scholarly journals Analysis of Climate change from high elevation sites of North West Himalaya based on tree ring data

1970 ◽  
Vol 5 (7) ◽  
pp. 138
Author(s):  
Santosh K Shah ◽  
Amalava Bhattacharyya ◽  
Vandana Chaudhary
Keyword(s):  
Climate Change ◽  
Tree Ring ◽  
High Elevation ◽  
Special Issue ◽  
North West ◽  
West Himalaya ◽  
Tree Ring Data

DOI = 10.3126/hjs.v5i7.1320 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.138

Tree growth across the Nepal Himalaya during the last four centuries

2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Environmental Changes ◽  
Ring Width ◽  
High Elevation ◽  
Forest Growth ◽  
Tree Ring Width ◽  
Early 19Th Century ◽  
Tree Ring Data ◽  
Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

scholarly journals A Tree-Ring Based Late Summer Temperature Reconstruction (AD 1675–1980) for the Northeastern Mediterranean

Radiocarbon ◽  
2014 ◽  
Vol 56 (4) ◽  
pp. S69-S78 ◽  
Author(s):  
Valerie Trouet
Keyword(s):  
Tree Ring ◽  
Late Summer ◽  
Temperature Reconstruction ◽  
High Elevation ◽  
Global Scale ◽  
Summer Temperature ◽  
Latewood Density ◽  
Reconstructed Temperature ◽  
Tree Ring Data ◽  
Summer Temperature Reconstruction

This article presents a late summer temperature reconstruction (AD 1675–1980) for the northeastern Mediterranean (NEMED) that is based on a compilation of maximum latewood density tree-ring data from 21 high-elevation sites. This study applied a novel approach by combining individual series from all sites into one NEMED master chronology. This approach retains only the series with a strong and temporally robust common signal and it improves reconstruction length. It further improved the regional character of the reconstruction by using as a target averaged gridded instrumental temperature data from a broad NEMED region (38–45°N, 15–25°E). Cold (e.g. 1740) and warm (e.g. 1945) extreme years and decades in the reconstruction correspond to regional instrumental and reconstructed temperature records. Some extreme periods (e.g. cold 1810s) reflect European-wide or global-scale climate conditions and can be explained by volcanic and solar forcing. Other extremes are strictly regional in scope. For example, 1976 was the coldest NEMED summer over the last 350 years, but was anomalously dry and hot in northwestern Europe and is a strong manifestation of the summer North Atlantic Oscillation (sNAO). The regional NEMED summer reconstruction thus contributes to an improved understanding of regional (e.g. sNAO) vs. global-scale (i.e. external) drivers of past climate variability.

scholarly journals Using Tree Rings to Predict the Response of Tree Growth to Climate Change in the Continental United States during the Twenty-First Century

2010 ◽  
Vol 14 (19) ◽  
pp. 1-20 ◽  
Author(s):  
A. Park Williams ◽  
Joel Michaelsen ◽  
Steven W. Leavitt ◽  
Christopher J. Still
Keyword(s):  
Climate Change ◽  
United States ◽  
Tree Ring ◽  
Tree Growth ◽  
Ring Width ◽  
First Century ◽  
Annual Growth ◽  
Climate Variations ◽  
Tree Ring Data ◽  
Twenty First Century

Abstract In the early 1900s, tree-ring scientists began analyzing the relative widths of annual growth rings preserved in the cross sections of trees to infer past climate variations. Now, many ring-width index (RWI) chronologies, each representing a specific site and species, are archived online within the International Tree-Ring Data Bank (ITRDB). Comparing annual tree-ring-width data from 1097 sites in the continental United States to climate data, the authors quantitatively evaluated how trees at each site have historically responded to interannual climate variations. For each site, they developed a climate-driven statistical growth equation that uses regional climate variables to model RWI values. The authors applied these growth models to predict how tree growth will respond to twenty-first-century climate change, considering four climate projections. Although caution should be taken when extrapolating past relationships with climate into the future, the authors observed several clear and interesting patterns in the growth projections that seem likely if warming continues. Most notably, the models project that productivity of dominant tree species in the southwestern United States will decrease substantially during this century, especially in warmer and drier areas. In the northwest, nonlinear growth relationships with temperature may lead to warming-induced declines in growth for many trees that historically responded positively to warmer temperatures. This work takes advantage of the unmatched temporal length and spatial breath of annual growth data available within the ITRDB and exemplifies the potential of this ever-growing archive of tree-ring data to serve in meta-analyses of large-scale forest ecology.

