Search

Background Salar is a Turkic-speaking Islamic ethnic group in China living mainly in Xunhua Salar Autonomous County (Xunhua or Xunhua County), Qinghai-Tibet Plateau. Salar people are skilled in horticulture and their homegarden (HG) management. They are regarded as the first people on the Qinghai-Tibet Plateau to practice horticulture, especially manage their HGs, traditional farming systems, and supplementary food production systems. Traditional knowledge of Salar people associated with their HGs always contributes significantly to the local livelihood, food security, ornamental value, and biodiversity conservation. The cultivation of different plants in HGs for self-sufficiency has a long tradition in China’s rural areas, especially in some mountainous areas. However, Salar traditional HGs have not been described. The present paper aims to report the features of Salar HGs mostly based on agrobiodiversity and its ecosystem services. Methods The methods used in this work included semi-structured interviews and participatory observation. A total of 60 households in three townships, 9 villages were surveyed. There are 4–12 family members in each household, aged from 20 to 86 years old. The homestead size is between 200 and 1200 m2. Plant species cultivated in Salar HGs were identified according to Flora of China. Based on a comprehensive survey of Salar HGs and related to background data, we identified and characterized the most important services and functions provided by Salar HGs. Results According to primary production systems, there are 4 different types of Salar HGs, including ornamental focus, product focus, dual-purpose and multi-purpose. In total, 108 (excluding weeds and bonsai) plant species were recorded in Salar HGs, within 43 plant families. The most important and frequently used plants are Rosa chinensis, Armeniaca vulgar, Prunus salicina, and Ziziphus jujuba. About 4 to 32 plant species were recorded in each homegarden. We found that the Salar HGs, as a typical agroecosyste, prossess multiple servcices and functions that directly benefit households according to the field investigation. Conclusion This paper reveals the floristic diversity of Salar HGs. It presents useful information in the homegarden agroecosystem of Salar people, such as HG types and species diversity in Salar HGs. Ecosystem functions and services research suggested that the Salar HG agroecosystem provides agroecosystem services mainly related to supply and culture services. Salar HGs are important as food supplement resources, aesthetics symbol, and cultural spaces.

China is one of the countries most affected by earthquakes. Improving public cognition and response to earthquake disaster (EDCR) is an effective means to reduce seismic risk and losses. The 2013 Lushan earthquake area was also stricken by the 2008 Wenchuan earthquake. Most of the residents in this area have been affected by both earthquakes, which provides a rare opportunity to gain insight into the interaction between public’s EDCR and their earthquake disaster experience. Using a questionnaire survey on over 200 local residents selected by stratified sampling method, this paper investigates the public’s cognition and response capability with regard to earthquake disaster in the 2013 Mw6.6 Lushan earthquake area, Sichuan Province, China, with a particular emphasis on exploration on the relationship between people’s earthquake disaster experience and their disaster cognition and response behaviors. The results show that the overall EDCR level of local residents is moderate—their average cognition and response score for earthquake disaster is only 0.60. The number of earthquakes experienced, education, and family income level are the three most important factors that significantly impact an individual’s overall EDCR capability. Those who have experienced more earthquakes better adapt to the impacts of disaster. Especially, the experience learned from the 2008 Mw7.9 Wenchuan earthquake played a positive role in the cognition and response of the public to the 2013 Lushan earthquake. In addition, people with higher education could master more knowledge of earthquake disaster and better control their emotions. Similarly, respondents with a higher family income had more resources and ways to engage in more reasonable response behaviors to manage disaster effects. Based on these findings, it is suggested that local policy-makers implement targeted earthquake disaster education and knowledge dissemination strategies, especially develop and expand various experiential learning modes (e.g., emergency exercise/drilling, situational learning, virtual reality, scenario approach, safety/disaster experience center, participatory activities) for the local public and beyond to more effectively strengthen their cognition of disaster and response capability.

