scholarly journals Effects of soil fauna on litter decomposition in Chinese forests: a meta-analysis

PeerJ ◽  
2022 ◽  
Vol 10 ◽  
pp. e12747
Author(s):  
Peng Zan ◽  
Zijun Mao ◽  
Tao Sun
Keyword(s):  
Litter Decomposition ◽  
Effect Size ◽  
Decomposition Rate ◽  
Temperate Forest ◽  
Litter Quality ◽  
Soil Fauna ◽  
Spatial Scales ◽  
Meta Analysis ◽  
Decomposition Rates ◽  
The Impact

Litter quality and climate have been presumed to be the dominant factors regulating litter decomposition rates on broad spatial scales. However, the role of soil fauna on litter decomposition is poorly understood, despite the fact that it could strongly influence decomposition by fragmentation and subsequent modification of the activities of microorganisms.In this study, we carried out a meta-analysis on the effects of soil fauna on litter decomposition rates in Chinese forests, ranging from boreal to tropical forests, based on data from 20 studies. The effects of climatic factors on decomposition rate were assessed by comparing the contribution of soil fauna to litter decomposition from studies carried out at different latitudes.The degree of influence of the soil fauna was in the order tropical (200%) > subtropical (47%) > temperate forest (28%). Comparing the effect size of soil fauna, it was found that when soil fauna was excluded, the decomposition rate, calculated using Olson’s equation, was most affected in tropical forest (−0.77), while the litter decomposition rate both subtropical (−0.36) and temperate forest (−0.19) were also suppressed to varying degrees (P < 0.001). These results highlight that soil fauna could promote litter decomposition to different extents. Using stepwise multiple linear regression, the effect size of the soil fauna was negatively correlated with the cellulose and nitrogen concentrations of the initial litter material. In Chinese forests, litter decomposition rates were reduced, on average, by 65% when soil fauna was excluded. The impact of soil fauna on decomposition was shown to be closely related to climate and litter quality.

scholarly journals Ligustrum lucidum invasion decreases abundance and relative contribution of soil fauna to litter decomposition but increases decomposition rate in a subtropical montane forest of NW Argentina

2021 ◽  
Author(s):  
Romina Daiana Fernandez ◽  
María Laura Moreno ◽  
Natalia Pérez Harguindeguy ◽  
Roxana Aragón
Keyword(s):  
Litter Decomposition ◽  
Decomposition Rate ◽  
Litter Quality ◽  
Invasive Plant ◽  
Soil Fauna ◽  
Mountain Forest ◽  
Forest Types ◽  
Soil Macrofauna ◽  
Ligustrum Lucidum ◽  
Relative Contribution

Invasive plant species can alter litter decomposition rates through changes in litter quality, environment conditions and decomposer organisms (microflora and soil fauna) but limited research has examined the direct impact on soil fauna. We assessed the abundance and relative contribution of soil meso- and macrofauna to litter decomposition in invaded forest by Ligustrum lucidum and non-invaded forest in a subtropical mountain forest of northwest Argentina using litterbags (0.01, 2 and 6 mm mesh size). Additionally, we analyzed litter quality and soil properties of both forest types. Soil fauna abundance was lower in invaded than in non- invaded forest. The contribution of soil macrofauna to litter decomposition was important in both forest types, but soil mesofauna contribution was only significant in non-invaded forest. Litter decomposition was significantly faster in invaded than in non-invaded forest, consistent with its highest quality. Invaded forest had significantly lower litter accumulation, lower soil moisture and greater soil pH than non-invaded forest. Our results showed that, although soil fauna was less abundant and played a less pronounced role in litter decomposition in invaded forest; these changes did not translate into a reduced litter decomposition rate due to the higher quality of litter produced in the invaded forest.

scholarly journals Combined effects of water temperature, grazing snails and terrestrial herbivores on leaf decomposition in urban streams

