Regional difference of the start time of the recent warming in Eastern China: prompted by a 165-year temperature record deduced from tree rings in the Dabie Mountains

Tree-ring studies from tropical to subtropical regions are rarer than that from extratropical regions, which greatly limit our understanding of some critical climate change issues. Based on the tree-ring-width chronology of samples collected from the Dabie Mountains, we reconstructed the April-June mean temperature for this region with an explained variance of 46.8%. Five cold (1861-1869, 1889-1899, 1913-1920, 1936-1942 and 1952-1990) and three warm (1870-1888, 1922-1934 and 2000-2005) periods were identified in the reconstruction. The reconstruction not only agreed well with the instrumental records in and around the study area, but also showed good resemblance to previous temperature reconstructions from nearby regions, indicating its spatial and temporal representativeness of the temperature variation in the central part of eastern China. Although no secular warming trend was found, the warming trend since 1970 was unambiguous in the Dabie Mountains (0.064 A degrees C/year). Further temperature comparison indicated that the start time of the recent warming in eastern China was regional different. It delayed gradually from north to south, starting at least around 1940 AD in the north part, around 1970 AD in the central part and around 1980s in the south part. This work enriches the high-resolution temperature reconstructions in eastern China. We expect that climate warming in the future would promote the radial growth of alpine Pinus taiwanensis in the subtropical areas of China, therefore promote the carbon capture and carbon storage in the Pinus taiwanensis forest. It also helps to clarify the regional characteristic of recent warming in eastern China.</p

Sunshine duration reconstruction in the southeastern Tibetan Plateau based on tree-ring width and its relationship to volcanic eruptions

Sunshine is as essential as temperature and precipitation for tree growth, but sunshine duration reconstructions based on tree rings have not yet been conducted in China. In this study, we presented a 497-year sunshine duration reconstruction for the southeastern Tibetan Plateau using a width chronology of Abies forrestii from the central Hengduan Mountains. The reconstruction accounted for 53.5% of the variance in the observed sunshine during the period of 1961-2013 based on a stable and reliable linear regression. This reconstructed sunshine duration contained six sunny periods (1630-1656, 1665-1697, 1731-1781, 1793-1836, 1862-1895 and 1910-1992) and seven cloudy periods (1522-1629, 1657-1664, 1698-1730, 1782-1792, 1837-1861, 1896-1909 and 1993-2008) at a low-frequency scale. There was an increasing trend from the 16th century to the late 18th and early 19th centuries and a decreasing trend from the mid-19th to the early 21st centuries. Sunshine displayed inverse patterns to the local Palmer drought severity index on a multidecadal scale, indicating that this region likely experienced droughts under more sunshine conditions. The decrease in sunshine particularly in recent decades was mainly due to increasing atmospheric anthropogenic aerosols. In terms of the interannual variations in sunshine, weak sunshine years matched well with years of major volcanic eruptions. The significant cycles of the 2- to 7-year, 20.0-year and 35.2-year durations as well as the 60.2-year and 78.7-year durations related to the El-Nino Southern Oscillation, the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation suggested that the variation in sunshine duration in the southeastern Tibetan Plateau was possibly affected by large-scale ocean-atmosphere circulations. (C) 2018 Elsevier B.V. All rights reserved

Multi-omics analysis reveals the mechanism underlying the edaphic adaptation in wild barley at Evolution Slope (Tabigha)

At the microsite “Evolution Slope”, Tabigha, Israel, wild barley (Hordeum spontaneum) populations adapted to dry Terra Rossa soil, and its derivative abutting wild barley population adapted to moist and fungi-rich Basalt soil. However, the mechanisms underlying the edaphic adaptation remain elusive. Accordingly, whole genome bisulfite sequencing, RNA-sequencing, and metabolome analysis are performed on ten wild barley accessions inhabiting Terra Rossa and Basalt soil. A total of 121 433 differentially methylated regions (DMRs) and 10 478 DMR-genes are identified between the two wild barley populations. DMR-genes in CG context (CG-DMR-genes) are enriched in the pathways related with the fundamental processes, and DMR-genes in CHH context (CHH-DMR-genes) are mainly associated with defense response. Transcriptome and metabolome analysis reveal that the primary and secondary metabolisms are more active in Terra Rossa and Basalt wild barley populations, respectively. Multi-omics analysis indicate that sugar metabolism facilitates the adaptation of wild barley to dry Terra Rossa soil, whereas the enhancement of phenylpropanoid/phenolamide biosynthesis is beneficial for wild barley to inhabit moist and fungi pathogen-rich Basalt soil. The current results make a deep insight into edaphic adaptation of wild barley and provide elite genetic and epigenetic resources for developing barley with high abiotic stress tolerance

