scholarly journals A Meta-Analysis on Degraded Alpine Grassland Mediated by Climate Factors: Enlightenment for Ecological Restoration

2022 ◽  
Vol 12 ◽  
Author(s):  
Jiale Yu ◽  
Lingfan Wan ◽  
Guohua Liu ◽  
Keming Ma ◽  
Hao Cheng ◽  
...  
Keyword(s):  
Ecological Restoration ◽  
Large Scale ◽  
Meta Analysis ◽  
Wiener Index ◽  
Belowground Biomass ◽  
Alpine Grassland ◽  
Tibet Plateau ◽  
Climate Factors ◽  
Available Nitrogen ◽  
Precipitation And Temperature

Alpine grassland is the main ecosystem on the Qinghai-Tibet Plateau (QTP). Degradation and restoration of alpine grassland are related to ecosystem function and production, livelihood, and wellbeing of local people. Although a large number of studies research degraded alpine grassland, there are debates about degradation patterns of alpine grassland in different areas and widely applicable ecological restoration schemes due to the huge area of the QTP. In this study, we used the meta-analysis method to synthesize 80 individual published studies which were conducted to examine aboveground and underground characteristics in non-degradation (ND), light degradation (LD), moderate degradation (MD), heavy degradation (HD), and extreme degradation (ED) of alpine grassland on the QTP. Results showed that aboveground biomass (AGB), belowground biomass (BGB), Shannon-Wiener index (H′), soil moisture (SM), soil organic carbon (SOC), soil total nitrogen (TN), and available nitrogen (AN) gradually decreased along the degradation gradient, whereas soil bulk density (BD) and soil pH gradually increased. In spite of a tendency to soil desertification, losses of other soil nutrients and reduction of enzymes, there was no linear relationship between the variations with degradation gradient. Moreover, the decreasing extent of TN was smaller in areas with higher precipitation and temperature, and the decreasing extent of AGB, SOC, and TN was larger in areas with a higher extent of corresponding variables in the stage of ND during alpine grassland degradation. These findings suggest that in areas with higher precipitation and temperature, reseeding and sward cleavage can be used for restoration on degraded alpine grassland. Fencing and fertilization can be used for alpine grassland restoration in areas with lower precipitation and temperature. Microbial enzymes should not be used to restore degraded alpine grassland on a large scale on the QTP without detailed investigation and analysis. Future studies should pay more attention to the effects of climate factors on degradation processes and specific ecological restoration strategies in different regions of the QTP.

scholarly journals A Meta-Analysis of The Effects of Grazing On Plant Diversity, Biomass and Soil Properties of Alpine Grassland On The Tibetan Plateau

2021 ◽  
Author(s):  
Wenlong Li ◽  
Chenli Liu ◽  
Huakun Zhou ◽  
Wenying Wang ◽  
Jing Xu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Plant Diversity ◽  
Meta Analysis ◽  
Wiener Index ◽  
Belowground Biomass ◽  
Alpine Grassland ◽  
The Tibetan Plateau ◽  
Soil C ◽  
Soil C And N ◽  
C And N

Abstract Aim As one of the main human disturbance factors in the alpine grassland on the Tibetan Plateau, grazing not only directly affects grassland plant diversity and biomass, but also indirectly changes soil carbon (C) and nitrogen (N) of grassland. Despite of extensive field grazing experiments, the impacts of grazing on grassland diversity, soil C and N remain uncertain due to different grazing management.Methods We conducted a meta-analysis of 70 peer-reviewed publications to evaluate the general response of 11 variables related to alpine grassland plant-soil ecosystems to grazing.Results The results showed that grazing significantly increased species richness, Shannon-Wiener index and Pielou evenness index by 9.8%, 7.3% and 3.7%, respectively. Aboveground biomass, belowground biomass, soil organic carbon, soil total nitrogen, soil C: N ratio and soil moisture decreased by 41.9%, 17.7%, 13.1%, 12.6%, 3.3% and 20.8%, respectively. Soil bulk density and soil pH increased by 17.5% and 2.2%, respectively. Specifically, moderate grazing, long-duration (>5 years) and winter grazing contributed to the increase in the species richness, Shannon-Wiener index, and Pielou evenness index. Aboveground biomass, belowground biomass, soil organic carbon, soil total nitrogen and soil C: N ratio showed a decreasing trend with enhanced grazing intensity. Furthermore, grazing duration, grazing season, livestock type and grassland type also affected alpine grassland plant diversity, biomass, soil C and N.Conclusions Grazing is beneficial to the maintenance of plant diversity, but negatively affects the storage of soil C and N in alpine grassland on the Tibetan Plateau. We suggest that grazing should follow intermediate grazing practice and synthesize other appropriate grazing patterns, such as seasonal and rotation grazing, thus, further research on grazing management is needed in this regard.

