects on spring phytoplankton dynamics
Authors: GAEDKE URSULA , RUHENSTROTH‐BAUER MIRIAM , WIEGAND INA , TIROK KATRIN , ABERLE NICOLE , BREITHAUPT PETRA , LENGFELLNER KATHRIN , WOHLERS JULIA , SOMMER ULRICH 
Published: June 2009

AbstractTo improve our mechanistic understanding and predictive capacities with respect to climate change effects on the spring phytoplankton bloom in temperate marine systems, we used a process‐driven dynamical model to disentangle the impact of potentially relevant factors which are often correlated in the field. The model was based on comprehensive indoor mesocosm experiments run at four temperature and three light regimes. It was driven by time‐series of water temperature and irradiance, considered edible and less edible phytoplankton separately, and accounted for density‐dependent grazing losses. It successfully reproduced the observed dynamics of well edible phytoplankton in the different temperature and light treatments. Four major factors influenced spring phytoplankton dynamics: temperature, light (cloudiness), grazing, and the success of overwintering phyto‐ and zooplankton providing the starting biomasses for spring growth. Our study predicts that increasing cloudiness as anticipated for warmer winters for the Baltic Sea region will retard phytoplankton net growth and reduce peak heights. Light had a strong direct effect in contrast to temperature. However, edible phytoplankton was indirectly strongly temperature‐sensitive via grazing which was already important in early spring at moderately high algal biomasses and counter‐intuitively provoked lower and later algal peaks at higher temperatures. Initial phyto‐ and zooplankton composition and biomass also had a strong effect on spring algal dynamics indicating a memory effect via the broadly under‐sampled overwintering plankton community. Unexpectedly, increased initial phytoplankton biomass did not necessarily lead to earlier or higher spring blooms since the effect was counteracted by subsequently enhanced grazing. Increasing temperature will likely exhibit complex indirect effects via changes in overwintering phytoplankton and grazer biomasses and current grazing pressure. Additionally, effects on the phytoplankton composition due to the species‐specific susceptibility to grazing are expected. Hence, we need to consider not only direct but also indirect effects, e.g. biotic interactions, when addressing climate change impacts.
Protease‐activated receptor 2 signalling promotes dendritic cell antigen transport and T‐cell activationin vivo
Authors: Ramelli Giancarlo , Fuertes Silvia , Narayan Sharmal , Busso Nathalie , Acha‐Orbea Hans , So Alexander 
Published: June 2009

SummaryDeficiency of protease‐activated receptor‐2 (PAR2) modulates inflammation in several models of inflammatory and autoimmune disease, although the underlying mechanism(s) are not understood. PAR2 is expressed on endothelial and immune cells, and is implicated in dendritic cell (DC) differentiation. We investigatedin vivothe impact of PAR2 activation on DCs and T cells in PAR2 wild‐type (WT) and knockout (KO) mice using a specific PAR2 agonist peptide (AP2). PAR2 activation significantly increased the frequency of mature CD11chighDCs in draining lymph nodes 24 hr after AP2 administration. Furthermore, these DCs exhibited increased expression of major histocompatibility complex (MHC) class II and CD86. A significant increase in activated (CD44+ CD62−) CD4+and CD8+T‐cell frequencies was also observed in draining lymph nodes 48 hr after AP2 injection. No detectable change in DC or T‐cell activation profiles was observed in the spleen. The influence of PAR2 signalling on antigen transport to draining lymph nodes was assessed in the context of delayed‐type hypersensitivity. PAR2 WT mice that were sensitized by skin‐painting with fluorescein isothiocyanate (FITC) to induce delayed‐type hypersensitivity possessed elevated proportion of FITC+DCs in draining lymph nodes 24 hr after FITC painting when compared with PAR2 KO mice (0·95% versus 0·47% of total lymph node cells). Collectively, these results demonstrate that PAR2 signalling promotes DC trafficking to the lymph nodes and subsequent T‐cell activation, and thus provides an explanation for the pro‐inflammatory effect of PAR2 in animal models of inflammation.
Natural lysophospholipids reduce Mycobacterium tuberculosis‐induced cytotoxicity and induce anti‐mycobacterial activity by a phagolysosome maturation‐dependent mechanism in A549 type II alveolar epithelial cells
Authors: Greco Emanuela , Santucci Marilina B. , Sali Michela , De Angelis Francesca R. , Papi Massimiliano , De Spirito Marco , Delogu Giovanni , Colizzi Vittorio , Fraziano Maurizio 
Published: June 2009

SummaryHuman alveolar epithelial cells actively contribute to the innate immune response in the lung and play an important role in mycobacterial dissemination during primary infection, by undergoing cell death and by releasing mycobacteria. In the present study, we report that natural lysophospholipids, such as lysophosphatidic acid or sphingosine 1‐phosphate, reduce Mycobacterium tuberculosis‐induced cytotoxicity and enhance anti‐mycobacterial activity in the A549 cell line, used as a model of type II alveolar epithelial cells. Intracellular mycobacterial killing was strictly dependent on phagolysosome maturation, which in turn was promoted by the activation of a Ca2+dependent phospholipase D. Finally, the restriction of mycobacteria in highly microbiocidal compartments was associated, in vitro, with a significant decrease in mycobacterial dissemination to macrophages. Taken as whole, these results suggest that the pulmonary lysophospholipid microenvironment may play a protective role during the early phases of host–pathogen interaction by enhancing anti‐mycobacterial activity in type II alveolar epithelial cells.
An integrated view of the regulation of NKG2D ligands
Authors: Stern‐Ginossar Noam , Mandelboim Ofer 
Published: June 2009

SummaryNKG2D is one of the best characterized activating receptors and is expressed on natural killer cells and on various T‐cell subsets. This receptor recognizes several different ligands that are induced by cellular stresses. In this review, we described the mechanisms controlling the expression of NKG2D ligands, with the emphasis on post‐transcriptional and post‐translational regulation.
Endodontics or implants? A review of decisive criteria and guidelines for single tooth restorations and full arch reconstructions
Authors: Zitzmann N. U. , Krastl G. , Hecker H. , Walter C. , Weiger R. 
Published: June 2009

AbstractThis review describes practical criteria and a systematic process to aid the treatment planning decision of whether to preserve teeth by root canal treatment (RCT) or extract and provide an implant. Recommendations presented are based on best available evidence from the literature and the expert views of specialists in endodontics and restorative dentistry, including dental implantology. A MEDLINE search was conducted using the terms ‘root canal therapy’, ‘dental implants’, ‘decision making’, ‘treatment planning’, ‘outcome’ and ‘human’, and supplemented by hand‐searching. When evaluating the outcome of root canal treatment, an observation period of 4–5 years is required for complete healing of periapical lesions. Dental implants, however, present a de novo situation and a functional period of at least 5 years is often required before peri‐implant diseases are established and detected. Good long‐term success rates and greater flexibility in clinical management indicate that RCT or retreatment should be performed first in most instances unless the tooth is judged to be unrestorable. When deciding if a compromised tooth of questionable prognosis should be maintained or replaced by an implant, both local, site‐specific and more general patient‐related factors should be considered. Following systematic evaluation and consideration of the best treatment option in a particular case, a treatment recommendation may then be given in favour or against tooth retention. Whilst single risks are possibly accepted for single tooth restorations, teeth with questionable prognosis and multiple pre‐treatment requirements are better not included as abutments in fixed dental prostheses to reduce the risk to survival of the entire restoration.