bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional traits as predictors of vital rates across the life cycle of tropical trees
Authors: Visser Marco D. , Bruijning Marjolein , Wright S. Joseph , Muller‐Landau Helene C. , Jongejans Eelke , Comita Liza S. , de Kroon Hans 
Published: February 2016

SummaryThe ‘functional traits’ of species have been heralded as promising predictors for species’ demographic rates and life history. Multiple studies have linked plant species’ demographic rates to commonly measured traits. However, predictive power is usually low – raising questions about the practical usefulness of traits – and analyses have been limited to size‐independent univariate approaches restricted to a particular life stage.Here we directly evaluated the predictive power of multiple traits simultaneously across the entire life cycle of 136 tropical tree species from centralPanama. Using a model‐averaging approach, we related wood density, seed mass, leaf mass per area and adult stature (maximum diameter) to onset of reproduction, seed production, seedling establishment, and growth and survival at seedling, sapling and adult stages.Three of the four traits analysed here (wood density, seed mass and adult stature) typically explained 20–60% of interspecific variation at a given vital rate and life stage. There were strong shifts in the importance of different traits throughout the life cycle of trees, with seed mass and adult stature being most important early in life, and wood density becoming most important after establishment. Every trait had opposing effects on different vital rates or at different life stages; for example, seed mass was associated with higher seedling establishment and lower initial survival, wood density with higher survival and lower growth, and adult stature with decreased juvenile but increased adult growth and survival.Forest dynamics are driven by the combined effects of all demographic processes across the full life cycle. Application of a multitrait and full‐life cycle approach revealed the full role of key traits, and illuminated how trait effects on demography change through the life cycle. The effects of traits on one life stage or vital rate were sometimes offset by opposing effects at another stage, revealing the danger of drawing broad conclusions about functional trait–demography relationships from analysis of a single life stage or vital rate. Robust ecological and evolutionary conclusions about the roles of functional traits rely on an understanding of the relationships of traits to vital rates across all life stages.
Getting the smell of it – odour cues structure pollinator networks
Authors: Hambäck Peter A. 
Published: February 2016

Floral visitors vary greatly among plant species and depend on the volatiles emitted by the flowers. Creeping thistle is normally visited by bees and bumblebees while common yarrow is rather visited by flies. Manipulating the flower volatiles caused pollinator communities to become more similar among the two plant species. Image credit: Robert Junker and Anna‐Amelie Larue.In Focus: Larue, A.‐A.C., Raguso, R.A. & Junker, R.R. (2015) Experimental manipulation of floral scent bouquets restructures flower–visitor interactions in the field. Journal of Animal Ecology, 85, 396–408.Pollinators use multiple cues to locate suitable flowers, and recent studies argue that flower volatiles are more important than previously believed. However, the role of volatiles is seldom separated from other cues. Larue, Raguso & Junker (2015) manipulated the volatile profile of two plants that are normally visited by different pollinators. Achillea millefolium is normally not visited by honeybees and bumblebees, but these pollinator groups did visit plants that were sprayed with volatiles from Cirsium arvense. Cirsium arvense, on the other hand, was less visited by honeybees and bumblebees when sprayed with volatiles from A. millefolium. These findings highlight the potential role of volatiles in structuring pollinator communities on plants.
Thresholds and gradients in a semi‐arid grassland: long‐term grazing treatments induce slow, continuous and reversible vegetation change
Authors: Porensky Lauren M. , Mueller Kevin E. , Augustine David J. , Derner Justin D. 
Published: February 2016

Summary

Temporal changes in semi‐arid ecosystems can include transitions between alternative stable states, involving thresholds and multiple domains of attraction, but can also include relatively continuous, symmetric and reversible shifts within a single stable state. Conceptual state‐and‐transition models (STMs) describe both types of ecosystem dynamics by including state transitions (plant community changes difficult‐to‐reverse without substantial input or effort) and phase shifts (easily reversible community changes) as consequences of management practices and environmental variability. Grazing management is purported to be the primary driver of state transitions in current STMs for North American grasslands, but there is limited empirical evidence from these grasslands showing that grazing can cause difficult‐to‐reverse transitions between alternate stable states.

In a northern mixed‐grass prairie in Wyoming, USA, we examined plant community responses to (i) long‐term (33‐year) grazing intensity treatments (none, light, moderate and heavy stocking rates) and (ii) 8 years of light or no grazing in pastures that were grazed heavily for the previous 25 years.

Long‐term grazing treatments were associated with distinct, but not stable, plant communities. From year 22 to 33, heavier stocking rates decreased cover of dominant C3 grasses and increased cover of the dominant C4 grass Bouteloua gracilis.