scholarly journals Response of Lamiophlomis rotata (Benth.) Kudo to degradation of alpine grasslands in the western Sichuan plateau, China

2020 ◽  
Author(s):  
Tong Niu ◽  
Hui Sun ◽  
Rui Gu ◽  
Shihong Zhong ◽  
Lin Liu ◽  
...  
Keyword(s):  
Large Scale ◽  
Alpine Grassland ◽  
Tibetan Medicine ◽  
Tibet Plateau ◽  
Adaptation Mechanism ◽  
Submicroscopic Structure ◽  
Western Sichuan ◽  
Morphological Studies ◽  
Degraded Grassland ◽  
Artificial Cultivation

Abstract Background: Lamiophlomis rotata (Benth.)Kudo, also known as Duyiwei in China, is considered to be one of the most common Tibetan medicine. It is famous for the significant effects on improving blood circulation and relieving pain. Due to the environmental deterioration and excessive consumption, the wild resources of L.rotata is decreasing year by year. However, its artificial cultivation has not been realized. This study aimed to initially explore the adaptation mechanism of L.rotata to degraded alpine grassland, and provide reference for its wild tending and artificial cultivation.Methods: In this study, we used a sample method to conduct a population ecological survey of plants and collect plant leaf samples from mildly, moderately, and extremely degraded grassland. The content of SOD, POD, CAT, PRO, MDA, SS, SP, carotene, chlorophyll A and chlorophyll B in different sample leaves was measured by colorimetry. Microscopic characteristics of the cross-section, epidermis and submicroscopic structure of the leaves were observed and compared.Results: The density of L. rotata in moderately degraded grassland was the highest，where L. rotata had the strongest resistance. And the analysis of seven physiological indicators combined with stress resistance showed that the average content of MDA, SOD, POD, CAT and SS is the highest in L. rotata of the moderately degraded grassland. The microscopic observation showed that, by increasing the thickness of the epidermis, the density of the glandular scales, the proportion of palisade tissue and the number of gland scales, L. rotata was able to adapt to the degraded grassland. Meanwhile, morphological studies have shown that L. rotata could enhance root growth in the degraded grassland. Furthermore, in response to the degradation of alpine grassland on the Qinghai-Tibet Plateau, L. rotata population and biomass distribution in the underground parts have increased. However, L. rotata does not have a competitive advantage in mildly degraded grassland. Compare with the mildly and moderately habitat, the population of L. rotata is small in the extremely degraded habitat.Conclusion: The results showed that among the 3 levels of degraded grassland, L. rotata in the moderately degraded grassland shows the strongest resistance. This study can provide a reference for breeding and ecological planting of L. rotata, suggests that in the nursery stage, the medium degraded grassland should be chosen for ecological breeding to enhance the survival rate of seedlings. While after large-scale planting, reasonable community interventions, like the P. fruticosa+F. rubra community, should be built to simulate the yield of medicinal materials.

scholarly journals Effects of Different Grazing Disturbances on the Plant Diversity and Ecological Functions of Alpine Grassland Ecosystem on the Qinghai-Tibetan Plateau

2021 ◽  
Vol 12 ◽  
Author(s):  
Wenlong Li ◽  
Chenli Liu ◽  
Wenying Wang ◽  
Huakun Zhou ◽  
Yating Xue ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Diversity ◽  
Wiener Index ◽  
Grazing Management ◽  
Alpine Grassland ◽  
Tibet Plateau ◽  
Ecological Functions ◽  
Grassland Ecosystems ◽  
Evenness Index ◽  
General Response

