46 results on '"Ruirui Yan"'
Search Results
2. Stocking rate changed the magnitude of carbon sequestration and flow within the plant-soil system of a meadow steppe ecosystem
- Author
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Hongbin Xu, Jiaguo Qi, Xiaoping Xin, Jiquan Chen, Linghao Li, Dongyan Jin, Ruirui Yan, and Yuchun Yan
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Topsoil ,Stocking ,Agronomy ,Soil test ,Shoot ,Grazing ,Soil Science ,Environmental science ,Ecosystem ,Plant Science ,Carbon sequestration ,Grazing pressure - Abstract
Livestock grazing is one of the most common utilization methods and exerts a significant effect on the carbon allocations between the above- and belowground components of a grassland ecosystem. The major aim of this study were to evaluate the proportions of 13C allocation to various C pools of the plant-soil system of a meadow steppe ecosystem in response to changes of stocking rate. In situ stable 13C isotope pulse labeling was conducted in a long-term grazing experiment with 4 stocking rate. Plant materials and soil samples were taken at eight occasions (0, 3, 10, 18, 31, 56 and 100 days after labeling) to analyze the decline in 13C over time, and their composition signature of 13C were analyzed by the isotope ratio mass spectrometer technique. We found a significantly greater decline in assimilated 13C of shoot and living root for the heavily grazed swards compared to other stocking rates, with the highest relocation rate of 13C into soil C pool compared to other fractions. In addition, light grazing significantly allocated 13C assimilates in the belowground pool compared to other stocking rates, especially in the live root and topsoil C-pools. In this study, the effects of grazing on the carbon transfers and stocks within the plant-soil system of the meadow steppe were highly grazing pressure dependent. Plant-soil system in light stocking rate presented the highest C utilization efficiency, however, plants allocated more C to soil C pools with heavily stocking rate.
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- 2021
3. Effects of grazing intensity on soil nematode community structure and function in different soil layers in a meadow steppe
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Jinling Zhao, Xiaoping Xin, Jie Shen, Fengjuan Pan, Yanfeng Hu, Linghao Li, Ye Jiang, Ruirui Yan, Neil B. McLaughlin, and Dan Zhao
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Abiotic component ,Biomass (ecology) ,Agronomy ,Soil functions ,Soil water ,Grazing ,Soil Science ,Environmental science ,Soil horizon ,Plant community ,Plant Science ,Water content - Abstract
Aims Grazing is a key driver of plant communities and soil functions in grassland ecosystems. Soil nematodes play a vital role in soil ecological functions. however, few studies have explored how grazing shapes soil nematode community in different soil layers.Methods we investigated the composition, abundance, diversity, metabolic footprint, and food web metrics of soil nematodes over a gradient of grazing in the 0-10 cm and 10-20 cm soil layers in a meadow steppe. The relationships between nematode community structure and biotic and abiotic factors were analyzed by principal component analysis (PCA) and structural equation model (SEM) analysis. Results Light grazing tended to increase the abundance of soil nematodes. Intensive grazing decreased the biomass carbon and metabolic footprints of plant parasites, fungivores, and total soil nematodes in 0-10 cm soils. There was no difference in the biomass carbon and metabolic footprints of soil nematodes among different grazing intensities in the 10-20 cm soil layer. Soil moisture, aboveground biomass, belowground biomass and Shannon diversity of grass contributed more to changes in soil nematode composition in both soil layers. In the 0-10 cm soil layer, grazing directly and indirectly affected soil nematode diversity via soil moisture and aboveground biomass, while grazing directly affected soil nematode diversity in 10-20 cm soil layer. Conclusions Our results indicate that soil depth can weaken the effect of grazing intensities on soil nematode fauna. Grazing affected the soil nematode community structure via different paths in different soil layers.
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- 2021
4. Effects of stocking rate on the interannual patterns of ecosystem biomass and soil nitrogen mineralization in a meadow steppe of northeast China
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Xiaoping Xin, Jinling Zhao, Linghao Li, Zhang Yu, Wang Miao, Ruirui Yan, and Fengjuan Pan
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0106 biological sciences ,Biomass (ecology) ,Grassland degradation ,Soil Science ,Edaphic ,04 agricultural and veterinary sciences ,Plant Science ,Mineralization (soil science) ,Plant litter ,complex mixtures ,01 natural sciences ,Stocking ,Agronomy ,Grazing ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Ecosystem ,010606 plant biology & botany - Abstract
Understanding the effects of livestock grazing on the ecosystem biomass and soil nitrogen processes of grassland ecosystems is critical to improving knowledge on the mechanisms underlying grassland degradation and accurately assessing the influence of grazing management on grassland functions. We examined the interannual patterns of ecosystem biomass and soil nitrogen mineralization in response to cattle grazing in a Chinese meadow steppe. The soil core incubation method was employed for soil N transfer estimation, whilst the fumigation extraction method, a modified Baermann funnel method and harvest method were used for various measurements of ecosystem biomass parameters. We found that cattle grazing caused consistent significant increases in soil temperature, irrespective of the stocking rate and year, whereas significant effects on soil moisture and edaphic properties were observed only in individual years and/or at specific stocking rates. Consistent positive effects at moderate stocking rates were observed for aboveground net primary production and soil nematode biomass in all study years. The across stocking rate pattern of N mineralization in response to cattle stocking appeared to be year-specific, although negative effects were found in most cases. In contrast, the interannual pattern of N mineralization was determined principally by the interannual patterns in precipitation and soil moisture and was much less affected by cattle grazing. Soil N mineralization in this meadow steppe was affected by cattle grazing via two major mechanisms, i.e., its effects on the aboveground net primary production (ANPP) and thus the quantity of plant litter input into the soil and its effects on soil temperature and moisture. Overall, our study spanned the longest consecutive years with the broadest range of stocking rates thus far of its kind, which revealed for the first time that the soil nitrogen mineralization pattern with respect to stocking rate was year-specific. Our findings have important implications for adaptive management and sustainable utilization of Chinese grasslands.
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- 2021
5. Effects of mowing frequency on abundance, genus diversity and community traits of soil nematodes in a meadow steppe in northeast China
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Fengjuan Pan, Ruirui Yan, Yonglei Jiang, Chunge Li, H. Y. Tan, Lu Yang, Yan-Yu Hu, Cunguo Wang, Xiaoping Xin, and J. Cao
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0106 biological sciences ,Biomass (ecology) ,geography ,geography.geographical_feature_category ,Ecology ,Steppe ,Community structure ,Soil Science ,Edaphic ,Plant community ,04 agricultural and veterinary sciences ,Plant Science ,Biology ,01 natural sciences ,Grassland ,Intermediate Disturbance Hypothesis ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Ecosystem ,010606 plant biology & botany - Abstract
Soil nematodes, as key bioindicators, play crucial roles in soil ecological process. Management of grasslands, such as meadow steppes in northeast China, is often done by mowing, which has an impact on soil nematode communities. However, few studies have explored effects of mowing frequency on the community structure and biomass of soil nematodes. Routine field and laboratory methods concerning plant community, soil properties, and soil nematodes were applied in this study. Soil nematode community structure was analyzed by using nonmetric multidimensional scaling (NMDS) and principal component analysis (PCA). The relationships between nematode genus and biotic and abiotic factors were analyzed by redundancy analysis (RDA). High mowing frequency significantly reduced abundance, biomass, and functional or metabolic regimes of soil nematodes in this ecosystem, whereas moderate mowing frequency enhanced those indices and regimes. Our findings showed that changing patterns in nematode indices across the mowing frequency conformed with the intermediate disturbance theory. Variations in soil nematode community were related to changes in belowground biomass, aboveground litter, soil available nitrogen and acidity, and the effects of edaphic and vegetal traits appeared to be trophic or genus-specific. This study has potential benefits for grassland restoration in northeast China.
