73 research outputs found

    Changes in Snow Phenology from 1979 to 2016 over the Tianshan Mountains, Central Asia

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    Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly understood throughout the entire TS due to the lack of in situ observations, limitations of optical remote sensing due to clouds, and decentralized political landscapes. Using passive microwave remote sensing snow data from 1979 to 2016 across the TS, this study investigates the spatiotemporal variations of snow phenology and their attributes and implications. The results show that the mean snow onset day (Do), snow end day (De), snow cover duration days (Dd), and maximum snow depth (SDmax) from 1979 to 2016 were the 78.2nd day of hydrological year (DOY), 222.4th DOY, 146.2 days, and 16.1 cm over the TS, respectively. Dd exhibited a spatial distribution of days with a temperature of \u3c0 \u3e°C derived from meteorological station observations. Anomalies of snow phenology displayed the regional diversities over the TS, with shortened Dd in high-altitude regions and the Fergana Valley but increased Dd in the Ili Valley and upper reaches of the Chu and Aksu Rivers. Increased SDmax was exhibited in the central part of the TS, and decreased SDmax was observed in the western and eastern parts of the TS. Changes in Dd were dominated by earlier De, which was caused by increased melt-season temperatures (Tm). Earlier De with increased accumulation of seasonal precipitation (Pa) influenced the hydrological processes in the snowmelt recharge basin, increasing runoff and earlier peak runoff in the spring, which intensified the regional water crisi

    Streamflow Pattern Variations Resulting from Future Climate Change in Middle Tianshan Mountains Region in China

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    In arid and semi-arid regions of North West china, glacier-melt, seasonal snowmelt and rainfall are the primary sources of flow in the rivers that originate from alpine areas. Spring and summer peak flow resulting from snowmelt and rainfall, respectively, are the main characteristics of streamflow pattern. Because of the damages caused by the spring and summer peak flow, a better understanding of the streamflow pattern variation under future climate warming is crucial. To analyze the variation of streamflow pattern under climate warming, the Kaidu River and the Manasi River watersheds in northern and southern slopes of Middle Tianshan Mountains, located in Xinjiang were selected as study areas. These watersheds receive water from water sources in different proportions. A modified hydrological model was forced with metrological data from CIMP5 data set and the streamflow in Kaidu and Manasi River watersheds were simulated. The results indicate that one-peak-flow pattern is projected to turn to the two-peak-flow pattern in the Manasi River watershed in the future. The two-peak flow pattern will continue in the Kaidu River watershed, but the dominant peak flow will shift from summer to spring in future. This study provides useful information for water resources managers to take different actions to reduce damages caused by spring and summer peak flow under future climate warming

    Developmental features and yields of three promising upland rice varieties in Zimbabwe

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    Three upland rice varieties: NERICA 1, 3 and 7 that were proved to be promising by previous trails in Zimbabwe, were selected as experimental materials to evaluate their developmental features and yields in irrigated conditions. The results indicate that plant height increased sharply first, and then slowly until the highest values that kept invariant. Tiller number per hill showed S-shaped curves which increased and reached relatively stable values first, then decreased slightly and finally increased again to produce the second time tiller. The leaf number per plant was apparently went up and down, which ascended to the peak values and then started to descend. NERICA 1 had many features which differed from NERICA 3 and NERICA 7, such as early maturing, short plant height, multiple tiller and multiple leave. It had the highest number of panicles and grains among the three varieties though it had nearly the same grain weight with NERICA 3 and NERICA 7. These results will be helpful to release these varieties in Zimbabwe.Keywords: Developmental feature, upland rice variety, yield, yield components, ZimbabweAfrican Journal of Biotechnology Vol. 12(21), pp. 3208-321

    Changes in soil labile and recalcitrant carbon pools after land-use change in a semi-arid agro-pastoral ecotone in Central Asia

