Constructing a Stress Management Model Based on the Ecological Characteristics of the Tibetan Plateau

—Assessing the environmental vulnerability of the Plateau is beneficial for a number of reasons, including understanding how the region's environmental vulnerability developed and was formed, as well as for promoting the region's green development and protecting the environment. This study has created a national response to pressure management model by integrating traditional management practices with the national response to pressure, and by examining the spatial and temporal characteristics of nature resources in the Plateau from 2000 to 2015. The findings demonstrate that the rate of change in Tibet Plateau's delicate ecological environment is relatively slow, indicating the necessity for new management strategies to safeguard the natural environment.


Introduction
Environmental problems not only seriously hinder the fragile ecological environment worse and seriously affect the sustainable development of regional social economy. Social and economic development and ecological environment protection can not be emphasized, and can only be coordinated through reasonable means. For example, the assessment of ecological environment vulnerability should be carried out periodically and comprehensively from the macro perspective; the selection of evaluation indicators should be purposeful and targeted according to the specific environmental problems. However, the traditional data and technical methods have some shortcomings such as lag and low accuracy, and remote sensing technology has been widely used in recent years because of its large detection coverage, fast information acquisition, and large amount of information. In this paper, the land use data, vegetation data, DEM data obtained from sensing images are used to evaluate the vulnerability of related ecological environment. Based on this, this paper also uses GIS technology in the index processing and visual expression of ecological environment evaluation.
As the region with the highest altitude in the world, because of its unique geographical environment, it has become the most sensitive area to global change, the early warning area and sensitive area of global climate warming, and frequent disasters in the region. As an important water conservation area and climate change indicator in China, when the water conservation and ecological protection functions of the eastern edge of the Qinghai Tibet Plateau decline, it will have a significant impact not only on China, but also on the world. To sum up, it is of great significance to carry out the ecological vulnerability assessment of the eastern edge of the Qinghai Tibet Plateau and explore the formation mechanism and spatiotemporal evolution of the regional ecological vulnerability.

Related works
According to literature [1][2], the vulnerable area of China's ecological environment accounts for 63% of the land area. However, due to the special climate conditions, Northwest China has become the most vulnerable area in China. From the perspective of natural environment, the continental climate in this area is very typical, with large annual temperature diurnal difference, drought and less rain, cold winter, hot summer, loose soil, rich sand sources, and sparse vegetation. The Northwest Loess Plateau belongs to the Yellow River, with the most serious water and soil loss. In addition, 3/4 of the large deserts in the north and all the Gobi Desert are concentrated on the Qinghai Tibet Plateau, and desertification is prominent [3][4]. Global climate change and extensive human destruction of water conservation forests have resulted in excessive melting of mountain glaciers, reduction of river runoff and continuous acceleration of drought [5][6]. From the perspective of human activities, in recent years, a series of activities in northwest China, such as deforestation, grass destruction, land reclamation, land reclamation from lakes, and illegal construction of industrial bases in ecological protection areas, have led to prominent ecological and environmental problems in some regions. For example, in Qilian Mountain Nature Reserve, large-scale mineral exploitation, illegal construction of hydropower enterprises, and illegal discharge and release of pollutants have led to a large reduction of forest land and grassland, vegetation degradation, surface collapse, river cutoff, ground collapse, and serious pollution of water, soil and gas [7][8]. In addition, literature [9][10] found that in densely populated inland river basins, uncontrolled deforestation and extensive agricultural irrigation caused environmental problems such as water resources reduction, desert invasion, and rapid shrinkage of oasis area. For example, the excessive exploitation of groundwater in the Shiyang River basin has caused a sharp decline in the groundwater level, water mineralization, vegetation degradation, land desert, soil salinization and other problems. In addition, the industrialization and urbanization process in the northwest region promoted the economic development of the third and fourth tier cities, but the blind pursuit of economic growth and the neglect of environmental protection made the air pollution in the region increasingly serious. In northwest China, where natural resources are scarce and the contradiction between people and land is prominent, ecological environment problems have severely challenged human livelihoods [11][12].
According to the literature [13][14], the special geographical location, natural environmental conditions and frequent human interference of the Qinghai Tibet Plateau have made the fragile environment in the region worse, and the environmental problems, such as serious land degradation, rapid shrinkage of oases, large area reduction of vegetation coverage, and conflict between water supply and demand, are prominent. Literature [15][16] first proposed the concept of ecological environment fragile zone, which believed that "in an ecosystem, the" interface "formed between two or more kinds of material systems, as well as the spatial domain extending from the interface, is an ecological fragile zone. In the 1980s, the decline of soil fertility, desertification of land, environmental pollution and other ecological environment deterioration occurred one after another. Human beings began to realize the series of measures to control desertification and establish "three north" protective forests, and achieved certain ecological benefits [17][18]. Since then, supported by the key scientific and technological research project "Research on Comprehensive Improvement and Restoration Technology of Ecological Environment" implemented, the Chinese Academy of Sciences has further promoted large-scale research on fragile ecological environment improvement in China.
To sum up, the Qinghai Tibet Plateau is the source of rivers in most regions of China, and also the source of sandstorms. It is also the important task of natural resources protection and sandstorms protection. Therefore, this paper studies the regional ecological environment vulnerability in four time nodes in 2005, 2010, 2015 and 2020.

