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1.
A millennium-long tree-ring width chronology of living and dead larch (Larix decidua Mill.) specimens from the Maritime French Alps was introduced 35?years ago. This record has been included in various large-scale temperature reconstructions, though recent analyses revealed only weak associations with regional summer temperatures. Calibration and verification trials against instrumental measurements were, however, limited by the original record’s early ending in 1974. Here we introduce an update of this widely considered chronology until 2007 and back into medieval times. A total of 297 new larch samples from high-elevation settings in the southern French Alps were included, and the combined 398 measurement series allowed effects of tree-ring detrending and chronology development to be explored. Comparisons with meteorological temperature, precipitation and drought indices revealed weak and temporally inconsistent climate sensitivity. To further place these local findings in a biogeographic context, we used >3,000 larch trees from 61 locations across the Alpine arc. This unique network approach confirmed fading temperature sensitivity with decreasing latitude, and thus questioned the overall reliability of ring width-based temperature reconstructions in the Mediterranean region. Our results further emphasize the pending need to develop chronologies from maximum latewood densities and stable isotope ratios across the lower latitudes, and to carefully evaluate ecological site conditions and methodological data restrictions prior to compiling local data into global networks.  相似文献   

2.
We present new tree-ring width, δ13C, and δ18O chronologies from the Koksu site (49°N, 86° E, 2,200 m asl), situated in the Russian Altai. A strong temperature signal is recorded in the tree-ring width (June-July) and stable isotope (July-August) chronologies, a July precipitation signal captured by the stable isotope data. To investigate the nature of common climatic patterns, our new chronologies are compared with previously published tree-ring and stable isotope data from other sites in the Altai region. The temperature signal preserved in the conifer trees is strongly expressed at local and regional scales for all studied sites, resulting in even stronger temperature and precipitation signals in combined average chronologies compared to separate chronologies. This enables the reconstruction of June-July and July-August temperatures for the last 200 years using tree-ring and stable carbon isotopes. A July precipitation reconstruction based on oxygen isotopic variability recorded in tree-rings can potentially improve the understanding of hydrological changes and the occurrence of extreme events in the Russian Altai.  相似文献   

3.
 Distinct periods of warmth have been identified in instrumental records for New Zealand and the surrounding southwest Pacific over the past 120 years. Whether this warming is due to natural climate variability or the effects of increasing greenhouse gases is difficult to determine given the limited length of instrumental record. Longer records derived from tree rings can help reduce uncertainties in detection of possible causes of climatic change, although relatively few such records have been developed for the Southern Hemisphere. In this work, we describe five temperature-sensitive tree-ring width chronologies for New Zealand which place the recent warming trend into a long-term (pre-anthropogenic) context. Included are three pink pine (Halocarpus biformis) chronologies, two for Stewart Island and one for the North Island of New Zealand. Two silver pine (Lagarostrobus colensoi) series, one each from the North and South Islands, are updated from previous work. The length of record ranges from AD 1700 for Putara, North Island to AD 1400 for Ahaura, South Island. The pink and silver pine are different species from those used previously to reconstruct temperatures for New Zealand. All five chronologies are positively and significantly correlated with warm-season (November-April) individual station temperature records, a New Zealand-wide surface air temperature index and gridded land/marine temperatures for New Zealand and vicinity. The highest 20 and 40-year growth periods in all five tree-ring series coincide with the New Zealand temperature increase after 1950. An exception is found for the 40-year interval at Ahaura, the least temperature-sensitive of the five sites. A t-test comparison indicates that these recent growth intervals are significantly higher (0.01 to 0.0001 level) than any of those prior to the twentieth century for three of the five sites, dating as far back as AD 1500. The results suggest that the recent warming has been distinctive, although not clearly unprecedented, relative to temperature conditions inferred from tree-ring records of prior centuries. Received: 18 February 1997/Accepted: 11 September 1997  相似文献   