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7580 ◽  
Author(s):  
Hongyong Xiang ◽  
Yixin Zhang ◽  
David Atkinson ◽  
Raju Sekar
Keyword(s):  
Organic Matter ◽  
Water Temperature ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Decomposition Rate ◽  
Litter Quality ◽  
Urban Streams ◽  
Combined Effects ◽  
Decomposition Rates ◽  
Terrestrial Insects

The decomposition of organic matter in freshwaters, such as leaf litter, can affect global nutrient (e.g., carbon) cycling. This process can be influenced by fast urbanization through increased water temperature, reduced aquatic diversity and changed leaf litter quality traits. In this study, we performed a mesocosm experiment to explore the individual and combined effects of warming (8°C higher and ambient), the presence versus absence of grazing snails (Parafossarulus striatulus), and intraspecific difference of leaf litter quality (intact versus > 40% area of Liriodendron chinense leaves grazed by terrestrial insects) on litter decomposition in urban streams. Litter decomposition rates ranged from 0.019 d−1 to 0.058 d−1 with an average decomposition rate of 0.032 ± 0.002 d−1. All the three factors had significant effects on litter decomposition rate. Warming and the presence of snails accelerated litter decomposition rates by 60% and 35% respectively. Litter decomposition rates of leaves damaged by terrestrial insects were 5% slower than that of intact leaves, because litter quality of terrestrial insect-damaged leaves was lower (i.e., higher specific leaf weight) than intact leaves. For treatments with snails, warming stimulated microbial and snail mediated litter decomposition rates by 35% and 167%, respectively. All combinations of treatments showed additive effects on litter decomposition except for the interaction between warming and snails which showed positive synergistic effects. In addition, neither temperature nor litter quality affected snail growth rate. These results imply that higher water temperature and the presence of abundant snails in urban streams greatly enhanced litter decomposition. Moreover, the effect of pest outbreaks, which resulted in lower litter quality, can cascade to aquatic ecosystems by retarding microbe-mediated litter decomposition. When these factors co-occurred, warming could synergistically interact with snails to speed up the depletion of organic matter, while the effect of leaf quality on litter decomposition may be diminished at high water temperature. These effects could further influence stream food webs and nutrient cycling.

Evaluating the effectiveness of interventions to reducing screen time in children: meta-analysis of randomized controlled trials

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Duygu Akçay ◽  
Nuray Barış
Keyword(s):  
Effect Size ◽  
Subgroup Analysis ◽  
Screen Time ◽  
Meta Analysis ◽  
Intervention Group ◽  
Evidence Base ◽  
Control Group ◽  
Content Type ◽  
Mean Differences ◽  
The Impact

Purpose The purpose of this paper is to evaluate the impact of interventions focused on reducing screen time in children. Design/methodology/approach Studies that aim to investigate the effects of interventions aimed at reducing the time spent in front of the screen (i.e. screen time). A Random-effects model was used to calculate the pooled standard mean differences. The outcome was to evaluate the screen time in children in the 0–18 age range. A subgroup analysis was performed to reveal the extent to which the overall effect size varied by subgroups (participant age, duration of intervention and follow). Findings For the outcome, the meta-analysis included 21 studies, and the standard difference in mean change in screen time in the intervention group compared with the control group was −0.16 (95% confidence interval [CI], −0.21 to −0.12) (p < 0.001). The effect size was found to be higher in long-term (=7 months) interventions and follow-ups (p < 0.05). Originality/value Subgroup analysis showed that a significant effect of screen time reduction was observed in studies in which the duration of intervention and follow-up was =7 months. As the evidence base grows, future researchers can contribute to these findings by conducting a more comprehensive analysis of effect modifiers and optimizing interventions to reduce screen time.

scholarly journals Reliability of Computerized Neurocognitive Tests for Concussion Assessment: A Meta-Analysis

2017 ◽  
Vol 52 (9) ◽  
pp. 826-833 ◽  
Author(s):  
James L. Farnsworth ◽  
Lucas Dargo ◽  
Brian G. Ragan ◽  
Minsoo Kang
Keyword(s):  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Effect Size ◽  
Sampling Error ◽  
Meta Analysis ◽  
Intraclass Correlation ◽  
Cognitive Testing ◽  
Test Duration ◽  
Neurocognitive Tests ◽  
The Impact

