Dataset Information

Methodological comparison of alpine meadow evapotranspiration on the Tibetan Plateau, China.

ABSTRACT: Estimation of evapotranspiration (ET) for alpine meadow areas in the Tibetan Plateau (TP) is essential for water resource management. However, observation data has been limited due to the extreme climates and complex terrain of this region. To address these issues, four representative methods, Penman-Monteith (PM), Priestley-Taylor (PT), Hargreaves-Samani (HS), and Mahringer (MG) methods, were adopted to estimate ET, which were then compared with ET measured using Eddy Covariance (EC) for five alpine meadow sites during the growing seasons from 2010 to 2014. And each site was measured for one growing season during this period. The results demonstrate that the PT method outperformed at all sites with a coefficient of determination (R2) ranging from 0.76 to 0.94 and root mean square error (RMSE) ranging from 0.41 to 0.62 mm d-1. The PM method showed better performance than HS and MG methods, and the HS method produced relatively acceptable results with higher R2 (0.46) and lower RMSE (0.89 mm d-1) compared to MG method with R2 of 0.16 and RMSE of 1.62 mm d-1, while MG underestimated ET at all alpine meadow sites. Therefore, the PT method, being the simpler approach and less data dependent, is recommended to estimate ET for alpine meadow areas in the Tibetan Plateau. The PM method produced reliable results when available data were sufficient, and the HS method proved to be a complementary method when variables were insufficient. On the contrary, the MG method always underestimated ET and is, thus, not suitable for alpine meadows. These results provide a basis for estimating ET on the Tibetan Plateau for annual data collection, analysis, and future studies.

SUBMITTER: Chang Y

PROVIDER: S-EPMC5728505 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Methodological comparison of alpine meadow evapotranspiration on the Tibetan Plateau, China.

Chang Yaping Y Wang Jie J Qin Dahe D Ding Yongjian Y Zhao Qiudong Q Liu Fengjing F Zhang Shiqiang S

PloS one 20171213 12

Estimation of evapotranspiration (ET) for alpine meadow areas in the Tibetan Plateau (TP) is essential for water resource management. However, observation data has been limited due to the extreme climates and complex terrain of this region. To address these issues, four representative methods, Penman-Monteith (PM), Priestley-Taylor (PT), Hargreaves-Samani (HS), and Mahringer (MG) methods, were adopted to estimate ET, which were then compared with ET measured using Eddy Covariance (EC) for five a ...[more]

PMID: 29236754

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Project description:Background and Aims:There is no knowledge of winter plant phenology and its controlling factors on the Qinghai-Tibetan Plateau (QTP). Thus, we conducted a 4 year winter phenology and growth dynamics study in the alpine meadow on the eastern QTP. Methods:From November 2013 to March 2017, the phenology of the 'winter-growth' and 'winter-green' species was recorded every 5 d. In November-February from 2014 to 2015, the above-ground biomass (AGB) in random plots was calculated to distinguish different growth patterns among winter growing species. The percentage of winter abundance relative to the summer population for forbs and the percentage of absolute coverage for grasses (W/S) were calculated to describe the importance of the winter population to the summer population. The soil moisture (SM) and soil temperature (ST) were used to explore the controlling factors on the AGB. Pearson's correlation analysis between winter phenology data and environmental variables, including air temperature (Tair), snow cover fraction (SCF), SM and ST, was used to investigate the factors affecting winter phenology during November-February from 2014 to 2017. Key Results:There were 107 species in total in the sites, including ten 'winter-growth' species and four 'winter-green' species. Among the 'winter-green' species, Festuca ovina and Deschampsia cespitosa were the dominant species in the sites. The 'winter-growth' species grew new leaves or ramets or transitioned to reproductive growth. Gentiana spathulifolia even flowered in winter. 'Winter-growth' made important contributions to the annual AGB, e.g. winter growth of G. spathulifolia accounted for 23.26 % of its annual AGB, while 14.74 % of the annual AGB of G. crassuloides was from winter growth. In addition, winter warming and snowfall reduction under global climate change on the eastern QTP may decrease the AGB increment of the 'winter-growth' and delay the green-up onset date of 'winter-green' species. Also, winter warming and snowfall reduction may advance the first flowering date of 'winter-growth' species. Conclusions:In contrast to previous views that plants on the QTP were generally considered to remain dormant in winter, our study revealed that alpine meadow plants had strong winter growth which suggested the importance of re-evaluating the dynamics of ecosystem function of alpine meadow, including its contribution to the global carbon balance. It was also shown that soil moisture availability is more important than warmer temperature in controlling the green-up onset of 'winter-green' species on the eastern QTP, which contrasts with the traditional view that warmer winters could advance green-up. As snowmelt is the only source of soil water in winter, the prediction of the green-up trend may be further complicated by snowfall variation in winter.