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- 2020
6. Nitrogen increased aboveground biomass of Leymus chinensis grown in semi‐arid grasslands of inner Mongolia, China
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Jun Zhang, Hong Wang, Yuting Bai, Ruirui Yan, Michael P. Schellenberg, Ruiyang Zhang, Zhijun Wei, and Guodong Han
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Agronomy ,biology ,chemistry ,chemistry.chemical_element ,Environmental science ,Leymus ,China ,Inner mongolia ,biology.organism_classification ,Aboveground biomass ,Agronomy and Crop Science ,Arid ,Nitrogen - Published
- 2020
7. Controls of Seasonal and Interannual Variations on Soil Respiration in a Meadow Steppe in Eastern Inner Mongolia
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Xu Wang, Kaikai Fan, Yuchun Yan, Baorui Chen, Ruirui Yan, Xiaoping Xin, and Linghao Li
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Agronomy and Crop Science ,soil respiration ,grassland ,interannual ,precipitation ,antecedent effects - Abstract
Understanding long-term seasonal and interannual patterns of soil respiration with their controls is essential for accurately quantifying carbon fluxes at a regional scale. During the period from 2009 to 2014, an automatic measurement system (LI-8150, Licor Ldt., Lincoln, NE, USA) was employed for the measurement of soil respiration in a meadow steppe of eastern Inner Mongolia. We found that the seasonal pattern of soil respiration was controlled mainly by the soil temperature, which explained about 82.19% of the variance. Annual soil respiration varied between 391.4 g cm−2 and 597.7 g cm−2, and significantly correlated with soil moisture, suggesting that soil moisture was the most predominant factor controlling the annual variations of soil respiration in this meadow steppe. A double factorial exponential model including both soil temperature (TS) and soil water content (SWC) (y = 6.084 × exp(0.098 TS × SWC) − 5.636) explains 72.2% of the overall variance in soil respiration. We also detected a temporal inconsistency of 2–3 months in the effects of precipitation on soil respiration versus canopy biomass production, which was presumably a main mechanism explaining the weak relationships between soil respiration and phytomass components in this ecosystem. Our findings have important implications for better understanding and accurately assessing the carbon cycling characteristics of terrestrial ecosystems in response to climate change in a temporal perspective.
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- 2022
8. Effects of Livestock Grazing on Interannual Variation of Soil Methane Uptake in an Inner Mongolian Meadow Steppe
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Yuchun Yan, Xiaoping Xin, Changliang Shao, xiaotao lv, Zhang Yu, Jiquan Chen, Jinqiang Chen, Linghao Li, Ruirui Yan, and Xu Wang
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chemistry.chemical_compound ,Variation (linguistics) ,Agronomy ,chemistry ,Meadow steppe ,Livestock grazing ,Environmental science ,Methane - Abstract
Background and aims. This study aimed at identifying the effects of livestock grazing on interannual variation in soil CH4 uptake and underlying mechanisms in a meadow steppe ecosystem. Methods. A multi-year grazing experiment subject to six stocking rates was conducted to quantify CH4 fluxes as well as the changes in driving factors: vegetation traits, soil physicochemical properties and climatic parameters. The closed static chamber technique and a gas chromatograph were used to measure methane fluxes. Multivariate regression analysis was performed to explore empirical relationships. Results. With increasing stocking rate, the multi-year mean CH4 uptake rate decreased in a sigmoid curve-shaped manner, with the threshold point appearing in the light grazing treatment. The interannual changes in soil CH4 uptake were highly dependent on stocking rate, with increasing, leveling and decreasing trends detected with increasing grazing intensity. Major factors affecting CH4 fluxes included vegetation traits, soil moisture, and soil nitrogen content, with the soil NH4+-N content assuming the most important role. However, predominant factors regulating interannual changes in CH4 uptake were rainfall, belowground biomass, and soil nitrogen regime. Conclusions. The steppe ecosystem acted as a CH4 sink, irrespective of stocking rate and year. However, light grazing can be the threshold grazing intensity in terms of both the CH4 uptake potential and primary production in this steppe ecosystem. Our findings have important implications for further understanding magnitudes and regulations of CH4 uptake in grassland soils worldwide.
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- 2021
9. The Impact Of Long-term Grazing Intensity On Functional Groups Richness, Biomass, And Species Diversity In an Inner Mongolian Steppe Grassland
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Yousif Mohamed Zainelabdeen, Ahmed Ibrahim Ahmed, Ruirui Yan, Xiaoping Xin, Cao Juan, and Jimoh Saheed Olaide
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Biomass (ecology) ,Agronomy ,Perennial plant ,Grazing ,Forb ,Species evenness ,Plant community ,Biennial plant ,Species richness ,Biology - Abstract
Livestock grazing is one of the major land uses, causing changes in the plant community's structure and grasslands composition. We assessed the effect of grazing intensity on aboveground biomass, species richness, and plant functional group (PFG) diversity in a temperature meadow steppe in Hulunbuir in northern China, involving 78 plant species from eight functional groups. Four grazing intensity classes were characterized, including light, moderate, heavy, and no grazing, based on stocking rates of 0.23, 0.46, 0.92, and 0.00 animal units per hectare. Our results show that the richness of short species, including perennial short grass, perennial short grass, and legume increased under light to moderate grazing, while no effect of grazing was observed on the richness of shrubs. With increasing grazing intensity, the aboveground biomass of perennial tall grasses and perennial tall forbs decreased significantly, while that of annual/biennial plant functional groups increased. The community diversity and evenness of annual/biennial plants increased significantly with grazing intensity. We concluded that heavy grazing has negative impacts on plant functional group richness and aboveground biomass.
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- 2021
10. Variation of Livestock Grazing Intensity Modified the Magnitude of Carbon Sequestration and Flow within the Plant-Soil System of a Meadow Steppe Ecosystem
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Xiaoping Xin, Jiquan Chen, Ruirui Yan, Yuchun Yan, Jiaguo Qi, Linghao Li, Dongyan Jin, and Hongbin Xu
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Agronomy ,Livestock grazing ,Meadow steppe ,Flow (psychology) ,Environmental science ,Magnitude (mathematics) ,Plant soil ,Ecosystem ,Carbon sequestration ,Intensity (heat transfer) - Abstract
Aims: Livestock grazing, one of the principal utilization patterns, usually exerts a substantial effect on the carbon allocations between the above- and belowground components of a grassland ecosystem. The major aims of this study were to evaluate the proportions of 13C allocation to various C pools of the plant-soil system of a meadow steppe ecosystem in response to livestock grazing intensity.Methods: In situ stable 13C isotope pulse labeling was conducted in the plots of a long-term grazing experiment with 4 levels of grazing intensities. Plant and soil materials were sampled at on eight occasions (0, 3, 10, 18, 31, 56 and 100 days after labeling) to analyze the decline in 13C over time, and their composition signature of 13C were analyzed by the isotope ratio mass spectrometer technique.Results: We found a significantly larger decline in assimilated 13C for the heavily grazed swards compared to other grazing intensities, with the relocation rate of 13C from shoots to belowground C pool being the highest. In contrast, light grazing significantly allocated 13C assimilates in the belowground pool, especially in the live root and topsoil C-pools.Conclusions: The effects of livestock grazing on the carbon transfers and stocks within the plant-soil system of the meadow steppe were highly intensity dependent, and different carbon pools differed in response to gradient changes in grazing intensity.
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- 2021
11. Heavy Grazing Reduces the Diversity of Soil Microbial Communities in Meadow Grassland Under Long-Term Grazing
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Xiaoping Xin, Ruiqiang Li, Zhang Yu, Xu Wang, Linghao Li, Jinqiang Chen, Weibing Xun, Ruirui Yan, and Ruifu Zhang
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geography ,geography.geographical_feature_category ,Ecology ,media_common.quotation_subject ,Grazing ,Environmental science ,Grassland ,Term (time) ,Diversity (politics) ,media_common - Abstract
Background: Soil microorganisms are an important part of the grassland ecosystem and promote material transformation and energy flow in the entire ecological environment. Moreover, Hulun Buir grassland is the material basis for the development of animal husbandry. Therefore, it is of great scientific significance to study the changes of soil microbial community caused by grazing in Hulunbuir grassland for the sustainable and stable development of grassland ecosystem. Methods: The present research used high-throughput sequencing of soil microorganism (bacteria and fungi) genes to compare microbial communities in 6 levels of grazing intensity (0.00, 0.23, 0.34, 0.46, 0.69, and 0.92 Au ha-1) under the Hulun Buir structure and the diversity characteristics of Leymus chinensis meadow steppe.Results: The 0-10 cm soil layer of the G0.34 test area had the highest content, and the content of the G0.92 test area was lower than the other grazing treatments. With increasing depth, the carbon and nitrogen contents of microorganisms decreased. The diversity of soil bacteria in the light grazing test area (0.23Au ha-1) was higher than the heavy grazing area, and the diversity of fungi in the non-grazing area was higher than the specific grazing areas. Most bacterial species were enriched in the G0.00 grazing areas, and the other grazing intensities were less abundant. The underground biomass (P = 0.039) significantly influenced the bacterial community structure, and pH (P =0.032), total nitrogen (P =0.011) and litter (P =0.007) significantly influenced the fungal community.Conclusions: In conclusion, the structures of bacterial and fungal communities are very sensitive to grazing and varied with grazing intensity. Our findings demonstrated that a grazing intensity of approximately 0.23 Au ha-1 was the most appropriate for the grassland of the meadow in Hulun Buir.
