Artemisia /Chenopodiaceae ratio from surface lake sediments on the central and western Tibetan Plateau and its application

Lake sedimentary DNA (sedDNA) is an established tool to trace past changes in vegetation composition and plant diversity. However, little is known about the relationships between sedimentary plant DNA and modern vegetational and environmental conditions. In this study, we investigate i) the relationships between the preservation of sedimentary plant DNA and environmental variables, ii) the modern analogue of ancient plant DNA assemblages archived in lake sediments, and iii) the usability of sedimentary plant DNA for characterization of terrestrial and aquatic plant composition and diversity based on a large dataset of PCR-amplified plant DNA data retrieved from 259 lake surface sediments from the Tibetan Plateau and Siberia. Our results indicate the following: i) Lake-water electrical conductivity and pH are the most important variables for the preservation of plant DNA in lake sediments. We expect the best preservation conditions for sedimentary plant DNA in small deep lakes characterized by high water conductivities (&#8805;100 &#956;S cm-1) and neutral to slightly alkaline pH conditions (7&#8211;9). ii) Plant DNA metabarcoding is promising for palaeovegetation reconstruction in high mountain regions, where shifts in vegetation are solely captured by the sedDNA-based analogue matching and fossil pollen generally has poor modern analogues. However, the biases in the representation of some taxa could lead to poor analogue conditions. iii) Plant DNA metabarcoding is a reliable proxy to reflect modern vegetation types and climate characteristics at a sub-continental scale. However, the resolution of the trnL P6 loop marker, the incompleteness of the reference library, and the extent of sedDNA preservation are still the main limitations of this method. iv) Plant DNA metabarcoding is a suitable proxy to recover modern aquatic plant diversity, which is mostly affected by July temperature and lake-water conductivity. Ongoing warming might decrease macrophyte richness in the Tibetan Plateau and Siberia, and ultimately threaten the health of these important freshwater ecosystems. To conclude, sedimentary plant DNA presents a high correlation with modern vegetation and may therefore be an important proxy for reconstruction of past vegetation.

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Dzaekha game drives for antelope hunting on the north-western Tibetan Plateau

10.2307/j.ctv24q4zh6.20 ◽

2021 ◽

pp. 427-446

Author(s):

Toni Huber

Keyword(s):

Tibetan Plateau ◽

The North ◽

Western Tibetan Plateau ◽

North Western

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Association of the pre-monsoon thermal field over north India and the western Tibetan Plateau with summer monsoon rainfall over India

Annales Geophysicae ◽

10.5194/angeo-33-1051-2015 ◽

2015 ◽

Vol 33 (8) ◽

pp. 1051-1058 ◽

Cited By ~ 1

Author(s):

S. D. Bansod ◽

S. Fadnavis ◽

S. P. Ghanekar

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Asian Summer Monsoon ◽

Summer Monsoon Rainfall ◽

North India ◽

Monsoon Region ◽

The North ◽

Western Tibetan Plateau ◽

Asian Summer ◽

Summer Monsoon Region

Abstract. In this paper, interannual variability of tropospheric air temperatures over the Asian summer monsoon region during the pre-monsoon months is examined in relation to Indian summer monsoon rainfall (ISMR; June to September total rainfall). For this purpose, monthly grid-point temperatures in the entire troposphere over the Asian summer monsoon region and ISMR data for the period 1949–2012 have been used. Spatial correlation patterns are investigated between the temperature field in the lower tropospheric levels during May over the Asian summer monsoon region and ISMR. The results indicate a strong and significant northwest–southeast dipole structure in the spatial correlations over the Indian region, with highly significant positive (negative) correlations over the regions of north India and the western Tibetan Plateau region – region R1 (north Bay of Bengal: region R2). The observed dipole is seen significantly up to a level of 850 hPa and eventually disappears at 700 hPa. Thermal indices evaluated at 850 hPa level, based on average air temperatures over the north India and western Tibetan Plateau region (TI1) and the north Bay of Bengal region (TI2) during May, show a strong, significant relationship with the ISMR. The results are found to be consistent and robust, especially in the case of TI1 during the period of analysis. A physical mechanism for the relationship between these indices and ISMR is proposed. Finally the composite annual cycle of tropospheric air temperature over R1 during flood/drought years of ISMR is examined. The study brings out the importance of the TI1 in the prediction of flood/drought conditions over the Indian subcontinent.

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Diurnal and Seasonal Variations of Surface Energy and CO2 Fluxes over a Site in Western Tibetan Plateau

Atmosphere ◽

10.3390/atmos11030260 ◽

2020 ◽

Vol 11 (3) ◽

pp. 260 ◽

Cited By ~ 1

Author(s):

Xingbing Zhao ◽

Changwei Liu ◽

Nan Yang ◽

Yubin Li

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Tibetan Plateau ◽

Surface Energy ◽

Seasonal Variations ◽

Surface Energy Balance ◽

Diurnal Variations ◽

Heat Fluxes ◽

Co2 Fluxes ◽

Western Tibetan Plateau

Land surface process observations in the western Tibet Plateau (TP) are limited because of the abominable natural conditions. During the field campaign of the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX III), continuous measurements on the four radiation fluxes (downward/upward short/long-wave radiations), three heat fluxes (turbulent sensible/latent heat fluxes and soil heat flux) and also CO2 flux were collected from June 2015 through January 2017 at Shiquanhe (32.50° N, 80.08° E, 4279.3 m above sea level) in the western Tibetan Plateau. Diurnal and seasonal variation characteristics of these surface energy and CO2 fluxes were presented and analyzed in this study. Results show that (1) diurnal variations of the seven energy fluxes were found with different magnitudes, (2) seasonal variations appeared for the seven energy fluxes with their maxima in summer and minima in winter, (3) diurnal and seasonal variations of respiration caused by the biological and chemical processes within the soil were found, and absorption (release) of CO2 around 0.1 mg m−2 s−1 occurred at afternoon of summer (midnight of winter), but the absorption and release generally canceled out from a yearly perspective; and (4) the surface energy balance ratio went through both diurnal and seasonal cycles, and in summer months the slopes of the fitting curve were above 0.6, but in winter months they were around 0.5. Comparing the results of the Shiquanhe site with the central and eastern TP sites, it was found that (1) they all generally had similar seasonal and diurnal variations of the fluxes, (2) caused by the low rainfall quantity, latent heat flux at Shiquanhe (daily daytime mean always less than 90 W m−2) was distinctively smaller than at the central and eastern TP sites during the wet season (generally larger than 100 W m−2), and (3) affected by various factors, the residual energy was comparatively larger at Shiquanhe, which led to a small surface energy balance ratio.

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