scholarly journals Soil <i>δ</i><sup>15</sup>N is a better indicator of ecosystem nitrogen cycling than plant <i>δ</i><sup>15</sup>N: A global meta-analysis

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 733-742
Author(s):  
Kaihua Liao ◽  
Xiaoming Lai ◽  
Qing Zhu
Keyword(s):  
Meta Analysis ◽  
Global Scale ◽  
N Cycling ◽  
Mean Annual Temperature ◽  
Experimental Warming ◽  
Analysis Method ◽  
Higher Temperature ◽  
The Mean ◽  
Increasing Temperature ◽  
Soil Δ15n

Abstract. The nitrogen-15 (15N) natural abundance composition (δ15N) in soils or plants is a useful tool to indicate the openness of ecosystem N cycling. This study aimed to evaluate the influence of the experimental warming on soil and plant δ15N. We applied a global meta-analysis method to synthesize 79 and 76 paired observations of soil and plant δ15N from 20 published studies, respectively. Results showed that the mean effect sizes of the soil and plant δ15N under experimental warming were −0.524 (95 % CI (confidence interval): −0.987 to −0.162) and 0.189 (95 % CI: −0.210 to 0.569), respectively. This indicated that soil δ15N had negative response to warming at the global scale, where warming had no significant effect on plant δ15N. Experimental warming significantly (p<0.05) decreased soil δ15N in Alkali and medium-textured soils, in grassland/meadow, under air warming, for a 4–10-year warming period and for an increase of >3 ∘C in temperature, whereas it significantly (p<0.05) increased soil δ15N in neutral and fine-textured soils and for an increase of 1.5–3 ∘C in temperature. Plant δ15N significantly (p<0.05) increased with increasing temperature in neutral and fine-textured soils and significantly (p<0.05) decreased in alkali soil. Latitude did not affect the warming effects on both soil and plant δ15N. However, the warming effect on soil δ15N was positively controlled by the mean annual temperature, which is related to the fact that the higher temperature can strengthen the activity of soil microbes. The effect of warming on plant δ15N had weaker relationships with environmental variables compared with that on soil δ15N. This implied that soil δ15N was more effective than plant δ15N in indicating the openness of global ecosystem N cycling.

scholarly journals Soil and plant δ<sup>15</sup>N have a different response to experimental warming: A global meta-analysis

2021 ◽  
Author(s):  
Kaihua Liao ◽  
Xiaoming Lai ◽  
Qing Zhu
Keyword(s):  
Meta Analysis ◽  
Global Scale ◽  
N Cycling ◽  
Mean Annual Temperature ◽  
Experimental Warming ◽  
Alkali Soil ◽  
Neutral Soil ◽  
The Mean ◽  
Different Response ◽  
Soil Δ15n

Abstract. The 15N natural abundance composition (δ15N) in soils or plants is a useful tool to indicate the openness of ecosystem N cycling. This study was aimed to evaluate the influence of the global warming on soil and plant δ15N. We applied a global meta-analysis method to synthesize 79 and 76 paired observations for soil and plant δ15N from 20 published studies, respectively. Results showed that the mean effect sizes of the soil and plant δ15N under experimental warming were −0.524 (95 % CI: −0.987 to −0.162) and 0.189 (95 % CI: −0.210 to 0.569), respectively. This indicated that soil and plant δ15N had negative and positive responses to warming at the global scale, respectively. Experimental warming significantly (p < 0.05) decreased soil δ15N in Alkali soil, grassland/meadow, and under air warming, whereas it significantly (p < 0.05) increased soil δ15N in neutral soil. Plant δ15N significantly (p < 0.05) increased with increasing temperature in neutral soil and significantly (p < 0.05) decreased in alkali soil. Latitude did not affect the warming effects on both soil and plant δ15N. However, the warming effect on soil δ15N was positively controlled by the mean annual temperature, which is related to the fact that the higher temperature can strengthen the activity of soil microbes. The effect of warming on plant δ15N had weaker relationships with environmental variables compared with that on soil δ15N. This implied that soil δ15N tended to be more efficient in indicating the openness of global ecosystem N cycling than plant δ15N.