4.
利用2012年10月采自吉尔吉斯斯坦西天山chon-kyzyl-suu附近的森林上线和下线两个采样点的雪岭云杉树轮样本,建立了上下线树轮宽度年表,结合近百年CRU（0.5?.5）气温和降水资料,分析该地区森林上下线树轮对气候响应的异同。研究表明,森林上下线树轮年表一致性较好,尤其是窄轮出现年份基本相同;对气温响应方面,森林上线树轮年表与春季尤其是4-5月份平均温度显著负相关;而森林下线树轮年表与夏季尤其是6-7月平均气温显著相关。降水方面,树轮年表与上年7月到当年6月降水相关最好,森林下线年表与上年7月到当年6月的降水量相关系数超过0.61;上线也达到了0.49。与中国境内雪岭云杉对气候响应基本相同,位于吉尔吉斯斯坦的西天山北坡树轮宽度同样对降水的响应更为敏感,尤其在森林下线;降水可能是该地区树木生长的主要限制性因子,降水对森林下线树轮径向生长起决定性作用。空间相关分析表明,树轮年表能较好的代表西天山大部分区域上年7月到当年6月的降水量,尤其是西天山北坡吉尔吉斯斯坦境内。  相似文献   

5.
位于西昆仑山北坡的叶尔羌河是塔里木河的三大源流之一,该流域山区分布的雪岭云杉为过去气候变化研究提供了理想的载体。本文建立了叶尔羌河流域4个雪岭云杉树轮宽度年表和区域合成年表,探讨了树轮年表对叶城气象站气温、降水等气候要素的响应特征。结果表明雪岭云杉树轮年表具有较高平均敏感度、缺轮率和序列间相关系数,年表的质量较高。区域合成年表与叶城站上年6月至当年5月降水量相关系数为0.393,与当年3—9月平均最低气温相关系数为0.624。一阶差相关分析表明,树轮年表与最低气温的高频变化特征并不一致,二者较高的正相关主要是由于温度升高趋势的贡献。树轮年表与乌恰站上年7月至当年4月降水量相关系数为0.535。西昆仑山北坡雪岭云杉树轮年表与周边对水分敏感的树轮气候记录对比表明,其低频变化趋势以及缺年集中出现的年份均具有较好的一致性。由于气候干旱、下垫面条件恶劣,位于叶尔羌河流域的西昆仑山北坡雪岭云杉树木径向生长的限制因子仍然为水分条件,而非气温。  相似文献   

6.
利用阿尔泰山中部地区3个采样点的树轮宽度资料,建立年表,对比3个树轮宽度标准化年表（STD）相关特征参数及年表与气候的响应,结果表明：大东沟（DDG）年表和二道房子（EDF）年表的平均敏感度和信噪比等参数均较大,表明2个年表含有较丰富的气候信息。2个年表的显著性水平达到0.01的自相关大多在4阶以内,表明气候对阿尔泰山中部树轮宽度生长的影响主要表现在当年及其后的3 a,其＂滞后效应＂较明显。位于阿尔泰山中部森林中下部林缘的大东沟树轮宽度年表（DDG）与上年11月-当年4月的降水量有显著的正相关（r=0.503,p〈0.001）;而位于阿尔泰山中部森林上树线附近的哈依萨萨依树轮宽度年表（HYS）对当年6-7月的月平均最低气温有明显的正相关（r=0.462,p〈0.001）,但同时与当年1月的降水有很好的响应。  相似文献   

7.
Summary We analyse the spatial representation of five previously published multi-century to millennial length dendroclimatological reconstructions of Fennoscandian summer temperatures. The reconstructions, ranging from local to regional scale, were based on either tree-ring width (TRW) or maximum latewood density (MXD) data or on a combination of the two. TRW chronologies are shown to provide reasonably good spatial information mainly for July temperatures, but a combination of TRW and MXD yields a better spatial representation for the whole summer season (June–August). A multiple-site reconstruction does not necessarily provide better spatial representation than a single site reconstruction, depending on the criterion for selecting data and also on the strength of the climate signal in the tree-ring data. In a new approach to analyse the potential for further developing Fennoscandian temperature reconstructions, we selected from a network of TRW and MXD chronologies those having the strongest temperature information a priori, to obtain a strong common climate signal suitable for a regional-scale reconstruction. Seven separate, but not independent, reconstructions based on progressively decreasing numbers of chronologies were created. We show that it is possible to improve the spatial representation of available reconstructions back to around AD 1700, giving high correlations (>0.7) with observed summer temperatures for nearly the whole of Fennoscandia, and even higher correlations (>0.85) over much of central-northern Fennoscandia. Further sampling of older trees (e.g. dry-dead and subfossil wood) would be needed to achieve the same high correlations prior to AD 1700. Our analysis suggests that it should be possible to select a few key sites for improving the reconstructions before AD 1700. Since tree-ring data from northern Fennoscandia are used in all available hemispheric-scale temperature reconstructions for the last millennium, there is also a potential for slightly improving the quality of the hemispheric-scale reconstructions, by including an improved reconstruction for Fennoscandia. However, adding new chronologies from previously unsampled regions would potentially improve hemispheric-scale temperature reconstructions more substantially. Authors’ addresses: Isabelle Gouirand, Anders Moberg, Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden; Hans W. Linderholm, Regional Climate Group, Department of Earth Sciences, G?teborg University, SE-405 30 G?teborg, Sweden; Barbara Wohlfarth, Department of Geology and Geochemistry, Stockholm University, SE-106 91 Stockholm, Sweden.  相似文献   

