An alpine treeline in a carbon dioxide-rich world: synthesis of a nine-year free-air carbon dioxide enrichment study

We evaluated the impacts of elevated CO2 in a treeline ecosystem in the Swiss Alps in a 9-year free-air CO2 enrichment (FACE) study. We present new data and synthesize plant and soil results from the entire experimental period. Light-saturated photosynthesis (A max) of ca. 35-year-old Larix decidua and Pinus uncinata was stimulated by elevated CO2 throughout the experiment. Slight down-regulation of photosynthesis in Pinus was consistent with starch accumulation in needle tissue. Above-ground growth responses differed between tree species, with a 33% mean annual stimulation in Larix but no response in Pinus. Species-specific CO2 responses also occurred for abundant dwarf shrub species in the understorey, where Vaccinium myrtillus showed a sustained shoot growth enhancement (+11%) that was not apparent for Vaccinium gaultherioides or Empetrum hermaphroditum. Below ground, CO2 enrichment did not stimulate fine root or mycorrhizal mycelium growth, but increased CO2 effluxes from the soil (+24%) indicated that enhanced C assimilation was partially offset by greater respiratory losses. The dissolved organic C (DOC) concentration in soil solutions was consistently higher under elevated CO2 (+14%), suggesting accelerated soil organic matter turnover. CO2 enrichment hardly affected the C-N balance in plants and soil, with unaltered soil total or mineral N concentrations and little impact on plant leaf N concentration or the stable N isotope ratio. Sustained differences in plant species growth responses suggest future shifts in species composition with atmospheric change. Consistently increased C fixation, soil respiration and DOC production over 9years of CO2 enrichment provide clear evidence for accelerated C cycling with no apparent consequences on the N cycle in this treeline ecosyste

Differences in Stronger Versus Weaker Firefighters in Selected Measures of Power

International Journal of Exercise Science 15(4): 552-560, 2022. Firefighters are required to perform a wide array of physically demanding job tasks, such as forcible entry, charged hose advances and victim extractions. An adequate level of muscular strength and power are required to successfully perform these tasks. The purpose of this study is to investigate the differences in stronger and weaker firefighters in measures of power. Archived data for twenty-seven (age = 34.3 ± 7.9 yr, body height = 176.3 ± 7.2 cm, body mass = 89.4 ± 15.7 kg) full-time firefighters were analyzed. Participants were placed into one of two groups [i.e., stronger (HIGH) (n = 13) and weaker (LOW) (n = 14)], based on their relative isometric mid-thigh pull (IMTPr) performance. Power measures included counter-movement jump (CMJ) height, and peak anaerobic power in watts (PAPW). Significant mean score differences were not discovered between HIGH and LOW IMTPr groups on any measures of lower-body power. Moderate positive correlations were observed between IMTP and CMJ (r = .519; p = .01). This study identified significant differences in absolute and relative strength between firefighters who were able to lift at least 2.0x their bodyweight versus those who were not. Additionally, absolute strength (as assessed by the IMTP) was significantly and positively correlated to CMJ height when compared to their weaker counterparts. These findings may provide insight into approaches for improving occupational performance and durability through the physical development of firefighters via strength and conditioning programs which focus on developing absolute strength, relative strength, and power

Climate sensitivity of shrub growth across the tundra biome

The tundra biome is experiencing rapid temperature increases that have been linked to a shift in tundra vegetation composition towards greater shrub dominance. Shrub expansion can amplify warming by altering the surface albedo, energy and water balance, and permafrost temperatures. To account for these feedbacks, global climate models must include realistic projections of vegetation dynamics, and in particular tundra shrub expansion, yet the mechanisms driving shrub expansion remain poorly understood. Dendroecological data consisting of multi-decadal time series of annual growth of shrub species provide a previously untapped resource to explore climate-growth relationships across the tundra biome. We analysed a dataset of approximately 42,000 annual growth records from 1821 individuals, comprising 25 species from eight genera, from 37 arctic and alpine sites. Our analyses demonstrate that the sensitivity of shrub growth to climate was (1) heterogeneous across the tundra biome, (2) greater at sites with higher soil moisture and (3) strongest for taller shrub species growing at the northern or upper elevational edge of their range. Across latitudinal gradients in the Arctic, climate sensitivity of growth was greatest at the boundary between low- and high-arctic vegetation zones, where permafrost conditions are changing and the majority of the global permafrost soil carbon pool is stored. Thus, in order to more accurately estimate feedbacks among shrub change, albedo, permafrost thaw, carbon storage and climate, the observed variation in climate-growth relationships of shrub species across the tundra biome will need to be incorporated into earth system models.JRC.H.3-Forest Resources and Climat