scholarly journals Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: sunny slope versus shady slope

2017 ◽  
Author(s):  
Chongjuan Chen ◽  
Yufu Jia ◽  
Yuzhen Chen ◽  
Imran Mehmood ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Regional Scale ◽  
Local Environment ◽  
Global Scale ◽  
Influential Factors ◽  
N Cycling ◽  
N Availability ◽  
Soil N ◽  
The Difference ◽  
Soil Δ15n

Abstract. Nitrogen cycling is tightly associated with environment. Sunny slope of a given mountain could significantly differ from shady slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and △δ15Nleaf-soil (△δ15Nleaf-soil = leaf δ15N − soil δ15N) could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and △δ15Nleaf-soil should differ across the two slopes. However, such a comparative study between two slopes has never been conducted yet. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from that at regional scale. This led to our argument that environmental effects on leaf and soil δ15N could depend on local environment. To confirm our hypothesis and argument, we measured leaf and soil δ15N on the sunny and shady slopes of Mount Tianshan. Remarkable environment differences between the two slopes provided an ideal opportunity for our test. The study showed that leaf δ15N, soil δ15N and △δ15Nleaf-soil on the sunny slope were greater than that on the shady slope although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the sunny slope has higher soil N transformation rates and soil N availability than the shady slope. Besides, this study observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C / N and silt / clay ratio on the shady slope, whereas on the sunny slope only leaf C / N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation and silt / clay ratio on the shady slope, whereas on the sunny slope MAP and soil moisture exerted significant effects. Precipitation exerted contrary effects on soil δ15N between the two slopes. Thus, this study supported our argument that the relationships between leaf and soil δ15N and environmental factors are local-dependent.

The importance of temperature and lipid accumulation for initiation and duration of Calanus hyperboreus spawning

2020 ◽  
Vol 42 (2) ◽  
pp. 159-171
Author(s):  
Mads Schultz ◽  
Torkel Gissel Nielsen ◽  
Eva Friis Møller
Keyword(s):  
Population Dynamics ◽  
Lipid Metabolism ◽  
Lipid Content ◽  
Egg Production ◽  
Arctic Ecosystems ◽  
Calanus Hyperboreus ◽  
Higher Temperature ◽  
The Mean ◽  
Increasing Temperature ◽  
The Impact

Abstract Large, lipid-storing copepods play a central role in marine Arctic ecosystems. Knowledge of the mechanisms that control their oogenesis is important for understanding their phenology and population dynamics. We investigated the impact of female lipid content on the timing and cumulative egg production (EP) of Calanus hyperboreus at 0, 3 and 6°C. The lipid content of females in early autumn was a good predictor of their EP potential. However, we saw no indication of a threshold in lipid content for initiation of spawning. Higher temperature resulted in 17 and 24 days earlier spawning at 3 and 6°C compared with 0°C, and the mean spawning duration was 8 and 30 days shorter, respectively. This illustrates that temperature affects the phenology of C. hyperboreus. When EP began, lipid metabolism increased 2–4 times. The females allocated 1.3 μg lipid per egg independent of temperature. However, the basic metabolism increased with increasing temperature; consequently, a smaller fraction of lipid was allocated for EP when the temperature increased.

scholarly journals The relationship between body mass index and preeclampsia: A systematic review and meta-analysis

2019 ◽  
Author(s):  
Morteza Motedayen ◽  
Mohammad Rafiei ◽  
Mostafa Rezaei Tavirani ◽  
Kourosh Sayehmiri ◽  
Majid Dousti
Keyword(s):  
Systematic Review ◽  
Body Mass Index ◽  
Body Mass ◽  
Meta Analysis ◽  
Fetal Mortality ◽  
Analysis Method ◽  
Mortality And Morbidity ◽  
The Mean ◽  
The Relationship ◽  
Risk Of Preeclampsia