Spatial autocorrelation
The spatial autocorrelation coefficient is usually used to calculate the ecological environment vulnerability. Moran index and Geary coefficient are two commonly used indicators. Among them, the similarity degree of attribute values of spatial adjacent or spatial adjacent regional units is reflected by Moran index, and the Geary coefficient is used to reflect the similarity genus of regional units. The calculation formula is as follows.
The assumption of global autocorrelation analysis is that the space is homogeneous, but in geographic space, there are differences between regions, within regions, etc., so we need to use local autocorrelation to analyze the data of each sub region to explore whether the changes of the attribute information of the entire region are heterogeneous. In this study, G statistic is mainly used, and its observation value is: When Z>0, it is reflected in the concentration of high value and high value, that is, the hot area; When Z<0, it is reflected in the concentration of low value and low value, that is, the cold spot area. The PSR model is a mature and commonly used method to evaluate ecological vulnerability. Therefore, on the basis of the PSR model, this study adds the management, quantifies the government and individual behaviors, and then incorporates them into the evaluation system. The technical roadmap of the whole model is shown in Figure 1.

PSR model of Qinghai Tibet Plateau
The eastern fringe of the Qinghai Tibet Plateau is a transitional zone between traditional Han culture and minority culture, with rich cultural resources. Due to the high mountains and deep valleys in most areas of the region, the transportation is inconvenient, which hinders the ethnic cultural exchange and the spread of religious culture, forming a variety of cultures. However, at the same time, the valley has formed a cultural transmission channel, which enables various ethnic cultures and religious cultures to coexist here and live in harmony, creating cultural prosperity and diversity. This natural human channel barrier effect, combined with the cultural gradient effect caused by the vertical zone, makes the eastern edge of the Qinghai Tibet Plateau a rich area of tourism resources in China. Relying on rich natural landscape resources and cultural resources, tourism is becoming an important engine to drive the eastern edge of the Qinghai Tibet Plateau out of poverty and development. The scope of this study is shown in Figure 2. Through the inspection of map data, the missing and missing measurements and some abnormal data are averaged in the adjacent months or years before and after, and a large range of abnormal data are eliminated to ensure the accuracy and operability of the subsequent interpolation and the reliability of the interpolation results.

Data source
Among them, meteorological data (temperature, precipitation, wind speed) are from China Meteorological Data Network and processed into grid data using Kriging interpolation method. In the remote sensing data, NDVI, population kilometer grid, night light data, soil erosion data, Palmer drought index data is from the TerraClimate data set, and DEM data is from the US Geological Survey. Some missing data are obtained by interpolation. Due to different data sources and data forms, all data are converted to raster data, and projection conversion and resampling are performed. The spatial resolution of data is 1000m × 1000 M.
According to the definition of ecological land and the actual situation of Shanghang County, the land use of Shanghang County is divided into 7 categories, including forest land, cultivated land, garden plot, shrub, water area, construction land and bare land. It should be noted that the shrubbery is separated from the forest land type to reflect the landscape type in the study area. In addition, the shrubbery is also the actual process state and should not be classified into the first level type in general. Based on the field research in 2005-2020 period, each type of land use is specifically defined on the map.