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- 2020
12. Response of biomass allocation strategies to plant-soil C:N:P stoichiometry in Alfalfa artificial grassland of different ages on the Mu Us Desert, China
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yuanying li, ruirui yan, Wei Zhang, zhouchang yu, Xiao-ping Xin, yi zhou, Peizhi Yang, and zhiguo xie
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Biomass (ecology) ,geography ,geography.geographical_feature_category ,Chemistry ,fungi ,food and beverages ,Sowing ,Plant soil ,complex mixtures ,Grassland ,Nutrient content ,Animal science ,Medicago sativa ,Soil fertility ,Stoichiometry - Abstract
C:N:P stoichiometry is widely used in ecological research, but its role in the allocation of plant biomass is unclear. To explore this issue, we collected soil and alfalfa samples from 1, 2, 3, 5, 7, 9 and 10 year of alfalfa (Medicago sativa) plantations on the Mu Us Desert, China. We examined the aboveground and underground biomass of each plantation, the C, N, P contents, stoichiometric ratio of plants and soil, and soil biological characteristics. The C content of alfalfa increased first and then decreased with the growth age, which was opposite to N and P content, their most significant changes were in the 7-year stand. The individual changes of C-N-P in alfalfa led to the C:N and C:P increased first and then decreased, N:P increasing with the growth age. Soil OC, TN, C:P and N:P were increasing with the stand age, and TP content and C:N were increasing first and then decreasing. The C contents, C:P and N:P between alfalfa and soil were strongly correlated. N:P and underground biomass were positively correlated, while negatively correlated to aboveground. Our results show that the nutrient content and stoichiometric ratio in soil and plants were closely associated, after 7 years planting, the alfalfa’s growth was limited by P, it responds to the increased N:P by increasing root-shoot ratio, and soil fertility had also been improved at same time. Overall, these results provide a reference for further research on stoichiometry as an indicator to alfalfa yields on the Mu Us Desert.
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- 2020
13. Spatial and temporal variations in fractional vegetation cover and its driving factors in the Hulun Lake region
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Pingping Mao, Jing Zhang, Ming Li, Yiliang Liu, Xu Wang, Ruirui Yan, Beibei Shen, Xiang Zhang, Jie Shen, Xiaoyu Zhu, Dawei Xu, and Xiaoping Xin
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Climate-livestock index ,Spatial-temporal variation ,Ecology ,Fractional vegetation cover ,General Decision Sciences ,Changes in climate parameters ,respiratory system ,QH540-549.5 ,Ecology, Evolution, Behavior and Systematics ,circulatory and respiratory physiology ,respiratory tract diseases - Abstract
Climate change and human activities are critical to fractional vegetation cover (FVC). However, until now, their combined effects on FVC have not been well quantified. In this paper we analyze the temporal and spatial variations in the fractional vegetation cover in the Hulun Lake region from 1986 to 2017 and its response to changes in climate parameters and human activities; additionally, the impact of changes in climate parameters and human activities on FVC are discussed. The results showed that according to the Mann-Kendall (M−K) trend test analysis, 65.01% of the FVC in the Hulun Lake region decreased to varying degrees, of which 24.55% showed a significant decrease and only 8.61% increased significantly. Based on the M−K mutation test analysis of FVC and analysis of driving factors from 1986 to 2017, 1999 was the time point at which abrupt changes in FVC, annual precipitation and moisture index occurred in the Hulun Lake region, and water was an important factor affecting FVC. The regression analysis of FVC and the driving factors from 1986 to 2017 showed that the moisture index and the number of livestock could not be eliminated from the regression equation. Additionally, there was a significant correlation between the FVC and the climate livestock index (P
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- 2022
14. Spatial patterns and driving factors of aboveground and belowground biomass over the eastern Eurasian steppe
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Jingfeng Xiao, Ping Wang, Ming Li, Lei Ding, Dawei Xu, Zhenwang Li, Xu Wang, Xiaoping Xin, Beibei Shen, Ruirui Yan, and Yuchun Yan
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Satellite Imagery ,geography ,Biomass (ecology) ,Environmental Engineering ,geography.geographical_feature_category ,Steppe ,Climate Change ,Temperature ,Grassland degradation ,Biodiversity ,Climate change ,Vegetation ,Grassland ,Pollution ,Arid ,Humans ,Environmental Chemistry ,Environmental science ,Biomass ,Physical geography ,Waste Management and Disposal ,Ecosystem - Abstract
The Eurasian steppe is the largest steppe region in the world and is an important part of the global grassland ecosystem. The eastern Eurasian steppe has favorable hydrothermal conditions and has the highest productivity and the richest biodiversity. Located in the arid and semi-arid region, the eastern Eurasian steppe has experienced large-scale grassland degradation due to dramatic climate change and intensive human activities during the past 20 years. Hence, accurate estimation of aboveground biomass (AGB, gC m−2) and belowground biomass (BGB, gC m−2) is necessary. In this study, plenty of AGB and BGB in-situ measurements were collected among dominated grassland types during summer in 2013 and 2016–2018 in the eastern Eurasian steppe. Vegetation indices from the Moderate Resolution Imaging Spectroradiometer (MODIS), Digital Elevation Model (DEM) and climate variables were chosen as independent variables to establish predictive models for AGB and BGB with random forest (RF). Both AGB (R2 = 0.47, MAE = 21.06 gC m−2, and RMSE = 27.52 gC m−2) and BGB (R2 = 0.44, MAE = 173.02 gC m−2, and RMSE = 244.20 gC m−2) models showed acceptable accuracy. Then the RF models were applied to generate spatially explicit AGB and BGB estimates for the study area over the last two decades (2000–2018). Both AGB and BGB showed higher values in the Greater Khingan Mountains and decreased gradually to the east and west sides. The mean values for AGB and BGB were 62.16 gC m−2 and 531.35 gC m−2, respectively. The climatic factors were much more important in controlling biomass than anthropogenic drivers, and shortage of water and raising temperature were the main limiting factor of AGB and BGB, respectively, in the peak growth season. These findings provide scientific data for the scientific management of animal husbandry and can contribute to the sustainable development of grassland ecology in the eastern Eurasian steppe.
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- 2022
15. Grazing modulates soil temperature and moisture in a Eurasian steppe
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Shijie Lv, Jinqaing Chen, Jiquan Chen, Changliang Shao, Chen Baorui, Xiaoping Xin, Xu Wang, Xu Lijun, Dongyan Jin, Guo Zhenjie, David J. Eldridge, Ruirui Yan, and Yuchun Yan
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Atmospheric Science ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Moisture ,Steppe ,Water storage ,Growing season ,Forestry ,04 agricultural and veterinary sciences ,Snow ,complex mixtures ,01 natural sciences ,Grassland ,Agronomy ,Soil water ,Grazing ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Agronomy and Crop Science ,0105 earth and related environmental sciences - Abstract
Few studies have addressed the potential grazing effects on microclimate, such as surface temperature and moisture, and their feedback effects on grassland function. A continuous, approximately three-year long study was conducted in experimental plots of various grazing intensities, and in situ soil temperature and moisture were measured. The results indicated that grazing significantly altered soil temperature and moisture. Soil temperature increased exponentially with increasing grazing intensity in the warm season due to the removal of aboveground biomass (AGB) and decreased linearly with increasing grazing intensity in the cold season due to decreases in both AGB and wind-blown snow accumulation. Heavy grazing increased soil temperature (10 cm depth) by an average of 2.6 °C from April to October (the largest hourly temperature increase was 8.8 °C), representing a soil warming effect 3.7 times that of global warming. Our findings showed that, compared with ungrazed plots, grazed plots had decreased soil water storage due to less winter snow accumulation, especially in the early growing season (EGS) because of the smaller amount of winter snow accumulation than in ungrazed plots. In the EGS, the average water storage in the 0–100 cm layer of the ungrazed plots was 23.3%, which was 1.3–1.8 times that of the grazed plots. Our results showed that grazing also produced warming and drying effects on grassland soil. The long-term feedback effects of grazing-induced soil warming and drying on the ecosystem might be an important mechanism accelerating the degradation and desertification of these grasslands.
