16 research outputs found
Himalayan glaciers experienced significant mass loss during later phases of little ice age
We express our gratitude to Prof. Sunil Bajpai, Director, BSIP for providing official permission to publish (vide BSIP/RDCC/89/2016â2017) and necessary facilities to carry out this work. We also thank the PCCFs Uttarakhand, Himachal Pradesh and Jammu and Kashmir, and DFO Uttarkashi and other forest office staffs of the Indian Himalayan states for their help and providing necessary facilities during tree-ring sampling. We thank Mrs. Meenakshi Joshi (IFS) Uttarakhand for her insights on the topic and constructive suggestions. We thank Prof. Hans W. Linderholm and Prof. Dan J. Smith for sharing the mass balance time-series for StorglaciĂ€ren (Sweden) and Canadian glaciers, respectively. M.S. acknowledges the financial support by the Department of Science and Technology, New Delhi vide SERB-DST Project No. SR/FTP/ES-127/2014 [Young Scientist Scheme]. P.S.R. extends his sincere acknowledgement to SERBâDST projects SR/DGH/44/2012 and SR/DGH/56/2013 for financial support to carry out this research work.Peer reviewedPublisher PD
Tree rings of Rhododendron arboreum portray signal of monsoon precipitation in the Himalayan region
The Himalayas has a significant impact not just on the Indian subcontinentâs monsoon patterns but also on the global climate. Monsoon failure causing drought has become more common in recent years. As a result, it poses a major threat to ecosystem sustainability. We reported for the first time, a climatic-sensitive tree ring chronology of a broadleaf tree, Rhododendron arboreum, spanning 1732â2017 CE from the Himalayan region. We discovered that the climate during the monsoon season limits the growth of this tree in this region. The correlation analysis between tree ring chronology and climate revealed a significant positive relationship with precipitation (r = 0.63, p < 0.001) and a negative relationship with temperature (r = â0.48, p < 0.01) during the months of JuneâAugust (JJA). This strong relationship allowed us to reconstruct monsoon precipitation spanning 1780 to 2017 CE which explained 40% of the variance of the observed climate data for the calibration period. The reconstructed data are validated by the existence of a significant association with the gridded JJA precipitation data of the Climate Research Unit (CRU) of this region. The monsoon rainfall record captured extremely wet years during 1793, 1950, 2011, 2013, and 2017 and extremely dry years during 1812, 1833, 1996, 2002, 2004, and 2005. The extremely dry and wet years well coincided with major catastrophic historical and instrumental droughts and floods in the region. Furthermore, the reconstructed data are also validated by the significant positive correlation (r = 0.36, p < 0.001, n = 163) with the all Indian summer monsoon rainfall series. Such data will be useful to predict the incidence of future droughts, which can help to assess the vulnerability of the forest ecosystem to extreme events
Reconstruction of JanuaryâApril discharge of Zemu Chuu â A first stage of Teesta River North Sikkim Eastern Himalaya based on tree-ring data of fir
Study region: Zemu Chuu (river), Lachen, North Sikkim, Eastern Himalaya India.
Study focus: Using tree-ring data of fir (Abies densa) the temporal variation of 222 years JanuaryâApril mean discharge of Zemu Chuu, upper reaches of the Teesta River at Lachen, North Sikkim Eastern Himalaya was investigated. This was based on linear regression reconstruction model which explained variance of 50.1% during calibration period (AD 1976â1996). The model was verified by reduction of error (RE), sign test (ST), product mean test (Pmt), root mean square error (RMSE) and DurbinâWatson test (DW). The RE never falls below zero suggesting the model had explanatory power over the entire period of reconstruction.