Objective:  Although widely used, computerized neurocognitive tests (CNTs) have been criticized because of low reliability and poor sensitivity. A systematic review was published summarizing the reliability of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scores; however, this was limited to a single CNT. Expansion of the previous review to include additional CNTs and a meta-analysis is needed. Therefore, our purpose was to analyze reliability data for CNTs using meta-analysis and examine moderating factors that may influence reliability. Data Sources:  A systematic literature search (key terms: reliability, computerized neurocognitive test, concussion) of electronic databases (MEDLINE, PubMed, Google Scholar, and SPORTDiscus) was conducted to identify relevant studies. Study Selection:  Studies were included if they met all of the following criteria: used a test-retest design, involved at least 1 CNT, provided sufficient statistical data to allow for effect-size calculation, and were published in English. Data Extraction:  Two independent reviewers investigated each article to assess inclusion criteria. Eighteen studies involving 2674 participants were retained. Intraclass correlation coefficients were extracted to calculate effect sizes and determine overall reliability. The Fisher Z transformation adjusted for sampling error associated with averaging correlations. Moderator analyses were conducted to evaluate the effects of the length of the test-retest interval, intraclass correlation coefficient model selection, participant demographics, and study design on reliability. Heterogeneity was evaluated using the Cochran Q statistic. Data Synthesis:  The proportion of acceptable outcomes was greatest for the Axon Sports CogState Test (75%) and lowest for the ImPACT (25%). Moderator analyses indicated that the type of intraclass correlation coefficient model used significantly influenced effect-size estimates, accounting for 17% of the variation in reliability. Conclusions:  The Axon Sports CogState Test, which has a higher proportion of acceptable outcomes and shorter test duration relative to other CNTs, may be a reliable option; however, future studies are needed to compare the diagnostic accuracy of these instruments.

scholarly journals Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes

2013 ◽  
Vol 16 (8) ◽  
pp. 1045-1053 ◽  
Author(s):  
Pablo García-Palacios ◽  
Fernando T. Maestre ◽  
Jens Kattge ◽  
Diana H. Wall
Keyword(s):  
Litter Decomposition ◽  
Litter Quality ◽  
Soil Fauna

Increased atmospheric CO2 and litter quality

1998 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
M Francesca Cotrufo ◽  
Björn Berg ◽  
Werner Kratz
Keyword(s):  
Chemical Composition ◽  
Leaf Litter ◽  
Decomposition Rate ◽  
Litter Quality ◽  
Castanea Sativa ◽  
Plant Litter ◽  
Decomposition Rates ◽  
Chemical Changes ◽  
Substrate Quality ◽  
N Concentration