Soil moisture is a key land surface parameter that reflects conditions of drought in agricultural areas, such that variations in soil moisture significantly impact agricultural production. At a large spatial scale, soil moisture can be indicated using the temperature vegetation drought index (TVDI), which is based on soil moisture monitoring. Such metrics allow us to know whether or not the soil in a region is experiencing drought. The TVDI can be estimated by using either the normalized difference vegetation index (NDVI) or the enhanced vegetation index (EVI) combined with land surface temperature (LST) data. Our objectives were to study the applicability of the NDVI-based TVDI (TVDINDVI) and EVI-based TVDI (TVDIEVI) in the monitoring of soil moisture at a large time-space scale. The TVDINDVI and TVDIEVI were calculated by constructing a feature space based on the NDVI (or EVI) and LST to obtain the corresponding dry/wet-edge equation. By establishing a correlation relationship between the TVDIs and soil moisture at soil depths of 0–10, 0–40, 0–100, and 0–200 cm, the applicability of the TVDIEVI and TVDINDVI was investigated for seven different climatic regions in mainland China. The relationships between soil moisture at the 0–10-cm depth and the NDVI (or EVI) in cold and warm seasons were obtained. Linear functions of soil moisture and the TVDINDVI (TVDIEVI) were constructed. From the results, both the TVDINDVI and TVDIEVI were more suitable for monitoring soil moisture at the 0–10-cm depth than at the other depths. The regions that had the best correlations between soil moisture and the TVDINDVI (TVDIEVI) were in northwestern China during the cold season and southeastern China during the warm season (from April to September), meaning that the TVDI was more applicable in these region/season combinations. The TVDINDVI showed better performance in reflecting soil moisture conditions than the TVDIEVI, especially in the warm season. The applicability of the TVDIEVI for soil moisture at the 0–10-cm depth was better than that of the TVDINDVI in northwestern China. However, in the other regions, the TVDINDVI performed better. The performance of TVDINDVI (TVDIEVI) was better than TVDIEVI (TVDINDVI) under different circumstances, which was related to the goodness of fit for wet/dry-edge equations, natural variability of NDVI/EVI/LST, depths, changes in seasons (vegetation cover), and regions. This research compared the applications of the TVDI in China comprehensively.

The assessment of wetland changes on the Tibetan Plateau (TP) is an important component of global change research. The Damqu River Basin (DRB) lies within the southern source of the Yangtze River and is part of the core wetlands area of the Three Rivers Source Region (TRSR). We examined the distribution of wetlands across this region based on remote sensing image interpretations. The results revealed clear evidence of changes over the period between 1988 and 2015, with the ​​wetland area in 2015 being 8964.51 km2 (53.52% of the total basin). Wetlands at this time were concentrated between 4700 and 5000 m (upper limit: 5600 m), with land slopes between 0 and 6°, and a northward aspect. The data also showed that the wetland area decreased by 71.16 km2 between 1988 and 2015, equivalent to 0.79% of the 1988 total. The annual value of the normalized difference vegetation index (NDVI) decreased over 63.36% of the region within the DRB during 1988–2015. The area of three major lakes in the DRB declined from 2009 to 2015. The results of this analysis demonstrated that precipitation variation was the underlying cause of the observed vegetation index and lake area changes within the DRB between 1988 and 2015.

The Tibetan Plateau (TP) is an important ecological security barrier for China and, indeed, for all Asia. Land use and land cover changes in the plateau not only affect the ecological environment and regional development of the plateau itself but also affect the stability and economic development of ecosystems in eastern China and other parts of Asia. This paper is based on an examination of the achievements of land use and cover change in the TP and a reanalysis of data including that of Climate Change Initiative Land Cover from 1992 to 2015; land use data provided by the Resource and Environmental Science Data Center of the Chinese Academy of Sciences for 1995, 2000, 2010 and 2015; and statistical data from Qinghai and Tibet. The paper analyzes the overall characteristics of land use and land cover changes in the TP and the spatial and temporal processes and their driving forces of land use and land cover change in typical regions and land types. This research is important not only for land change science and global change research but also for the promotion of the plateau and its adjacent areas. In recent decades, research has shown that the land use and land cover structure of the TP is stable, and the proportion of first-level land use type change was less than 7% from 1992 to 2015. Most of these changes are single time changes, with multiple land change occurring only in 1.85% of the total change area. The quality of land cover has been improved in areas where no land type change occurred. The Normalized Difference Vegetation Index (NDVI) showed an increasing trend in 24.45% of the area and a decreasing trend in only 1.31% of the area. The area of cultivated land, forest, grassland, wetland, and construction land on the plateau has increased, whereas bare land, glacier, and snow cover area has decreased. In most parts of the TP, the quality of alpine grassland has improved; however, in some areas, it has degraded at a local scale. Most of the woodland has recovered well after phased changes. Prior to 1980, there was a rapid increase in cultivated land area, but this has since become stable with only minor increases. However, the utilization intensity of cultivated land has increased significantly in recent years. Construction land has expanded significantly, and the recent growth rate has accelerated since 2010. Both the increasing speed of change and the construction land area in Qinghai Province are higher than in Tibet. There has been a general trend of a slight decrease in bare land change. In densely populated areas in the Yellow River-Huangshui River Valley and the One-River-Two-Tributaries area, land types that are closely related to human utilization such as construction land, cultivated land, and artificial woodland have undergone obvious changes. In pastoral areas, such as the Northern Tibetan Plateau and the Source Regions of The Three Rivers, overgrazing and ecological construction have significantly affected land cover. In the Qomolangma National Nature Preserve, land use types are diverse; changes are complex; and land cover is more sensitive to both climate change and human activity. There are limitations to the study of land change in the plateau, such as the difficulty of meeting the needs of ecological construction with existing data and the lack of in-depth understanding of the process of land use change and its environmental effects. Field monitoring and remote sensing techniques must be strengthened in order to clarify the process of land use intensity change and its impact on the ecological environment of the TP. These improvements will better serve the construction of an ecological security barrier and the sustainable development of the region.