- Published
- 2018
16. Influence of wind erosion on dry aggregate size distribution and nutrients in three steppe soils in northern China
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Dawei Xu, Chen Baorui, Xiaoping Xin, Ruirui Yan, Yuchun Yan, Xu Lijun, Xu Wang, Guo Zhenjie, and Jinqaing Chen
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Hydrology ,Total organic carbon ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Soil test ,Steppe ,04 agricultural and veterinary sciences ,01 natural sciences ,Nutrient ,Soil retrogression and degradation ,Soil water ,040103 agronomy & agriculture ,Erosion ,0401 agriculture, forestry, and fisheries ,Environmental science ,Aeolian processes ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Wind erosion is a key process that causes soil degradation in the semiarid steppe regions of northern China. However, few studies have quantitatively measured the changes in dry aggregate distribution and nutrients in steppe soils under continuously varying wind erosion intensity. The objectives of this study were as follows: (1) to explore the different responses of three steppe soils to natural windblown treatments and (2) to quantify the changes in soil dry aggregate distribution, particle size distribution and soil nutrient contents under various wind erosion intensities for three steppe soils. We obtained samples of the following soils subjected to varying wind intensity via a natural windblown treatment: meadow steppe (MS), typical steppe (TS) and desert steppe (DS). Then, the physical and chemical properties of all soil samples were measured. The results showed that dry aggregate fractions
- Published
- 2018
17. Mapping daily leaf area index at 30 m resolution over a meadow steppe area by fusing Landsat, Sentinel-2A and MODIS data
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Baorui Chen, Jinxun Liu, Xiaoping Xin, Huan Tang, Ruirui Yan, Feng Gao, Xu Wang, Zhiliang Zhu, Beibei Shen, Chengquan Huang, Lei Ding, and Zhenwang Li
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Canopy ,010504 meteorology & atmospheric sciences ,0211 other engineering and technologies ,02 engineering and technology ,Vegetation ,01 natural sciences ,Atmospheric radiative transfer codes ,Spectroradiometer ,General Earth and Planetary Sciences ,Environmental science ,Satellite imagery ,Spatial variability ,Moderate-resolution imaging spectroradiometer ,Leaf area index ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Remote sensing - Abstract
The leaf area index (LAI) is a key vegetation canopy structure parameter and is closely associated with vegetation photosynthesis, transpiration, and energy balance. Developing a landscape-scale LAI dataset with a high temporal resolution (daily) is essential for capturing rapidly changing vegetation structure at field scales and supporting regional biophysical modeling efforts. In this study, two daily 30 m LAI time series from 2014 to 2016 over a meadow steppe site in northern China were generated using a spatial and temporal adaptive reflectance fusion model (STARFM) combined with an LAI retrieval radiative transfer model (PROSAIL). Gap-filled Landsat 7, Landsat 8 and Sentinel-2A surface reflectance (SR) images were used to generate fine-resolution LAI maps with the PROSAIL look-up table method. Two daily 500 m moderate-resolution imaging spectroradiometer (MODIS) LAI product-the existing MCD15A3H LAI product and one was generated from the MCD43A4 SR product and the PROSAIL model, were used to p...
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- 2018
18. Quantitative monitoring of grazing intensity in the temperate meadow steppe based on remote sensing data
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Yuchun Yan, Dawei Xu, Baorui Chen, Xiaoping Xin, Xu Lijun, Ruirui Yan, and Xinbo Sun
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010504 meteorology & atmospheric sciences ,business.industry ,0211 other engineering and technologies ,02 engineering and technology ,01 natural sciences ,Remote sensing (archaeology) ,Meadow steppe ,Grazing ,Temperate climate ,General Earth and Planetary Sciences ,Environmental science ,Livestock ,Physical geography ,business ,Intensity (heat transfer) ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences - Abstract
Grazing intensity (GI) is difficult to measure accurately because of the diversity of grazing livestock, their mobility in the grazing space and the uncertainty of grazing times. Thus, GI monitorin...
- Published
- 2018
19. Attribution of explanatory factors for change in soil organic carbon density in the native grasslands of Inner Mongolia, China
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Phil J. Murray, Chen Baorui, Xiaoping Xin, Dongyan Jin, Zhao Zhang, Yifei Qin, Gele Qing, and Ruirui Yan
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Mixed model ,010504 meteorology & atmospheric sciences ,04 agricultural and veterinary sciences ,Soil carbon ,Management, Monitoring, Policy and Law ,Inner mongolia ,01 natural sciences ,Plant ecology ,Grazing ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Soil horizon ,Soil properties ,Physical geography ,Temporal scales ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology - Abstract
The variation in soil organic carbon density (SOCD) has been widely documented at various spatial and temporal scales. However, an accurate method for examining the attribution of explanatory factors for change in SOCD is still lacking. This study aims to attribute and quantify the key climatic factors, anthropogenic activities, and soil properties associated with SOCD change in the native grasslands of Inner Mongolia, China, by comparing data between the 1960s and the 2010s. In 2007 and 2011, we resampled 142 soil profiles which were originally sampled during 1963–1964 in the native grasslands of Inner Mongolia. SOCD was determined in A horizon (eluvial horizon) of the soil. We selected the explanatory factors based on a random forest method, and explored the relationships between SOCD change and each of the explanatory factors using a linear mixed model. Our results indicated that the change in SOCD varied from the east to the west of Inner Mongolia, and SOCD was 18% lower in the 2010s than in the 1960s. The lower SOCD in the 2010s may primarily be attributed to the increasing in mean annual water surface evaporation, which explained approximately 10% and 50% of the total variation and explainable variation in the change in SOCD, respectively. The sand content of the soil is also a significant explanatory factor for the decrease in SOCD, which explained about 4% and 21% of the total variation and explainable variation in the change in SOCD, respectively. Furthermore, the collection of quantitative information on grazing frequency and duration may also help to improve our understanding of the anthropogenic factors that govern the change in SOCD.
- Published
- 2018
20. Large herbivore-induced changes in phytogenic hillocks: links to soil and windblown sediment on the desert steppe in China
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Tianle Wang, Zhijun Wei, Wenting Liu, Ruirui Yan, and Shijie Lü
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0106 biological sciences ,Herbivore ,Soil texture ,Sediment ,04 agricultural and veterinary sciences ,010603 evolutionary biology ,01 natural sciences ,Arid ,Desert steppe ,Agronomy ,Particle-size distribution ,Grazing ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Ecology, Evolution, Behavior and Systematics ,Hillock - Abstract
Phytogenic hillocks are a type of wind-deposited biological micro-topography exhibiting a bulging shape under plant clusters in arid regions. In this study, we quantitatively measured the phenotypic characteristics of phytogenic hillocks, the soil particle size distribution in phytogenic hillocks and bare surfaces, and the sediment particle size distribution in hillocks of three heights under different grazing treatments. The results showed that the proportion of dense cluster phytogenic hillocks in the no grazing treatment was higher than in the moderate grazing treatment, and the proportion of scattered cluster phytogenic hillocks under moderate grazing was higher than under no grazing. The total area of dense cluster phytogenic hillocks under no grazing was higher than under heavy grazing and under moderate grazing. For the scattered cluster phytogenic hillocks, the total area was greatest under moderate grazing, followed by heavy grazing and, finally, no grazing. For single hillocks, grazing had a significant impact on the width of dense cluster phytogenic hillocks, while the heavy grazing treatment had a significant impact on the height of scattered cluster phytogenic hillocks. The results for windblown sediment showed that the only significant difference among grazing treatments occurred at a height of 2–8 cm. Grazing changed the relationships among the phenotypic characteristics of phytogenic hillocks, the soil particle size of phytogenic hillocks, and the particle size of wind-deposited sediments. Our results suggested that grazing increased the proportion of scattered cluster phytogenic hillocks and caused the relationship between somewhat bare land and phytogenic hillocks to change from symbiosis to competition.