There is evidence that N concentration in hardwood leaf litter is reduced when plants are raised in an elevated CO2 atmosphere. Reductions in the N concentration of leaf litter have been found for tree species raised under elevated CO2, with reduction in N concentration ranging from ca. 50% for sweet chestnut (Castanea sativa) to 19% for sycamore (Acer platanoides). However, the effects of elevated CO2 on the chemical composition of litter has been investigated only for a limited number of species. There is also little information on the effects of increased CO2 on the quality of root tissues. If we consider, for example, two important European forest ecosystem types, the dominant species investigated for chemical changes are just a few. Thus, there are whole terrestrial ecosystems in which not a single species has been investigated, meaning that the observed effects of a raised CO2 level on plant litter actually has a large error source. Few reports present data on the effects of elevated CO2 on litter nutrients other than N, which limits our ability to predict the effects of elevated CO2 on litter quality and thus on its decomposability. In litter decomposition three separate steps are seen: (i) the initial stages, (ii) the later stages, and (iii) the final stages. The concept of "substrate quality," translated into chemical composition, will thus change between early stages of decomposition and later ones, with a balanced proportion of nutrients (e.g., N, P, S) being required in the early decomposition phase. In the later stages decomposition rates are ruled by lignin degradation and that process is regulated by the availability of certain nutrients (e.g., N, Mn), which act as signals to the lignin-degrading soil microflora. In the final stages the decomposition comes to a stop or may reach an extremely low decomposition rate, so low that asymptotic decomposition values may be estimated and negatively related to N concentrations. Studies on the effects of changes in chemical composition on the decomposability of litter have mainly been made during the early decomposition stages and they generally report decreased litter quality (e.g., increased C/N ratio), resulting in lower decomposition rates for litter raised under elevated CO2 as compared with control litter. No reports are found relating chemical changes induced by elevated CO2 to litter mass-loss rates in late stages. By most definitions, at these stages litter has turned into humus, and many studies demonstrated that a raising of the N level may suppress humus decomposition rate. It is thus reasonable to speculate that a decrease in N levels in humus would accelerate decomposition and allow it to proceed further. There are no experimental data on the long-term effect of elevated CO2 levels, and a decrease in the storage of humus and nutrients could be predicted, at least in temperate and boreal forest systems. Future works on the effects of elevated CO2 on litter quality need to include studies of a larger number of nutrients and chemical components, and to cover different stages of decomposition. Additionally, the response of plant litter quality to elevated CO2 needs to be investigated under field conditions and at the community level, where possible shifts in community composition (i.e., C3 versus C4 ; N2 fixers versus nonfixers) predicted under elevated CO2 are taken into account.Key words: climate change, substrate quality, carbon dioxide, plant litter, chemical composition, decomposition.

scholarly journals Efectos de la intervención en conciencia morfológica sobre la lectura, escritura y comprensión: Meta-análisis

2015 ◽  
Vol 32 (1) ◽  
pp. 60 ◽  
Author(s):  
Mercedes I. Rueda-Sánchez ◽  
Patricia López-Bastida
Keyword(s):  
Effect Size ◽  
Selection Criteria ◽  
Meta Analysis ◽  
Reading Difficulties ◽  
Morphological Awareness ◽  
Awareness Training ◽  
Moderating Variables ◽  
Reading Vocabulary ◽  
Morphological Awareness Training ◽  
The Impact

The aim is to check, through a meta-analysis, the impact of morphological awareness training on writing, reading, comprehension and vocabulary of grade schooler. 31 studies were included in the meta-analysis; they were obtained from 19 articles that meet the selection criteria. Morphological awareness instruction has a high-medium and significant effect size in studied variables of literacy. On writing, <em>g</em>=0.491, <em>SE</em>=0.078, <em>IQ</em>=0339-0643, <em>p</em>=.000, reading, <em>g</em>=0.473, <em>SE</em>=0.096, <em>IQ</em>=0284-0662, <em>p</em>=.000, comprehension, <em>g</em>=0.468, <em>SE</em>=0.123, <em>IQ</em>=0227-0708, <em>p</em>= .000 and finally vocabulary, <em>g</em>=0.501, <em>SE</em>=0.152, <em>IQ</em>=0203-0798, <em>p</em>= .001. The test of Heterogeneity <em>Q</em> is only significant on writing so other moderating variables were explored but no differences between groups were found. It shows morphological awareness training improves reading, vocabulary and comprehension of grade schooler with and without reading difficulties. Nevertheless, the results on writing are more heterogeneous.

Abstract WMP37: Methodological Quality and Meta-Analysis of Animal Studies of Mesenchymal Stromal Cells for Ischemic Stroke

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Kate Xie* ◽  
Quynh Vu* ◽  
Mark Eckert ◽  
Weian Zhao ◽  
Steven C Cramer
Keyword(s):  
Mesenchymal Stromal Cells ◽  
Effect Size ◽  
Stromal Cells ◽  
Methodological Quality ◽  
Meta Analysis ◽  
Quality Score ◽  
Behavioral Effects ◽  
Behavioral Measure ◽  
Routes Of Administration ◽  
The Impact