scholarly journals Influence of sampling and disturbance history on climatic sensitivity of temperature-limited conifers

The Holocene ◽  
2018 ◽  
Vol 28 (10) ◽  
pp. 1574-1587 ◽  
Author(s):  
Miloš Rydval ◽  
Daniel L Druckenbrod ◽  
Miroslav Svoboda ◽  
Volodymyr Trotsiuk ◽  
Pavel Janda ◽  
...  
Keyword(s):  
Tree Ring ◽  
Ring Width ◽  
Low Frequency ◽  
High Elevation ◽  
Climate Signal ◽  
High Frequency Response ◽  
Climatic Trends ◽  
Tree Ring Data ◽  
Temperature Signal ◽  
Romanian Carpathians

Accurately capturing medium- to low-frequency trends in tree-ring data is vital to assessing climatic response and developing robust reconstructions of past climate. Non-climatic disturbance can affect growth trends in tree-ring-width (RW) series and bias climate information obtained from such records. It is important to develop suitable strategies to ensure the development of chronologies that minimize these medium- to low-frequency biases. By performing high density sampling (760 trees) over a ~40-ha natural high-elevation Norway spruce ( Picea abies) stand in the Romanian Carpathians, this study assessed the suitability of several sampling strategies for developing chronologies with an optimal climate signal for dendroclimatic purposes. There was a roughly equal probability for chronologies (40 samples each) to express a reasonable ( r = 0.3–0.5) to non-existent climate signal. While showing a strong high-frequency response, older/larger trees expressed the weakest overall temperature signal. Although random sampling yielded the most consistent climate signal in all sub-chronologies, the outcome was still sub-optimal. Alternative strategies to optimize the climate signal, including very high replication and principal components analysis, were also unable to minimize this disturbance bias and produce chronologies adequately representing climatic trends, indicating that larger scale disturbances can produce synchronous pervasive disturbance trends that affect a large part of a sampled population. The Curve Intervention Detection (CID) method, used to identify and reduce the influence of disturbance trends in the RW chronologies, considerably improved climate signal representation (from r = 0.28 before correction to r = 0.41 after correction for the full 760 sample chronology over 1909–2009) and represents a potentially important new approach for assessing disturbance impacts on RW chronologies. Blue intensity (BI) also shows promise as a climatically more sensitive variable which, unlike RW, does not appear significantly affected by disturbance. We recommend that studies utilizing RW chronologies to investigate medium- to long-term climatic trends also assess disturbance impact on those series.

Impact of Climate change on tropical terrestrial water use efficiency

2020 ◽  
Author(s):  
Shweta Kumari ◽  
Mark A Adams
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Water Use Efficiency ◽  
Eddy Covariance ◽  
Water Use ◽  
Tree Ring ◽  
Tropical Regions ◽  
The North ◽  
Tree Ring Data ◽  
Use Efficiency

<p>Variability in precipitation and temperature are key markers of climate change. Extreme events like heat waves, droughts, frosts, wind storms, flooding rains and fires greatly affect ecosystem and terrestrial carbon balance. Tropical regions in particular make strong contributions to the global carbon cycle and are the focus of our research. Our initial analysis confirmed the long-known pattern of large variability in rainfall in the tropical southern hemisphere (i.e. between the Tropic of Capricorn and the Equator) w.r.t. the north, with less variation in temperature between the hemispheres. In the follow-up analysis, we focus on exchanges of carbon and water and water use efficiency, based on 39 eddy covariance flux sites which represent 25 years of data across the tropics. Our working hypothesis is that long-term increases in temperature and significant changes (+/-) in rainfall will be reflected in changes in water use efficiency and cropping period, albeit with greater spatial and temporal variation in the south than in the north. We are also investigating relationships between water use efficiency of tropical regions calculated using eddy covariance flux data, with that calculated using tree ring data. We seek to combine methodologies that can help drive our understanding of the impact of climate change on water use efficiency of tropical regions.</p><p><strong><span>Keywords: </span></strong><span>Eddy covariance, Tropics, Water use efficiency, Carbon cycle, Tree ring data</span></p>

scholarly journals A Tree-Ring Based Late Summer Temperature Reconstruction (AD 1675–1980) for the Northeastern Mediterranean