Incorporating clinical guidelines through clinician decision-making

<p>Abstract</p> <p>Background</p> <p>It is generally acknowledged that a disparity between knowledge and its implementation is adversely affecting quality of care. An example commonly cited is the failure of clinicians to follow clinical guidelines. A guiding assumption of this view is that adherence should be gauged by a standard of conformance. At least some guideline developers dispute this assumption and claim that their efforts are intended to inform and assist clinical practice, not to function as standards of performance. However, their ability to assist and inform will remain limited until an alternative to the conformance criterion is proposed that gauges how evidence-based guidelines are incorporated into clinical decisions.</p> <p>Methods</p> <p>The proposed investigation has two specific aims to identify the processes that affect decisions about incorporating clinical guidelines, and then to develop ad test a strategy that promotes the utilization of evidence-based practices. This paper focuses on the first aim. It presents the rationale, introduces the clinical paradigm of treatment-resistant schizophrenia, and discusses an exemplar of clinician non-conformance to a clinical guideline. A modification of the original study is proposed that targets psychiatric trainees and draws on a cognitively rich theory of decision-making to formulate hypotheses about how the guideline is incorporated into treatment decisions. Twenty volunteer subjects recruited from an accredited psychiatry training program will respond to sixty-four vignettes that represent a fully crossed 2 × 2 × 2 × 4 within-subjects design. The variables consist of criteria contained in the clinical guideline and other relevant factors. Subjects will also respond to a subset of eight vignettes that assesses their overall impression of the guideline. Generalization estimating equation models will be used to test the study's principal hypothesis and perform secondary analyses.</p> <p>Implications</p> <p>The original design of phase two of the proposed investigation will be changed in recognition of newly published literature on the relative effectiveness of treatments for schizophrenia. It is suggested that this literature supports the notion that guidelines serve a valuable function as decision tools, and substantiates the importance of decision-making as the means by which general principles are incorporated into clinical practice.</p

Plant responses to long-term "in situ" CO₂ enrichment and soil warming at treeline in the Swiss Alps

