Aim
Climate variability threatens to destabilize production in many ecosystems. Asynchronous species dynamics may buffer against such variability when a decrease in performance by some species is ...offset by an increase in performance of others. However, high climatic variability can eliminate species through stochastic extinctions or cause similar stress responses among species that reduce buffering. Local conditions, such as soil nutrients, can also alter production stability directly or by influencing asynchrony. We test these hypotheses using a globally distributed sampling experiment.
Location
Grasslands in North America, Europe and Australia.
Time period
Annual surveys over 5 year intervals occurring between 2007 and 2014.
Major taxa studied
Herbaceous plants.
Methods
We sampled annually the per species cover and aboveground community biomass net primary productivity (NPP), plus soil chemical properties, in 29 grasslands. We tested how soil conditions, combined with variability in precipitation and temperature, affect species richness, asynchrony and temporal stability of primary productivity. We used bivariate relationships and structural equation modelling to examine proximate and ultimate relationships.
Results
Climate variability strongly predicted asynchrony, whereas NPP stability was more related to soil conditions. Species richness was structured by both climate variability and soils and, in turn, increased asynchrony. Variability in temperature and precipitation caused a unimodal asynchrony response, with asynchrony being lowest at low and high climate variability. Climate impacted stability indirectly, through its effect on asynchrony, with stability increasing at higher asynchrony owing to lower inter‐annual variability in NPP. Soil conditions had no detectable effect on asynchrony but increased stability by increasing the mean NPP, especially when soil organic matter was high.
Main conclusions
We found globally consistent evidence that climate modulates species asynchrony but that the direct effect on stability is low relative to local soil conditions. Nonetheless, our observed unimodal responses to variability in temperature and precipitation suggest asynchrony thresholds, beyond which there are detectable destabilizing impacts of climate on primary productivity.
An efficient synthesis of LY2886721 (1) in five steps and 46% overall yield from the chiral nitrone cycloadduct 2 is presented. Minimizing formation of a des-fluoro impurity during hydrogenolysis to ...cleave the isoxazolidine ring and remove the benzyl chiral auxiliary was a key challenge. Installation of the aminothiazine moiety required careful stoichiometry control of the reagents BzNCS and CDI, including in situ conversion monitoring, to minimize byproduct formation. A remarkably regioselective peptide coupling afforded 1 without competing acylation at the aminothiazine nitrogen or bis-acylation. Consideration of the combined chemistry and crystallization process identified an optimal solvent system for the peptide coupling and a reactive crystallization that afforded 1 in high purity and with physical property control. A slurry milling operation near the end of the crystallization, followed by “pH cycles” to digest fines formed during milling, significantly reduced the crystal aspect ratio and provided desirable API bulk density and powder flow properties.
: Currently there is no clinical evidence of oncological risk associated with fat grafting (FG) although its safety has been questioned based on in vitro and in vivo research. This case-controlled ...study was designed to investigate the risk of relapse associated with fat grafting in women with a breast cancer history.
Of 328 women with previously treated malignant breast disease who underwent fat grafting at the Nottingham Breast Institute, complete data was available for 211 (Invasive carcinoma = 184, DCIS = 27). Mean follow-up was 88 months from primary cancer surgery and 32 months following FG. Control subjects were matched 2:1 for; date of primary cancer operation (within 2 years), age (within 5 years), type of surgery, tumour histology, ER status and disease free status by time equivalent to that of fat grafting. Final endpoints were tumour recurrence and death. Outcome results were compared with a systematic review of all patients undergoing fat grafting with adequate follow-up reported in the literature.
No significant excess oncological events were observed in patients who had FG compared to controls with regards to local (0.95% v 1.90%, p=0.33), regional (0.95% v 0%, p=0.16) and distant recurrences (3.32% v 2.61%, p=0.65). A systematic review identified case series with a total of 1573 women who had fat grafting after primary oncological breast surgery. The locoregional relapse rate for these patients was 2.92% (0.95%/year).
This study has found no evidence of increased oncological risk associated with fat grafting in women previously treated for breast cancer.
