scholarly journals Global signal of top-down control of terrestrial plant communities by herbivores

2018 ◽  
Vol 115 (24) ◽  
pp. 6237-6242 ◽  
Author(s):  
Shihong Jia ◽  
Xugao Wang ◽  
Zuoqiang Yuan ◽  
Fei Lin ◽  
Ji Ye ◽  
...  
Keyword(s):  
Plant Communities ◽  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Basic Site ◽  
Plant Interactions ◽  
Top Down ◽  
Plant Abundance ◽  
Terrestrial Plant ◽  
Positive Effects

The theory of “top-down” ecological regulation predicts that herbivory suppresses plant abundance, biomass, and survival but increases diversity through the disproportionate consumption of dominant species, which inhibits competitive exclusion. To date, these outcomes have been clear in aquatic ecosystems but not on land. We explicate this discrepancy using a meta-analysis of experimental results from 123 native animal exclusions in natural terrestrial ecosystems (623 pairwise comparisons). Consistent with top-down predictions, we found that herbivores significantly reduced plant abundance, biomass, survival, and reproduction (allP< 0.01) and increased species evenness but not richness (P= 0.06 andP= 0.59, respectively). However, when examining patterns in the strength of top-down effects, with few exceptions, we were unable to detect significantly different effect sizes among biomes, based on local site characteristics (climate or productivity) or study characteristics (study duration or exclosure size). The positive effects on diversity were only significant in studies excluding large animals or located in temperate grasslands. The results demonstrate that top-down regulation by herbivores is a pervasive process shaping terrestrial plant communities at the global scale, but its strength is highly site specific and not predicted by basic site conditions. We suggest that including herbivore densities as a covariate in future exclosure studies will facilitate the discovery of unresolved macroecology trends in the strength of herbivore–plant interactions.

scholarly journals Mammalian herbivory exacerbates plant community responses to long-term increased soil nutrients in two Alaskan tundra plant communities

2018 ◽  
Vol 4 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Laura Gough ◽  
David R. Johnson
Keyword(s):  
Plant Communities ◽  
Field Experiments ◽  
Meta Analysis ◽  
Top Down ◽  
Betula Nana ◽  
Community Changes ◽  
The Difference ◽  
Meta Analyses ◽  
Alaskan Tundra

The interaction between bottom-up and top-down forces in regulating plant communities is a long-standing topic of interest in ecology. Factorial field experiments examining these factors have been relatively few, but recent meta-analyses provide predictions that can be tested in a range of ecosystems. We tested the prediction that added nutrients would reduce species richness and evenness, while herbivore activity would offset those changes in two tundra plant communities after 11 years. In moist acidic tundra (MAT), herbivores reduced richness more in fertilized plots when mammals were present compared with fertilized plots without herbivores. In dry heath (DH), evenness was significantly reduced in fertilized plots only when herbivores were present, also providing evidence that herbivores enhanced community changes caused by greater nutrient availability. The difference in response between MAT and the meta-analysis predictions appears to be driven by Betula nana, the species that dramatically increased with added nutrients in MAT. Unlike in similar studies and in DH, B. nana is not as palatable as most of the species in the community and is generally avoided by herbivores. These results highlight how the effects of herbivory and nutrients differ across communities and can be affected by the traits of the species present.

scholarly journals Frugivore gut passage increases seed germination: an updated meta-analysis

2021 ◽  
Author(s):  
Haldre S Rogers ◽  
Brittany R Cavazos ◽  
Ann Marie Gawel ◽  
Alex T Karnish ◽  
Courtenay A Ray ◽  
...  
Keyword(s):  
Seed Germination ◽  
Plant Communities ◽  
Meta Analysis ◽  
Ecological Impacts ◽  
Plant Performance ◽  
Positive Effects ◽  
Gut Passage ◽  
Multiple Predictor ◽  
Meta Analyses ◽  
Pulp Removal

