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Though aboveground biomass (AGB) has an important contribution to the global carbon cycle, the information about storage and climatic effects of AGB is scare in Three-River Source Region (TRSR) shrub ecosystems. This study investigated AGB storage and its climatic controls in the TRSR alpine shrub ecosystems using data collected from 23 sites on the Tibetan Plateau from 2011 to 2013. We estimated the AGB storage (both shrub layer biomass and grass layer biomass) in the alpine shrubs as 37.49 Tg, with an average density of 1447.31 g m<sup>-2</sup>. Biomass was primarily accumulated in the shrub layer, which accounted for 92% of AGB, while the grass layer accounted for only 8%. AGB significantly increased with the mean annual temperature (<i>P</i> < 0.05). The effects of the mean annual precipitation on AGB were not significant. These results suggest that temperature, rather than precipitation, has significantly effects on of aboveground vegetation growth in the TRSR alpine shrub ecosystems. The actual and potential increase in AGB density was different due to global warming varies among different regions of the TRSR. We conclude that long-term monitoring of dynamic changes is necessary to improve the accuracy estimations of potential AGB carbon sequestration across the TRSR alpine shrub ecosystems.
High throughput sequencing technology is also called Next Generation Sequencing (NGS), which can sequence hundreds and thousands sequences in different samples at the same time. In the present study, the culture-independent high throughput sequencing technology was applied to sequence the fungi metagenomic DNA of the fungal internal transcribed spacer 1(ITS 1) in the root of Sinopodophyllum hexandrum. Sequencing data suggested that after the quality control, 22 565 reads were remained. Cluster similarity analysis was done based on 97% sequence similarity, which obtained 517 OTUs for the three samples (LD1, LD2 and LD3). All the fungi which identified from all the reads of OTUs based on 0.8 classification thresholds using the software of RDP classifier were classified as 13 classes, 35 orders, 44 family, 55 genera. Among these genera, the genus of Tetracladium was the dominant genera in all samples(35.49%, 68.55% and 12.96%).The Shannon's diversity indices and the Simpson indices of the endophytic fungi in the samples ranged from 1.75-2.92, 0.11-0.32, respectively.This is the first time for applying high through put sequencing technol-ogyto analyze the community composition and diversity of endophytic fungi in the medicinal plant, and the results showed that there were hyper diver sity and high community composition complexity of endophytic fungi in the root of S. hexandrum. It is also proved that the high through put sequencing technology has great advantage for analyzing ecommunity composition and diversity of endophtye in the plant.
Although large amounts of soil organic carbon (SOC) stored in the shrublands, information about SOC storage was little on the Tibetan Plateau. This study aims to evaluate the spatial patterns and storage of SOC in the shrublands and the relationships of climatic variables and soil pH on the Tibetan Plateau.<br>We used 177 profiles of soil samples obtained from 59 shrubland sites on the northeast Tibetan Plateau from 2011 to 2013. Ordinary least squares regressions, curve estimation, and multiple linear regressions were used to evaluate controlling factors on SOC stock. Kriging interpolation was used to upscale sit-level measurements to the whole study area.<br>We found that SOC storage in the northeast Tibetan shrublands was 1.36 Pg C in the top 1 m with an average SOC stock of 12.38 kg m<sup>−2</sup>. SOC stock decreased from east to west and south to north but generally increased significantly with the mean annual temperature (MAT) and the mean annual precipitation (MAP), and tended to decrease with soil pH. Although similar relationships were also observed in alpine shrublands, the trends among SOC stock, MAP, and MAT were not observed in desert shrublands. Our results indicate that a reduction in soil pH accelerates the C sequestration potential. Furthermore, global warming contributed to C sequestration in alpine shrublands, specifically, SOC stock increased 8.44 kg m<sup>−2</sup> with an increased unit of MAT in alpine shrublands just considering temperature effects. Meanwhile, the C sequestration was different among different regions due to the uneven increases in precipitation. However, in desert shrublands, MAP and MAT did not significantly affect SOC stock.<br>The results indicate that though a reduction in soil pH could contribute to C sequestration, MAT and MAP have different effects on SOC stock in different Tibetan Plateau shrublands. Increased MAT and MAP were 0.05 °C and 1.67 mm every year on the Tibetan Plateau, which will increase C sequestration in alpine shrublands, but might have limited impacts on desert shrublands, which help us comprehend soil C cycling in the global climate change scenario.