Reversing stocking rates from heavy to light or no grazing resulted in reversal of changes induced by prior heavy stocking for dominant C3 grasses, but not for B. gracilis. For both groups, rates of change following grazing treatment reversals were consistent with rates of change during the initial years of the experiment (1982–1990).

Synthesis and applications. In a semi‐arid rangeland with a long evolutionary history of grazing, different long‐term grazing intensity treatments caused slow, continuous and directional changes with important management implications, but did not appear to induce alternative stable states. For this and similar ecosystems, quantifying the time‐scales and compositional gradients associated with key phase shifts may be more important than identifying thresholds between alternative stable states.
Contrasting effects of spatial heterogeneity and environmental stochasticity on population dynamics of a perennial wildflower
Authors: Crone Elizabeth E. 
Published: February 2016

Summary

Understanding how variation in growth, survival and reproduction affect population dynamics is a fundamental question in ecology. Although the effects of among‐year variation (environmental stochasticity) are well understood, the effects of among‐site variation (spatial heterogeneity) are less clearly defined.

I evaluated the effects of spatial and temporal variation on the population dynamics of Pulsatilla patens, pasqueflower, a perennial prairie forb. I conducted a 10‐year demographic monitoring study, and quantified vital rate variation among sites and years using generalized linear models. I incorporated vital rate functions using this variation into integral projection models for stochastic and spatially heterogeneous environments.

I also explored the effects of temporal and spatial autocorrelation, by exploring model predictions over the range of possible values for temporal autocorrelation and local seed dispersal.

Vital rates varied more among years than among sites. However, environmental stochasticity and spatial heterogeneity had similar magnitude effects on population dynamics. These effects were also qualitatively different: environmental stochasticity reduced population growth rates relative to the average, whereas spatial heterogeneity increased population growth rates.

Spatial autocorrelation and negative temporal autocorrelation led to higher population growth rates, although environmental stochasticity still reduced growth rates for all autocorrelation values, and spatial heterogeneity increased growth rates for all autocorrelation values. Some form of autocorrelation would be necessary for model projections to match observed population trends.

Synthesis. Spatial heterogeneity is as important as environmental stochasticity for population dynamics, but it is much less often incorporated into population projection models. This study points to a number of interesting avenues for future research into the roles of spatial heterogeneity and spatiotemporal variation for long‐term population dynamics.
Environmental drivers of demographic variation across the global geographical range of 26 plant species
Authors: Treurnicht Martina , Pagel Jörn , Esler Karen J. , Schutte‐Vlok AnneLise , Nottebrock Henning , Kraaij Tineke , Rebelo Anthony G. , Schurr Frank M. 
Published: February 2016

Summary

Understanding how rates of reproduction and survival respond to environmental variation across species’ geographical ranges is a key task for both basic and applied ecology. So far, however, environmental drivers of range‐wide demographic variation have only been studied in a few plant species without considering the potentially confounding effects of population density on demographic rates.

We present a large‐scale demographic study of 26 shrub species (Proteaceae) from the Cape Floristic Region. All study species have a fire‐dependent life cycle and are serotinous: they exclusively form a canopy seed bank which contains the seeds produced since the last fire. Fire triggers seed release from the canopy so that recruitment is largely limited to a short period after fire.

Across the global geographical ranges of the study species, we collected 3454 population‐level records of total fecundity since the last fire (size of individual canopy seed banks), per‐capita recruitment (ratio between post‐fire recruits and pre‐fire adults) and adult fire survival. We used linear regressions to quantify how climate, population density, fire interval and soil nutrients affect demographic variation.

A trade‐off between survival and reproduction is evident throughout the geographical ranges of our study species: resprouting species with fire‐protected buds had much higher fire survival than nonsprouters without fire‐protected buds (97% vs. 2%) but they also had substantially lower fecundity and recruitment rates. We found little intraspecific variation in fire survival rates but considerable intraspecific variation in fecundity and recruitment.

Range‐wide variation in fecundity was dominated by fire interval whereas recruitment was mostly climate‐driven. Population density and soil nutrients generally had smaller effects but were important for the fecundity and recruitment of several species. Effects of fire interval on fecundity were consistent across species, but other demography–environment relationships showed substantial interspecific differentiation.

