Determination and Analysis of Soil Organic Matter Content in Greenhouses around Lhasa City

The soil organic matter content in the greenhouses around Lhasa City was determined by potassium dichromate-sulfuric acid digestion method. The results showed that the soil organic matter content differed among different soil layers of the greenhouses around Lhasa City, and it was relatively low in the deep soil. The soil organic matter content also differed among greenhouses with different cultivation modes. In the same soil layer, the organic matter content in arched greenhouse was lower than that in semi-arched greenhouse. Among all the soil samples, the samples with organic matter content below the critical value （20 g/kg） accounted for 61.33%, and the samples with higher organic matter content （≥30 g/kg） accounted for 10.64%. The soil organic matter content in the greenhouses of different counties of Lhasa City ranked as Dazi County＇s〉Duilongdeqing County＇s〉Qushui County＇s. In overall, the organic matter content in the soil of greenhouses around Lhasa City was medium-low, and the fertility of the greenhouse soil was at the middle level.

Resources of Colored-leaf Trees and Their Phenological Ornamental Characteristics in Lhasa City

By using biological five points,expert consultation and fuzzy comprehensive evaluation,the species,phenological ornamental characteristics,and landscape application of colored-leaf trees in Lhasa City were surveyed systematically. The results show that there are 42 species of colored-leaf trees in Lhasa City,belonging to 31 genera and 18 families,of which there are 5,19,and 18 species of spring,autumn,and common colored-leaf trees,accounting for 11.90%,45.24% and 42.86% of total number of the investigated tree species respectively. It is clearly seen that there are too few species of spring colored-leaf trees in the city. There are 19 and 17 species of trees possessing red and yellow leaves,while the leaves of other 6 species of colored-leaf trees are shown in other colors,and the number of their species accounts for 45.24%,40.48% and 14.28% of total number of the investigated tree species respectively. The best ornamental periods of spring,autumn and common colored-leaf trees in Lhasa City average 38.4,41.8 and 251.8 d respectively. Prunus cerasifera Ehrhar f. atropurpurea Rehd.,Ulmus pumila L.,Populus × beijingensis W. Y. Hsu,and Salix alba are applied most frequently in Lhasa City,and their relative frequency is 18.67%,10.29%,9.91% and 8.95% respectively. According to the comprehensive assessment value of their ornamental characteristics,the ornamental characteristics of 15 species of colored-leaf trees in Lhasa City are good or very good,and there is a positive correlation between the comprehensive assessment value and relative frequency. Based on the investigation,the current application situation and problems of colored-leaf trees in Lhasa City were analyzed,and solutions to the problems were proposed.

The “Floating Population” in Lhasa City

Lhasa,to some extent,is regarded as a holiday city.It is hard to meet people when they are in a rush. Whenever a pilgrimage procession passes by,you can always see the pilgrims holding their praying wheels, followed by dogs,while they walk peacefully along the path of the pilgrimage.On the edges of streets and laneways,tea bars are teeming with people playing cards or chatting.Once they sit down,they might easily let half a day slip by.

City Sculptures in Lhasa

Some 1,300 years ago,the 32nd tsampo of the Tubo Kingdom unified whole TibetPlateau and founded the Tubo Kingdom Lhasa was made its capital. From then on,the city of Lhasa fell prey to scrambles between various generations of Tibetankings and Buddhist sects.

Hydrochemical insights on the signatures and genesis of water resources in a high-altitude city on the Qinghai-Xizang Plateau, South-west China

Water resources have crucial implications for the steady development of the urban social economy.This study investigated the hydrochemical signatures and genesis of water resources in the urban area of Lhasa City(UALC).To this end,several analyses,such as ion ratio analysis and correlation analysis,were performed by comprehensively applying mathematical statistics and integrated hydrochemical methods.The results show relatively low concentrations of major ions in the groundwater and surface water(GSW)of the UALC.The primary anions and cations are HCO3-and Ca2+,reflecting the HCOg-Ca water type.Nevertheless,groundwater exhibits higher concentrations of key chemical components compared to surface water.GsW are weakly alkaline,with pH values of 7.78 and 7.61,respectively,and they have low salinity with average concentrations of total dissolved solids being 190.74 and 112.17 mg/L,respectively.Anthropogenic inputs have minimal influence on the hydrochemical features of GSw,whereas rock weathering is the dominant controlling factor.Furthermore,cation exchange.is a significant hydrogeochemical.process influencing their hydrochemical features.According to the isotope analysis(H and 180),the primary source of recharge for GSW is atmospheric precipitation,with some input from melted ice and snow.Moreover,GSW samples from the UALC show relatively similar 2H and 18O isotopic compositions,indicating the existence of a discernible hydraulic connection linking the two water sources.The research findings can serve as a valuable scientific reference and foundation for the sustainable development,effective utilization,and proper safeguarding of regional water resources in high-altitude areas.