scholarly journals Multi-Year NDVI Values as Indicator of the Relationship between Spatiotemporal Vegetation Dynamics and Environmental Factors in the Qaidam Basin, China

2021 ◽  
Vol 13 (7) ◽  
pp. 1240
Author(s):  
Junpeng Lou ◽  
Guoyin Xu ◽  
Zhongjing Wang ◽  
Zhigang Yang ◽  
Sanchuan Ni
Keyword(s):  
Environmental Factors ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Qaidam Basin ◽  
Elevation Gradient ◽  
Practical Significance ◽  
Elevation Gradients ◽  
Relative Contribution ◽  
Significant Difference ◽  
Different Altitudes

The Qaidam Basin is a unique and complex ecosystem, wherein elevation gradients lead to high spatial heterogeneity in vegetation dynamics and responses to environmental factors. Based on the remote sensing data of Moderate Resolution Imaging Spectroradiometer (MODIS), Tropical Rainfall Measuring Mission (TRMM) and Global Land Data Assimilation System (GLDAS), we analyzed the spatiotemporal variations of vegetation dynamics and responses to precipitation, accumulative temperature (AT) and soil moisture (SM) in the Qaidam Basin from 2001 to 2016. Moreover, the contribution of those factors to vegetation dynamics at different altitudes was analyzed via an artificial neural network (ANN) model. The results indicated that the Normalized Difference Vegetation Index (NDVI) values in the growing season showed an overall upward trend, with an increased rate of 0.001/year. The values of NDVI in low-altitude areas were higher than that in high-altitude areas, and the peak values of NDVI appeared along the elevation gradient at 4400–4600 m. Thanks to the use of ANN, we were able to detect the relative contribution of various environmental factors; the relative contribution rate of AT to the NDVI dynamic was the most significant (35.17%) in the low-elevation region (< 2900 m). In the mid-elevation area (2900–3900 m), precipitation contributed 44.76% of the NDVI dynamics. When the altitude was higher than 3900 m, the relative contribution rates of AT (39.50%) and SM (38.53%) had no significant difference but were significantly higher than that of precipitation (21.97%). The results highlight that the different environmental factors have various contributions to vegetation dynamics at different altitudes, which has important theoretical and practical significance for regulating ecological processes.

scholarly journals Diversity And Distribution Of CO2-Fixing Microbial Community Along Elevation Gradients In Meadow Soils On The Tibetan Plateau

2021 ◽  
Author(s):  
Haiyan Feng ◽  
Zhe Wang ◽  
Pengli Jia ◽  
Jingping Gai ◽  
Baodong Chen ◽  
...  
Keyword(s):  
Microbial Community ◽  
Tibetan Plateau ◽  
Environmental Factors ◽  
Carbon Cycling ◽  
Elevation Gradient ◽  
Microbial Community Composition ◽  
Vegetation Coverage ◽  
The Tibetan Plateau ◽  
Elevation Gradients ◽  
Bisphosphate Carboxylase

Abstract Soil CO2-fixing microbes play a significant role in CO2-fixation in the terrestrial ecosystems, particularly in the Tibetan Plateau. To understand carbon sequestration by soil CO2-fixing microbes and the carbon cycling in alpine meadow soils, microbial diversity and their driving environmental factors were explored along an elevation gradient from 3900m to 5100m, on both east and west slopes of Mila Mountain region on the Tibetan Plateau. The CO2-fixing microbial communities were characterized by high-throughput sequencing targeting the cbbL gene，encoding the large subunit for the CO2-fixing protein ribulose 1, 5-bisphosphate carboxylase/oxygenase. The overall OTU abundance is concentrated at an altitude between 4300m~4900m. The species richness and distribution uniformity on the east slope is better than those on the west slope. In terms of microbial community composition, Proteobacteria is dominant, and the most abundant genera are Cupriavidus, Rhodobacter, Sulfurifustis and Thiobacillus. The CO2-fixing microbial community structure dramatically shifted along the elevation. It was jointly driven by vegetation coverage, soil moisture content, and soil organic carbon and soil particle size, and most environmental factors are positively correlated. Our results are helpful to understand the variation in soil microbial community and its role in soil carbon cycling along elevation gradients.

scholarly journals Characteristics of Culturable Microbial Community in Rhizosphere/Non-rhizosphere Soil of Potentilla Fruticosa Population in Alpine Meadow Elevation Gradient