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- 2018
21. Interannual variation in ecosystem respiration in an Inner Mongolian meadow steppe in response to livestock grazing
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Dongyan Jin, Wang Miao, Xiaoping Xin, Ruiqiang Li, Zhang Yu, Ruirui Yan, and Linghao Li
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Canopy ,Abiotic component ,Ecosystem respiration ,Ecology ,Soil nutrient ,Phosphorus ,General Decision Sciences ,Growing season ,chemistry.chemical_element ,Canopy biomass ,Temperate steppe ,Agronomy ,Standing crop ,chemistry ,Grazing intensity ,Grazing ,Environmental science ,Ecosystem ,Soil moisture ,QH540-549.5 ,Ecology, Evolution, Behavior and Systematics - Abstract
Understanding the effects of livestock grazing on ecosystem respiration (Re) of grassland ecosystems is critical for accurately assessing the feedback of grazing management to climate change. We examined ecosystem respiration in response to varying cattle grazing intensities during growing seasons from 2009 to 2018 in a meadow steppe ecosystem of eastern Inner Mongolia. We found that ungrazed swards had the highest mean annual Re rate, with seasonal CVs in Re ranging from 37.53% to 46.04% for all treatments. When all treatments were analysed as a whole, we identified a significant positive relationship between the annual Re rate and annual peak value of standing plant aboveground biomass. Our findings showed that controlling factors on the mean annual Re differed substantially with grazing intensity. In ungrazed and lightly-grazed plots (G0.00 and G0.23), the mean annual Re rate was controlled mainly by canopy height and/or rainfall, while it was controlled more predominantly by contents of NH4+-N and available phosphorus in moderately and heavily grazed plots. We detected significant positive relationships of the annual Re rate with rainfall, soil moisture, ammonium nitrogen, and soil available phosphorus during the entire study period, whereas significant negative relationships were detected between the annual ecosystem respiration rate and the mean growing season temperature, irrespective of grazing intensity. Our findings revealed that grazing could substantially simplify the relationship between the mean annual Re rate and biotic and abiotic parameters. It may be concluded that the relationship between the annual Re rate and the standing crop aboveground biomass was a principal mechanism underlying the effects of gradient grazing on the Re of Chinese meadow steppe ecosystems.
- Published
- 2021
22. The superiority of the normalized difference phenology index (NDPI) for estimating grassland aboveground fresh biomass
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Beibei Shen, Cong Wang, Zhenwang Li, Dawei Xu, Ruirui Yan, Arnon Karnieli, Jin Chen, Yuchun Yan, Baorui Chen, Xu Wang, Xiaoping Xin, Jiquan Chen, Miaogen Shen, and Dameng Yin
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geography ,Biomass (ecology) ,geography.geographical_feature_category ,Phenology ,Soil Science ,Sampling (statistics) ,Geology ,Enhanced vegetation index ,Vegetation ,Grassland ,Normalized Difference Vegetation Index ,Environmental science ,Moderate-resolution imaging spectroradiometer ,Computers in Earth Sciences ,Remote sensing - Abstract
Accurate monitoring of grassland aboveground fresh biomass (called AGB in the study) and its spatial-temporal dynamics is indispensable for sustainable grassland management. The most common method used in estimating AGB with remotely sensed data is based on the relationship between field AGB measurements and vegetation indices (VIs); however, the existing VIs do not deliver adequate results due to the soil background and spatial, temporal and sampling size variability. In this study, the AGB estimation model with the normalized difference phenology index (NDPI) was evaluated in terms of model robustness and spatial and temporal scalability based on comparisons with the widely used ratio vegetation index (RVI), difference vegetation index (DVI), normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), soil-adjusted vegetation index (SAVI), modified soil-adjusted vegetation index (MSAVI), and optimized soil-adjusted vegetation index (OSAVI). The field measurements of AGB of the natural grassland in Inner Mongolia, China, collected in 2013, 2016, and 2017 and Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance products were used for analysis. The results based on training and independent validation data showed the following: (1) The R2 value between AGB and the NDPI was the highest (0.73) among all VIs, followed by soil-line-adjusted VIs, while the R2 values of the RVI and DVI were the lowest; (2) The NDPI-based model had the best robustness for different sampling sizes; (3) The NDPI-based model also had superior spatial and temporal scalability. The results from simulation experiments using the PROSAIL model also support the superiority of the NDPI in estimating AGB. The simulation analysis further reveals that the overall superiority of the NDPI originates from the fact that the NDPI overcomes the adverse impacts of the heterogeneity of the soil background and accounts for changes in the leaf water content that contribute substantially to AGB in grassland. These findings suggest that the NDPI-based AGB estimation model is advantageous for monitoring AGB in large grasslands with significant spatial-temporal heterogeneity.
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- 2021
23. Recognizing black point in wheat kernels and determining its extent using multidimensional feature extraction and a naive Bayes classifier
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Hao Yang, Chengquan Zhou, Guijun Yang, Dong Liang, Liang Han, Linsheng Huang, Lijun Xu, Ruirui Yan, Jun Hu, and Jibo Yue
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0106 biological sciences ,Pixel ,business.industry ,Binary image ,Feature extraction ,Forestry ,Pattern recognition ,04 agricultural and veterinary sciences ,Horticulture ,01 natural sciences ,Computer Science Applications ,Naive Bayes classifier ,Digital image ,Kernel (image processing) ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Segmentation ,Artificial intelligence ,business ,Agronomy and Crop Science ,Image resolution ,010606 plant biology & botany ,Mathematics - Abstract
Accurately identifying black point disease in wheat kernels from random samples within digital images is a fundamental and challenging task in disease identification. The performance of traditional methods is satisfactory in homogeneous environments, but their performance decreases when they are applied to images acquired in dynamic ones. In this paper, a multifeature-based machine learning method is proposed to identify and evaluate the incidence of black point disease. Ten wheat cultivars with different resistances to disease were selected to verify the accuracy of the method. First, a marker-based watershed algorithm was used to separate wheat kernels from the background to accomplish the coarse segmentation. After patches were generated from the coarse segmentation results, the patches were labeled manually and divided into two categories: black point areas and healthy areas. Gabor and Canny operators were used for texture and shape features respectively to build a feature matrix. Then, a classification model based on a naive Bayes classifier was trained to recognize the differences between the two types of patches by their features. The proposed model finally achieved the correct classification of each pixel from the testing sample and output the results in the form of a binary image, thus accomplishing the segmentation of the image. Finally, the severity of the disease was calculated according to the proportion of minimum circumscribed areas of the disease and the total area of the wheat kernel. Through the above operations, the incidence of black point disease in random samples can be determined. Five indicators, Qseg, Sr, Precision, Recall, and F-measure, were used to evaluate the segmentation effects. The average accuracy of segmentation results for the testing samples were 0.85, 0.89, 0.87, 0.86, and 83% respectively. Compared with other segmentation approaches, including the excess green method, the excess green minus excess red method, the color index of vegetation extraction, and two traditional threshold segmentation methods known as Otsu and maximum entropy threshold, the proposed algorithm had greater segmentation accuracy. Moreover, this method was demonstrated to be robust enough to be used for different illumination conditions, shooting angles, and image resolutions.
- Published
- 2021
24. Performances analysis of UAV-assisted wireless powered sensor network
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Jing Yan, Ruirui Yan, and Liming Wang
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Computer science ,business.industry ,Computer Networks and Communications ,Control and Systems Engineering ,Real-time computing ,Wireless ,Electrical and Electronic Engineering ,business ,Wireless sensor network ,Computer Science Applications - Published
- 2021
25. Grazing affects snow accumulation and subsequent spring soil water by removing vegetation in a temperate grassland
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Xiaoping Xin, Jinqiang Chen, Xingliang Xu, Dawei Xu, Dongyan Jin, Ruirui Yan, Yuchun Yan, and Xu Wang
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Canopy ,Temperate grassland ,Environmental Engineering ,010504 meteorology & atmospheric sciences ,Microclimate ,010501 environmental sciences ,Poaceae ,01 natural sciences ,Soil ,Snow ,Spring (hydrology) ,Grazing ,Animals ,Environmental Chemistry ,Herbivory ,Waste Management and Disposal ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,Vegetation ,Grassland ,Pollution ,Agronomy ,Soil water ,Environmental science ,Cattle ,Seasons ,Environmental Monitoring - Abstract
By altering plant and soil properties and microclimate environments, grazing has a profound influence on the structure and function of grassland ecosystems. However, few studies have addressed the potential grazing effects on snow accumulation and subsequent spring soil water after snow melting and soil thawing. In this study, vegetation properties, snow accumulation and soil water were measured in experimental plots subjected to 8 years of cattle grazing comprising six different grazing intensity treatments in a typical temperate grassland in eastern Eurasia. The results indicated that heavy grazing reduced the snow depth by 51% and the snow mass by 40%. Snow accumulation first rapidly increased but then remained relatively stable with increases in both the aboveground biomass and canopy height. An obvious inflection point occurred at approximately 200 g m−2 aboveground biomass and at a 12.5 cm canopy height. The obvious difference in soil water content between the heavily grazed and ungrazed treatments occurred mainly in the spring after snow melting and soil thawing. The spring soil water content (0–30 cm) reached 31.5% in the ungrazed treatment (G0), which was 1.7 times that in the heavily grazed treatment (G0.92). The soil water content increased exponentially with increasing vegetation properties (aboveground biomass, canopy height and canopy cover), and a similar trend occurred with increasing snow mass and snow depth. Our structural equation modeling showed that both vegetation properties and snow accumulation had significant positive effects on spring soil water. By removing vegetation, grazing at increased intensities had significant, indirect suppressive effects on snow accumulation and spring soil water. Therefore, to obtain increased amounts of snow accumulation and spring soil water, land managers should consider reducing the grazing intensity or leaving some plots ungrazed.