In situ studies lasting several years are essential for predicting how plant growth and ecosystem function will change under rising levels of atmospheric CO₂ and the associated changes in climate. High-latitude and high-elevation ecosystems are predicted to be particularly sensitive to environmental change, but relatively few manipulation experiments have been conducted in these regions. This doctoral thesis describes responses of two co-occurring tree species, Larix decidua and Pinus uncinata, and understorey dwarf shrub heath vegetation to 9 years of CO₂ enrichment (+200 ppm; 2001-2009) and 3 years of soil warming (+4 K; 2007-ongoing) at treeline in the Swiss Alps (Stillberg, Davos). We tested if elevated CO₂ stimulates tree growth in an environment where there is strong evidence that low temperature limits growth despite an adequate carbon supply. For this investigation, we pooled across soil warming treatments in order to focus on long-term responses to elevated CO₂. Larix ring width was stimulated by CO₂ enrichment throughout the treatment period, with a significant stimulation in years 3-7, while Pinus ring width showed no CO₂ effect. After 9 years of treatment, leaf canopy cover, stem basal area, and total new shoot production were greater in Larix trees growing under elevated CO₂, whereas Pinus showed no cumulative growth response. Larix ring width was stimulated more by elevated CO₂ in years with relatively high spring temperatures and an early snowmelt date, suggesting that temperatures were less limiting in these years and greater benefit was gained from extra carbon assimilated under elevated CO₂. The CO₂ effect size was also larger after relatively high temperatures and high solar radiation in the preceding growing season, perhaps reflecting gains due to larger carbon reserves. Contrasting responsiveness of these two species suggests that under future CO₂ concentrations, especially in combination with warmer and sunnier conditions, Larix will have a competitive advantage over less responsive species such as Pinus. Dwarf shrubs are a major component of alpine plant communities, and changes in the growth, abundance and distribution of these species are likely to have important ecological consequences. We studied growth responses of three dominant dwarf shrub species, Vaccinium myrtillus, Vaccinium gaultherioides and Empetrum hermaphroditum, to CO₂ enrichment and soil warming and how the treatments influenced understorey community composition. V. myrtillus growth was stimulated by elevated CO₂, with no decline over time in the annual shoot growth response, and to an even greater extent by soil warming. V. gaultherioides growth showed a slight positive effect of elevated CO₂, though only in experimental plots with Pinus, and no response to warming. E. hermaphroditum growth was not influenced by either treatment. Vascular plant species richness decreased in elevated CO₂ plots with Larix but not with Pinus, while the number of moss and lichen species decreased under soil warming. Overall, species-specific dwarf shrub growth responses indicate potential shifts in plant community composition at the alpine treeline. The frequency of freezing events during the growing season and the vulnerability to freezing of plants in temperate high-elevation environments could increase in the future. We conducted an experimental freezing study to determine effects of CO₂ enrichment and soil warming on the early growing season freezing resistance of 10 plant species. Long-term exposure to elevated CO₂ led to reduced freezing resistance in 5 species but did not influence phenology, implying that physiological changes caused by CO₂ enrichment were responsible for the effect. Soil warming showed little to no influence on the freezing resistance or phenology of the sampled species. Our results suggest that leaf tissue damage caused by episodic early season freezing events will increase in frequency for some species in the coming decades. The resulting shifts in relative freezing resistance among co-occurring species could alter competitive interactions. In an investigation of how the first season of soil warming influenced soil processes and ecosystem carbon balance, we found that soil respiration rates increased immediately with increased temperature while DOC leaching showed a delayed and much smaller response. Tracing of 13C-depleted CO₂ added for 7 years showed that the accelerated CO₂ effluxes from warmed soils were not driven by increased mineralization of recent plant litter and root respiration but by mineralization from older soil organic matter. Soil carbon losses clearly exceeded the estimated carbon accumulation by plants, which showed little response to one growing season of soil warming. These findings suggest that soil warming, representative of warmer and drier years, can lead to short-term carbon losses from alpine treeline ecosystems

Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis.

BackgroundThe need to control for the potential influence of menstrual cycle phase on resting metabolism (RMR) places a burden on research participants who must self-report onset of menstruation and researchers who must schedule metabolic testing accordingly.PurposeTo systematically review and analyze existing research to determine the effect of menstrual cycle on RMR.MethodsWe searched PubMed, CINAHL, MEDLINE, SPORTDiscus, and Scopus databases using the search terms "menstrual cycle and metabolic rate" and "menstrual cycle and energy expenditure." Eligibility criteria were English language, single-group repeated measures design, and RMR as either a primary or secondary outcome. Risk of bias was assessed based on study sample, measurement, and control of confounders. Differences between the follicular and luteal phases of the menstrual cycle were analyzed using the standardized mean difference in effect size.ResultsThirty English-language studies published between 1930 and December 2019 were included in the systematic review, and 26 studies involving 318 women were included in the meta-analysis. Overall, there was a small but significant effect favoring increased RMR in the luteal phase (ES = 0.33; 95% CI = 0.17, 0.49, p DiscussionLimitations include risk of bias regarding measurement of both menstrual cycle and RMR. Sample sizes were small and studies did not report control of potential confounders. Sub-group analysis demonstrated that in more recent studies published since 2000, the effect of menstrual phase was reduced and not statistically significant (ES = 0.23; 95% CI = -0.00, 0.47; p = 0.055). Until larger and better designed studies are available, based on our current findings, researchers should be aware of the potential confounding influence of the menstrual cycle and control for it by testing consistently in one phase of the cycle when measuring RMR in pre-menopausal women