Index system construction
The concept of RSP model on the Qinghai Tibet Plateau consists of three parts: ecological sensitivity, ecological resilience, and ecological pressure. Ecological vulnerability is measured by sensitivity and resilience. The higher the value of positive indicators, the more adverse impacts will be on the ecosystem, which will aggravate the ecological vulnerability; Otherwise, it is a negative indicator. As shown in Table 1. At the same time, they cannot be directly used for evaluation, so the evaluation indicators must be standardized to solve the problem of incomparable parameters. In this paper, the quantitative indicators are standardized by the range method, and the qualitative indicators are standardized by the hierarchical assignment method, including slope aspect indicators, land use type indicators, soil hydraulic erosion indicators and soil wind erosion indicators (see Table 2). From 2005 to 2020, the proportion of unused land has a small change, and the change is characterized by a trend of increasing; the proportion of water area is less than 1%, and the change is less, and the land use types are shown in Table 3.  showing positive promotion, and the temperature is -0.235. Therefore, temperature rise will have a negative impact on vegetation. Its model evolution diagram is shown in Figure 4.

5.1Temporal and spatial distribution characteristics
Since 1973, the earthquake disasters in the eastern margin of the Qinghai Tibet Plateau have shown an upward trend of concussion. After reaching the peak in 2008, the number and intensity of earthquakes in recent years have been at a high level, with strong potential safety hazards. The earthquake frequency and magnitude in this area are high. In recent years, there have been major earthquakes such as Wenchuan Earthquake, Lushan Earthquake, Jiuzhaigou Earthquake and Lijiang Earthquake, which not only damaged the local ecological environment. In this earthquake sequence, there were 8 earthquakes of magnitude 6-6.9 and 34 earthquakes of magnitude 5.0-5.9. It is the most serious natural disaster in China in recent years. On April 20, 2013, Lushan 7.0 earthquake caused nearly 200 deaths. On August 8, 2017, the M7.0 Jiuzhaigou earthquake caused 25 deaths and more than 500 injuries. The earthquake also triggered mudslides and landslides, which damaged the landscape of Jiuzhaigou and led to the disappearance of Spark Lake. As shown in Figure 5. Geological disasters are the most common types of disasters in the eastern margin of the Qinghai Tibet Plateau, mainly including earthquake, landslide, debris flow, collapse, slope, etc. According to the statistics of the geological hazard survey data, the geological hazard points in the eastern margin, such as the Hehuang Valley in the east of Qinghai Lake, the southeast of Minshan Mountain, the Great Snow Mountain, Qionglai Mountain, and the Three Parallel Rivers in Hengduan Mountain. In the west of Qinghai Lake, Gannan Grassland and Ruoergai area are less distributed in the north. Among the 8492 geological disaster points, debris flow accounts for the largest proportion, up to 40.3%, landslide accounts for the second place, accounting for 29.6%, and slope accounts for the third place, accounting for 15.4%. The Qinghai Lake and its surrounding areas, the western part of western Sichuan Plateau and other areas are the low frequency and sub low frequency areas of geological disasters. Among them, the distribution of drought frequency in different seasons is quite different. The high frequency area of spring drought is mainly distributed in Lanping of Nujiang Prefecture, Zhouqu and Diebu of Gannan Prefecture, with the drought frequency exceeding 27%. The sub high frequency area is distributed around the high frequency area, such as Lushui, Fugong and Weixi of Nujiang Prefecture, Nanping and Ruoergai of Aba Prefecture. The medium frequency area is mainly distributed from Qilian Mountain to Hehuang Valley. The drought frequency is less than 15%. Summer is the season with high incidence of drought, with high frequency of drought. The sub high frequency area is distributed in the north of Aba Prefecture and the east of Gannan Prefecture, with a drought risk of more than 33%. The medium frequency area is mainly distributed in Hengduan Mountains, with a drought frequency of 25% -30%. The low frequency and sub low frequency areas are mainly distributed in Hehuang Valley and Shiqu County in the west of Ganzi Prefecture, with a frequency of less than 20%. Autumn is the season with the highest drought risk. The drought risk in the whole region ranges from 21% to 46%. The drought risk in Nanping, Ruoergai, Diebu and Zhouqu in the north of Aba Prefecture exceeds 40%. The areas from Maoxian County to Maqu, from Luqu to Zhuoni, and most of Diqing Prefecture are sub high frequency areas, with the drought frequency exceeding 33%. The rest of Hengduan Mountains and Qilian Mountains are medium frequency and sub low frequency areas, with the drought frequency between 25% and 33%. The frequency of drought disasters in and around Qinghai Lake is the lowest. The frequency of drought disasters in winter is low, with only Zhouqu, Diebu and Lintan exceeding 30%. Most of Diqing Prefecture, Nanping, Ruoergai, Zhuoni and other places are sub high frequency areas. The frequency of drought disasters in Qinghai Lake and its surrounding areas is low in Qilian Mountains. As shown in Table 4.