2021 ◽  
Vol 1 ◽  
Author(s):  
Minxia Liu ◽  
Bowen Li ◽  
Lu Xu ◽  
Ruixin Yu
Keyword(s):  
Environmental Factors ◽  
Functional Groups ◽  
Environmental Changes ◽  
Rhizosphere Soil ◽  
Alpine Meadow ◽  
Elevation Gradient ◽  
Limiting Factor ◽  
Elevation Gradients ◽  
Potentilla Fruticosa ◽  
Microbial Functional Groups

Potentilla fruticosa is a typical shrub of alpine meadows with canopy effects that can greatly influence soil fertility and microbiological parameters. Changes in rhizosphere microorganisms can reflect the response of these plants to environmental changes. This study aimed to examine the rhizosphere and non-rhizosphere of P. fruticosa on the amount of selected microorganisms and main environmental factors at different elevation gradients (3,000, 3,250, 3,500, 3,750, and 4,000 m). The results suggested that bacteria were predominant of the microbial soil community in the rhizosphere and non-rhizosphere, while fungi and actinomycetes represented the minority. With the increase of altitude, the total amount of microbial, bacteria, and actinomycetes in the rhizosphere and non-rhizosphere of P. fruticosa showed a downward trend, and microbial functional groups showed that the “hump shape” changed, but the fungi showed the opposite. Variance inflation factor (VIF) screening environmental factors and path analysis were obtained. In the rhizosphere soil, bacteria were affected by Soil organic carbon (SOC), and soil bulk density (SBD) became the main environmental limiting factor with the increase of altitude. The main environmental limiting factor of actinomycetes changed from SBD to Soil total (ST). In the non-rhizosphere soil, the bacteria and actinomycetes changed from ST to SOC and SBD, respectively. The main environmental limiting factor of the fungi was SOC in the rhizosphere and non-rhizosphere. Soil water content (SWC) was the main environmental determinant factor for all microbial groups, microbial functional groups were related to Soil total nitrogen (STN). Our results help to understand the relationship between nutrient cycling and the ecosystem function of alpine meadow plant soil microorganisms and provide theoretical support for alpine meadow ecosystem restoration, biodiversity protection, and the use of microbial resources.

scholarly journals Spatio-Temporal Characteristics of Drought Events and Their Effects on Vegetation: A Case Study in Southern Tibet, China

2020 ◽  
Vol 12 (24) ◽  
pp. 4174
Author(s):  
Zu-Xin Ye ◽  
Wei-Ming Cheng ◽  
Zhi-Qi Zhao ◽  
Jian-Yang Guo ◽  
Ze-Xian Yang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Vegetation Index ◽  
Soil Layer ◽  
Standardized Precipitation Index ◽  
Southern Tibet ◽  
Spi Index ◽  
Soil Fraction ◽  
Relative Contribution ◽  
Vegetation Characteristic ◽  
The Impact

Frequent droughts in a warming climate tend to induce the degeneration of vegetation. Quantifying the response of vegetation to variations in drought events is therefore crucial for evaluating the potential impacts of climate change on ecosystems. In this study, the standardized precipitation index (SPI) was calculated using the precipitation data sourced from the China Meteorological Forcing Dataset (CMFD), and then the drought events in southern Tibet from 1982 to 2015 were identified based on the SPI index. The results showed that the frequency, severity, and intensity of drought events in southern Tibet decreased from 1982 to 2015, and the highest frequency of drought was found between 1993 and 2000. To evaluate the impact of drought events on vegetation, the vegetation characteristic indexes were developed based on the normalized difference vegetation index (NDVI) and the drought characteristics. The assessment of two drought events showed that the alpine grasslands and alpine meadows had high vegetation vulnerability (AI). The assessment of multiple drought events showed that responses of vegetation to drought were spatially heterogeneous, and the total explain rate of environmental factors to the variations in AI accounted for 40%. Among the many environmental factors investigated, the AI were higher at middle altitudes (2000–3000 m) than low altitudes (<2000 m) and high altitudes (3000–4500 m). Meanwhile, the silt soil fraction in the upper soil layer (0–30 cm) had the greatest positive correlation with AI, suggesting that areas with a high silt soil fraction were more sensitive to drought. The relative contribution rates of environmental factors were predicted by a multivariate linear regression (MLR) model. The silt soil fraction was found to make the greatest relative contribution (23.3%) to the changes in AI.

scholarly journals Elevation and Climate Effects on Vegetation Greenness in an Arid Mountain-Basin System of Central Asia

2020 ◽  
Vol 12 (10) ◽  
pp. 1665 ◽  
Author(s):  
Xiaoli Tai ◽  
Howard E. Epstein ◽  
Bo Li
Keyword(s):  
Central Asia ◽  
Temperature Change ◽  
Vegetation Index ◽  
Positive Response ◽  
Regional Scale ◽  
Warming Trend ◽  
Practical Significance ◽  
Elevation Gradients ◽  
Vegetation Greenness ◽  
Response To Temperature