8.
新疆伊犁乌孙山北坡树轮灰度年表的建立及气候意义   总被引：1，自引：0，他引：1  
利用2006年采自新疆伊犁乌孙山北坡3个采点的树轮样本,建立了树轮宽度年表,采用树轮图像分析法进一步建立了3种宽度年表和5种灰度年表。宽度年表对比发现,树木年轮对气候响应南疆强于北疆,北疆其它地方强于伊犁地区,而乌孙山北坡与伊犁其它地区比较,树轮宽度对气候的响应较敏感。树轮图像分析法建立的8种年表特征进行对比发现,恰依恰孜宽度年表对气候的响应最为强烈;而阿乌里亚乔克标准化灰度年表对气候的响应较好。相关分析表明,全轮灰度、早材灰度和最大灰度与4、5月气温相关较好。4月降水和实测宽度、全轮宽度以及早材宽度相关较好,而6月降水与全轮灰度和早材灰度相关较好。早材宽度对气候的响应强于晚材宽度;全轮灰度和早材灰度对气候的响应较好。利用树轮图像分析所得到的8个树轮参数年表可增加气候重建代用指标,提高气候重建的精度。  相似文献   

9.
Håkan Grudd 《Climate Dynamics》2008,31(7-8):843-857
This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period ad 500–2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A bootstrapped response function analysis using regional climate data shows that tree growth is forced by April–August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63–64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around ad 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around ad 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on ad 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this “Medieval Warm Period” in northern Fennoscandia was much warmer than previously recognized.  相似文献   

10.
Maximum latewood density data from trees at thirteen temperature-sensitive sites along the northern treeline of North America are used to evaluate the spatial patterns of response to four known volcanic events just prior to the period of modern observations: in 1640, 1783, 1815 and 1835. A previously unknown event is also postulated for 1699. This tree-ring density parameter is used because it shows a stronger and more consistent short-term, temperature-related volcanic signal than ring width. Normalized density departures following these events vary in sign and magnitude from region to region, with the coldest summer conditions inferred for the Northwest Territories in 1641, Alaska in 1783, Quebec and Labrador in 1816 and the Northwest Territories in 1836. For these as well as other events, low density values are often among the most extreme on record at their respective locations. We suggest that these regional variations in tree growth reflect cooling induced by volcanism and the distribution of cooling influenced by atmospheric circulation patterns.  相似文献   

11.
Eight tree-ring chronologies from coastal sites along the Gulf of Alaska (GOA) are used to develop a 227-year (1762–1988) reconstruction of spring/summer (March–September) coastal land temperatures for the region. This reconstruction explains 35% of the variance in the instrumental temperature data. The tree-ring records and reconstruction reflect the documented 1976 transition from cold to warm conditions in the North Pacific and are consistent with regional temperature compilations. Three of the eight ring-width series, from elevational timberline sites where trees are particularly stressed by temperature, extend back to A.D. 1600 and are used to identify additional occurrences of such transitions. The first principal component (PC) scores of these three longer records are positively correlated with spring (March–May) land and sea surface temperatures for the GOA region and are used to reconstruct land surface temperatures. Decadal-scale fluctuations in the reconstructions show agreement with decade-long changes in the intensity of the Aleutian Low pressure cell over the past century, suggesting that the tree-ring data may provide an index of past circulation changes for the northeast Pacific. Blackman-Tukey spectral analyses of both reconstructions indicate significant power at 7–11 years, with additional peaks at 3 years for the spring/summer reconstruction and 19 years for the longer spring temperature series. The modes of variation at about 3 and 7 years may correspond to those associated with the El Niño-Southern Oscillation bandwidth, whereas the 19-year term may relate to a proposed 20-year cycle of North Pacific circulation. The spring temperature series shows generally increased growth over the past century, coinciding with warmer spring temperatures in south coastal Alaska over this interval. Comparison with the entire spring series suggests that the recent warming exceeds temperature levels of prior centuries, extending back to A.D. 1600.  相似文献   