- Published
- 2019
26. Additional file 1: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Figure S1. Sketch map of the experimental site. (PDF 133 kb)
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- 2018
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27. Additional file 4: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Table S2. Detailed soil incubation conditions for moisture and/or temperature perturbance testing. (DOCX 16 kb)
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- 2018
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28. Additional file 5: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Figure S3. Heatmap for (A) bacterial and (B) fungal communities. Color scale from greatest (red) to lowest (green) relative abundances within rows. Only the classifiable microbial classes are shown. (PDF 301 kb)
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- 2018
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29. Additional file 7: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
- Abstract
Figure S5. Soil bacterial activity represented by the ratio of enzymatic activity to bacterial abundance under a temperature gradient. n = 1224 for each segmented graph (2 microcosm replicates for each treatment × 3 temperature levels × 17 soil samples per plot × 3 plot replicates × 4 grazing intensities = 1224 microcosms). Only the significantly correlated activity and bacterial abundance were calculated. (PDF 8671 kb)
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- 2018
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30. Additional file 8: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Figure S6. Soil bacterial activity represented by the ratio of enzymatic activity to bacterial abundance under a water content gradient. n = 1224 for each segmented graph (2 microcosm replicates for each treatment × 3 water content levels × 17 soil samples per plot × 3 plot replicates × 4 grazing intensities = 1224 microcosms). Only the significantly correlated activity and bacterial abundance were calculated. (PDF 8614 kb)
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- 2018
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31. Additional file 6: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Figure S4. Bacterial and fungal (A) α-diversity (local OTU richness); (B) γ-diversity (regional OTU richness); (C) β-diversity (unweighted Unifrac distance); (D) β-diversity (weighted Unifrac distance). Statistical analyses were performed independently for diversity indices at two seasons using Duncan’s multiple comparison test. The results were shown with colored letters a to d. Differences between samples of the same treatment at two seasons were performed using Tukey’s HSD test and indicated by symbols * (**: P
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- 2018
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32. Additional file 2: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
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Figure S2. Sampling scheme. A total of 17 soil cores (red points in the diagram) were taken from each plot. (PDF 18 kb)
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- 2018
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33. Additional file 10: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
- Abstract
Figure S8. Soil fungal activity represented by the ratio of enzymatic activity to fungal abundance under a water content gradient. n = 1224 for each segmented graph (2 microcosm replicates for each treatment × 3 water content levels × 17 soil samples per plot × 3 plot replicates × 4 grazing intensities = 1224 microcosms). Only the significantly correlated activity and bacterial abundance were calculated. (PDF 8195 kb)
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- 2018
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34. Additional file 9: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
- Abstract
Figure S7. Soil fungal activity represented by the ratio of enzymatic activity to fungal abundance under a temperature gradient. n = 1224 for each segmented graph (2 microcosm replicates for each treatment × 3 temperature levels × 17 soil samples per plot × 3 plot replicates × 4 grazing intensities = 1224 microcosms). Only the significantly correlated activity and bacterial abundance were calculated. (PDF 7855 kb)
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- 2018
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35. Additional file 3: of Grazing-induced microbiome alterations drive soil organic carbon turnover and productivity in meadow steppe
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Weibing Xun, Ruirui Yan, Ren, Yi, Dongyan Jin, Xiong, Wu, Guishan Zhang, Zhongli Cui, Xiaoping Xin, and Ruifu Zhang
- Abstract
Table S1. Soil water content (%) at sampling times (June and August, 2015). (DOCX 16 kb)
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- 2018
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36. Comparison of two inversion methods for leaf area index using HJ-1 satellite data in a temperate meadow steppe
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Hongbin Zhang, Baorui Chen, Xiaoping Xin, Xiaoyu Li, Ruirui Yan, Baohui Zhang, Qiong Wu, Yuhai Bao, Yunxiang Jin, Zhenwang Li, and Quansheng Hai
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Canopy ,geography ,geography.geographical_feature_category ,Inversion methods ,Soil science ,Inner mongolia ,Grassland ,Satellite data ,Meadow steppe ,Temperate climate ,General Earth and Planetary Sciences ,Environmental science ,Physical geography ,Leaf area index - Abstract
Leaf area index LAI is one of the most important parameters for determining grassland canopy conditions. LAI controls numerous biological and physical processes in grassland ecosystems. Remote-sensing techniques are effective for estimating grassland LAI at a regional scale. Comparison of LAI inversion methods based on remote sensing is significant for accurate estimation of LAI in particular areas. In this study, we developed and compared two inversion models to estimate the LAI of a temperate meadow steppe in Hulunbuir, Inner Mongolia, China, based on HJ-1 satellite data and field-measured LAI data. LAI was measured from early June to late August in 2013, obtained from 326 sampling data. The back propagation BP neural network method proved better than the statistical regression model for estimating grassland LAI, the accuracy of the former being 82.8%. We then explored the spatio-temporal distribution in LAI of Stipa baicalensis Roshev. in the meadow steppe of Hulunbuir, including cut, grazed, and fenced plots. The LAI in the cut and grazed plots reflected the growth variations in S. baicalensis Roshev. However, because of the obvious litter layer, the LAI in the fenced plots was underestimated.
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- 2015
37. Variation of soil respiration and its environmental factors in Hulunber meadow steppe
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Shu Zhao, Xin Xiaoping, Guixia Yang, Ruirui Yan, Yuchun Yan, and Xu Wang
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Soil respiration ,Animal science ,Meadow steppe ,Diurnal temperature variation ,Soil water ,Q10 ,Environmental science ,Growing season ,Soil science ,General Medicine ,Diel vertical migration ,Morning - Abstract
In order to understand the variations of soil respiration with the controlling environmental factors, continuous monitoring was carried out in Hulunber meadow steppe by an automated chamber system, LI-8150, from 2009 to 2011. The results showed that soil respiration exhibited an apparent diurnal variation and seasonal dynamics. Diel maximum soil respiration often appeared between 13:00 and 14:00, while the minimum occurred between 4:00 and 5:00 in the morning. Soil respiration in the growing season from May to September was higher than that in the non-growing season. The peak value often occurred in July and August and the lowest was close to zero in winter. Soil respiration had a significant exponential relationship with soil temperature at 5 cm depth (P < 0.01), which could explain the 86.1–91.1% variation in soil respiration. A significant linear relationship was indicated between soil respiration and soil water content at 10 cm depth (P < 0.05). Soil respirations in 2009, 2010 and 2011 were estimated to be 465.0 gC m−2, 539.2 gC m−2 and 553.2 gC m−2 respectively. In addition, the temperature sensitivities of soil respiration (Q10) were calculated as 3.32, 3.55 and 4.05, respectively. The value of Q10 could cause a lower evaluation derived from observation in a short time, such as considering only the growing season. Field observation of soil respiration should cover all the possible time in the whole year, including the growing and non-growing seasons.