Based on data from a questionnaire survey about the 2010 Ms 7.1 Yushu earthquake in Qinghai Province, China, this study examines the impacts of belief in Tibetan Buddhism on Tibetans’ response to the earthquake disaster. The results reveal that (1) impacted by their belief in Tibetan Buddhism, some Tibetans attribute the cause of the earthquake to punishment from God even though some of them understand a naturalistic explanation of the earthquake. Religious attribution of the earthquake has negative effects on Tibetans’ awareness of the importance of earthquake disaster risk reduction such as learning about earthquakes and developing earthquake survival skills; their ability with regard to their behavioral response is affected, but their psychological reaction is not. (2) Tibetan Buddhist belief and Tibetan Buddhist clergy served as important resources and support to help Tibetans cope with the earthquake disaster. The degree of religiosity was found to be positively correlated with people’s willingness to seek religious support and with their self-evaluations on the importance of religious support for disaster response. The findings of this study highlight the need to carefully consider local religious beliefs when planning disaster risk reduction strategies in Tibetan communities.

Extreme temperature events, which are part of global climate change, are a growing threat to crop production, especially to such temperature-sensitive crops as rice. As a result, the traditional rice-growing areas are also likely to shift. The MaxEnt model was used for predicting the areas potentially suitable for rice in the short term (2016–2035) and in the medium term (2046–2065) and under two scenarios developed by the Intergovernmental Panel on Climate Change, namely representative concentration pathway (RCP) 4.5 (the intermediate scenario) and RCP 8.5 (sometimes referred to as the worst-case scenario). The predictions, on verification, were seen to be highly accurate: the AUC—area under the curve—value of the MaxEnt model was &gt, 0.85. The model made the following predictions. (1) Areas highly suitable for rice crops will continue to be concentrated mainly in the current major rice-production areas, and areas only marginally suitable will be concentrated mainly in the rainforest region. (2) Overall, although the current pattern of the distribution of such areas would remain more or less unchanged, their extent will mainly decrease in the subtropics but increase in the tropics and in high-latitude regions. (3) The extent of such areas will decrease in the short term but increase in the medium term.

The latest Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) dataset version 6, which is the successor of the multi-satellite 3B42 dataset from the Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA), is now recommended for many purposes. It is unclear how the quality of the latest IMERG data products compares to that of the delisted TMPA series data sets. This study evaluated the accuracy of TRMM 3B42 version 7 and IMERG final version 6 products at 677 stations in the 7 subregions of China over 2000–2019 at the daily, monthly and annual timescales based on gauge-observed precipitation data. The performance of TMPA and IMERG precipitation products was assessed by six statistical indices. The product with the best performance was corrected based on the linear relationship of monthly precipitation between remote sensing products and ground-observed precipitation. The correction was then used for the predicting and mapping of precipitation in July 2019. The results showed that (1) IMERG outperformed TMPA at all three timescales, and the accuracy increased with the expanding timescale. (2) IMERG exhibited better performance in all subregions than TMPA and performed best in the mid-temperate semihumid zone and worst in the mid-temperature arid zone. (3) IMERG showed higher accuracy than TMPA in all months for most subregions and mainland China but performed worse in dry (December, January and February) and wet (July, August and September) months. (4) The linear relationship between remote sensing products and ground-observed precipitation could be used to correct and predict satellite precipitation data without up-to-date gauge observations, the predicted map indicated the good spatial variation in precipitation and better accuracy than the original IMERG data. In conclusion, the IMERG dataset was more accurate and could be used for precipitation investigations at large scales in China.

