scholarly journals How Does Spring Phenology Respond to Climate Change in Ecologically Fragile Grassland? A Case Study from the Northeast Qinghai-Tibet Plateau

2021 ◽  
Vol 13 (22) ◽  
pp. 12781
Author(s):  
Xin Yang ◽  
Yuanyuan Hao ◽  
Wenxia Cao ◽  
Xiaojun Yu ◽  
Limin Hua ◽  
...  
Keyword(s):  
Climate Change ◽  
Environmental Factors ◽  
Global Climate ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
Threshold Method ◽  
Spring Phenology ◽  
Important Indicator ◽  
Qinghai Tibet Plateau

Vegetation phenology is an important indicator of global climate change, and the response of grassland phenology to climate change is particularly sensitive in ecologically fragile areas. To enhance the ecological security of the Tibetan Plateau, it is crucial to determine the relationship between fluctuations in the start of the growing season (SOS) and the response to environmental factors. We investigated the trends of the intra-annual (ten-day) and interannual spatiotemporal dynamics of the SOS on the Northeast Qinghai-Tibet Plateau (NQTP) from 2000–2020 with MOD09GA data. We identified the response relationships with environmental factors (climate, terrain) using the maximum value composite method and the Savitzky–Golay filtering and dynamic threshold method. The SOS was concentrated from the 110th to 150th days; the average annual SOS was on the 128th day, with a spatial pattern of “early in the east and late in the west”. The overall trend of the SOS was advanced (45.48%); the regions with the advanced trend were mainly distributed in the eastern part of the NQTP. The regions with a delayed SOS were mainly concentrated in the higher-altitude regions in the southwest (38.31%). The temperature, precipitation and SOS exhibited a reverse fluctuation trend around the midpoint of 2010. Precipitation affected the SOS earlier than temperature. When temperature became a limitation of the SOS, precipitation had a more significant regulatory effect on the SOS. The SOS and aspect, slope and altitude were distributed in axisymmetric, pyramidal and inverted pyramidal shapes, respectively. The SOS on shaded slopes was earlier and more intensive than that on sunny slopes. With increasing slope, the area of the SOS decreased, and it occurred later. The SOS area was largest at 4500–5000 m and decreased at lower and higher altitude intervals. The SOS occurred later as altitude increased.

scholarly journals Spatial and Temporal Differences in Alpine Meadow, Alpine Steppe and All Vegetation of the Qinghai-Tibetan Plateau and Their Responses to Climate Change

2021 ◽  
Vol 13 (4) ◽  
pp. 669
Author(s):  
Hanchen Duan ◽  
Xian Xue ◽  
Tao Wang ◽  
Wenping Kang ◽  
Jie Liao ◽  
...  
Keyword(s):  
Climate Change ◽  
Alpine Meadow ◽  
Global Climate ◽  
Growing Season ◽  
Tibet Plateau ◽  
Vegetation Types ◽  
Analysis Method ◽  
Alpine Steppe ◽  
Qinghai Tibet Plateau ◽  
Variation Trends

Alpine meadow and alpine steppe are the two most widely distributed nonzonal vegetation types in the Qinghai-Tibet Plateau. In the context of global climate change, the differences in spatial-temporal variation trends and their responses to climate change are discussed. It is of great significance to reveal the response of the Qinghai-Tibet Plateau to global climate change and the construction of ecological security barriers. This study takes alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau as the research objects. The normalized difference vegetation index (NDVI) data and meteorological data were used as the data sources between 2000 and 2018. By using the mean value method, threshold method, trend analysis method and correlation analysis method, the spatial and temporal variation trends in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau were compared and analyzed, and their differences in the responses to climate change were discussed. The results showed the following: (1) The growing season length of alpine meadow was 145~289 d, while that of alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau was 161~273 d, and their growing season lengths were significantly shorter than that of alpine meadow. (2) The annual variation trends of the growing season NDVI for the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau increased obviously, but their fluctuation range and change rate were significantly different. (3) The overall vegetation improvement in the Qinghai-Tibet Plateau was primarily dominated by alpine steppe and alpine meadow, while the degradation was primarily dominated by alpine meadow. (4) The responses between the growing season NDVI and climatic factors in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau had great spatial heterogeneity in the Qinghai-Tibet Plateau. These findings provide evidence towards understanding the characteristics of the different vegetation types in the Qinghai-Tibet Plateau and their spatial differences in response to climate change.