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    Soil organic matter is a heterogeneous and complex entity that consists of a diverse range of compounds. However, the responses of soil organic carbon (SOC) fractions with different biochemical stabilities to land-use change are inadequately addressed. In this study, soil samples (0-60 cm) were collected with a 10 cm interval from grassland (GS), cropland (CS), woodland (WS), and orchard (OS) using paired-site approach in a typical semi-arid agro-pastoral ecotone in the Ili River Valley, Central Asia, to: (1) clarify the vertical changes in soil labile (LPI and LPII) and recalcitrant C pools (RP) after GS conversion to CS and CS conversion to WS and OS; and to (2) evaluate the impact of land-use change on SOC stability. The results indicated that LPI stocks in topsoil (0-30 cm) and subsoil (30-60 cm) showed opposite responses to land-use change. In contrast, LPII and RP stocks in both soil layers significantly decreased after conversion of GS to CS, and significantly increased after CS afforestation. These results demonstrated that RP in subsoils could also be altered by land-use change. In general, conversion from GS to CS decreased the recalcitrance index of SOC (RISOC), which increased after conversion from CS to WS. The results implied that cultivation decreased the stability of SOC, causing the depletion of SOC stock, whereas CS conversion to WS enhanced the stability of SOC, promoting SOC sequestration. The negative correlations between RISOC, pH, and electrical conductivity (EC1:5) suggested that soil pH and salinity were potential indicators reflecting the biochemical recalcitrance of SOC. Since both soil pH and EC1:5 showed decreasing trends after conversion from CS to WS and OS, the results suggested that afforestation on CS contributed to mitigate soil salinization while promoting SOC sequestration in this semi-arid agro-pastoral ecotone

    Human Migration through Bottlenecks from Southeast Asia into East Asia during Last Glacial Maximum Revealed by Y Chromosomes

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    Molecular anthropological studies of the populations in and around East Asia have resulted in the discovery that most of the Y-chromosome lineages of East Asians came from Southeast Asia. However, very few Southeast Asian populations had been investigated, and therefore, little was known about the purported migrations from Southeast Asia into East Asia and their roles in shaping the genetic structure of East Asian populations. Here, we present the Y-chromosome data from 1,652 individuals belonging to 47 Mon-Khmer (MK) and Hmong-Mien (HM) speaking populations that are distributed primarily across Southeast Asia and extend into East Asia. Haplogroup O3a3b-M7, which appears mainly in MK and HM, indicates a strong tie between the two groups. The short tandem repeat network of O3a3b-M7 displayed a hierarchical expansion structure (annual ring shape), with MK haplotypes being located at the original point, and the HM and the Tibeto-Burman haplotypes distributed further away from core of the network. Moreover, the East Asian dominant haplogroup O3a3c1-M117 shows a network structure similar to that of O3a3b-M7. These patterns indicate an early unidirectional diffusion from Southeast Asia into East Asia, which might have resulted from the genetic drift of East Asian ancestors carrying these two haplogroups through many small bottle-necks formed by the complicated landscape between Southeast Asia and East Asia. The ages of O3a3b-M7 and O3a3c1-M117 were estimated to be approximately 19 thousand years, followed by the emergence of the ancestors of HM lineages out of MK and the unidirectional northward migrations into East Asia

    Streamflow Forecast and Reservoir Operation Performance Assessment Under Climate Change

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    This study attempts to investigate potential impacts of future climate change on streamflow and reservoir operation performance in a Northern American Prairie watershed. System Dynamics is employed as an effective methodology to organize and integrate existing information available on climate change scenarios, watershed hydrologic processes, reservoir operation and water resource assessment system. The second version of the Canadian Centre for Climate Modelling and Analysis Coupled Global Climate Model is selected to generate the climate change scenarios with daily climatic data series for hydrologic modeling. Watershed-based hydrologic and reservoir water dynamics modeling focuses on dynamic processes of both streamflow generation driven by climatic conditions, and the reservoir water dynamics based on reservoir operation rules. The reliability measure describes the effectiveness of present reservoir operation rules to meet various demands which are assumed to remain constant for the next 100 years in order to focus the study on the understanding of the structure and the behaviour of the water supply. Simulation results demonstrate that future climate variation and change may bring more high-peak-streamflow occurrences and more abundant water resources. Current reservoir operation rules can provide a high reliability in drought protection and flood control

    Greenhouse Gas Emissions from Cotton Field under Different Irrigation Methods and Fertilization Regimes in Arid Northwestern China

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    Drip irrigation is broadly extended in order to save water in the arid cotton production region of China. Biochar is thought to be a useful soil amendment to reduce greenhouse gas (GHG) emissions. Here, a field study was conducted to compare the emissions of nitrous oxide (N2O) and methane (CH4) under different irrigation methods (drip irrigation (D) and furrow irrigation (F)) and fertilization regimes (conventional fertilization (C) and conventional fertilization + biochar (B)) during the cotton growth season. The accumulated N2O emissions were significantly lower with FB, DC, and DB than with FC by 28.8%, 36.1%, and 37.6%, while accumulated CH4 uptake was 264.5%, 226.7%, and 154.2% higher with DC, DB, and FC than that with FB, respectively. Irrigation methods showed a significant effect on total global warming potential (GWP) and yield-scaled GWP (P<0.01). DC and DB showed higher cotton yield, water use efficiency (WUE), and lower yield-scaled GWP, as compared with FC and FB. This suggests that in northwestern China mulched-drip irrigation should be a better approach to increase cotton yield with depressed GHG. In addition, biochar addition increased CH4 emissions while it decreased N2O emissions

    Effects of levofloxacin hydrochlordie on photosystem II activity and heterogeneity of Synechocystis sp.

