Resident food consumption is affected by factors such as the natural geographic environment and urbanization. At the same time, food consumption will affect regional food security and the development of agriculture and animal husbandry through market mechanisms. Taking the Yarlung Zangbo River and its two tributaries of Tibet (also known as Three-Rivers Region) as a typical case, this paper obtained the food consumption data of 262 rural residents by field surveys based on stratified sampling, and then analyzed the food consumption structure of the rural residents and its influencing factors in the Tibetan Plateau. The results indicated that: (1) The consumption of plant foods of the residents in the sample is 3.19 times that of animal foods, with vegetable and grain as the main plant food and meat and milk as the main animal food. And highland barley and highland barley liquor are important in the diet of Tibetans. (2) The scale and structure of food consumption of residents are closely related to the index of food self-sufficiency, and the characteristics of self-sufficient food consumption are significant. (3) Among different regions, family sizes, scales of migrant worker, income levels and family ages, the food consumption structure of residents varies, and the differences in the consumption of flour and fruits between different families are the most significant. (4) Regional differences, family sizes and migrant worker scales are the main factors that affect the comprehensive difference of food consumption in the sample rural areas. The research results of the paper can provide scientific basis and guidance suggestions for the improvement of food consumption structure, promotion of dietary nutrition and transformation and development of agriculture and animal husbandry in the Tibetan Plateau.

The Qinghai-Tibet Plateau (QTP) has unique features of high-cold environments and natural conditions, which have limited the natural distribution and orderly development of its population, and then has formed a large and widely distributed Unpopulated Areas (UPAs). However, the information of the area size, distribution extent, geographical characteristics and regional differences of the UPAs in this plateau is still not available. Therefore, it is significant to define accurately the spatial extent and geographical distribution of the UPAs for the assessment of resources and environmental carrying capacity and constructing the national parks and ecological security barrier in this plateau. Based on the distribution information of residential areas in the QTP, from the characteristics of topography, climate, ecology (oxygen content), land use and other elements, the study aims to examine the relationship of natural-ecological-land use system. Therefore, we developed a comprehensive evaluation model of the "UPAs" through the spatial overlay of multiple elements. The key thresholds determined in the aspects of physical and ecological (oxygen content) limits and land use characteristics, were then used to define the geographical distribution and to examine spatial characteristics of the UPAs in the QTP, China. The results showed that: (1) With the cumulative proportion of residential distribution < 0.1%, we defined the topographic thresholds of the UPAs including the elevation > 5665 m, relative height difference > 2402 m, the relief degree of land surface (RDLS) > 8.59, and the climatic thresholds including the relative humidity > 76.2% and the temperature humidity index (THI) < 33 or > 71. (2) According to the distribution of residential areas and oxygen content tolerance of the human being, the oxygen content thresholds of UPAs were determined as air pressure < 500 hPa, oxygen content < 40%. (3) The resultant UPAs on the QTP covers an area of 1912 km ², including 699 km² in Xinjiang, 413 km² in Sichuan, 331 km² in Tibet, 291 km² in Qinghai, and 178 km² in Gansu. The UPAs are scattered sporadically, mostly distributed in Gonggashan Mountain region in Sichuan, the extremely high mountain areas such as Mount Everest in the Himalayas, and the northern Hoh Xil and Lop Nur region, as well as a small part of the UPAs in the Qaidam Basin of Qinghai.

Microplastics as emerging pollutants have attracted increasing attention. This study explored the microplastics in water and soil environments of Qinghai-Tibet Plateau and discussed their potential sources. We collected 53 water samples and 52 soil samples from May to July in 2019 in two major regions, i.e. the southern Qinghai-Tibet Plateau and the Qilian Mountains region (national ecological restoration area in the plateau). The microplastic abundance of water in the southern Qinghai-Tibet Plateau was significantly higher than that in the Qilian Mountains, while no significant difference existed in soil samples between two regions (p > 0.05). The concentration ranges of microplastics were 0-1916.66 items/m³ and 0-260 items/kg in water and soil, with the average values being (438.21±454.94) items/m³ and (48.35±36.25) items/kg, respectively. Microplastics in water were mostly transparent fiber with the main polymer being polypropylene, while the most common form in soil was transparent film with the dominant polymer being polyethylene. Source analysis showed that the major sources of microplastics in water might be laundry wastewater and waste from tourism, while agricultural plastic mulch would be potentially responsible for microplastics in soil. The results proved the existence of microplastics in most of soil and water environments in the Qinghai-Tibet Plateau, and provided important supports for future studies on microplastics migration and transformation mechanism at high altitudes.