Synthesis. This study extends demographic research beyond the population to cover the geographical ranges of multiple species. Such large‐scale studies are a necessary first step of a research agenda that aims to understand how range dynamics emerge from first principles of demography, how they are shaped by functional traits and macroevolution and how they will be impacted by global change.
Forest community response to invasive pathogens: the case of ash dieback in a British woodland
Authors: Needham Jessica , Merow Cory , Butt Nathalie , Malhi Yadvinder , Marthews Toby R. , Morecroft Michael , McMahon Sean M. 
Published: February 2016

SummaryLarge‐scale mortality events in forests are increasing in frequency and intensity and can lead to both intermediate‐ and long‐term changes in these systems. Specialist pests and pathogens are unique disturbances, as they commonly target individual species that are relatively prevalent in the community.Understanding the consequences of pathogen‐caused mortality requires using sometimes limited available data to create statistical models that can forecast future community states.In the last two decades, ash dieback disease has swept through Europe causing widespread mortality ofFraxinus excelsiorL. (European ash) across much of its distribution. In theUK,F. excelsioris an abundant and ecologically important species.Using demographic data from an 18 ha plot in Wytham Woods, Oxfordshire, we built models that forecast the response of this forest plot to the loss ofF. excelsior. We combine integral projection models and individual‐based models to link models of growth, survival and fecundity to population dynamics. We demonstrate likely responses in Wytham by comparing projections under different levels ofF. excelsiormortality. To extrapolate results to other systems, we test hypotheses regarding the role of abundance, spatial structure and demographic differences between species in determining community response to disease disturbance.We show that the outcome of succession is determined largely by the differing demographic strategies and starting abundances of competing species. Spatial associations between species were shown to have little effect on community dynamics at the spatial scale of this plot.Synthesis. Host‐specific pests and pathogens are an increasingly important type of disturbance. We have developed a framework that makes use of forest inventory data to forecast changes in the population dynamics of remaining species and the consequences for community structure. We use our framework to predict how a typical British woodland will respond to ash dieback disease and show how vital rates, spatial structure and abundance impact the community response to the loss of a key species.
Global coherence during discourse production in adults: a review of the literature
Authors: Ellis Charles , Henderson Amy , Wright Heather Harris , Rogalski Yvonne 
Published: February 2016

AbstractBackgroundGlobal coherence is a metric of expressive language performance that represents the speaker's ability to initiate, plan and maintain a topic of discussion. Studies indicate that disruptions of global coherence can occur during the ageing process and following neurological disease or injury. However, little is known about the specific impact that the ageing process, disease or injury has on global coherence during discourse production.AimsTo review the literature on global coherence in adult populations and assess the impact that age, disease or injury has on global coherence during expressive language tasks.Methods & ProceduresWe completed an in‐depth search of Medline and PyschInfo (1990–2014) to identify studies of global coherence in adult populations. We identified studies that included a comparison group and utilized a measure of global coherence during expressive language production among adults.Outcomes & ResultsTwenty studies comprised of 692 study participants who met inclusion criteria were identified for the review of the literature. Studies included participants without neurological impairments and individuals with aphasia, traumatic brain injury, dementia, generalized memory impairment and other neurological conditions. Study results indicated global coherence is an expressive language skill that is influenced by the ageing process and neurological disease or injury.Conclusions & ImplicationsAlthough evidence indicated that global coherence is negatively influenced by ageing and neurological disease/injury, the heterogeneity of study populations, measurement tools and study designs were limiting factors in determining the exact nature by which these factors impact the skill of global coherence.
Linking demography with drivers: climate and competition
Authors: Teller Brittany J. , Adler Peter B. , Edwards Collin B. , Hooker Giles , Ellner Stephen P. 
Published: February 2016

SummaryIn observational demographic data, the number of measured factors that could potentially drive demography (such as daily weather records between two censuses) can easily exceed the number of independent observations. Thus, identifying the important drivers requires alternatives to standard model selection and variable selection methods.Spline methods that estimate smooth functions over continuous domains (such as space or time) have the potential to resolve high‐dimensional problems in ecological systems. We consider two examples that are important for many plant populations: competition with neighbours that vary in size and distance from the focal individual and climate variables during a window of time before a response (growth, survival, etc.) is measured.For competition covariates, we use a simulation study based on empirical data to show that a monotone spline estimate of competition kernels via approximate AIC returns very accurate estimates. We then apply the method to long‐term, mapped quadrat data on the four dominant species in an Idaho (US) sagebrush steppe community.For climate predictors and their temporal lags, we use simulated data sets to compare functional smoothing methods with competing linear (LASSO) or machine learning (random forests) methods. Given sufficient data, functional smoothing methods outperformed the other two methods.Functional smoothing methods can advance data‐driven population modelling by providing alternatives to specifying competition kernelsa prioriand to arbitrarily aggregating continuous environmental covariates. However, there are important open questions related to modelling of nonlinear climate responses and size × climate interactions.
plant: A package for modelling forest trait ecology and evolution
Authors: Falster Daniel S. , FitzJohn Richard G. , Brännström Åke , Dieckmann Ulf , Westoby Mark 
Published: February 2016

Summary

Population dynamics in forests are strongly size‐structured: larger plants shade smaller plants while also expending proportionately more energy on building and maintaining woody stems. Although the importance of size structure for demography is widely recognized, many models either omit it entirely or include only coarse approximations.