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    Effects of LH on photosynthesis of Synechocystis sp. were investigated by a variety of in vivo chlorophyll fluorescence. O-2 evolution and the photosystem II (PSII) activity were clearly inhibited by LH. Exposure to LH increased the proportion of PSII beta and this weakened the connectivity between PS11 units and hindered excitation energy-transfer between PSII units. LH decreased the density of the active photosynthetic reaction centers, inhibited electron transport, and increased the dissipated energy flux per reaction center. The inhibitory effect of LH on Q(A)(-) reoxidation process could be divided into several stages. LH first inhibited the electron transfer from Q(A)(-) to Q(B) by weakening the connectivity between Q(A)(-) and Q(B), and PQ binding began taking part in Q(A)(-) reoxidation. At the second stage, the connectivity between Q(A)(-) and PQ pool was broken and inhibition on PQ binding occurred. At this stage, some Q(A)(-) began to be oxidized by S-2(Q(A)Q(B))(-). Finally, when the connectivity between Q(A)(-) and Q(B) and PQ was completely broken, all Q(A)(-) was oxidized through charge recombination. (C) 2009 Elsevier Ltd. All rights reserved

    Genomic Insights into the Formation of Human Populations in East Asia

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    厦门大学人类学研究所、厦门大学生命科学学院细胞应激生物学国家重点实验室王传超教授课题组与哈佛医学院David Reich教授团队合作,联合全球43个单位的85位共同作者组成的国际合作团队通过古DNA精细解析东亚人群形成历史。研究人员利用古DNA数据检验了东亚地区农业和语言共扩散理论,综合考古学、语言学等证据,该研究系统性地重构了东亚人群的形成、迁徙和混合历史。这是目前国内开展的东亚地区最大规模的考古基因组学研究,此次所报道的东亚地区古人基因组样本量是以往国内研究机构所发表的样本量总和的两倍,改变了东亚地区尤其是中国境内考古基因组学研究长期滞后的局面。 该研究是由王传超教授团队与哈佛医学院(David Reich教授)、德国马普人类历史科学研究所(Johannes Krause教授)、复旦大学现代人类学教育部重点实验室(李辉教授和金力院士)、维也纳大学进化人类学系(Ron Pinhasi副教授)、南洋理工大学人文学院(Hui-Yuan Yeh助理教授)、俄罗斯远东联邦大学科学博物馆(Alexander N Popov研究员)、西安交通大学(张虎勤教授)、蒙古国国家博物馆研究中心、乌兰巴托国立大学考古系、华盛顿大学人类学系、台湾成功大学考古所、加州大学人类学系等全球43个单位的85位共同作者组成的国际合作团队联合完成的。厦门大学人类学研究所、厦门大学生命科学学院细胞应激生物学国家重点实验室为论文第一完成单位。厦门大学人类学研究所韦兰海副教授、胡荣助理教授、郭健新博士后、何光林博士后和杨晓敏硕士参与了研究工作。The deep population history of East Asia remains poorly understood due to a lack of ancient DNA data and sparse sampling of present-day people1,2. We report genome-wide data from 166 East Asians dating to 6000 BCE-1000 CE and 46 present-day groups. Hunter-gatherers from Japan, the Amur River Basin, and people of Neolithic and Iron Age Taiwan and the Tibetan plateau are linked by a deeply-splitting lineage likely reflecting a Late Pleistocene coastal migration. We follow Holocene expansions from four regions. First, hunter-gatherers of Mongolia and the Amur River Basin have ancestry shared by Mongolic and Tungusic language speakers but do not carry West Liao River farmer ancestry contradicting theories that their expansion spread these proto-languages. Second, Yellow River Basin farmers at ~3000 BCE likely spread Sino-Tibetan languages as their ancestry dispersed both to Tibet where it forms up ~84% to some groups and to the Central Plain where it contributed ~59-84% to Han Chinese. Third, people from Taiwan ~1300 BCE to 800 CE derived ~75% ancestry from a lineage also common in modern Austronesian, Tai-Kadai and Austroasiatic speakers likely deriving from Yangtze River Valley farmers; ancient Taiwan people also derived ~25% ancestry from a northern lineage related to but different from Yellow River farmers implying an additional north-to-south expansion. Fourth, Yamnaya Steppe pastoralist ancestry arrived in western Mongolia after ~3000 BCE but was displaced by previously established lineages even while it persisted in western China as expected if it spread the ancestor of Tocharian Indo-European languages. Two later gene flows affected western Mongolia: after ~2000 BCE migrants with Yamnaya and European farmer ancestry, and episodic impacts of later groups with ancestry from Turan.We thank David Anthony, Ofer Bar-Yosef, Katherine Brunson, Rowan Flad, Pavel Flegontov,Qiaomei Fu, Wolfgang Haak, Iosif Lazaridis, Mark Lipson, Iain Mathieson, Richard