The evolution trend of geological disasters over spatial and temporal in the context of global warming —— taking the Qinghai-Tibet Plateau as an example

2020 ◽  
Author(s):  
Yiru Jia
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Influencing Factors ◽  
Rainy Season ◽  
Global Climate ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
Geological Disasters ◽  
The World ◽  
Disaster Data

<p>The Tibetan plateau (QTP) has the highest average elevation in the world. As the third pole in the world, it has the largest cryosphere system at low and mid latitudes. It is a sensitive area of climate change, and the climate change is more significant. Global climate change has led to higher temperatures and increased rainfall on the Tibetan Plateau. This will lead to changes in the frequency and pattern of geological disasters. This spatiotemporal change and its influencing factors are not clear, so we collected a total of 898 geological disasters in the QTP from 1905 to 2015. Then we process the data to obtain various meteorological indicators of the QTP and combine them with the changes in the distribution of disaster points. Furthermore, the distribution pattern of the disaster points with the spatiotemporal changes of slope, altitude, precipitation and temperature is obtained. Statistics on the disaster data corresponding to each meteorological index are then made. Through the analysis of the distribution map and the statistical results of the data, the correlation between the occurrence of geological disasters and each element is obtained. The disaster points are superimposed with multiple influencing factors, and the influence of multiple factors on the distribution of geological hazards is discussed. The results showed that geological disasters have gradually expanded from the traditional high-incidence area of southern and eastern edges to the interior. The frequency of disasters in high altitude areas is increasing, and gradually extended from the rainy season to the non-rainy season.</p>

scholarly journals Disaster Chain Analysis of Avalanche and Landslide and the River Blocking Dam of the Yarlung Zangbo River in Milin County of Tibet on 17 and 29 October 2018

2019 ◽  
Vol 16 (23) ◽  
pp. 4707 ◽  
Author(s):  
Huicong Jia ◽  
Fang Chen ◽  
Donghua Pan
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Tibet Plateau ◽  
Sequence Of Events ◽  
Chain Analysis ◽  
Flow Formation ◽  
Yarlung Zangbo River ◽  
Disaster Chain ◽  
Secondary Disasters ◽  
Qinghai Tibet Plateau

As a “starting zone” and “amplifier” of global climate change, the Qinghai–Tibet Plateau is very responsive to climate change. The global temperature rise has led directly to an acceleration of glacial melting in the plateau and various glacier avalanche disasters have frequently occurred. The landslide caused by glacier avalanches will damage the surrounding environment, causing secondary disasters and a disaster chain effect. Take the disaster chain of the Yarlung Zangbo River at Milin County in Tibet on 17 and 29 October 2018 as an example; a formation mechanical model was proposed. The evolution mechanism for the chain of events is as follows: glacial melt → loose moraine deposit → migration along the steep erosion groove resulting in glacier clastic deposition then debris flow → formation of the dam plug to block the river → the dammed lake. This sequence of events is of great significance for understanding the developmental trends for future avalanches, landslides, and river blocking dam disasters, and for disaster prevention planning and mitigation in the Qinghai–Tibet Plateau.

scholarly journals Spatio-Temporal Changes of Snow Cover and Its Relationship With Meteorological Factors on the Qinghai-Tibet Plateau, China

2021 ◽  
Author(s):  
Haoyu Jin ◽  
xiaohong chen
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Snow Cover ◽  
Remote Sensing Data ◽  
Downward Trend ◽  
Tibet Plateau ◽  
Important Indicator ◽  
Sensing Data ◽  
Spatio Temporal ◽  
Qinghai Tibet Plateau

Abstract The Qinghai-Tibet Plateau (TP) is one of the most sensitive areas to climate change, and its ecological environment changes directly or indirectly reflect the global climate change trend. The snow cover ratio (SCR) is an important indicator reflecting the climate and environmental changes of the TP. The daily remote sensing data of snow cover on the TP from 2003 to 2014 were used to study the spatio-temporal distribution of snow cover on the TP. The results have shown that the average snowmelt day on the TP starts on the 103rd day and ends on the 223rd day of a year, and the snowmelt duration has a downward trend. Snow is mainly distributed in the Nyainqentanglha Mountains, Karakoram Mountains and Himalayas. The SCR in summer has a downward trend, while in autumn has a rising trend. This shows that the difference in SCR during the year has enlarged, increasing the risk of snowmelt floods. The SCR is highly correlated with temperature, but weakly correlated with precipitation. Using the long-term remote sensing data of snow cover, the distribution of glacier coverage on the TP can be extracted, in which glaciers on the TP account for about 1%. This research provides an important reference for in-depth understanding of the snow cover changes on the TP and their impact on the environment.

scholarly journals Dynamic Disturbance Analysis of Grasslands Using Neural Networks and Spatiotemporal Indices Fusion on the Qinghai-Tibet Plateau

2022 ◽  
Vol 12 ◽  
Author(s):  
Fengli Zou ◽  
Qingwu Hu ◽  
Haidong Li ◽  
Jie Lin ◽  
Yichuan Liu ◽  
...  
Keyword(s):  
Climate Change ◽  
Vegetation Type ◽  
Global Climate ◽  
Dynamic Monitoring ◽  
Tibet Plateau ◽  
Change Analysis ◽  
Neural Network Learning ◽  
Factors Affecting ◽  
Growing Period ◽  
Qinghai Tibet Plateau