Background Rheum tanguticum Maxim. ex Balf is one of the plants generically known as rhubarb, a culinary vegetable that has long been used as a herbal remedy both in China and Europe. Increasing demand for rhubarb has triggered the overexploitation of Rh. tanguticum. Cultivation is therefore necessary for quality control and protection of wild resources. Nitrogen fertilizer plays an important role in cultivation. This study aimed to explore how nitrogen fertilizer affects the growth and quality of rhubarb on the Qinghai-Tibetan plateau. Results Nitrogen fertilizer promoted growth but had no significant influence on the active compounds of Rh. tanguticum. Generally, the N2 (150 kg ha(-1)) and N3 (225 kg ha(-1)) levels showed the most improved growth indexes, with no significant differences between them. The growth index and the amounts of eight of the nine studied active compounds in Rh. tanguticum increased from each year to the next and differed among growth stages. The contents of the active compounds were higher at the green stage and lower at the growth stage, which was opposite to the seasonal trends in root dry matter ratio. Gallic acid levels decreased with the growth of the plant. Conclusion The N2 level (150 kg ha(-1)) was the recommended nitrogen fertilizer level in this study. It was revealed that seasonal changes rather than nitrogen fertilizer influenced active compounds in the root of Rh. tanguticum. (c) 2018 Society of Chemical Industry
<br>Display Omitted<br>• Optimal dosages of phosphate and potassium fertilizer on <b>R. tanguticum</b> were firstly explored. • The U-shaped fluctuation curve of total anthraquinone content is firstly proposed. • Optimization of chromatographic columns was firstly proposed when detecting index constituents. • Total anthraquinone content of two-year-old plants had reached <b>Chinese Pharmacopoeia</b> standard.<br>The dried root of <b>Rheum tanguticum</b> plays an important role in formulations and prescriptions in traditional Chinese medicine and Kampo medicine. Due to over-exploitation, <b>R. tanguticum</b> resources have decreased sharply in recent years. The main objective of our investigation (a 3-year field experiment) was to explore the effect of different levels of phosphorus (superphosphate) and potassium (potassium sulfate) fertilizer on the biomass (root fresh weight, root increment, and root dry weight), yield, dry matter content, and anthraquinone content of this plant at different harvesting stages (green stage, growth stage, and wilting stage) under alpine conditions. The root fresh weight and root dry weight increased significantly at the wilting stage following treatment with 90 kg P2O5/ha (100% and 59%, respectively) in 2016 and 75 kg K2O/ha (43% and 41%, respectively) in 2015 compared to the control. The yield of root dry weight obtained from three-year-old <b>R. tanguticum</b> plants was 9200 kg/ha when 90 kg P2O5/ha of phosphorus fertilizer was applied, and 10,400 kg/ha when 75 kg K2O/ha of potassium fertilizer was applied. This yield reached a maximum at the wilting stage. The anthraquinone content of two-year-old <b>R. tanguticum</b> plants had already reached the standard level of the <b>Chinese Pharmacopoeia</b>; however, three-year-old plants had double the anthraquinone content of two-year-old plants. Phosphorus and potassium fertilizers had no obvious influence on the anthraquinone content of <b>R. tanguticum</b> at the same harvesting stage.
Alpine shrubland ecosystems in the Three Rivers Source Region (TRSR) store substantial soil organic carbon (SOC), but the storage, patterns and control of SOC in those ecosystems have rarely been investigated. In this study, using data from 66 soil profiles surveyed from 22 sites between 2011 and 2013, we estimated the storage and patterns of SOC, and their relationships with climatic factors, elevation, ground cover and slope. Our results showed that SOC storage in the top 100 cm across the TRSR shrubland was 0.68 ± 0.38 Pg C, with an average SOC density (soil carbon storage per area) of 26.21 ± 14.58 kg m−2. Spatially, SOC density increased with longitude and latitude. Vertically, SOC in the topsoil at 30 cm and 50 cm accounted for 56% and 75%, respectively, of the total at 100 cm. SOC density showed a decreasing trend with increasing elevation, but it was greater in regions of higher ground cover. The density had no relationship with either mean annual precipitation or slope. Increasing mean annual temperature had positive effects on SOC density, which is inconsistent with the global trend. With increasing soil depth, however, the effects of temperature on SOC density were not significant. Therefore, in a global warming scenario, increasing temperature gives shrubland considerable C sink potential on the topsoil, and the regions of C sequestration differ as a result of uneven increases in temperature. Hence, further monitoring of dynamic changes is necessary to provide a more accurate assessment of potential C sequestration in TRSR shrubland.<br>• Storage and patterns of SOC were investigated in the TRSR shrubland. • SOC has no relationship with both precipitation and slope. • SOC was decreasing with elevation, but larger with both ground cover and temperature.