- Published
- 2015
38. Impacts of Differing Grazing Rates on Canopy Structure and Species Composition in Hulunber Meadow Steppe
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Linghao Li, Ruirui Yan, Yuchun Yan, Shimin Liu, Xu Wang, Yu Deng, Xiaoping Xin, Baohui Zhang, and Guixia Yang
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Canopy ,Ecology ,food and beverages ,Species diversity ,Management, Monitoring, Policy and Law ,Biology ,Intermediate Disturbance Hypothesis ,Standing crop ,Agronomy ,Grazing ,Dominance (ecology) ,Animal Science and Zoology ,Species richness ,Conservation grazing ,Nature and Landscape Conservation - Abstract
In this study, the impacts of cattle grazing with differing grazing rates on species composition, canopy structural traits, standing crop of canopy biomass, and plant species diversity were examined in a meadow steppe of the Hulunber grasslands, Northeastern China. Six stocking-rate treatments (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU.ha - 1 ) with three replicates were established, and observations were conducted from 2009 to 2011. Our findings demonstrate that short-term grazing substantially altered the species composition and relative dominance, standing crop of aboveground biomass, and canopy structural traits, whereas no significant changes in species diversity and evenness occurred in response to different-rated grazing in this meadow steppe, which has a long-term evolutionary grazing history and high-resources availabilities. We found that perennial graminoid significantly decreased, while forbs and annuals increased at the same time, with increasing grazing intensity and duration; canopy height and coverage decreased substantially with increasing stocking rates, whereas significant changes in plant density occurred only at heavy grazing in the second and third years; and significant negative linear relations were found between the standing crop of biomass and grazing intensity in each individual year or for 3 years on average. Significantly highest species richness and canopy dominance occurred only at the intermediate grazing rate in the third year, and intermediate grazing intensity also maintained a highly constant standing crop of canopy biomass in the 3 years, all being in accordance with the intermediate disturbance hypothesis. Our findings imply that monitoring changes in species composition, canopy traits, and standing crop of biomass in grassland communities can provide important references for assessing current grazing management scenarios and conducting timely adaptive practices to maintain the long-term ability of grassland systems to perform their ecological functions.
- Published
- 2015
39. Grazing Affects the Ecological Stoichiometry of the Plant–Soil–Microbe System on the Hulunber Steppe, China
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Yunlong Zhang, Yongjuan Zhang, Xiaoyong Chen, Xu Wang, Xiaoping Xin, Chen Ning, Juan Cao, Hou Lulu, Qiang Yu, and Ruirui Yan
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0106 biological sciences ,Nutrient cycle ,N-limitation ,Steppe ,animal diseases ,Geography, Planning and Development ,TJ807-830 ,chemistry.chemical_element ,Management, Monitoring, Policy and Law ,TD194-195 ,complex mixtures ,010603 evolutionary biology ,01 natural sciences ,Renewable energy sources ,belowground ,Nutrient ,parasitic diseases ,Ecological stoichiometry ,Grazing ,GE1-350 ,natural sciences ,nutrient ratios ,geography ,Rhizosphere ,Biomass (ecology) ,geography.geographical_feature_category ,Environmental effects of industries and plants ,microbial biomass ,temperate meadow steppe ,Renewable Energy, Sustainability and the Environment ,Phosphorus ,food and beverages ,04 agricultural and veterinary sciences ,Environmental sciences ,Agronomy ,chemistry ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,rhizosphere ,aboveground - Abstract
Grazing affects nutrient cycling processes in grasslands, but little is known by researchers about effects on the nutrient stoichiometry of plant&ndash, soil&ndash, microbe systems. In this study, the influence of grazing intensity (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU ha&minus, 1) on carbon (C), nitrogen (N) and phosphorus (P) and their stoichiometric ratios in plants, soil, and microbes was investigated in a Hulunber meadow steppe, Northeastern China. The C:N and C:P ratios of shoots decreased with grazing increased. Leaf N:P ratios <, 10 suggested that the plant communities under grazing were N-limited. Heavy grazing intensities increased the C:N and C:P ratios of microbial biomass, but grazing intensity had no significant effects on the stoichiometry of soil nutrients. The coupling relationship of C:N ratio in plant&ndash, microbial systems was tightly significant compared to C:P ratio and N:P ratio according to the correlation results. The finding suggested grazing exacerbated the competition between plants and microorganisms for N and P nutrition by the stoichiometric changes (%) in each grazing level relative to the no grazing treatment. Therefore, for the sustainability of grasslands in Inner Mongolia, N inputs need to be increased and high grazing intensities reduced in meadow steppe ecosystems, and the grazing load should be controlled within G0.46.
- Published
- 2019
40. Quantitative effects of wind erosion on the soil texture and soil nutrients under different vegetation coverage in a semiarid steppe of northern China
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Xingliang Xu, Guixia Yang, Chen Baorui, Xiaoping Xin, Xu Wang, Ruirui Yan, and Yuchun Yan
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Soil test ,Soil texture ,Soil retrogression and degradation ,Erosion ,Soil Science ,Environmental science ,Soil science ,Plant Science ,Dryland salinity ,Vegetation ,Soil carbon ,Soil conservation ,complex mixtures - Abstract
Many studies reported the influence of wind erosion on soil degradation and the effect of vegetation coverage on preventing wind erosion. However, fewer studies have quantitatively measured the grassland soil particle size fractions and nutrients’ loss caused by wind erosion under different vegetation coverage. Aims: We conducted a field experiments to (1) to explore the effect of vegetation coverage on soil wind erosion; (2) examine quantitatively the effects of wind erosion on soil texture, and determine the most erodible particles fraction of soil; (3) to examine quantitatively the soil carbon, nutrients such as nitrogen and phosphorus loss caused by wind erosion under different vegetation coverage. Methods: Six vegetation coverage treatments (0 %, 15 %, 35 %, 55 %, 75 % and 95 %) were constructed. To be able to monitor wind erosion status under more diverse weather conditions, three consecutive repeat experiments under different weather condition were conducted. Results: The results show that all the residue soil samples after wind erosion became coarser than that of original soil samples. The degree of change for the soil particle size distribution before and after wind erosion gradually increased with the less of vegetation coverage. The critical particle size for distinguishing the original soil sample and the residue soil after wind erosion occurred in the range of 125 μm and 210 μm depending on the vegetation cover. The fractions below or above the critical particle size are either easy to deplete or favoured by wind erosion, respectively. The most reduction occurs between 50 and 90 μm depending on the different weather condition and vegetation coverage. Due to the disproportionately greater amounts of nutrients in the fine soil particles, the preferential depletion of fine particles directly lead to a preferentially significant depletion of organic carbon and nutrients. The organic carbon and nutrient contents in the residue soil after erosion decreased significantly compared to that in the original soil. The soil nutrient loss ratio decrease significantly with the increase of vegetation coverage. Conclusions: Wind erosion is an important factor to affect the evolution of soil texture and soil nutrient. Vegetation coverage has a major impact on both preventing wind erosion and decreasing loss ratio of fine particles and nutrients. If we want to effectively protect the fine particles and nutrients, the vegetation cover should be maintained at least above 35 %.
- Published
- 2013
41. Effect of vegetation coverage on aeolian dust accumulation in a semiarid steppe of northern China
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Guixia Yang, Chen Baorui, Xingliang Xu, Ruirui Yan, Yuchun Yan, Xiaoping Xin, and Xu Wang
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Total organic carbon ,Hydrology ,geography ,geography.geographical_feature_category ,Steppe ,Soil texture ,Field experiment ,complex mixtures ,Grassland ,Nutrient ,medicine ,Environmental science ,Aeolian processes ,medicine.symptom ,Vegetation (pathology) ,Earth-Surface Processes - Abstract
Wind erosion and sand storms are common phenomena in semiarid steppes of northern China and could have important impact on soil nutrient balances. Vegetation coverage is one of the key factors influencing wind erosion and aeolian dust accumulation. We conducted a field experiment to investigate the effects of vegetation coverage on airborne dust accumulation and evaluated effects of dust input on the contribution of nutrients to vegetation-mulched fields. Five vegetation coverage treatments (15%, 35%, 55%, 75% and 95%) were constructed, with 0% coverage as a control. Vegetation coverage significantly affected dust accumulation in degenerated semiarid grasslands. The amounts of dust trapped by the increasing coverages were 1.7, 1.8, 2.0, 2.1 and 2.1 times of that by the control plot, respectively. The total accumulations reached a maximum of 2.5 g m(-2) day(-1) at 75% coverage and remained stable with further increasing vegetation coverage. The particles in the dust trapped by treatment without vegetation coverage were significantly coarser than those by treatments with vegetation. In addition, the dust trapped by treatments with vegetation contained more organic carbon, nitrogen and phosphorus content than that by the control plot. This finding indicates that areas with higher vegetation coverage can obtain more nutrients by trapping airborne dust in semiarid steppes. (C) 2011 Elsevier B.V. All rights reserved.