Tree-ring stable carbon isotope-based April-June relative humidity reconstruction since AD 1648 in Mt. Tianmu, China

Based on accurate dating, we have determined the stable carbon isotope ratios (delta C-13) of five Cryptomeria fortunei specimens from Mt. Tianmu, a subtropical area in southern China. The five delta C-13 time series records are combined into a single representative delta C-13 time series using a &quot;numerical mix method.&quot; These are normalized to remove temporal variations of delta(13) C in atmospheric CO2 to obtain a carbon isotopic discrimination (Delta C-13) time series, in which we observe a distinct correlation between Delta C-13 and local April to June mean relative humidity (RH (AMJ) ) (n = 64, r = 0.858, p &lt; 0.0001). We use this relationship to reconstruct RH (AMJ) variations from ad 1648 to 2014 at Mt. Tianmu. The reconstructed sequence show that over the past 367 years, Mt. Tianmu area was relatively wet, but in the latter part of the twentieth century, under the influence of increasing global warming, it has experienced a sharp reduction in relative humidity. Spatial correlation analysis reveals a significant negative correlation between RH (AMJ) at Mt. Tianmu and Sea Surface Temperature (SSTs) in the western equatorial Pacific and Indian Ocean. In other words, there is a positive correlation between tree-ring delta C-13 in Mt. Tianmu and SSTs. Both observed and reconstructed RH (AMJ) show significant positive correlations with East Asian and South Asian monsoons from 1951 to 2014, which indicate that RH (AMJ) from Mt. Tianmu reflects the variability of the Asian summer monsoon intensity to a great extent. The summer monsoon has weakened since 1960. However, an increase in relative humidity since 2003 implies a recent enhancement in the summer monsoon

The genome and gene editing system of sea barleygrass provide a novel platform for cereal domestication and stress tolerance studies

The tribe Triticeae provides important staple cereal crops and contains elite wild species with wide genetic diversity and high tolerance to abiotic stresses. Sea barleygrass (Hordeum marinum Huds.), a wild Triticeae species, thrives in saline marshlands and is well known for its high tolerance to salinity and waterlogging. Here, a 3.82-Gb high-quality reference genome of sea barleygrass is assembled de novo, with 3.69 Gb (96.8%) of its sequences anchored onto seven chromosomes. In total, 41 045 high-confidence (HC) genes are annotated by homology, de novo prediction, and transcriptome analysis. Phylogenetics, non-synonymous/synonymous mutation ratios (Ka/Ks), and transcriptomic and functional analyses provide genetic evidence for the divergence in morphology and salt tolerance among sea barleygrass, barley, and wheat. The large variation in post-domestication genes (e.g. IPA1 and MOC1) may cause interspecies differences in plant morphology. The extremely high salt tolerance of sea barleygrass is mainly attributed to low Na+ uptake and root-to-shoot translocation, which are mainly controlled by SOS1, HKT, and NHX transporters. Agrobacterium-mediated transformation and CRISPR/Cas9-mediated gene editing systems were developed for sea barleygrass to promote its utilization for exploration and functional studies of hub genes and for the genetic improvement of cereal crops

Anthropogenic Aerosols Cause Recent Pronounced Weakening of Asian Summer Monsoon Relative to Last Four Centuries

