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Investigation of the altitude of maximum precipitation (AMP) and the factors that determine this height supports the understanding of vertical precipitation distribution in mountains. Based on the field precipitation measurement on the northern flank of the Qilian Mountains, the AMP was investigated at vertical profiles from 1,483 to 4,484 m. It found a 2,300 m-AMP in winter and a 4,200 m-AMP in other seasons and on a yearly scale. The AMPs increase from the cold and dry season to the warm and wet season and therefore increase with precipitation. During winter, the interaction of the predominant high-pressure system, the thermal inversion layer below 2,200 m, and the westerly lead to the 2,300-m AMP. In other seasons, the convergent Tibetan Plateau monsoon causes the water vapor move to the Qilian Mountains, and the enhanced uplifting by the mountain produces greater precipitation with altitude, forming the AMP at the higher areas. The front steepest terrain is the primary factor causing the formation of 4,200-m AMP in the study area. The annual AMP may be roughly equal to seven-eighths of the altitude of the mountain top on the north flank of the Qilian Mountains. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) experienced a rapid warming and wetting in recent decades. The elevation dependence of warming rate has been established, while the question of trend in precipitation against the elevation gradient remains open. By using the in situ observation of precipitation, air temperature, and surface specific humidity from 91 stations over and around the TP, this study investigated how the trends in summer precipitation varied along the elevation gradient over and around the TP during the period 1970-2014. The major findings are as follows: (1) the trends in summer precipitation from 1970 to 2014 displayed an increasing tendency at a rate of 0.83% decade-1 km-1 with the increased elevation, and the rate for 1991–2014 (2.23% decade-1 km-1) is even greater and (2) the temporal trends in surface air temperature, surface specific humidity (surface water vapour) from in situ observations and total column of water vapour from Japanese 55-year reanalysis (JRA-55) data overmost stations consistently display similar elevation dependence, which provides a plausible explanation for the elevation dependence of the summer precipitation trends based on the Clausius–Clapeyron relationship. The large-scale atmospheric circulations are other possible factors influencing the elevation dependence of summer precipitation trends, which needs further investigations. [ABSTRACT FROM AUTHOR]

Eddy covariance measurements from 2012 to 2015 were used to investigate the interannual variation in carbon dioxide exchange and its control over an alpine meadow on the south-east margin of the Tibetan Plateau. The annual net ecosystem exchange (NEE) in the 4 years from 2012 to 2015 was -114.2, -158.5, -159.9 and -212.6 gCm-2yr-1, and generally decreased with the mean annual air temperature (MAT). An exception occurred in 2014, which had the highest MAT. This was attributed to higher ecosystem respiration (RE) and similar gross primary production (GPP) in 2014 because the GPP increased with the MAT, but became saturated due to the limit in photosynthetic capacity. In the spring (March to May) of 2012, low air temperature (Ta) and drought events delayed grass germination and reduced GPP. In the late wet season (September to October) of 2012 and 2013, the low Ta in September and its negative effects on vegetation growth caused earlier grass senescence and significantly lower GPP. This indicates that the seasonal pattern of Ta has a substantial effect on the annual total GPP, which is consistent with results obtained using the homogeneity-of-slopes (HOS) model. The model results showed that the climatic seasonal variation explained 48.6% of the GPP variability, while the percentages explained by climatic interannual variation and the ecosystem functional change were 9.7 and 10.6 %, respectively. [ABSTRACT FROM AUTHOR]

Toxocara vitulorum has been rarely reported in yaks at high altitudes and remote areas of Sichuan Province of Tibetan Plateau of China. The current study was designed to investigate the prevalence, associated risk factors, and phylogenetic characteristics of T. vitulorum in yak calves on the Qinghai Tibetan plateau. Fecal samples were collected from 891 yak calves and were examined for the presence of T. vitulorum eggs by the McMaster technique. A multivariable logistic regression model was employed to explore variables potentially associated with exposure to T. vitulorum infection. T. vitulorum specimens were collected from the feces of yaks in Hongyuan of Sichuan Province, China. DNA was extracted from ascaris. After PCR amplification, the sequencing of ND1 gene was carried out and phylogenetic analyses was performed by MEGA 6.0 software. The results showed that 64 (20.1%; 95% CI 15.8-24.9%), 75 (17.2; 13.8-21.1), 29 (40.9; 29.3-53.2), and 5 (7.6; 2.5-16.8) yak calves were detected out to excrete T. vitulorum eggs in yak calve feces in Qinghai, Tibet, Sichuan, and Gansu, respectively. The present study revealed that high infection and mortality by T. vitulorum is wildly spread on the Qinghai Tibetan plateau, China by fecal examination. Geographical origin, ages, and fecal consistencies are the risk factors associated with T. vitulorum prevalence by logistic regression analysis. Molecular detection and phylogenetic analysis of ND1 gene of T. vitulorum indicated that T. vitulorum in the yak calves on the Qinghai Tibetan plateau are homologous to preveiously studies reported. [ABSTRACT FROM AUTHOR]

The genetic diversity, population structure, and extent of linkage disequilibrium (LD) were investigated at a genome-wide level in 255 sixrowed barley (Hordeum vulgare L. ssp. Vulgare) landraces from the Qinghai-Tibetan Plateau using 1264 polymorphic diversity array technology (DArT) markers. The mean polymorphism information content (PIC) of the DArT markers ranged between 0.008 and 0.500 with an average of 0.213. Bayesian, principal coordinate analysis, and phylogenetic analysis supported that six-rowed barley landraces from this region are divided into five distinct subpopulations centered on the regions of origin of the germplasm. The genetic distances calculated for all the individual pairs were geographically dependent, as revealed by Mantel tests (r = 0.35, P < 0.001) and spatial autocorrelation analysis. The LD values, expressed as r², declined with increasing genetic distance, and the same tendency occurred on each chromosome. In general, LD values were low (9.1% of adjacent markers; P < 0.001), and mean LD values across the whole genome decayed to below the critical r2 of 0.22 after 3.32 cM. Approximately 19.0% of marker pairs (mean r² = 0.586) located on the same chromosome and 4.9% of pairs (mean r² = 0.318) located on different chromosomes were in LD (r² = 0.22). Our results discerned relevant patterns of genetic diversity, population structure, and LD among members of a Qinghai- Tibet Plateau barley landraces panel proposed to be 'typical' of a target region or environment and have important implications for further studies on association mapping and practical breeding in high-altitude naked barley. [ABSTRACT FROM AUTHOR]