12.
We developed four Georgei fir (Abies georgei var. smithii) tree-ring width chronologies at the timberline in the Sygera Mts. in southeast Tibet, China. All individual standard chronologies and a regional well-replicated ring-width composite chronology (RC) show significantly positive correlations with mean summer (June-August) temperature. Herein mean summer temperature was reconstructed for southeast Tibet back to A.D. 1765 based on RC. This reconstruction successfully captures recent warming observed in the instrumental record since 1961 with the last decade being the warmest period in the past 242 years. It agrees in general with other temperature reconstructions of the Tibetan Plateau and extratropical northern hemisphere. This study allows seeing recent warming on a longer time scale in southeast Tibet.  相似文献   

13.
利用树轮资料重建1751-2005年崆峒山地区夏季温度变化   总被引：4，自引：0，他引：4  
利用采自崆峒山区的66根油松树轮样芯,建立了采样点的标准年表、差值年表和自回归标准化年表。相关分析表明,标准年表与当年夏季均温有显著的相关性,通过建立回归方程,重建了1751-2005年崆峒山地区夏季温度序列。结果表明,自1751年以来,研究区存在3个高温期（1786-1847年、1894-1937年、1987-2004年）和3个低温期（1764-1785年、1852-1893年、1952-1986年）。与Nino3指数、南方涛动指数（SOI）和太阳黑子数等对比表明,崆峒山地区对全球大尺度气候变化及太阳活动都有较好的响应。  相似文献   

14.
Violins and climate   总被引：4，自引：0，他引：4  
Summary This paper explores the possibility of using ring-width measurements derived from string instruments as a potential source of palaeoclimate information. From a data-base of 1800 measured series, we have identified two sub-sets that compare well with living high elevation spruce (Picea abies (L.) Karst) chronologies from the Bavarian Forest and Austrian Alps. The problems of using historical tree-ring data for dendroclimatic purposes are addressed and by combining the living and historic ring-width data from these two regions, a preliminary proxy of past June/July mean temperatures is developed. This proxy summer temperature record shows striking similarities with a tree-ring based temperature reconstruction for the Central Eastern Alps, the CLIMHIST June/July temperature record from Switzerland and glacial records from the Austrian Alps. This explorative study demonstrates that ring-width series from string instruments may allow the identification of generalised source regions of wood used for instrument making and, most importantly, provide a new unique source for palaeoclimate information at a variety of both temporal and spatial scales for high elevations in central Europe.  相似文献   

15.
Ensemble empirical mode decomposition for tree-ring climate reconstructions   总被引：1，自引：1，他引：0  
A novel data adaptive method named ensemble empirical mode decomposition (EEMD) was used to reconstruct past temperature and precipitation variability in two 2,328- and 1,837-year tree-ring chronologies from the Dulan region, northeastern Qinghai–Tibetan Plateau. Our results show that EEMD can be used to extract low-frequency signals from the Dulan tree-ring data. The extracted low-frequency temperature trends in the two chronologies correlate significantly with Northern Hemisphere temperatures over the past two millennia. In addition, the newly reconstructed precipitation data have a higher standard deviation than that of data reconstructed with the conventional ordinary least squares and variance matching methods and yield the best amplitude match to the instrumental data. This study shows that EEMD is a powerful tool for extracting the full spectrum of climate information in tree-ring chronologies.  相似文献   