Grazing is one of the main human disturbance factors in alpine grassland on the Qinghai-Tibet Plateau (QTP), which can directly or indirectly influence the community structures and ecological functions of grassland ecosystems. However, despite extensive field grazing experiments, there is currently no consensus on how different grazing management approaches affect alpine grassland diversity, soil carbon (C), and nitrogen (N). Here, we conducted a meta-analysis of 70 peer-reviewed publications to evaluate the general response of 11 variables related to alpine grassland ecosystems plant diversity and ecological functions to grazing. Overall, the results showed that grazing significantly increased the species richness, Shannon–Wiener index, and Pielou evenness index values by 9.89% (95% CI: 2.75–17.09%), 7.28% (95% CI: 1.68–13.62%), and 3.74% (95% CI: 1.40–6.52%), respectively. Aboveground biomass (AGB) and belowground biomass (BGB) decreased, respectively, by 41.91% (95% CI: −50.91 to −32.88%) and 17.68% (95% CI: −26.94 to −8.52%). Soil organic carbon (SOC), soil total nitrogen (TN), soil C:N ratio, and soil moisture decreased by 13.06% (95% CI: −15.88 to −10.15%), 12.62% (95% CI: −13.35 to −8.61%), 3.27% (95% CI: −4.25 to −2.09%), and 20.75% (95% CI: −27.89 to −13.61%), respectively, whereas, soil bulk density and soil pH increased by 17.46% (95% CI: 11.88–24.53%) and 2.24% (95% CI: 1.01–3.64%), respectively. Specifically, moderate grazing, long-durations (>5 years), and winter grazing contributed to increases in the species richness, Shannon–Wiener index, and Pielou evenness index. However, AGB, BGB, SOC, TN, and soil C:N ratios showed a decrease with enhanced grazing intensity. The response ratio of SOC was positively associated with AGB and BGB but was negatively related to the Shannon–Wiener index and Pielou evenness index. Furthermore, the effects of grazing on plant diversity, AGB, BGB, SOC, and TN in alpine grassland varied with grazing duration, grazing season, livestock type, and grassland type. The findings suggest that grazing should synthesize other appropriate grazing patterns, such as seasonal and rotation grazing, and, furthermore, additional research on grazing management of alpine grassland on the QTP is needed in the future.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

Identification of and Correction for Publication Bias: Comment

2019 ◽  
Author(s):  
Amanda Kvarven ◽  
Eirik Strømland ◽  
Magnus Johannesson
Keyword(s):  
Publication Bias ◽  
False Positive ◽  
Large Scale ◽  
Meta Analysis ◽  
False Positive Rate ◽  
Effect Sizes ◽  
Replication Studies ◽  
Moderate Reduction ◽  
Positive Rate ◽  
Meta Analyses

Andrews & Kasy (2019) propose an approach for adjusting effect sizes in meta-analysis for publication bias. We use the Andrews-Kasy estimator to adjust the result of 15 meta-analyses and compare the adjusted results to 15 large-scale multiple labs replication studies estimating the same effects. The pre-registered replications provide precisely estimated effect sizes, which do not suffer from publication bias. The Andrews-Kasy approach leads to a moderate reduction of the inflated effect sizes in the meta-analyses. However, the approach still overestimates effect sizes by a factor of about two or more and has an estimated false positive rate of between 57% and 100%.

Association between ALDH2 Gene Polymorphism and Late-onset Alzheimer Disease: An Up-to-date Meta-analysis

2020 ◽  
Vol 17 (2) ◽  
pp. 105-111
Author(s):  
Haitao Liu ◽  
Wei Ge ◽  
Wei Chen ◽  
Xue Kong ◽  
Weiming Jian ◽  
...  
Keyword(s):  
Gene Polymorphism ◽  
Large Scale ◽  
Late Onset ◽  
Meta Analysis ◽  
Case Control ◽  
Cochrane Library ◽  
Positive Trend ◽  
Case Control Studies ◽  
China National Knowledge Infrastructure ◽  
Aldh2 Gene

Objectives: Previous case-control studies have focused on the relationship between ALDH2 gene polymorphism and late-onset Alzheimer's Disease (LOAD), but no definite unified conclusion has been reached. Therefore, the correlation between ALDH2 Glu504Lys polymorphism and LOAD remains controversial. To analyze the correlation between ALDH2 polymorphism and the risk of LOAD, we implemented this up-to-date meta-analysis to assess the probable association. Methods: Studies were searched through China National Knowledge Infrastructure (CNKI), VIP Database for Chinese Technical Periodicals, China Biology Medicine, PubMed, Cochrane Library, Clinical- Trials.gov, Embase, and MEDLINE from January 1, 1994 to December 31, 2018, without any restrictions on language and ethnicity. Results: Five studies of 1057 LOAD patients and 1136 healthy controls met our criteria for the analysis. Statistically, the ALDH2 GA/AA genotype was not linked with raising LOAD risk (odds ratio (OR) = 1.48, 95% confidence interval (CI) = 0.96-2.28, p = 0.07). In subgroup analysis, the phenomenon that men with ALDH2*2 had higher risk for LOAD (OR = 1.72, 95%CI = 1.10-2.67, p = 0.02) was observed. Conclusions: This study comprehends only five existing case-control studies and the result is negative. The positive trend might appear when the sample size is enlarged. In the future, more large-scale casecontrol or cohort studies should be done to enhance the association between ALDH2 polymorphism and AD or other neurodegenerative diseases.