Many plants rely on animal mutualists for reproduction. Quantifying how animal mutualists impact plant performance provides a foundation for modelling how change in animal communities affects the composition and functioning of plant communities. We performed a meta-analysis of 2539 experiments, 6 times more than the last comprehensive meta-analysis, examining how gut passage by frugivores influences seed germination. We simultaneously analyzed multiple predictor variables related to study methodology, location, and frugivore identity to disentangle methodological from ecological impacts on effect sizes. We found that gut passage by birds, fish, reptiles, bats, primates, and other mammals on average increased seed germination, but that the magnitude varied across vertebrate groups. The positive effects of gut passage were largely explained by the de-inhibitory effects of pulp removal rather than by the scarification of seed tissues. Some previous studies and meta-analyses that found no effect of gut passage only tested scarification or did not distinguish between these tests of scarification and pulp removal. We found that, for a typical fleshy-fruited plant species, the lack of gut passage reduces germination by 60%. From an evolutionary perspective, this indicates a large risk associated with reliance on animal mutualists that is balanced against the benefits of animal-mediated seed dispersal. From a conservation perspective, this highlights the potential for large demographic consequences of frugivore declines on plant populations. Our database and findings advance quantitative predictions for the role of fruit-frugivore interactions in shaping plant communities in the Anthropocene.

scholarly journals Responses of nitrogen concentrations and pools to multiple environmental change drivers: A meta‐analysis across terrestrial ecosystems

2019 ◽  
Vol 28 (5) ◽  
pp. 690-724 ◽  
Author(s):  
Kai Yue ◽  
Yan Peng ◽  
Dario A. Fornara ◽  
Koenraad Van Meerbeek ◽  
Lars Vesterdal ◽  
...  
Keyword(s):  
Environmental Change ◽  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
Nitrogen Concentrations

scholarly journals Is Brief Exposure to Green Space in School the Best Option to Improve Attention in Children?

2021 ◽  
Vol 18 (14) ◽  
pp. 7484
Author(s):  
Asier Anabitarte ◽  
Gonzalo García-Baquero ◽  
Ainara Andiarena ◽  
Nerea Lertxundi ◽  
Nerea Urbieta ◽  
...  
Keyword(s):  
Air Pollution ◽  
School Children ◽  
Green Space ◽  
Meta Analysis ◽  
Statistical Design ◽  
Green Spaces ◽  
Attention Network Test ◽  
Positive Effects ◽  
Gender Biases ◽  
Before And After

The positive effects of Green Spaces on health are thought to be achieved through the mechanisms of mitigation, instoration and restoration. One of the benefits of Green Spaces may be the restoration of attention and so the objective of this research is testing empirically whether exposure to a green environment improves attention in school children. For so doing, we first used a split-unit statistical design in each of four schools, then combined the primary results via meta-analysis. The Attention Network Test (ANT) was used to measure attention before and after exposure and a total of 167 seven-year-old students participated in the experiments. Overall, our experimental results do not support the hypothesis that students’ exposure to activities in green vs. grey spaces affected their performance in ANT. This was so despite the fact that neither age nor gender biases have been detected and despite that our experiments have been proved to be sufficiently statistically powerful. It would be advisable to consider air pollution and noise. We also recommend that participants attend the experiment with mental exhaustion to maximize the ability to detect significant changes.

scholarly journals The effects of clinical decision support system for prescribing medication on patient outcomes and physician practice performance: a systematic review and meta-analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sharare Taheri Moghadam ◽  
Farahnaz Sadoughi ◽  
Farnia Velayati ◽  
Seyed Jafar Ehsanzadeh ◽  
Shayan Poursharif
Keyword(s):  
Systematic Review ◽  
Decision Support ◽  
Patient Outcomes ◽  
Clinical Decision Support ◽  
Meta Analysis ◽  
Clinical Decision ◽  
Cochrane Library ◽  
Physician Practice ◽  
Positive Effects ◽  
Practice Performance