Mountain-basin systems (MBS) in Central Asia are unique and complex ecosystems, wherein their elevation gradients lead to high spatial heterogeneity in vegetation and its response to climate change. Exploring elevation-dependent vegetation greenness variation and the effects of climate factors on vegetation has important theoretical and practical significance for regulating the ecological processes of this system. Based on the MODIS NDVI (remotely sensed normalized difference vegetation index), and observed precipitation and temperature data sets, we analyzed vegetation greenness and climate patterns and dynamics with respect to elevation (300–3600 m) in a typical MBS, in Altay Prefecture, China, during 2000–2017. Results showed that vegetation exhibited a greening (NDVI) trend for the whole region, as well as the mountain, oasis and desert zones, but only the desert zone reached significant level. Vegetation in all elevation bins showed greening, with significant trends at 400–700 m and 2600–3500 m. In summer, lower elevation bins (below 1500 m) had a nonsignificant wetting and warming trend and higher elevation bins had a nonsignificant drying and warming trend. Temperature trend increased with increasing elevation, indicating that warming was stronger at higher elevations. In addition, precipitation had a significantly positive coefficient and temperature a nonsignificant coefficient with NDVI at both regional scale and subregional scale. Our analysis suggests that the regional average could mask or obscure the relationship between climate and vegetation at elevational scale. Vegetation greenness had a positive response to precipitation change in all elevation bins, and had a negative response to temperature change at lower elevations (below 2600 m), and a positive response to temperature change at higher elevations. We observed that vegetation greenness was more sensitive to precipitation than to temperature at lower elevations (below 2700 m), and was more sensitive to temperature at higher elevations.

scholarly journals Changes in the stoichiometry of Castanopsis fargesii along an elevation gradient in a Chinese subtropical forest

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11553
Author(s):  
Danping Liu ◽  
Dexiang Zheng ◽  
Yaoyao Xu ◽  
Yifei Chen ◽  
Hesong Wang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Ecological Stoichiometry ◽  
Forest Ecosystems ◽  
Global Climate ◽  
Elevation Gradient ◽  
Biogeochemical Cycle ◽  
Elevation Gradients ◽  
Castanopsis Fargesii ◽  
Leaf P ◽  
Leaf N

Elevation is important for determining the nutrient biogeochemical cycle in forest ecosystems. Changes in the ecological stoichiometry of nutrients along an elevation gradient can be used to predict how an element cycle responds in the midst of global climate change. We investigated changes in concentrations of and relationships between nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the leaves and roots of the dominant tree species, Castanopsis fargesii, along an elevation gradient (from 500 to 1,000 m above mean sea level) in a subtropical natural forest in China. We analyzed correlations between C. fargesii’s above-ground biomass and stoichiometry with environmental factors. We also analyzed the soil and plant stoichiometry of this C. fargesii population. Our results showed that leaf N decreased while leaf K and Ca increased at higher elevations. Meanwhile, leaf P showed no relationship with elevation. The leaf N:P indicated that C. fargesii was limited by N. Elevation gradients contributed 46.40% of the total variance of ecological stoichiometry when assessing environmental factors. Our research may provide a theoretical basis for the biogeochemical cycle along with better forest management and fertilization for this C. fargesii population.

scholarly journals Influence of environmental factors on the genetic variation of the aquatic macrophyte Ranunculus subrigidus on the Qinghai-Tibetan Plateau

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Zhigang Wu ◽  
Xinwei Xu ◽  
Juan Zhang ◽  
Gerhard Wiegleb ◽  
Hongwei Hou
Keyword(s):  
Genetic Diversity ◽  
Tibetan Plateau ◽  
Environmental Factors ◽  
Local Adaptation ◽  
Aquatic Macrophyte ◽  
Spatial Genetic Structure ◽  
Long Distance ◽  
Elevation Gradients ◽  
Mantel Tests ◽  
Genetic Patterns