The Asian Summer Monsoon (ASM) affects ecosystems, biodiversity, and food security of billions of people. In recent decades, ASM strength (as represented by precipitation) has been decreasing, but instrumental measurements span only a short period of time. The initiation and the dynamics of the recent trend are unclear. Here for the first time, we use an ensemble of 10 tree ring-width chronologies from the west-central margin of ASM to reconstruct detail of ASM variability back to 1566 CE. The reconstruction captures weak/strong ASM events and also reflects major locust plagues. Notably, we found an unprecedented 80-year trend of decreasing ASM strength within the context of the 448-year reconstruction, which is contrary to what is expected from greenhouse warming. Our coupled climate model shows that increasing anthropogenic sulfate aerosol emissions over the Northern Hemisphere could be the dominant factor contributing to the ASM decrease. Plan Language Summary Monsoonal rainfall has a certain influence on agriculture and industry in the regions of Asian Summer Monsoon (ASM). An understanding of the spatial-temporal variability of the ASM and the associated dynamics is vital for terrestrial ecosystems, water resources, forests, and landscapes. We have developed a 448-year ASM reconstruction back to 1566 CE using 10 tree ring chronologies from the margin region of ASM. We find that historical severe droughts and locust plague disasters during weak ASM events. The recent decreasing ASM trend persisting for over 80 years is unprecedented over the past 448 years. Coupled climate models show that increasing anthropogenic aerosol emissions are the dominant underlying factor. Our aim is that the time series will find a wide range of utility for understanding past climate variability and for predicting future climate change.National Natural Science Foundation of China [41630531]; National Research Program for Key Issues in Air Pollution Control [DQGG0104]; Chinese Academy of Sciences [QYZDJ-SSW-DQC021, XDPB05, GJHZ1777]; Institute of Earth Environment, Chinese Academy of Sciences; State Key Laboratory of Loess and Quaternary Geology6 month embargo; first published: 09 April 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Two centuries temperature variations over subtropical southeast China inferred from Pinus taiwanensis Hayata tree-ring width

High-resolution long-term temperature reconstructions in subtropical southeast China (SSC) are very scarce, yet indispensable for the comprehensive understanding of climate change in China, even in East Asia. We reconstructed the first previous growth-season temperature in the Sanqingshan Mountains (SQS), southeast China since 1806 based on tree-ring width data. The reconstruction accounts for 56.4 % of the total variance in the instrumental record over 1954-2009. Unlike the Northern Hemispheric warming during recent two centuries, the reconstruction captured a slowly cooling trend from 1806 to 1980, followed by a rapid warming afterward. 2003-2009 was the warmest period in the reconstruction. 1970-2000 was colder than the last stage of the Little Ice Age (LIA). Most of the warm and cold periods in this reconstruction could be found in the tree-ring based temperature reconstructions of vicinity area, indicating that the temperature variations in SSC were almost synchronous at least at decadal scale. This regional coherence of temperature variation was further confirmed by the spatial correlation patterns with the CRU TS3.22 grid dataset. A strong positive relationship between the temperature over SQS region and sea surface temperature (SST) over the North Pacific Ocean (NP) has been noted, suggesting that SST variations over NP and the related Pacific Decadal Oscillation significantly influenced the temperature variability over SSC. To better understand the climate variability during the LIA and the regional differences in temperature variations over SQS and northern Hemisphere, long data sets from more diverse areas of southern China are needed

Altitudinal difference of growth-climate response models in the north subtropical forests of China

Altitudinal difference increases the complexity of the response of tree growth to climate change in the mountainous areas, and may change the carbon sequestration capacity of forests under the ongoing warming climate. In this work, four tree-ring width chronologies from Pinus henryi Mast. growing at different altitudes of Shiyan, the northern subtropical China were developed. Results of Pearson correlation analysis, factor analysis and redundancy analysis indicate that tree growth-climate response models can be divided into two types according to the altitudinal gradient: the high-altitude model, represented by SWDH and WDSH above 1330 m a.s.l., and the low-altitude model, represented by WDSL and DDZL less than 1070 m a.s.l. The biggest difference between the two models is that tree growth at the low altitudes shows significantly negative response to temperature in the previous September-December and current April-May, and positive response to moisture conditions from the previous September to current May, April-May in particular; while the high-altitude ones show consistently positive responses to temperature in current February-April, but no significant response to seasonal moisture condition. The existence of a temperature-related altitudinal threshold between 1070 m a.s.l. to 1330 m a.s.l. may change the hydro-thermal combination models above and below the threshold, thus lead to the change of climatic response models along altitude gradient. 30-yr moving correlation analysis reveals that the relationships between tree growth and the limiting climatic factors present evident altitudinal difference: gradually strengthened at the high altitudes but weakened at the low altitudes. It is distinct that water availability and demand are critical for the growth of low-altitude trees, and high-altitude trees show a stronger positive response to climate warming, therefore could be an important carbon sink in the future. In addition, future forest management should focus on the low altitudes and formulate effective protection strategies