Abstract Background Clinical Decision Support Systems (CDSSs) for Prescribing are one of the innovations designed to improve physician practice performance and patient outcomes by reducing prescription errors. This study was therefore conducted to examine the effects of various CDSSs on physician practice performance and patient outcomes. Methods This systematic review was carried out by searching PubMed, Embase, Web of Science, Scopus, and Cochrane Library from 2005 to 2019. The studies were independently reviewed by two researchers. Any discrepancies in the eligibility of the studies between the two researchers were then resolved by consulting the third researcher. In the next step, we performed a meta-analysis based on medication subgroups, CDSS-type subgroups, and outcome categories. Also, we provided the narrative style of the findings. In the meantime, we used a random-effects model to estimate the effects of CDSS on patient outcomes and physician practice performance with a 95% confidence interval. Q statistics and I2 were then used to calculate heterogeneity. Results On the basis of the inclusion criteria, 45 studies were qualified for analysis in this study. CDSS for prescription drugs/COPE has been used for various diseases such as cardiovascular diseases, hypertension, diabetes, gastrointestinal and respiratory diseases, AIDS, appendicitis, kidney disease, malaria, high blood potassium, and mental diseases. In the meantime, other cases such as concurrent prescribing of multiple medications for patients and their effects on the above-mentioned results have been analyzed. The study shows that in some cases the use of CDSS has beneficial effects on patient outcomes and physician practice performance (std diff in means = 0.084, 95% CI 0.067 to 0.102). It was also statistically significant for outcome categories such as those demonstrating better results for physician practice performance and patient outcomes or both. However, there was no significant difference between some other cases and traditional approaches. We assume that this may be due to the disease type, the quantity, and the type of CDSS criteria that affected the comparison. Overall, the results of this study show positive effects on performance for all forms of CDSSs. Conclusions Our results indicate that the positive effects of the CDSS can be due to factors such as user-friendliness, compliance with clinical guidelines, patient and physician cooperation, integration of electronic health records, CDSS, and pharmaceutical systems, consideration of the views of physicians in assessing the importance of CDSS alerts, and the real-time alerts in the prescription.

scholarly journals Effective Components of School-Based Prevention Programs for Child Abuse: A Meta-Analytic Review

2021 ◽  
Author(s):  
Jeanne Gubbels ◽  
Claudia E. van der Put ◽  
Geert-Jan J. M. Stams ◽  
Mark Assink
Keyword(s):  
Child Abuse ◽  
Program Effectiveness ◽  
Meta Analysis ◽  
Prevention Programs ◽  
Effect Sizes ◽  
Positive Effects ◽  
School Based ◽  
Analytic Review ◽  
Program Components ◽  
Self Protection

AbstractSchool-based programs seem promising for child abuse prevention. However, research mainly focused on sexual child abuse and knowledge is lacking on how individual program components contribute to the effectiveness of school-based prevention programs for any form of child abuse. This study aimed to examine the overall effect of these school-based programs on (a) children’s child abuse-related knowledge and (b) self-protection skills by conducting two three-level meta-analyses. Furthermore, moderator analyses were performed to identify how program components and delivery techniques were associated with effectiveness. A literature search yielded 34 studies (158 effect sizes; N = 11,798) examining knowledge of child abuse and 22 studies (99 effect sizes; N = 7804) examining self-protection skills. A significant overall effect was found of school-based programs on both knowledge (d = 0.572, 95% CI [0.408, 0.737], p < 0.001) and self-protection skills (d = 0.528, 95% CI [0.262, 0.794], p < 0.001). The results of the first meta-analysis on children’s child abuse knowledge suggest that program effects were larger in programs addressing social–emotional skills of children (d = 0.909 for programs with this component versus d = 0.489 for programs without this component) and self-blame (d = 0.776 versus d = 0.412), and when puppets (d = 1.096 versus d = 0.500) and games or quizzes (d = 0.966 versus d = 0.494) were used. The second meta-analysis on children’s self-protections skills revealed that no individual components or techniques were associated with increased effectiveness. Several other study and program characteristics did moderate the overall effects and are discussed. In general, school-based prevention programs show positive effects on both knowledge and self-protection skills, and the results imply that program effectiveness can be improved by implementing specific components and techniques.

scholarly journals Competition-free gaps are essential for the germination and recruitment of alpine species along an elevation gradient in the European Alps