New hydrological insights for the region: The explored strong relationship between tree ring records and instrumental data enable to develop mean JanuaryâApril months (premonsoon) river discharge of Zemu Chuu from remote area of Sikkim. Reconstructed data reveals high stream-flow when it is more than the mean plus one standard deviation and as low when flow is less than the mean minus one standard deviation. There were such 23 high discharge and 21 extremely low years over the past AD 1775â1996. This premonsoon reconstruction of river flow would be of great significance when scarcity of water is acute in the North East Himalaya
Spring-temperature variations in Western Himalaya, India, as reconstructed from tree-rings: AD 1390-1987
The Himalayan region plays a very important role in influencing the regional and
extra-regional circulation system. Long-term instrumental or proxy climate records for this
region are scant, but are essential for a global perspective of climate variability. A 598
-year (AD 1390-1987) reconstruction of spring (March-May) temperature has been derived for
the first time for the western Himalayan region, India using a well replicated ring-width
chronology of Himalayan cedar (Cedrus deodara (D. Don) G. Don). The reconstruction showing
annual to multi-year episodes of cool and warm springs is well correlated with the
instrumental record of spring temperature for 1876-1987 (r = 0.53, p < 0.001). Prominent
large-magnitude century-scale excursions in negative anomalies of spring temperature which
might reflect the regional influence of the âLittle Ice Ageâ are not indicated in our data.
The seventeenth century experienced monotonically warm springs. Neither recostruction or
instrumental data provide evidence of warming during the last few decades of this century
which could be attributed to anthropogenic causes. A strong out-of-phase relationship
between the instrumental sprin-temperature record over the western Himalayan region and
sea-surface temperatures (SSTs) of ensuing months (June-May) over the equatorial Pacific
Ocean has been noted. This suggests that temperature responsive tree-ring chronologies from
the Himalayan region could also serve as a valuable proxy of the Southern
Oscillation
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Potential For Developing Fire Histories In Chir Pine (Pinus Roxburghii) Forest In The Himalayan Foothills
We report on the potential for developing long-term fire histories from chir pine (Pinus roxburghii Sarg.) forests in the Western Himalayan foothills based on a preliminary study from a stand located in the state of Uttarakhand in northern India. Rings from trees collected to develop a master skeleton plot chronology were generally complacent with false rings present during most years, but were crossdatable with only minor difficulty. The oldest tree confidently crossdated back to 1886, with good sample depth (5 trees) from 1911, which helped date the fire scars in cross-sections collected from three trees. Fire frequency as determined from fire-scar dates was high, with mean and median fire intervals of 3 years from 1938 to 2006. Fires were likely from human ignitions given the prevalence of human land use in the site. Fire scars were generally recorded at false-ring boundaries and likely represent burning during the hot, dry period in May or early June before the onset of monsoon rainfall beginning in mid-June. Although only three fire-scarred trees were sampled, this preliminary assessment shows there is a potential for additional samples from other stands to develop longer-term fire histories to better understand the role of fire in the ecology and management of chir pine throughout its range in the Himalaya region.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
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Dendrochronological Reconnaissance of the Conifers of Northwest India
Tree-ring samples were collected from six coniferous species in the western Himalayan ranges during the summer of 1984 in order to evaluate their potential for use in dendroclimatic reconstructions. Picea, Abies, and Pinus spp. had previously been collected for ring widths and densitometric analysis by Hughes and co-workers on relatively mesic subalpine sites near the Vale of Kashmir. Our results support this earlier work in that ring-width series from these habitats are relatively complacent and contain little dendroclimatic information. Density and ring widths are largely temperature-dependent. However, our sampling included Cedrus deodara and Pinus gerardiana from lower altitudes in the dry inner valleys of the Pir Panjal Range, south of Kashmir. Both species exhibit great age, high mean sensitivity and good intra- and inter-specific crossdating, and yielded chronology statistics suggestive of a drought response. We strongly recommend that they receive high priority in future tree-ring research in northwest India.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
Dendroclimatic reconstruction of April-May temperature fluctuations in the Western Himalaya of India since A.D. 1698