5.2Index normalization verification
In the process of processing qualitative indicators, combining with relevant literature and consulting with relevant experts, the assignment criteria of soil type and soil erosion degree grade in the study area were obtained (see Table 5). The ecological environment vulnerability is based on the sensitivity of the ecological environment to external interference and the ability to self repair in a specific region and time scale. It is the overall comprehensive role of the vulnerability of various environmental elements, and the most objective manifestation, including the internal and external environmental vulnerabilities. The internal environmental vulnerability is an unstable character of the internal structure of the ecosystem itself over time, while the external environmental vulnerability is a change response when the ecosystem is disturbed by external factors and cannot restore the original structure. The basic principles and necessary conditions for evaluating the regional ecological environment vulnerability are to comprehensively consider the characteristics of climate, hydrology, soil, vegetation and other internal factors in the study area, as well as the impact of external factors, that is, the disturbance of human activities on the ecosystem. The internal structure presents certain defects and the impact of human disturbance, resulting in a certain degree of vulnerability of the ecological environment in space within a certain time range. Based on the above reasons, this paper chooses climate hydrological environment, land environment and biological environment from two aspects of natural environment and social economy; 5 significant factors of social environment and economic environment were used to study the vulnerability. As shown in Figure 6. From the area ratio of vulnerable levels of the Qinghai Tibet Plateau in Figure 7, the vulnerability of the ecological environment in 2017 has decreased significantly. In 2020, while the area of potential and light vulnerability increased, indicating that the overall ecological environment quality in Shaanxi Province increased from 2010 to 2020. In 2017, the area of potential and micro vulnerability increased sharply, indicating that the ecological environment vulnerability in 2017 was significantly lower than that in the other two years, and the overall ecological environment quality became higher. In addition, with the rise of altitude or the increase of latitude, it is characterized by a decrease in precipitation and temperature. The relationship diagram between ecological vulnerability and annual average temperature shows that the ecological vulnerability generally decreases linearly with the increase of precipitation. From 0 to 400mm, with the increase of precipitation, the water limit gradually decreases, vegetation can develop, and the ecological vulnerability decreases rapidly. From 400 to 1000mm, the ecosystem is not completely limited by water, and may be affected by water and temperature synergistically, so the ecological vulnerability also fluctuates.

Conclusion
The eastern margin of Qinghai Plateau is located in the transitional area between the first and second boundaries of China, where the geological structure is complex and geological activities are active. Based on remote sensing data and statistical yearbook, this study introduces the Tibet Plateau environmental vulnerability assessment system based on psrm model. In 2010-2020, the environmental vulnerability index is divided into environmental vulnerability. According to the test, the environmental vulnerability index in this area is high, and more ecological restoration training is needed.