Alpine Botany ◽  
2021 ◽  
Author(s):  
Vera Margreiter ◽  
Janette Walde ◽  
Brigitta Erschbamer
Keyword(s):  
Vegetation Cover ◽  
Seedling Recruitment ◽  
Environmental Control ◽  
Elevation Gradient ◽  
European Alps ◽  
Plant Interactions ◽  
Experimental Conditions ◽  
Positive Effects ◽  
Seed Sowing ◽  
Plant Plant

AbstractSeed germination and seedling recruitment are key processes in the life cycle of plants. They enable populations to grow, migrate, or persist. Both processes are under environmental control and influenced by site conditions and plant–plant interactions. Here, we present the results of a seed-sowing experiment performed along an elevation gradient (2000–2900 m a.s.l.) in the European eastern Alps. We monitored the germination of seeds and seedling recruitment for 2 years. Three effects were investigated: effects of sites and home sites (seed origin), effects of gaps, and plant–plant interactions. Seeds of eight species originating from two home sites were transplanted to four sites (home site and ± in elevation). Seed sowing was performed in experimentally created gaps. These gap types (‘gap + roots’, ‘neighbor + roots’, and ‘no-comp’) provided different plant–plant interactions and competition intensities. We observed decreasing germination with increasing elevation, independent of the species home sites. Competition-released gaps favored recruitment, pointing out the important role of belowground competition and soil components in recruitment. In gaps with one neighboring species, neutral plant–plant interactions occurred (with one exception). However, considering the relative vegetation cover of each experimental site, high vegetation cover resulted in positive effects on recruitment at higher sites and neutral effects at lower sites. All tested species showed intraspecific variability when responding to the experimental conditions. We discuss our findings considering novel site and climatic conditions.

Effects of integrated interventions on growth and development of young children: A meta-analysis

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
S Dulal ◽  
A Prost ◽  
N Saville ◽  
S Karki ◽  
D Merom
Keyword(s):  
Language Development ◽  
Usual Care ◽  
Motor Development ◽  
Meta Analysis ◽  
Developmental Outcomes ◽  
Child Growth ◽  
Detectable Effect ◽  
Behaviour Change Techniques ◽  
Positive Effects ◽  
Randomised Controlled

Abstract Background We did a systematic review to understand: (a) the effects of integrated versus usual care on the developmental outcomes and nutritional status of children under five years; and (b) which intervention characteristics are associated with positive effects. Methods We searched eight electronic databases for studies published between January 2013 and September 2019. Eligible studies were Randomised Controlled Trials (RCTs) and non-randomised controlled studies of integrated nutrition and stimulation interventions with child growth and developmental outcomes. We extracted data on intervention characteristics including delivery strategies, behaviour change techniques, intervention intensity and delivery personnel. We meta-analysed data for Length-for-age/Height-for-age Z scores (LAZ/HAZ) and cognitive, motor and language development scores, and conducted subgroup analyses by main intervention characteristics. Results Twenty-two unique RCTs met the inclusion criteria, of which 16 were included in the meta-analysis. Compared to the usual care, pooled Effect Sizes (ES) showed small to medium benefits of integrated interventions on cognitive (n = 15, ES 0.64; 95% CI: 0.39, 0.88) and language development scores (n = 10, ES 0.47, 95% CI: 0.21, 0.73) but heterogeneity was high (I2&gt;75%). We found no significant effects of interventions on motor development scores (n = 12, ES 0.31, 95% CI: -0.02, 0.64) or LAZ/HAZ scores (n = 8, ES -0.03, 95% CI: -0.11, 0.03). The effects of interventions on developmental outcomes did not differ by intervention characteristics, and heterogeneity remained high in sub-group analyses. Conclusions Integrated nutrition and stimulation interventions had significant effects on cognitive and language development, but no detectable effect on motor development or linear growth. Our ability to identify intervention characteristics linked to positive effects can be improved by standardising the reporting of implementation processes. Key messages More high-quality trials with longer follow-up duration are needed to examine the role of integrated nutrition and stimulation interventions on growth and developmental outcomes. Future research should map the characteristics of integrated nutrition and stimulation interventions following standardised guidelines to understand their influence on the outcomes reported.

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