Ring-width chronologies of Himalayan cedar (Cedrus deodara (D. Don.) G. Don.), Himalayan pine (Pinus wallichiana A. B. Jackson), and Himalayan spruce (Picea smithiana(Wall.) Boiss.) from the western Himalayan region, India, have been used to reconstruct mean April-May temperature back to A.D. 1698. The reconstruction correlates significantly with the average April-May instrumental temperature record (r= +0.62, 1876-1988) and is characterized by annual to multiyear fluctuations. The most striking feature of the present reconstruction is the absence of any warming trend in the 20th century. Relationships between the mean April-May temperature for the western Himalayan region, Indian summer monsoon rainfall, and Southern Oscillation Index indicate that the tree-ring chronologies, as surrogate temperature records, will provide valuable data for climate change studies with regional and global perspectives
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Tree-Ring Chronologies from Nepal
Ten ring-width based chronologies from Nepal are described and the prospects for further dendroclimatic work there reviewed briefly. The initial results are encouraging, and more intensive subregional sampling is called for. All the cores examined showed distinct annual rings, and there was little evidence of double or missing rings, except juniper at some sites and in some Pinus roxburghii trees. Difficulty was encountered in dating Pinus wallichiana and Cupressus dumosa. Individual site chronologies of Cedros deodora, P. roxburghii and P. wallichiana were particularly promising, and of high elevation Abies spectabilis moderately so. Densitometric data are likely to be more useful for this species. The paucity of meteorological data in Nepal represents an obstacle to further dendroclimatic work there.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
Vegetational and climatic variations during the past 3100 years in southern India: evidence from pollen, magnetic susceptibility and particle size data
Vegetational history vis a vis climate change during the past 3100 cal. years BP was deciphered from pollen data supplemented with magnetic susceptibility and particle size data for a 2.5 m long sediment core from Pookot Lake, Kerala, southern India. Pollen data suggest a mixed assemblage of upland tropical elements and wetland mangrove taxa. The presence of trace amounts of pollen grains of montane taxa like Betula, Pinus and Alnus points to their long distance dispersal. Pollen grains of Ixora, Syzygium, Symplocos, Moraceae and Arecaceae that represent tropical vegetation were also recovered, indicating modern vegetation in and around Pookot Lake. Mangrove elements are mostly represented by species of Rhizophora and Ceriops decandra along with other taxa. High-rainfall periods are characterised by high sand % and low clay % and vice versa. The pollen data correspond well with magnetic susceptibility and particle size data. The data obtained suggest three broad phases of climate, with minor oscillations, during the past 3100 cal. years BP: (1) wet climate during 3100â2500 cal. years BP; (2) dry climate spanning a long period that ended around 1000 cal. years BP; (3) amelioration in climate after 1000 cal. years BP, reflected in the presence of luxuriant vegetation and high magnetic susceptibility values.by Amalava Bhattacharyya, Kizhur Sandeep, Sandhya Misra, Rajasekhariah Shankar, Anish K. Warrier, Zhou Weijian and Lu Xuefen
Vampyren; en sexsymbol och ett blodtörstande monster : En jÀmförelse av beskrivningen av vampyrerna i Stephenie Meyers Twilight och Bram Stokers Dracula, kopplat till genre, berÀttarperspektiv och Äldersgrupp.
This essay discusses the differences in depiction of vampires between Stephenie Meyerâs Twilight (2005) and Bram Stokerâs Dracula (1897). By using examples from the novels, the essay exemplifies how genre, narration, and readership affect the description of vampires within the two novels. The essay bases its discussion on genre on the premise that the vampire genre is in fact a genre to itself, but one with a broad variation. Furthermore, the essay briefly discusses the shift within the vampire genre, where vampires during the last centuries have gone from dangerous and scary to appealing and romantic. A connection is made between the shift within the vampire genre and Anne Riceâs vampire fiction. The discussion on genre shows how the romance, fantasy, and horror genres affect the depiction of vampires.Denna uppsats diskuterar hur vampyrer i verken Twilight (Meyer, 2005) och Dracula (Stoker, 1897) skildras pĂ„ olika sĂ€tt. Skillnader i beskrivningarna illustreras med hjĂ€lp av exempel frĂ„n de bĂ„da böckerna och berör genre, berĂ€ttarperspektiv och lĂ€sarkrets. Diskussionen i uppsatsen baseras pĂ„ att vampyrgenren Ă€r en egen genre med mĂ„nga olika beskrivningar av vampyren. Uppsatsen berör Ă€ven förĂ€ndringen i genren och lyfter kort hur vampyren frĂ„n början tolkas som farlig och skrĂ€mmande för att sedan framstĂ„ som attraktiv och romantisk. En koppling görs ocksĂ„ mellan förĂ€ndringen i vampyrgenren och Anne Rices vampyrnoveller. Vidare i diskussionen kring genre berörs Ă€ven hur genrerna romantik, fantasy och skrĂ€ck pĂ„verkar skildringen av vampyrerna i de nĂ€mnda verken