The developmental outcome of 33 newborn infants with clinical intrauterine malnutrition at birth and 13 clinically well nourished infants from a middle to high socio-economic population have been ...followed from birth to 12-14 years of age. Psychometric studies revealed a lowering of the IQ score in malnourished infants compared to well nourished infants (104 +/- 15 compared to 121 +/- 13, p less than 0.05) and a need for special education (p less than 0.03). Forty-five percent of the malnourished infants' birth weights were above the 10th percentile on the Colorado Intrauterine Growth Grid. The Full Scale IQ of malnourished infants with BW greater and less than 10th percentile on the Colorado Intrauterine Growth Grid were comparable. Malnourished infants with birth weights greater than 10th percentile had lower IQ scores than well nourished infants (101 +/- 13 compared to 121 +/- 13, p less than 0.006). Thirty-nine percent of the infants with handicaps would have been missed if only infants with birth weights less than 10th percentile were considered high risk.
Compositional variation in grassland plant communities Bakker, Jonathan D.; Price, Jodi N.; Henning, Jeremiah A. ...
Ecosphere (Washington, D.C),
June 2023, 2023-06-00, 20230601, 2023-06-01, Volume:
14, Issue:
6
Journal Article
Peer reviewed
Open access
Human activities are altering ecological communities around the globe. Understanding the implications of these changes requires that we consider the composition of those communities. However, ...composition can be summarized by many metrics which in turn are influenced by different ecological processes. For example, incidence‐based metrics strongly reflect species gains or losses, while abundance‐based metrics are minimally affected by changes in the abundance of small or uncommon species. Furthermore, metrics might be correlated with different predictors. We used a globally distributed experiment to examine variation in species composition within 60 grasslands on six continents. Each site had an identical experimental and sampling design: 24 plots × 4 years. We expressed compositional variation within each site—not across sites—using abundance‐ and incidence‐based metrics of the magnitude of dissimilarity (Bray–Curtis and Sorensen, respectively), abundance‐ and incidence‐based measures of the relative importance of replacement (balanced variation and species turnover, respectively), and species richness at two scales (per plot‐year alpha and per site gamma). Average compositional variation among all plot‐years at a site was high and similar to spatial variation among plots in the pretreatment year, but lower among years in untreated plots. For both types of metrics, most variation was due to replacement rather than nestedness. Differences among sites in overall within‐site compositional variation were related to several predictors. Environmental heterogeneity (expressed as the CV of total aboveground plant biomass in unfertilized plots of the site) was an important predictor for most metrics. Biomass production was a predictor of species turnover and of alpha diversity but not of other metrics. Continentality (measured as annual temperature range) was a strong predictor of Sorensen dissimilarity. Metrics of compositional variation are moderately correlated: knowing the magnitude of dissimilarity at a site provides little insight into whether the variation is driven by replacement processes. Overall, our understanding of compositional variation at a site is enhanced by considering multiple metrics simultaneously. Monitoring programs that explicitly incorporate these implications, both when designing sampling strategies and analyzing data, will have a stronger ability to understand the compositional variation of systems and to quantify the impacts of human activities.
Models in Ecosystem Science Canham, Charles D; Cole, Jonathan J; Lauenroth, William K
2021, 2021-04-13
eBook
Quantitative models are crucial to almost every area of ecosystem science. They provide a logical structure that guides and informs empirical observations of ecosystem processes. They play a ...particularly crucial role in synthesizing and integrating our understanding of the immense diversity of ecosystem structure and function. Increasingly, models are being called on to predict the effects of human actions on natural ecosystems. Despite the widespread use of models, there exists intense debate within the field over a wide range of practical and philosophical issues pertaining to quantitative modeling. This book--which grew out of a gathering of leading experts at the ninth Cary Conference--explores those issues. The book opens with an overview of the status and role of modeling in ecosystem science, including perspectives on the long-running debate over the appropriate level of complexity in models. This is followed by eight chapters that address the critical issue of evaluating ecosystem models, including methods of addressing uncertainty. Next come several case studies of the role of models in environmental policy and management. A section on the future of modeling in ecosystem science focuses on increasing the use of modeling in undergraduate education and the modeling skills of professionals within the field. The benefits and limitations of predictive (versus observational) models are also considered in detail. Written by stellar contributors, this book grants access to the state of the art and science of ecosystem modeling.
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