The regional and national scales variation and propagation characteristics of different types of droughts are critical for improving drought resilience, while information is limited in China. The objective of this research was to investigate the evolution and propagation characteristics of three types of droughts using standardized indices at multi-timescales in different sub-regions of China. The indices included Standardized Precipitation/Soil Moisture/Runoff Index (SPI/SSI/SRI) using the optimal probability density function, representing meteorological, agricultural, and hydrological droughts based on precipitation, soil water storage, and baseflow-groundwater runoff, respectively. Wavelet analysis was used to reveal their periodical characteristics. Modified Mann-Kendall trend test was used to compare the trend among drought indices. Correlation coefficients between SPI and SSI/SRI were calculated to identify the time-lags of SPI with SSI and SRI. In general, droughts indicated by SPI agreed well with the historical drought events at different sub-regions. The main periods of SSI were closer to SPI than SRI, indicating stronger connections of agricultural drought with meteorological drought. A weaker connection between meteorological and agricultural/hydrological droughts at shorter timescales was observed in northwestern arid and semi-arid regions. The propagation from meteorological to agricultural or hydrological droughts were well denoted by the lagged time (months) from SPI to SSI or SRI at a timescale ranged from 0 (mostly located in south China) to 5 months (mostly located in northeastern China) for 1-, 3-, 6-, 12-, or 24-month timescale; this was a new finding for China. The methods of wavelet combining trend test and Pearson coefficient showed meaningful power for revealing the drought propagation characteristics and the obtained results can be a good reference for other regions of the world since this study compared different climate zones from arid to humid conditions. The study provides crucial information and guidance to develop drought management strategies at regional to national scale and their critical time of action.

Huangshui River Valley (HRV) is a typical valley area located in the northeast of the Qinghai-Tibetan plateau. Its long and narrow space, large vertical gradient and diverse land use types bring great challenges to the land use zoning in this region. The paper aims to propose a gridding-self-organizing feature maps (SOFM) coupled method based on grid cell, which will be more reliable and refined, if compared to the method of commonly used administrative regions as the basic analytic units. Firstly the focused study area is divided into 500 m × 500 m grid cells. Six indexes, including grassland, cultivated land, forest land, construction land, population density and per capita income are both spatialized and quantified in every grid. Meanwhile, that SOFM neural network model is at the usage of classifying the land use into six zoning areas can be certain. And urban area, urban-rural transition area, agriculture-forestry transition area, typical agricultural area, agriculture-pastoral transition area, and typical pastoral area are sure to belong to them. Its results can vividly indicate the actual situation where land use pattern is in constant changes in Huangshui River Valley (HRV). The research will provide a specific method for the substantial utilization of land resources.

Increasing frequency and intensity of extreme drought events have harmed the environment, ecosystem, and agricultural productivity. However, the characteristics of agricultural drought in China have not been well understood. The remote sensing (RS) based gridded monthly precipitation, soil moisture, land surface temperature (LST), and normalized difference vegetation index (NDVI) datasets over 1982-2018 were utilized to derive standardized precipitation index (SPI), standardized soil moisture index (SSI), multivariate standardized drought index (MSDI), and vegetation health index (VHI). The variation patterns and trends of SPI, SSI, and MSDI at the 1-, 3-, and 6-month timescales against monthly VHI anomaly were compared to identify the best agricultural drought index in China. The drought variations in the four sub-regions (northwest, north, Qinghai-Tibet area, and south area) were also investigated. The results showed that: (1) Temporal patterns of VHI anomaly were similar to relative soil moisture and slightly different from precipitation. The spatial patterns of MSDI matched with VHI the best than SPI and SSI. (2) All three indices showed positive correlations with VHI at the three timescales. The highest correlation coefficients (r) between MSDI and VHI ranged from 0.25 to 0.67, 0.22 to 0.78, 0.23 to 0.69, and 0.19 to 0.74 in northwest China, north China, Qinghai-Tibet Plateau, and south China, respectively. (3) The connections between monthly VHI and the three drought indices were weaker at the 1-month timescale (0.16 r 0.25) than the 3-month (0.39 r 0.78) and 6-month (0.26 r 0.68) timescales. (4) The VHI significantly increased in most of China except north China. Overall, MSDI showed better performance for monitoring agricultural drought in China's mainland.