Here, we introduce the plant package, an extensible framework for modelling size‐ and trait‐structured demography, ecology and evolution in simulated forests. At its core, plant is an individual‐based model where plant physiology and demography are mediated by traits. Individual plants from multiple species can be grown in isolation, in patches of competing plants or in metapopulations under a disturbance regime. These dynamics can be integrated into metapopulation‐level estimates of invasion fitness and vegetation structure. Because fitness emerges as a function of traits, plant provides a novel arena for exploring eco‐evolutionary dynamics.

plant is an open source R package and is available at github.com/traitecoevo/plant. Accessed from R, the core routines in plant are written in C++. The package provides for alternative physiologies and for capturing trade‐offs among parameters. A detailed test suite is provided to ensure correct behaviour of the code.

plant provides a transparent platform for investigating how physiological rules and functional trade‐offs interact with competition and disturbance regimes to influence vegetation demography, structure and diversity.
Estimating demand for primary care‐based treatment for substance and alcohol use disorders
Authors: Barry Colleen L. , Epstein Andrew J. , Fiellin David A. , Fraenkel Liana , Busch Susan H. 
Published: February 2016

AbstractBackground and AimsWhile there is broad recognition of the high societal costs of substance use disorders (SUD), treatment rates are low. We examined whether, in the United States, participants with substance or alcohol use disorder would report a greater willingness to enter SUD treatment located in a primary care setting (primary care) or more commonly found specialty care setting in the United States (usual care).DesignRandomized survey‐embedded experiment.SettingUS web‐based research panel in which participants were randomized to read one‐paragraph vignettes describing treatment in usual care (specialty drug or alcohol treatment center), primary care or collaborative care within a primary care setting.ParticipantsA total of 42 451 panelists aged 18+ were screened for substance or alcohol use disorder using validated diagnostic criteria. Participants included 344 with a substance use disorder and 634 with an alcohol use disorder not in treatment with no prior treatment history.MeasuresWillingness to enter treatment across vignettes by condition.FindingsAmong participants with a substance use disorder, 24.6% of those randomized to usual care reported being willing to enter drug treatment compared with 37.2% for primary care [12.6 percentage point difference; 95% confidence interval (CI) = 0.8, 24.4) and 34.0% for collaborative care (9.4 percentage point difference; 95% CI = –2.0, 20.8). Among participants with an alcohol use disorder, 17.6% of those randomized to usual care reported being willing to enter alcohol treatment compared with 20.3% for primary care (2.6 percentage point difference; 95% CI = –4.9, 10.1) and 20.8% for collaborative care (3.1 percentage point difference; 95% CI = –4.3, 10.6). The most common reason for not being willing to enter drug (63%) and alcohol (78%) treatment was the belief that treatment was not needed.ConclusionsIn the United States, people diagnosed with substance or alcohol use disorders appear to be more willing to enter treatment in a primary care setting than in a specialty drug treatment center. Expanding availability of primary care‐based substance use disorder treatment could increase treatment rates in the United States.
Perineural versus intravenous dexamethasone as adjuncts to local anaesthetic brachial plexus block for shoulder surgery
Authors: Rosenfeld D. M. , Ivancic M. G. , Hattrup S. J. , Renfree K. J. , Watkins A. R. , Hentz J. G. , Gorlin A. W. , Spiro J. A. , Trentman T. L. 
Published: February 2016

SummaryThis randomised, double‐blind, placebo‐controlled study compared the effect of perineural with intravenous dexamethasone, both administered concomitantly with interscalene brachial plexus block for shoulder surgery. Patients received 8 mg dexamethasone mixed with ropivacaine in the block injection (n = 42), 8 mg dexamethasone intravenously at the time of the block (n = 37), or intravenous saline (n = 41) at the time of the block. Perineural and intravenous dexamethasone resulted in prolonged mean (SD) duration of block to 16.9 (5.2) h and 18.2 (6.4) h, respectively, compared with 13.8 (3.8) h for saline (p = 0.001). Mean (SD) opioid consumption (morphine equivalents) during the first 24 h after postanaesthesia recovery arrival was 12.2 (9.3) mg in the perineural dexamethasone, 17.1 (15.9) mg in the intravenous dexamethasone and 24.1 (14.3) mg in the saline groups (p = 0.001). Dexamethasone via either route reduced anti‐emetic use (p = 0.046). There was no effect on patient satisfaction. These results suggest that both perineural and intravenous dexamethasone are useful adjuncts to ropivacaine interscalene block, with the intravenous route preferred as this avoids the possibility of neural toxicity of dexamethasone.