Background: One of the causes of maternal and fetal mortality and morbidity is pregnancy-induced hypertension, the most common form of which is preeclampsia that causes many complications for mother and fetus. Objective: The aim of this systematic review and meta-analysis was to determine the relationship between body mass index (BMI) and preeclampsia in Iran. Materials and Methods: Using valid keywords in the SID database, PubMed, Scopus, data obtained from all the articles, which were reviewed in Iran between 2000 and 2016, were combined using the meta-analysis method (random-effects model) and analyzed using STATA version 11.1. Results: A total number of 5,946 samples were enrolled in 16 studies with the mean BMI values of 25.13, 27.42, and 26.33 kg /m2 in the healthy, mild, and severe preeclamptic groups, respectively. Conclusion: The results of this study revealed that there is a significant relationship between BMI and the risk of preeclampsia, so it can be said that BMI may be one of the ways to diagnose preeclampsia.

Response Rates in Online Surveys With Affective Disorder Participants

2020 ◽  
Vol 228 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Tanja Burgard ◽  
Michael Bošnjak ◽  
Nadine Wedderhoff
Keyword(s):  
Meta Analysis ◽  
Response Rates ◽  
Contact Mode ◽  
General Anxiety Disorder ◽  
General Anxiety ◽  
Face To Face ◽  
Survey Participation ◽  
The Mean ◽  
Design Characteristics ◽  
E Mail

Abstract. A meta-analysis was performed to determine whether response rates to online psychology surveys have decreased over time and the effect of specific design characteristics (contact mode, burden of participation, and incentives) on response rates. The meta-analysis is restricted to samples of adults with depression or general anxiety disorder. Time and study design effects are tested using mixed-effects meta-regressions as implemented in the metafor package in R. The mean response rate of the 20 studies fulfilling our meta-analytic inclusion criteria is approximately 43%. Response rates are lower in more recently conducted surveys and in surveys employing longer questionnaires. Furthermore, we found that personal invitations, for example, via telephone or face-to-face contacts, yielded higher response rates compared to e-mail invitations. As predicted by sensitivity reinforcement theory, no effect of incentives on survey participation in this specific group (scoring high on neuroticism) could be observed.

The Effect of Desmopressin on Reducing Blood Loss in Cardiac Surgery – A Meta-Analysis of Double-Blind, Placebo-Controlled Trials

1995 ◽  
Vol 74 (04) ◽  
pp. 1064-1070 ◽  
Author(s):  
Marco Cattaneo ◽  
Alan S Harris ◽  
Ulf Strömberg ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Cardiac Surgery ◽  
Blood Loss ◽  
Meta Analysis ◽  
Postoperative Blood Loss ◽  
Controlled Trials ◽  
Double Blind ◽  
Double Blind Placebo ◽  
Transfusion Requirements ◽  
The Mean ◽  
Excessive Blood Loss

SummaryThe effect of desmopressin (DDAVP) on reducing postoperative blood loss after cardiac surgery has been studied in several randomized clinical trials, with conflicting outcomes. Since most trials had insufficient statistical power to detect true differences in blood loss, we performed a meta-analysis of data from relevant studies. Seventeen randomized, double-blind, placebo-controlled trials were analyzed, which included 1171 patients undergoing cardiac surgery for various indications; 579 of them were treated with desmopressin and 592 with placebo. Efficacy parameters were blood loss volumes and transfusion requirements. Desmopressin significantly reduced postoperative blood loss by 9%, but had no statistically significant effect on transfusion requirements. A subanalysis revealed that desmopressin had no protective effects in trials in which the mean blood loss in placebo-treated patients fell in the lower and middle thirds of distribution of blood losses (687-1108 ml/24 h). In contrast, in trials in which the mean blood loss in placebo-treated patients fell in the upper third of distribution (>1109 ml/24 h), desmopressin significantly decreased postoperative blood loss by 34%. Insufficient data were available to perform a sub-analysis on transfusion requirements. Therefore, desmopressin significantly reduces blood loss only in cardiac operations which induce excessive blood loss. Further studies are called to validate the results of this meta-analysis and to identify predictors of excessive blood loss after cardiac surgery.