Reference evapotranspiration (ET0), as an estimate of the evaporative demand of the atmosphere, has been receiving extensive attention in researches on hydrological cycle. Sensitivity of ET0 to major climatic variables has significant applications in climatology, hydrology, and agrometeorology and is also important to improve our understanding of the connections between climatic conditions and ET0 variability. In this study, we used the Penman-Monteith equation to calculate ET0 and adopted a nondimensional sensitivity coefficient formula to analyze sensitivities of ET0 to four climatic variables based on daily meteorological data from eight meteorological sites in the Huangshui River basin and surrounding areas during 1961–2010. The results indicated that (1) strong correlations with R 2 up to 0.76 exist between observed E pan and calculated annual ET0; (2) ET0 had a decreasing trend in the Huangshui River basin (HRB) during 1961–2010; (3) Spatially, distribution of ET0 was largely correlated with altitude, for instance, the average annual ET0 was larger in low-altitude areas than in high-altitude areas; (4) ET0 was more sensitive to actual vapor pressure in high-altitude areas while it was more sensitive to temperature in low-altitude areas; and (5) ET0 showed a decreasing trend and was consistent with the decreases in net radiation and wind speed at seasonal and annual time scales in HRB during 1961–2010. Sensitivity analysis of ET0 to major climatic variables revealed that temperature was primarily responsible for changes in ET0 in the growing season while actual vapor pressure was the dominating factor causing changes in ET0 in the nongrowing season. However, annual averaged ET0 was more sensitive to actual vapor pressure (R 2 = 0.63), indicating that actual vapor pressure was possibly the primary climatic variable that causes changes in annual ET0.

The Tibetan Plateau (TP) is particularly sensitive to the influences of climate change. As indicators of climate change, lakes on the TP play a key role in the Earth’s climatic system. Lake Yazi (LY), Lake Tuohepingco (LT) and Lake Changtiao (LC) in the Tuohepingco Basin are three inland lakes on the plateau. The extents of LY, LT and LC were obtained using object-based image analysis for remote sensing and 22 images from Landsat satellites (from September to December between 1972 and 2015). Inter-annual changes in the extent of LY, LT and LC were then analyzed. The results show that the total area of the three lakes underwent a change from shrinkage to expansion between 1972 and 2015. In general, there was a trend toward shrinkage during 1972–1999, distinct expansion during 2000–2007 and slight expansion during 2008–2015. Moreover, we found that 14 other lakes have also expanded dramatically since 2000. Lakes at 30°N and 35°N (LY, LT and LC are also located in this region) exhibited the same dramatic period of expansion between 2000 and 2005. In other words, 2000 appears to be a critical transition point for changes in lake size on the TP. Lakes at the same latitudes in the Tibetan Plateau interior may have a similar period of dramatic expansion after 2000. The warming-triggered deglaciation or permafrost degradation, increased precipitation and decreased evapotranspiration may be the influencing factors of lake expansion in the Tuohepingco Basin. Temperature showed relatively higher correlation with lake extent, while precipitation and evaporation were slightly correlated with lake area. Given the importance of wetlands to human society, these are no trivial issues, and we now need accelerated research based on long-term and continuous remote sensing.

As the world’s highest railway, and the longest highland railway, the Qinghai–Tibet Railway (QTR) has been paid considerable attention by researchers. However, most attention has been paid to the ecological and environmental issues affecting it, and sustainable ecological, social, and economic development-related studies of the QTR are rare. In this study, by analyzing the passenger traffic, freight traffic, passenger-kilometers, and freight-kilometers of the QTR for the period 1982–2013 and the transport structure of the Tibetan Plateau (TP) for 1990–2013, the evolutionary process of the transport system in the TP following the construction of the QTR has been revealed. Subsequently, by comparing Gross Domestic Product (GDP), population, industrial structure, and urbanization level at the county and 1 km scales between surrounding and non-surrounding areas of the QTR, the differences in socioeconomic performance before and after its construction were detected. The results show that (1) in the TP, the highway-dominated transport system will break up and an integrated and sustainable transport system will form; (2) at the county scale, the annual growth rates of GDP of counties surrounding the QTR were greater than those of non-surrounding counties for the period 2000–2010. At the 1 km scale, following the opening of the completed line, the GDP of surrounding areas had a greater growth rate than before; (3) analysis at the county and 1 km scales indicated that population was not aggregated into the surrounding areas of the QTR in the period 2000–2010; (4) in terms of industrial structure, the proportion of primary industry decreased continuously, while the proportion of secondary and tertiary industries increased overall in the period 1984–2012. The QTR had no obvious impact on changes in the urbanization level of its surrounding areas.