Radiocarbon ◽  
2014 ◽  
Vol 56 (04) ◽  
pp. S69-S78 ◽  
Author(s):  
Valerie Trouet
Keyword(s):  
Tree Ring ◽  
Late Summer ◽  
Temperature Reconstruction ◽  
High Elevation ◽  
Global Scale ◽  
Summer Temperature ◽  
Latewood Density ◽  
Reconstructed Temperature ◽  
Tree Ring Data ◽  
Summer Temperature Reconstruction

This article presents a late summer temperature reconstruction (AD 1675–1980) for the northeastern Mediterranean (NEMED) that is based on a compilation of maximum latewood density tree-ring data from 21 high-elevation sites. This study applied a novel approach by combining individual series from all sites into one NEMED master chronology. This approach retains only the series with a strong and temporally robust common signal and it improves reconstruction length. It further improved the regional character of the reconstruction by using as a target averaged gridded instrumental temperature data from a broad NEMED region (38–45°N, 15–25°E). Cold (e.g. 1740) and warm (e.g. 1945) extreme years and decades in the reconstruction correspond to regional instrumental and reconstructed temperature records. Some extreme periods (e.g. cold 1810s) reflect European-wide or global-scale climate conditions and can be explained by volcanic and solar forcing. Other extremes are strictly regional in scope. For example, 1976 was the coldest NEMED summer over the last 350 years, but was anomalously dry and hot in northwestern Europe and is a strong manifestation of the summer North Atlantic Oscillation (sNAO). The regional NEMED summer reconstruction thus contributes to an improved understanding of regional (e.g. sNAO) vs. global-scale (i.e. external) drivers of past climate variability.

scholarly journals Relating ring width of Mediterranean evergreen species to seasonal and annual variations of precipitation and temperature

2011 ◽  
Vol 8 (5) ◽  
pp. 1141-1152 ◽  
Author(s):  
W. Nijland ◽  
E. Jansma ◽  
E. A. Addink ◽  
M. Domínguez Delmás ◽  
S. M. De Jong
Keyword(s):  
Climate Change ◽  
Tree Ring ◽  
Tree Species ◽  
Climatic Variability ◽  
Ring Width ◽  
Monthly Precipitation ◽  
Evergreen Species ◽  
Mediterranean Landscapes ◽  
Tree Ring Data ◽  
Precipitation And Temperature

Abstract. Plant growth in Mediterranean landscapes is limited by the typical summer-dry climate. Forests in these areas are only marginally productive and may be quite susceptible to modern climate change. To improve our understanding of forest sensitivity to annual and seasonal climatic variability, we use tree-ring measurements of two Mediterranean evergreen tree species: Quercus ilex L. and Arbutus unedo L. We sampled 34 stems of these species on three different types of substrates in the Peyne study area in southern France. The resulting chronologies were analysed in combination with 38 yr of monthly precipitation and temperature data to reconstruct the response of stem growth to climatic variability. Results indicate a strong positive response to May and June precipitation, as well as a significant positive influence of early-spring temperatures and a negative growth response to summer heat. Comparison of the data with more detailed productivity measurements in two contrasting years confirms these observations and shows a strong productivity limiting effect of low early-summer precipitation. The results show that tree-ring data from Q.ilex and A.unedo can provide valuable information about the response of these tree species to climate variability, improving our ability to predict the effects of climate change in Mediterranean ecosystems.

scholarly journals Comparing Approaches for Reconstructing Groundwater Levels in the Mountainous Regions of Interior British Columbia, Canada, Using Tree Ring Widths

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1374
Author(s):  
Stephanie C. Hunter ◽  
Diana M. Allen ◽  
Karen E. Kohfeld
Keyword(s):  
British Columbia ◽  
Tree Ring ◽  
Groundwater Level ◽  
High Elevation ◽  
Valuable Insight ◽  
Driven Systems ◽  
Groundwater Levels ◽  
Mountainous Regions ◽  
Tree Ring Data ◽  
Observation Wells