Grassland is the vegetation type with the widest coverage on the Qinghai-Tibet Plateau. Under the influence of multiple factors, such as global climate change and human activities, grassland is undergoing temporal and spatially different disturbances and changes, and they have a significant impact on the grassland ecosystem of the Qinghai-Tibet Plateau. Therefore, timely and dynamic monitoring of grassland disturbances and distinguishing the reasons for the changes are essential for ecological understanding and management. The purpose of this research is to propose a knowledge-based strategy to realize grassland dynamic distribution mapping and analysis of grassland disturbance changes in the region that are suitable for the Qinghai-Tibet Plateau. The purpose of this study is to propose an analysis algorithm that uses first annual mapping and then establishes temporal disturbance rules, which is applicable to the integrated exploration of disturbance changes in highland-type grasslands. The characteristic indexes of greenness and disturbance indices in the growing period were constructed and integrated with deep neural network learning to dynamically map the grassland for many years. The overall accuracy of grassland mapping was 94.11% and that of Kappa was 0.845. The results show that the area of grassland increased by 11.18% from 2001 to 2017. Then, the grassland disturbance change analysis method is proposed in monitoring the grassland distribution range, and it is found that the area of grassland with significant disturbance change accounts for 10.86% of the total area of the Qinghai-Tibet Plateau, and the disturbance changes are specifically divided into seven types. Among them, the type of degradation after disturbance mainly occurs in Tibet, whereas the main types of vegetation greenness increase in Qinghai and Gansu. At the same time, the study finds that climate change, altitude, and human grazing activities are the main factors affecting grassland disturbance changes in the Qinghai-Tibet Plateau, and there are spatial differences.

Orchestrating the nation

2018 ◽  
Author(s):  
Barley Norton
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Global Climate ◽  
East Asian ◽  
Ancestor Worship ◽  
National Heritage ◽  
The City ◽  
Historical Periods ◽  
Party State

This chapter addresses the cultural politics, history and revival of Vietnamese court orchestras, which were first established at the beginning of the Nguyễn dynasty (1802–1945). Based on fieldwork in the city of Hue, it considers the decolonizing processes that have enabled Vietnamese court orchestras to take their place alongside other East Asian court orchestras as a display of national identity in the global community of nations. The metaphor of ‘orchestrating the nation’ is used to refer to the ways in which Vietnamese orchestras have been harnessed for sociopolitical ends in several historical periods. Court orchestras as heritage have recourse to a generic, precolonial past, yet they are not entirely uncoupled from local roots. Through a case-study of the revival of the Nam Giao Sacrifice, a ritual for ‘venerating heaven’, the chapter addresses the dynamics of interaction and exchange between staged performances of national heritage and local Buddhist and ancestor worship rituals. It argues that with growing concern about global climate change, the spiritual and ecological resonances of the Nam Giao Sacrifice have provided opportunities for the Party-state to reassert its position as the supreme guardian of the nation and its people.

scholarly journals Contrasting Evolution Patterns of Endorheic and Exorheic Lakes on the Central Tibetan Plateau and Climate Cause Analysis during 1988–2017

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1962
Author(s):  
Zhilong Zhao ◽  
Yue Zhang ◽  
Zengzeng Hu ◽  
Xuanhua Nie
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Climatic Factors ◽  
Global Climate ◽  
Rapid Expansion ◽  
Annual Precipitation ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Climate Change Research ◽  
Mean Temperature

The alpine lakes on the Tibetan Plateau (TP) are indicators of climate change. The assessment of lake dynamics on the TP is an important component of global climate change research. With a focus on lakes in the 33° N zone of the central TP, this study investigates the temporal evolution patterns of the lake areas of different types of lakes, i.e., non-glacier-fed endorheic lakes and non-glacier-fed exorheic lakes, during 1988–2017, and examines their relationship with changes in climatic factors. From 1988 to 2017, two endorheic lakes (Lake Yagenco and Lake Zhamcomaqiong) in the study area expanded significantly, i.e., by more than 50%. Over the same period, two exorheic lakes within the study area also exhibited spatio-temporal variability: Lake Gaeencuonama increased by 5.48%, and the change in Lake Zhamuco was not significant. The 2000s was a period of rapid expansion of both the closed lakes (endorheic lakes) and open lakes (exorheic lakes) in the study area. However, the endorheic lakes maintained the increase in lake area after the period of rapid expansion, while the exorheic lakes decreased after significant expansion. During 1988–2017, the annual mean temperature significantly increased at a rate of 0.04 °C/a, while the annual precipitation slightly increased at a rate of 2.23 mm/a. Furthermore, the annual precipitation significantly increased at a rate of 14.28 mm/a during 1995–2008. The results of this study demonstrate that the change in precipitation was responsible for the observed changes in the lake areas of the two exorheic lakes within the study area, while the changes in the lake areas of the two endorheic lakes were more sensitive to the annual mean temperature between 1988 and 2017. Given the importance of lakes to the TP, these are not trivial issues, and we now need accelerated research based on long-term and continuous remote sensing data.

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