scholarly journals Large-Scale Analysis of the Spatiotemporal Changes of Net Ecosystem Production in Hindu Kush Himalayan Region

2021 ◽  
Vol 13 (6) ◽  
pp. 1180
Author(s):  
Da Guo ◽  
Xiaoning Song ◽  
Ronghai Hu ◽  
Xinming Zhu ◽  
Yazhen Jiang ◽  
...  
Keyword(s):  
Large Scale ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Carbon Sources ◽  
Spatial Dynamics ◽  
Tibet Plateau ◽  
Geostatistical Model ◽  
Hindu Kush ◽  
Temporal And Spatial ◽  
The Difference

The Hindu Kush Himalayan (HKH) region is one of the most ecologically vulnerable regions in the world. Several studies have been conducted on the dynamic changes of grassland in the HKH region, but few have considered grassland net ecosystem productivity (NEP). In this study, we quantitatively analyzed the temporal and spatial changes of NEP magnitude and the influence of climate factors on the HKH region from 2001 to 2018. The NEP magnitude was obtained by calculating the difference between the net primary production (NPP) estimated by the Carnegie–Ames Stanford Approach (CASA) model and the heterotrophic respiration (Rh) estimated by the geostatistical model. The results showed that the grassland ecosystem in the HKH region exhibited weak net carbon uptake with NEP values of 42.03 gC∙m−2∙yr−1, and the total net carbon sequestration was 0.077 Pg C. The distribution of NEP gradually increased from west to east, and in the Qinghai–Tibet Plateau, it gradually increased from northwest to southeast. The grassland carbon sources and sinks differed at different altitudes. The grassland was a carbon sink at 3000–5000 m, while grasslands below 3000 m and above 5000 m were carbon sources. Grassland NEP exhibited the strongest correlation with precipitation, and it had a lagging effect on precipitation. The correlation between NEP and the precipitation of the previous year was stronger than that of the current year. NEP was negatively correlated with temperature but not with solar radiation. The study of the temporal and spatial dynamics of NEP in the HKH region can provide a theoretical basis to help herders balance grazing and forage.

Legacy effect of warming on the heterotrophic respiration of alpine grassland on the Qinghai-Tibet Plateau

2021 ◽  
Vol 166 ◽  
pp. 104093
Author(s):  
Fei Peng ◽  
Wenjuan Zhang ◽  
Chimin Lai ◽  
Chengyang Li ◽  
Quangang You ◽  
...  
Keyword(s):  
Heterotrophic Respiration ◽  
Alpine Grassland ◽  
Tibet Plateau ◽  
Legacy Effect ◽  
Qinghai Tibet Plateau

Serum Copper Level and Polycystic Ovarian Syndrome: A Meta-Analysis

2021 ◽  
pp. 1-8
Author(s):  
Qingtao Jiang ◽  
Feng Zhang ◽  
Lei Han ◽  
Baoli Zhu ◽  
Xin Liu
Keyword(s):  
Large Scale ◽  
Polycystic Ovarian Syndrome ◽  
Meta Analysis ◽  
Serum Copper ◽  
Copper Level ◽  
Serum Copper Level ◽  
Copper Status ◽  
Plasma Copper ◽  
Mean Differences ◽  
Ovarian Syndrome

<b><i>Introduction:</i></b> The association of serum copper with polycystic ovarian syndrome (PCOS) has been studied for years, but no definite conclusion is drawn. Therefore, we conducted a meta-analysis to investigate serum copper concentrations in PCOS subjects compared with healthy controls. <b><i>Methods:</i></b> Electronic search was performed in PubMed, Google Scholar, and Scopus up to June 30, 2020, without any restriction. Standardized mean differences (SMDs) with corresponding 95% CIs in serum copper levels were employed with random-effects model. <i>I</i><sup>2</sup> was applied to evaluate heterogeneity among studies. <b><i>Results:</i></b> Nine studies, measuring plasma copper levels in 1,168 PCOS patients and 1,106 controls, were included. Pooled effect size suggested serum copper level was significantly higher in women with PCOS (SMD = 0.51 μg/mL, 95% CI = [0.30, 0.72], <i>p</i> &#x3c; 0.0001). The overall heterogeneity was not connected with subgroups of the country, but derived from the opposite result of 1 study. <b><i>Conclusion:</i></b> Our research generally indicated circulating copper level in PCOS sufferers was significantly higher than normal controls. Large-scale studies are still needed to elucidate the clear relation between copper status and etiology of PCOS.

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