Meadow,Inigo Olalde, Nick Patterson, Pontus Skoglund, Dan Xu, and the four reviewers for valuable comments. We thank Naruya Saitou and the Asian DNA Repository Consortium for sharing genotype data from present-day Japanese groups. We thank Toyohiro Nishimoto and Takashi Fujisawa from the Rebun Town Board of Education for sharing the Funadomari Jomon samples, and Hideyo Tanaka and Watru Nagahara from the Archeological Center of Chiba City who are excavators of the Rokutsu Jomon site. The excavations at Boisman-2 site (Boisman culture), the Pospelovo-1 site (Yankovsky culture), and the Roshino-4 site (Heishui Mohe culture) were funded by the Far Eastern Federal University and the Institute of History,Archaeology and Ethnology Far Eastern Branch of the Russian Academy of Sciences; research on Pospelovo-1 is funded by RFBR project number 18-09-40101. C.C.W was funded by the Max Planck Society, the National Natural Science Foundation of China (NSFC 31801040), the Nanqiang Outstanding Young Talents Program of Xiamen University (X2123302), the Major project of National Social Science Foundation of China (20&ZD248), a European Research Council (ERC) grant to Dan Xu (ERC-2019-ADG-883700-TRAM) and Fundamental Research Funds for the Central Universities (ZK1144). O.B. and Y.B. were funded by Russian Scientific Foundation grant 17-14-01345. H.M. was supported by the grant JSPS 16H02527. M.R. and C.C.W received funding from the ERC under the European Union’s Horizon 2020 research and innovation program (grant No 646612) to M.R. The research of C.S. is supported 30 by the Calleva Foundation and the Human Origins Research Fund. H.L was funded NSFC (91731303, 31671297), B&R International Joint Laboratory of Eurasian Anthropology (18490750300). J.K. was funded by DFG grant KR 4015/1-1, the Baden Württemberg Foundation, and the Max Planck Institute. Accelerator Mass Spectrometry radiocarbon dating work was supported by the National Science Foundation (NSF) (BCS-1460369) to D.J.K. and B.J.C. D.R. was funded by NSF grant BCS-1032255, NIH (NIGMS) grant GM100233, the Paul M. Allen Frontiers Group, John Templeton Foundation grant 61220, a gift from Jean-Francois Clin, and the Howard Hughes Medical Institute. 该研究得到了国家自然科学基金“中国东南各族群的遗传混合”、国家社科基金重大项目“多学科视角下的南岛语族的起源和形成研究”、厦门大学南强青年拔尖人才支持计划A类、中央高校基本科研业务费等资助

    Spatiotemporal Variation of Snowfall to Precipitation Ratio and Its Implication on Water Resources by a Regional Climate Model over Xinjiang, China

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    Snow contributes one of the main water sources to runoff in the arid region of China. A clear understanding of the spatiotemporal variation of snowfall is not only required for climate change assessment, but also plays a critical role in water resources management. However, in-situ observations or gridded datasets hardly meet the requirement and cannot provide precise spatiotemporal details on snowfall across the region. This study attempted to apply the Weather Research and Forecasting (WRF) model to clarify the spatiotemporal variation of snowfall and the ratio of snowfall to total precipitation over Xinjiang in China during the 1979&ndash;2015 period. The results showed that the snowfall increased in the southern edge of the Tarim Basin, the Ili Valley, and the Altay Mountains, but decreased in the Tianshan Mountains and the Kunlun Mountains. The snowfall/precipitation (S/P) ratio revealed the opposite trends in low-elevation regions and mountains in the study area. The S/P ratio rose in the Tarim Basin and the Junggar Basin, but declined in the Altay Mountains, the Tianshan Mountains, and the west edge of the Junggar Basin. The study area comprises two major rivers in the middle of the Tianshan Mountains. Both the runoff magnitude increase and earlier occurrence of snowmelt recharge in runoff identified for the 1980s were compared with the 2000s level in decreasing S/P ratio regions
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