The floating population has become an important driving force of population growth in the Qinghai-Tibet Plateau in recent years, and thus the settlement intention of the floating population is of vital importance to the sustainable urbanization of the Qinghai-Tibet Plateau. Based on the data of China's floating population dynamic monitoring survey in 2017, this paper measured the settlement intention of the floating population in the study area, and according to their migration source of Qinghai-Tibet Plateau area, and distinguished the short- and long-distance floating population, and then compared their settlement intentions. Following this, we built a multi-level logistic regression model to analyze the underlying driving forces of the settlement intentions of the floating population as well as the possible differences between the short- and long-distance floating population. The main findings are as follows: (1) The overall settlement intention of the floating population in the plateau area was not high, and only about 32% of the floating population intend to stay in the urban areas for a long time; except for Lhasa, Xining and Haixi, that proportion is only about 10% of the prefecture units. (2) The settlement intention of the short-distance floating population was significantly higher than that of the long-distance floating population, but the percentages of the short-distance floating population with long-term settlement intention in most prefecture units were still less than 20%. (3) Education level, income level, urban medical insurance, social integration, economic development level and natural conditions of the inflow destinations have significant influence on the settlement intention of the floating population. (4) The difference of settlement intention between short- and long-distance floating population was closely related to the migration motivation and the social integration. Based on the above findings, this paper suggests that it is necessary to take targeted measures to improve the settlement intention of the short- and long-distance floating population in terms of the influencing factors, and also explore the suitable urbanization pattern for the Qinghai-Tibet Plateau area, such as promoting the local urbanization.

Traditional trade routes that penetrate the natural barrier of the Himalayas are critical for connecting major Chinese and South Asian markets. Research on these trade routes can contribute significantly to facilitating the construction of the South Asia Channel and enhancing trans-Himalayan connectivity. Combining historical literature, field surveys, and Geographic Information System (GIS) techniques, this study examined the spatial distribution characteristics and dynamic mechanisms driving the formation, development, decline, and restoration of the routes, focusing on transverse valleys of the Himalayan arc. The key findings were as follows. First, there are 21 traditional trade routes traversing the Himalayan region: 6 Sino-Nepalese routes, 4 Sino-Bhutanese routes, and 11 Sino-Indian routes. The routes are arranged in a "one horizontal and multiple vertical" spatial pattern. Second, the evolution of the traditional trade routes has entailed five distinct phases: an incipient period (pre-7th century), formation (7th century-842 AD), development (842-1959), decline (1959-1962) and recovery (1962-present). Third, the incipient and formative developmental phases were prompted by the spread of Buddhism and the exchange of goods. The stability of local governments in Tibet and in the Central China Plains and favorable border trade policies along with Britain's colonial expansion and commercial interests stimulated further development of traditional trade routes. However, India's strategic miscalculation and "Forward Policy" instigated the decline phase, while China's strategic needs are currently the key driver of the restoration and construction phase. Finally, a lack of strategic mutual trust and existing border issues are the main obstacles impeding the restorative and construction phases. Future efforts to support the construction of the South Asia Channel and the stability and development of border regions should focus on strengthening multi-perspectival investigations and research on traditional trade routes, formulating strategies for corridor construction and control, and emphasizing the corridor's commerce, tourism, and cultural exchange functions.

Climate change, which can lead to environmental problems, has become a global concern, especially in the Tibetan Plateau. However, there are few studies on quantitative assessment of climate change on agricultural crops in the Tibetan Plateau. We used meteorological data and yearbook statistical data to assess the impact of climate change on cereal yields of Tibet. Three types of statistical models were selected, including fixed effect model, first-difference model and linear de-trend model. We analyzed the impacts of climate change (minimum temperature, precipitation, growing degree days, and solar radiation) on cereal yields at the county, city, and autonomous region scales in Tibet from 1993 to 2017. The results showed that the sensitivity of cereal production to temperature (minimum temperature and growing degree days) was greater than that to precipitation and solar radiation. The joint impacts of climate variables were positive, but the sensitivity and significance of different regions were different. Except for the negative impact of growing degree days on Lhasa, the impacts of minimum temperature, precipitation and solar radiation were positive on all cities. The impacts of climate trends on the cereal yields in Tibet Autonomous Region were positive and the results of different models were concentrated in the range of 1.5% to 4.8%. Among the three types of models, the fixed effect model performed best in robustness, and the linear de-trend model was better than the first-difference model. After we add the interaction between different climate variables, the robustness of the first-difference model decreased. Our study could help implement more spatially targeted agricultural adaptation measures to cope with the impact of climate change on the agricultural ecosystem of the Tibetan Plateau.