- Published
- 2011
42. MicroRNA-106a functions as an oncogene in human gastric cancer and contributes to proliferation and metastasis in vitro and in vivo
- Author
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Ning Zhang, Jun Zhang, Meng Zhu, Shuixiang He, and Ruirui Yan
- Subjects
0301 basic medicine ,Cancer Research ,Apoptosis ,Biology ,Metastasis ,03 medical and health sciences ,Mice ,Cell Movement ,Stomach Neoplasms ,Cell Line, Tumor ,microRNA ,medicine ,Animals ,Humans ,Neoplasm Metastasis ,Cell Proliferation ,Tissue Inhibitor of Metalloproteinase-2 ,Oncogene ,Cell growth ,Cancer ,Antagomirs ,General Medicine ,Apoptotic body ,medicine.disease ,Molecular biology ,Xenograft Model Antitumor Assays ,Gene Expression Regulation, Neoplastic ,MicroRNAs ,030104 developmental biology ,Oncology ,Gene Knockdown Techniques ,Cancer cell - Abstract
Mounting evidences has shown that miRNAs are involved in the development and progression of gastric cancer acts as tumor suppressor genes or oncogenes. In our previous studies, we have found that the up-regulation of miR-106a occurs frequently in human gastric cancer tissues compared with that of normal tissues. Here, we investigate the role of the ectopic expressed miR-106a in the progression and metastasis of gastric cancer in vitro and in vivo. FFPE samples have the priority to be included and qRT-PCR was used to detect the miR-106a expression. Human gastric cancer cells and immortalized gastric epithelial cell were selected and the miR-106a mimic and inhibitor were transfected. Cell growth was determined by MTT method. The flow cytometric analysis for cell apoptosis and transwell assays for evaluating the cell migration and invasion were conducted. Luciferase assay and western blot confirmed the direct binding site of miR-106a and its target. BALB/c nude mice were randomly divided to explore the implantation of gastric cancer cells transfected with miR-106a antagomir. Abnormal over-expression of miR-106a significantly promoted gastric cancer cell proliferation, metastasis, inhibited the cell apoptosis. Functional experiment ascertained that miR-106a interacted with FAS and mediated caspase3 pathway. Knockdown of miR-106a leaded to the attenuation of gastric cancer implantation capacity in vivo. Moreover, expression of TIMP2 was inversely associated with miR-106a in nodule tissues. Apoptotic body was also seen under electron microscope accompanied by silencing of miR-106a. Together, this data indicated that miR-106a may act as an oncogene and contribute to gastric cancer development.
- Published
- 2015
43. Grazing intensity and driving factors affect soil nitrous oxide fluxes during the growing seasons in the Hulunber meadow steppe of China
- Author
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Huajun Tang, Yunchun Yan, Chen Baorui, Philip J. Murray, Xu Wang, Guixia Yang, Xiaoping Xin, and Ruirui Yan
- Subjects
driving factor ,010504 meteorology & atmospheric sciences ,Steppe ,Growing season ,01 natural sciences ,meadow steppe ,Soil pH ,Grazing ,Nitrogen cycle ,Water content ,0105 earth and related environmental sciences ,General Environmental Science ,Biomass (ecology) ,geography ,geography.geographical_feature_category ,Renewable Energy, Sustainability and the Environment ,Public Health, Environmental and Occupational Health ,Plant community ,04 agricultural and veterinary sciences ,soil N2O fluxes ,grazing intensity ,Agronomy ,response and mechanism ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science - Abstract
In this study, the effects of cattle grazing intensity on soil nitrous oxide (N2O) fluxes were examined in the Hulunber meadow steppe of north-eastern China. Six stocking-rate treatments (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU ha−1) with three replicates were established, and observations were conducted from 2010 to 2014. Our results showed that substantial temporal fluctuations in N2O flux occurred amongst the different grazing intensities, with peak N2O fluxes after natural rainfall. Grazing had a long-term effect on the soil N2O flux in the grasslands. After 4–5 years of grazing, the N2O fluxes under increased levels of grazing intensity began to decrease significantly by 31.4%–60.2% in 2013 and 32.5%–50.5% in 2014 compared to the non-grazing treatment. We observed a significant negative linear relationship between the soil N2O fluxes and grazing intensity for the five-year mean. The soil N2O flux was significantly affected each year in all of the treatments. Over the five years, the temporal coefficient of variation (CVs) of the soil N2O flux generally declined significantly with increasing grazing intensity. The soil N2O emission rate was significantly positively correlated with soil moisture (SM), soil available phosphorus (SAP), soil ${{{\rm{NH}}}_{4}}^{+}-N,$ soil ${{{\rm{NO}}}_{3}}^{-}-N,$ above-ground biomass (AGB), plant ground cover and height and was negatively correlated with total soil nitrogen (TN). Stepwise regressions showed that the N2O flux was primarily explained by SM, plant height, TN, soil pH, and soil ${{{\rm{NH}}}_{4}}^{+}-N.$ Using structural equation modelling, we show that grazing significantly directly influenced the plant community and the soil environment, which then influenced the soil N2O fluxes. Our findings provide an important reference for better understanding of the mechanisms and identifying the pathways of grazing effects on soil N2O emission rates, and the key drivers plant community and soil environment within the nitrogen cycle that are mostly likely to affect N2O emissions in the Inner Mongolian meadow steppes.
- Published
- 2016
44. Impacts of Different grazing Rates on Canopy Structure and Species Composition in Hulunber Meadow Steppe
- Author
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Ruirui Yan, Xiaoping Xin, Yuchun Yan, Xu Wang, Baohui Zhang, Guixia Yang, Shimin Liu, Yu Deng, and Linhao LI
- Subjects
Ecology ,Animal Science and Zoology ,Management, Monitoring, Policy and Law ,Nature and Landscape Conservation - Published
- 2014
45. Monitoring and Modeling of Grassland Ecosystem Function Based on Remote Sensing and Field Observation
- Author
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Baohui Zhang, Chen Baorui, Ruirui Yan, Yuchun Yan, Huajun Tang, Xiaoping Xin, Guixia Yang, Gang Li, Hongbin Zhang, and Xu Wang
- Subjects
Remote sensing (archaeology) ,media_common.quotation_subject ,Environmental science ,Plant Science ,Function (engineering) ,Grassland ecosystem ,Agronomy and Crop Science ,Remote sensing ,Field observation ,media_common - Published
- 2009
46. Vegetation patches increase wind-blown litter accumulation in a semi-arid steppe of northern China
- Author
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Xu Wang, Philip J. Murray, Ruirui Yan, Yuchun Yan, Xiaoping Xin, and Xingliang Xu
- Subjects
010504 meteorology & atmospheric sciences ,Renewable Energy, Sustainability and the Environment ,Ecology ,ved/biology ,Soil organic matter ,ved/biology.organism_classification_rank.species ,Public Health, Environmental and Occupational Health ,04 agricultural and veterinary sciences ,Vegetation ,Plant litter ,01 natural sciences ,Arid ,Shrub ,Spatial heterogeneity ,Nutrient ,Agronomy ,040103 agronomy & agriculture ,Litter ,0401 agriculture, forestry, and fisheries ,Environmental science ,reproductive and urinary physiology ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Litter decomposition is an important source of soil organic matter and nutrients; however, few studies have explored how vegetation patches affect wind-driven litter mobility and accumulation. In this study, we aimed to test the following hypotheses: (1) vegetation patches can reduce litter removal and facilitate litter accumulation, (2) litter mobility results in the heterogeneous redistribution of carbon and nutrients over the land surface, and (3) litter removal rates differ among different litter types (e.g., leaf and stem). Four vegetation patch types and six litter types were used to investigate the impacts of vegetation patches on litter mobility and accumulation. The results show that compared with almost bare ground patches, patches with vegetation cover had significantly higher litter accumulation, with the shrub patch type having the highest accumulation amount. The rate of litter removal due to wind was highest for the almost bare surface type (P4) and lowest for the shrub patch (P1) and Stipa grandis community (P2) types. There were significant differences in the removal rate among the different litter types. These findings indicate that wind-based litter redistribution among bare, S. grandis-dominated, and shrub-dominated patches is at least partially responsible for increasing the spatial heterogeneity of resources on a landscape scale.
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