Voronoi Analysis of a Soccer Game

2004 ◽  
Vol 9 (3) ◽  
pp. 233-240 ◽  
Author(s):  
S. Kim
Keyword(s):  
Collective Behavior ◽  
Quantitative Assessment ◽  
The Other ◽  
Analysis Method ◽  
Random System ◽  
Soccer Game ◽  
Voronoi Polygons ◽  
The Mean

This paper describes a Voronoi analysis method to analyze a soccer game. It is important for us to know the quantitative assessment of contribution done by a player or a team in the game as an individual or collective behavior. The mean numbers of vertices are reported to be 5–6, which is a little less than those of a perfect random system. Voronoi polygons areas can be used in evaluating the dominance of a team over the other. By introducing an excess Voronoi area, we can draw some fruitful results to appraise a player or a team rather quantitatively.

Understanding the CoVID-19 pandemic Curve through statistical approach (Preprint)

2020 ◽  
Author(s):  
Ibrar Ul Hassan Akhtar
Keyword(s):  
Probability Density ◽  
Change Point ◽  
Statistical Approach ◽  
Sudden Change ◽  
Global Scale ◽  
Change Point Detection ◽  
Segment Length ◽  
Infected Population ◽  
The Mean ◽  
Point Detection

UNSTRUCTURED Current research is an attempt to understand the CoVID-19 pandemic curve through statistical approach of probability density function with associated skewness and kurtosis measures, change point detection and polynomial fitting to estimate infected population along with 30 days projection. The pandemic curve has been explored for above average affected countries, six regions and global scale during 64 days of 22nd January to 24th March, 2020. The global cases infection as well as recovery rate curves remained in the ranged of 0 ‒ 9.89 and 0 ‒ 8.89%, respectively. The confirmed cases probability density curve is high positive skewed and leptokurtic with mean global infected daily population of 6620. The recovered cases showed bimodal positive skewed curve of leptokurtic type with daily recovery of 1708. The change point detection helped to understand the CoVID-19 curve in term of sudden change in term of mean or mean with variance. This pointed out disease curve is consist of three phases and last segment that varies in term of day lengths. The mean with variance based change detection is better in differentiating phases and associated segment length as compared to mean. Global infected population might rise in the range of 0.750 to 4.680 million by 24th April 2020, depending upon the pandemic curve progress beyond 24th March, 2020. Expected most affected countries will be USA, Italy, China, Spain, Germany, France, Switzerland, Iran and UK with at least infected population of over 0.100 million. Infected population polynomial projection errors remained in the range of -78.8 to 49.0%.

scholarly journals Multispecies for multifunctions: combining four complementary species enhances multifunctionality of sown grassland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Suter ◽  
Olivier Huguenin-Elie ◽  
Andreas Lüscher
Keyword(s):  
Forage Quality ◽  
N Cycling ◽  
Forage Production ◽  
Mixture Effects ◽  
Novel Approach ◽  
Overall Performance ◽  
The Mean ◽  
High Forage ◽  
Diversity Effects ◽  
Species Mixtures

AbstractAssessing the overall performance of ecosystems requires a quantitative evaluation of multifunctionality. We investigated plant species diversity effects on individual functions and overall multifunctionality in a grassland experiment with sown monocultures and mixtures comprising four key grass and legume species. Nitrogen fertilisation rates were 50, 150, and 450 kg N ha−1 yr−1 (N50, N150, N450). Ten functions were measured representing forage production, N cycling, and forage quality, all being related to either productivity or environmental footprint. Multifunctionality was analysed by a novel approach using the mean log response ratio across functions. Over three experimental years, mixture effects benefited all forage production and N cycling functions, while sustaining high forage quality. Thus, mixture effects did not provoke any trade-off among the analysed functions. High N fertilisation rates generally diminished mixture benefits. Multifunctionality of four-species mixtures was considerably enhanced, and mixture overall performance was up to 1.9 (N50), 1.8 (N150), and 1.6 times (N450) higher than in averaged monocultures. Multifunctionality of four-species mixtures at N50 was at least as high as in grass monocultures at N450. Sown grass–legume mixtures combining few complementary species at low to moderate N fertilisation sustain high multifunctionality and are a ‘ready-to-use’ option for the sustainable intensification of agriculture.

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