INTRODUCTION: Mesenchymal stromal cells (MSC) are multipotent cells that support numerous restorative processes after stroke. The ease of isolation and immunoprivileged status of MSC have stimulated numerous preclinical stroke studies. We performed a meta-analysis to estimate study quality, size of behavioral effects, and the impact of variables such as timing of MSC administration in relation to stroke onset. METHODS: Studies of MSC and stroke were identified through PubMed and Web of Science. Studies of hemorrhage, not in English, or using modified MSC were excluded. A Quality Score was determined for each study, estimating methodological quality using 10 criteria derived from STAIR guidelines, with higher Quality Scores reflecting greater compliance with issues such as randomization and outcome blinding. Outcome data extracted for MSC and control arms were used to derive estimates of effect size using Cohen’s d. RESULTS: A total of 46 studies met criteria, with 39 studying rats, 6 mice, and 1 primates. There were 61 treatment groups, as some studies had >1 independent MSC treatment arms; MSC were introduced intravenously in 41, intracerebrally in 15, and intraarterially in 6. MSC source was rat in 24, human in 16, and mouse in 6. Time of MSC administration ranged from 5 weeks pre- to 1 month post-stroke. MSC dose ranged from 1x10^4 to 3.25x10^7. The median Quality Score was 6 (IQR 5-7). Quality Score was not related to time of MSC administration relative to stroke or to behavioral effect size. Median effect size was 2.05 for the Modified Neurological Severity Scale (n=23), 1.88 for Adhesive Removal Test (n=19), and 2.70 for the Rotarod Test (n=14). Effect sizes were substantial across all routes of administration and differed only for the mNSS (p<0.04), favoring the IC route. Effect size did not vary with time of MSC administration relative to stroke for any behavioral measure. CONCLUSIONS: The quality of preclinical MSC stroke studies has generally been good. MSC consistently provide very large behavioral benefits, across scales and routes of administration. The magnitude of behavioral effects was not related to the Quality Score or to the time of MSC administration relative to stroke. These findings support translation of MSC to human trials.

scholarly journals Considering the methodological limitations in the evidence base of antidepressants for depression: a reanalysis of a network meta-analysis

BMJ Open ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. e024886 ◽  
Author(s):  
Klaus Munkholm ◽  
Asger Sand Paludan-Müller ◽  
Kim Boesen
Keyword(s):  
Systematic Review ◽  
Clinical Study ◽  
Effect Size ◽  
Meta Analysis ◽  
Evidence Base ◽  
Risk Of Bias ◽  
Depression Symptom ◽  
Meta Analyses ◽  
The Impact ◽  
Clinical Study Reports

ObjectivesTo investigate whether the conclusion of a recent systematic review and network meta-analysis (Ciprianiet al) that antidepressants are more efficacious than placebo for adult depression was supported by the evidence.DesignReanalysis of a systematic review, with meta-analyses.Data sources522 trials (116 477 participants) as reported in the systematic review by Ciprianiet aland clinical study reports for 19 of these trials.AnalysisWe used the Cochrane Handbook’s risk of bias tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to evaluate the risk of bias and the certainty of evidence, respectively. The impact of several study characteristics and publication status was estimated using pairwise subgroup meta-analyses.ResultsSeveral methodological limitations in the evidence base of antidepressants were either unrecognised or underestimated in the systematic review by Ciprianiet al. The effect size for antidepressants versus placebo on investigator-rated depression symptom scales was higher in trials with a ‘placebo run-in’ study design compared with trials without a placebo run-in design (p=0.05). The effect size of antidepressants was higher in published trials compared with unpublished trials (p<0.0001). The outcome data reported by Ciprianiet aldiffered from the clinical study reports in 12 (63%) of 19 trials. The certainty of the evidence for the placebo-controlled comparisons should be very low according to GRADE due to a high risk of bias, indirectness of the evidence and publication bias. The mean difference between antidepressants and placebo on the 17-item Hamilton depression rating scale (range 0–52 points) was 1.97 points (95% CI 1.74 to 2.21).ConclusionsThe evidence does not support definitive conclusions regarding the benefits of antidepressants for depression in adults. It is unclear whether antidepressants are more efficacious than placebo.

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