Project description:BACKGROUND: GeoChip 3.0, a microbial functional gene array, containing ~28,000 oligonucleotide probes and targeting ~57,000 sequences from 292 functional gene families, provided a powerful tool for researching microbial community structure in natural environments. The alpine meadow is a dominant plant community in the Qinghai-Tibetan plateau, hence it is important to profile the unique geographical flora and assess the response of the microbial communities to environmental variables. In this study, Geochip 3.0 was employed to understand the microbial functional gene diversity and structure, and metabolic potential and the major environmental factors in shaping microbial communities structure of alpine meadow soil in Qinghai-Tibetan Plateau. RESULTS: A total of 6143 microbial functional genes involved in carbon degradation, carbon fixation, methane oxidation and production, nitrogen cycling, phosphorus utilization, sulphur cycling, organic remediation, metal resistance, energy process and other category were detected in six soil samples and high diversity was observed. Interestingly, most of the detected genes associated with carbon degradation were derived from cultivated organisms. To identify major environmental factors in shaping microbial communities, Mantel test and CCA Statistical analyses were performed. The results indicated that altitude, C/N, pH and soil organic carbon were significantly (P < 0.05) correlated with the microbial functional structure and a total of 80.97% of the variation was significantly explained by altitude, C/N and pH. The C/N contributed 38.2% to microbial functional gene variation, which is in accordance with the hierarchical clustering of overall microbial functional genes. CONCLUSIONS: High overall functional genes and phylogenetic diversity of the alpine meadow soil microbial communities existed in the Qinghai-Tibetan Plateau. Most of the genes involved in carbon degradation were derived from characterized microbial groups. Microbial composition and structures variation were significantly impacted by local environmental conditions, and soil C/N is the most important factor to impact the microbial structure in alpine meadow in Qinghai-Tibetan plateau.

Project description:Alpine meadow ecosystems are susceptible to climate changes. Still, climate impact on cuticular wax in alpine meadow plants is poorly understood. Assessing the variations of cuticular wax in alpine meadow plants across different latitudes might be useful for predicting how they may respond to climate change. We studied nine alpine meadows in a climate gradient in the east side of Qinghai-Tibetan Plateau, with mean annual temperature ranging from -7.7 to 3.2°C. In total, 42 plant species were analyzed for cuticular wax, averaged 16 plant species in each meadow. Only four plant species could be observed in all sampling meadows, including Kobresia humilis,Potentilla nivea,Anaphalis lacteal, and Leontopodium nanum. The amounts of wax compositions and total cuticular wax in the four plant species varied among sampling meadows, but no significant correlation could be observed between them and temperature, precipitation, and aridity index based on plant species level. To analyze the variations of cuticular wax on community level, we averaged the amounts of n-alkanes, aliphatic acids, primary alcohols, and total cuticular wax across all investigated plant species in each sampling site. The mean annual temperature, mean temperature in July, and aridity index were significantly correlated with the averaged amounts of wax compositions and total cuticular wax. The average chain length of n-alkanes in both plant and soil linearly increased with increased temperature, whereas reduced with increased aridity index. No significant correlation could be observed between mean annual precipitation and mean precipitation from June to August and the cuticular wax amounts and average chain length. Our results suggest that the survival of some alpine plants in specific environments might be depended on their abilities in adjusting wax deposition on plant leaves, and the alpine meadow plants as a whole respond to climate change, benefiting the stability of alpine meadow ecosystem.

Project description:BackgroundThe degradation of alpine meadows has induced substantial losses of soil organic carbon (SOC) on the Tibetan Plateau. A commonly-used method for rehabilitating degraded alpine meadows in this region is establishing cultivated grasslands through sowing seed mixtures, but its impact on the biochemical stability of SOC has remained inadequately explored.MethodsIn this study, a total of 20 composited 0-20 cm soil samples were collected from a heavily degraded alpine meadow (DM) and three adjacent cultivated grasslands established for 3 years (CG3), 12 years (CG12), and 17 years (CG17) on the eastern Tibetan Plateau, and the SOC pool was separated into labile C pool I (LOC I), labile C pool II (LOC II), and recalcitrant C pool (ROC) in order to investigate changes in contents of SOC fractions that have different biochemical stabilities after the establishment of cultivated grassland.ResultsAlthough the establishment of cultivated grasslands led to increases in soil total organic C content, the increase was only significant in samples with 17 years of cultivation. We found that the contents of the three SOC fractions were higher at CG3 and CG12 compared with those in the DM, and the differences were only significant for soil LOC II. By comparison, 17 years of cultivation led to significant increases in all of the SOC fraction contents. The results implied that different cultivation years had distinct impacts on SOC fractions in cultivated grasslands, and longer cultivation years contributed to accumulated soil ROC. The recalcitrance index of SOC in the DM was higher than that at CG3 and CG12, but lower than that at CG17. This was possibly due to the generally low litter quality of cultivated grasslands, which led to a slow release of complex compounds to soils. Moreover, it was observed that soil C:N ratio was a potential indicator of SOC biochemical stability because of their close correlation.ConclusionsOur findings suggest that the long-term establishment of cultivated grasslands on DM is a promising solution to recovering both the quantity and stability of SOC on the Tibetan Plateau.

Dataset Information

Methodological comparison of alpine meadow evapotranspiration on the Tibetan Plateau, China.

Publications

Methodological comparison of alpine meadow evapotranspiration on the Tibetan Plateau, China.

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