Abstract Background Due to the environmental heterogeneity along elevation gradients, alpine ecosystems are ideal study objects for investigating how ecological variables shape the genetic patterns of natural species. The highest region in the world, the Qinghai-Tibetan Plateau, is a hotspot for the studies of evolutionary processes in plants. Many large rivers spring from the plateau, providing abundant habitats for aquatic and amphibious organisms. In the present study, we examined the genetic diversity of 13 Ranunculus subrigidus populations distributed throughout the plateau in order to elucidate the relative contribution of geographic distance and environmental dissimilarity to the spatial genetic pattern. Results A relatively low level of genetic diversity within populations was found. No spatial genetic structure was suggested by the analyses of molecular variance, Bayesian clustering analysis and Mantel tests. Partial Mantel tests and multiple matrix regression analysis showed a significant influence of the environment on the genetic divergence of the species. Both climatic and water quality variables contribute to the habitat heterogeneity of R. subrigidus populations. Conclusions Our results suggest that historical processes involving long-distance dispersal and local adaptation may account for the genetic patterns of R. subrigidus and current environmental factors play an important role in the genetic differentiation and local adaptation of aquatic plants in alpine landscapes.

scholarly journals Biomass estimation of cultivated red algae Pyropia using unmanned aerial platform based multispectral imaging

Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Shuai Che ◽  
Guoying Du ◽  
Ning Wang ◽  
Kun He ◽  
Zhaolan Mo ◽  
...  
Keyword(s):  
High Throughput ◽  
Vegetation Index ◽  
Multispectral Imaging ◽  
Vegetation Indices ◽  
Spectral Imaging ◽  
Shielding Effect ◽  
Quadratic Model ◽  
Biomass Estimation ◽  
Marine Aquaculture ◽  
Significant Difference

Abstract Background Pyropia is an economically advantageous genus of red macroalgae, which has been cultivated in the coastal areas of East Asia for over 300 years. Realizing estimation of macroalgae biomass in a high-throughput way would great benefit their cultivation management and research on breeding and phenomics. However, the conventional method is labour-intensive, time-consuming, manually destructive, and prone to human error. Nowadays, high-throughput phenotyping using unmanned aerial vehicle (UAV)-based spectral imaging is widely used for terrestrial crops, grassland, and forest, but no such application in marine aquaculture has been reported. Results In this study, multispectral images of cultivated Pyropia yezoensis were taken using a UAV system in the north of Haizhou Bay in the midwestern coast of Yellow Sea. The exposure period of P. yezoensis was utilized to prevent the significant shielding effect of seawater on the reflectance spectrum. The vegetation indices of normalized difference vegetation index (NDVI), ratio vegetation index (RVI), difference vegetation index (DVI) and normalized difference of red edge (NDRE) were derived and indicated no significant difference between the time that P. yezoensis was completely exposed to the air and 1 h later. The regression models of the vegetation indices and P. yezoensis biomass per unit area were established and validated. The quadratic model of DVI (Biomass = − 5.550DVI2 + 105.410DVI + 7.530) showed more accuracy than the other index or indices combination, with the highest coefficient of determination (R2), root mean square error (RMSE), and relative estimated accuracy (Ac) values of 0.925, 8.06, and 74.93%, respectively. The regression model was further validated by consistently predicting the biomass with a high R2 value of 0.918, RMSE of 8.80, and Ac of 82.25%. Conclusions This study suggests that the biomass of Pyropia can be effectively estimated using UAV-based spectral imaging with high accuracy and consistency. It also implied that multispectral aerial imaging is potential to assist digital management and phenomics research on cultivated macroalgae in a high-throughput way.

scholarly journals Monitoring Vegetation Greenness in Response to Climate Variation along the Elevation Gradient in the Three-River Source Region of China

2021 ◽  
Vol 10 (3) ◽  
pp. 193
Author(s):  
Zhaoqi Wang ◽  
Xiang Liu ◽  
Hao Wang ◽  
Kai Zheng ◽  
Honglin Li ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Source Region ◽  
Elevation Gradient ◽  
Climate Variation ◽  
Mean Annual Precipitation ◽  
Near Infrared Reflectance ◽  
Area Index ◽  
Vegetation Greenness ◽  
The Mean ◽  
The Impact

The Three-River Source Region (TRSR) is vital to the ecological security of China. However, the impact of global warming on the dynamics of vegetation along the elevation gradient in the TRSR remains unclear. Accordingly, we used multi-source remote sensing vegetation indices (VIs) (GIMMS (Global Inventory Modeling and Mapping Studies) LAI (Leaf Area Index), GIMMS NDVI (Normalized Difference Vegetation Index), GLOBMAP (Global Mapping) LAI, MODIS (Moderate Resolution Imaging Spectroradiometer) EVI (Enhanced Vegetation Index), MODIS NDVI, and MODIS NIRv (near-infrared reflectance of vegetation)) and digital elevation model data to study the changes of VGEG (Vegetation Greenness along the Elevation Gradient) in the TRSR from 2001 to 2016. Results showed that the areas with a positive correlation of vegetation greenness and elevation accounted for 36.34 ± 5.82% of the study areas. The interannual variations of VGEG showed that the significantly changed regions were mainly observed in the elevation gradient of 4–5 km. The VGEG was strongest in the elevation gradient of 4–5 km and weakest in the elevation gradient of >5 km. Correlation analysis showed that the mean annual temperature was positively correlated with VIs, and the effect of the mean annual precipitation on VIs was more obvious at low altitude than in high altitude. This study contributes to our understanding of the VGEG variation in the TRSR under global climate variation and also helps in the prediction of future carbon cycle patterns.