Observed groundwater level records are relatively short (<100 years), limiting long-term studies of groundwater variability that could provide valuable insight into climate change effects. This study uses tree ring data from the International Tree Ring Database (ITRDB) and groundwater level data from 22 provincial observation wells to evaluate different approaches for reconstructing groundwater levels from tree ring widths in the mountainous southern interior of British Columbia, Canada. The twenty-eight reconstruction models consider the selection of observation wells (e.g., regional average groundwater level vs. wells classified by recharge mechanism) and the search area for potential tree ring records (climate footprint vs. North American Ecoregions). Results show that if the climate footprint is used, reconstructions are statistically valid if the wells are grouped according to recharge mechanism, with streamflow-driven and high-elevation recharge-driven wells (both snowmelt-dominated) producing valid models. Of all the ecoregions considered, only the Coast Mountain Ecoregion models are statistically valid for both the regional average groundwater level and high-elevation recharge-driven systems. No model is statistically valid for low-elevation recharge-driven systems (rainfall-dominated). The longest models extend the groundwater level record to the year 1500, with the highest confidence in the later portions of the reconstructions going back to the year 1800.

scholarly journals New perspective on spring vegetation phenology and global climate change based on Tibetan Plateau tree-ring data

2017 ◽  
Vol 114 (27) ◽  
pp. 6966-6971 ◽  
Author(s):  
Bao Yang ◽  
Minhui He ◽  
Vladimir Shishov ◽  
Ivan Tychkov ◽  
Eugene Vaganov ◽  
...  
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Tibetan Plateau ◽  
Tree Ring ◽  
Remote Sensing Data ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Vegetation Phenology ◽  
Sensing Data ◽  
Tree Ring Data

Phenological responses of vegetation to climate, in particular to the ongoing warming trend, have received much attention. However, divergent results from the analyses of remote sensing data have been obtained for the Tibetan Plateau (TP), the world’s largest high-elevation region. This study provides a perspective on vegetation phenology shifts during 1960–2014, gained using an innovative approach based on a well-validated, process-based, tree-ring growth model that is independent of temporal changes in technical properties and image quality of remote sensing products. Twenty composite site chronologies were analyzed, comprising about 3,000 trees from forested areas across the TP. We found that the start of the growing season (SOS) has advanced, on average, by 0.28 d/y over the period 1960–2014. The end of the growing season (EOS) has been delayed, by an estimated 0.33 d/y during 1982–2014. No significant changes in SOS or EOS were observed during 1960–1981. April–June and August–September minimum temperatures are the main climatic drivers for SOS and EOS, respectively. An increase of 1 °C in April–June minimum temperature shifted the dates of xylem phenology by 6 to 7 d, lengthening the period of tree-ring formation. This study extends the chronology of TP phenology farther back in time and reconciles the disparate views on SOS derived from remote sensing data. Scaling up this analysis may improve understanding of climate change effects and related phenological and plant productivity on a global scale.

scholarly journals Dendroclimatology in Fennoscandia – from past accomplishments to future potential

2010 ◽  
Vol 6 (1) ◽  
pp. 93-114 ◽  
Author(s):  
H. W. Linderholm ◽  
J. A. Björklund ◽  
K. Seftigen ◽  
B. E. Gunnarson ◽  
H. Grudd ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Ring ◽  
Large Scale ◽  
Regional Climate ◽  
Ring Width ◽  
Atmospheric Circulation Patterns ◽  
Northern Fennoscandia ◽  
Finnish Lapland ◽  
Recent Climate ◽  
Tree Ring Data

Abstract. Fennoscandia has a strong tradition in dendrochronology, and its large tracts of boreal forest make the region well suited for the development of tree-ring chronologies that extend back several thousands of years. Two of the world's longest continuous (most tree-ring chronologies are annually resolved) tree-ring width chronologies are found in northern Fennoscandia, with records from Torneträsk and Finnish Lapland covering the last ca. 7500 yr. In addition, several chronologies between coastal Norway and the interior of Finland extend back several centuries. Tree-ring data from Fennoscandia have provided important information on regional climate variability during the mid to late Holocene and have played major roles in the reconstruction of hemispheric and global temperatures. Tree-ring data from the region have also been used to reconstruct large-scale atmospheric circulation patterns, regional precipitation and drought. Such information is imperative when trying to reach better understanding of natural climate change and variability and its forcing mechanisms, and placing recent climate change within a long-term context.

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