Floristic study and assessment of the environmental factors governing the distribution of riparian plants in the Zat sub-Basin: Tensift Watershed, Morocco

2020 ◽  
Vol 45 (2) ◽  
pp. 7900-7915
Author(s):  
Mostakim Lahcen ◽  
Fetnassi Nidal ◽  
Ghamizi Mohamed
Keyword(s):  
Environmental Factors ◽  
Pearson Correlation ◽  
Ecological Status ◽  
Environmental Parameters ◽  
Quality Parameters ◽  
Phosphorus Concentration ◽  
Factors Affecting ◽  
Riparian Plants ◽  
Emergent Plants ◽  
Significant Difference

Measuring the phytodiversity and determining environmental factors affecting the abundance and distribution of riparian plants of Zat sub-basin in Morocco were carried out in this study. A hypothesis was tested whether there is any statistically significant difference in environmental parameters and plants communities among the Zat River and its tributaries. For this purpose, water quality parameters such as temperature, pH, salinity, electrical conductivity, Dissolved Oxygen, nitrate and phosphorus concentration, and riparian plants diversity were estimated at 17 stations along the Zat River and its tributaries during the periods (2018 and 2019). The Canonical Correspondence Analysis (CCA) and Pearson correlation were preformed to assess the relationship between environmental parameters, and the distribution and abundance of riparian plants inventoried. The presence of 113 species was recorded, distributed between 43 families and 97 genera, 9 of which were floating-leaved, 24 submerged, and 80 emergent plants. The rare and threatened species inventoried were represented by 7 taxa, whereas 6 species are reported as endemic. Raunkiaer classification showed a dominance of therophytes (38.39%) over the other groups. According to CCA, the abiotic parameters (DO, elevation, salinity and nitrate concentration) were statistically significant parameters governing the distribution and abundance of the riparian plants inventoried. The results obtained reveal the state of the riparian vegetation in the Zat subBasin, therefore we can consider them as a reliable component for the assessment of the ecological status of the aquatic environment.

INFLUENCE OF LEARNING AND TEACHING STYLE ON STUDENTS' ACADEMIC PERFORMANCE

2021 ◽  
Vol 72 (2) ◽  
pp. 46-56
Author(s):  
T.V. Lantseva ◽  
Keyword(s):  
Student Achievement ◽  
Academic Performance ◽  
Learning Styles ◽  
Student Teaching ◽  
Teaching Style ◽  
Teaching Styles ◽  
Practical Significance ◽  
Learning And Teaching ◽  
Significant Difference ◽  
New Knowledge

Research Problem. This article examines the practice and shows the theory and outcome of the study of whether there is a significant relationship of students' academic performance depending on their learning and teaching style, whether there is a significant difference in students' grades depending on their teachers' teaching styles, and whether there is a significant difference between students' academic performance. The purpose of the study focuses on gaining new knowledge about the relationship between the learning and teaching style of a university instructor and student's academic performance. The methodology, methods, and techniques of the study. This study used the Grasch-Richman Learning Styles Questionnaire, which includes tools to assess both learning styles and teaching styles. Our study was designed as a survey study (suitable for determining the existing situation without intervention) and used a quantitative research methodology. The study also used a teaching style inventory method. Results. The results of the study showed that student achievement scores did not change significantly based on their teaching styles; a significant difference was found between student achievement and the correspondence between faculty teaching style and student teaching style. Scientific novelty/practical significance. The new knowledge gained allows us to consider the implications of how emerging learning opportunities relate to student preparation in higher education and teacher level support. Conclusions and Recommendations. The results of our study confirm that learning, teaching styles, and student achievement are interrelated, but in examining these three variables, other variables such as the specific difficulties encountered in teaching a particular subject, the age group of students, and the context of the school must also be considered. There is no "bad" style of qualified teaching. It should not, however, interfere with a teacher's professional development. New knowledge about teaching/learning styles can be useful for beginning university teachers as well as for their students.

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