16.
Seven different tree-ring parameters (tree-ring width, earlywood width, latewood width, maximum density, minimum density, mean earlywood density, and mean latewood density) were obtained from Qinghai spruce (Picea crassifolia) at one chronology site in the Hexi Corridor, China. The chronologies were analyzed individually and then compared with each other. Growth–climate response analyses showed that the tree-ring width and maximum latewood density (MXD) are mainly influenced by warm season temperature variability. Based on the relationships derived from the climate response analysis, the MXD chronology was used to reconstruct the May–August maximum temperature for the period 1775–2008 A.D., and it explained the 38.1% of the total temperature variance. It shows cooling in the late 1700s to early 1800s and warming in the twentieth century. Spatial climate correlation analyses with gridded land surface data revealed that our warm season temperature reconstruction contains a strong large-scale temperature signal for north China. Comparison with regional and Northern Hemisphere reconstructions revealed similar low-frequency change to longer-term variability. Several cold years coincide with major volcanic eruptions.  相似文献   

17.
利用位于玛纳斯河流域地区不同海拔高度的6个采样点的树木年轮宽度资料,建立其宽度年表,并分别将位于上树线区域的2个年表和下树线区域的3个年表合成,得到森林上树线年表（MNU）和下树线年表（MNL）,将涝坝湾年表作为森林中部年表（MNM）。对比3个树轮宽度标准化年表的特征参数及年表对气候的响应,结果表明：（1）样本总体代表性、平均敏感度、信噪比、第一特征向量百分比随着海拔的升高而递减。（2）高频信息量随着海拔的升高而递减,而低频信息量随着海拔的升高而递增。（3）气温是制约森林上树线年表（MNU）的主要气候限制因子;而对于森林下树线年表（MNL）与森林中部年表（MNM）来说,降水起直接的正向影响作用,气温则发挥间接的反作用,均具有明确的树木生理学意义[1]。  相似文献   

18.
Tree-ring oxygen stable isotope data series from conifers growing on the Dachstein Plateau (Austrian Alps) were selected to demonstrate the applicability of the serial pooling method using shifted 5-year tree-ring blocks for summer temperature reconstruction. The addressed method allows the construction of long isotope chronologies with significant climate correlation and well preserved climate sensitivity applying the irreducible sample replication of five trees. The linear regression model for temperature reconstruction is verifiable and the predicted data are well correlated with instrumental data, especially reproducing the long-term temperature trend. However, the reduced mean variance leads to loss of extreme years, which can be regulated by the combination of one data series in annual resolution with five shifted 5-year block data series. This significantly improves the variance of the mean chronology, sufficiently to identify extremes. Therefore, we recommend the use of mixed data sets as a compromise between essential sample replication and economic considerations.  相似文献   

19.
Well replicated tree-ring width index chronologies have been developed for giant sequoia at three sites in the Sierra Nevada, California. Extreme low-growth events in these chronologies correspond with regional drought events in the twentieth century in the San Joaquin drainage, in which the giant sequoia sites are located. This relationship is based upon comparison of tree-ring indices with August Palmer Drought Severity Indices for California Climate Division 5. Ring-width indices in the lowest decile from each site were compared. The frequency of low-growth events which occurred at all three sites in the same year is reconstructed from 101 B.C. to A.D. 1988. The inferred frequency of severe drought events changes through time, sometimes suddenly. The period from roughly 1850 to 1950 had one of the lowest frequencies of drought of any one hundred year period in the 2089 year record. The twentieth century so far has had a below-average frequency of extreme droughts.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program  相似文献   

20.
在天山北坡不同区域间隔海拔高度100 m左右采集5个树轮梯度年表,分析树木径向生长沿海拔高度变化的规律。结果发现:在树轮年表特征中,平均轮宽、树龄和敏感度等存在海拔梯度变化,平均轮宽和敏感度随海拔升高而降低,而平均树龄则与海拔高度呈正相关。高海拔采样点在同一区域和不同区域间一致性最好,低海拔采样点次之,而森林中部最差,东部和中部低海拔区域采样点的一致性要好于西部,坡向、坡度等小生境的差异也是影响树轮生长垂直变化规律的重要因素。存在同时影响不同海拔高度树轮生长的环境要素,西部和中部高海拔树木对该要素的响应更显著,在更为干旱的天山北坡中部和东部,对树木径向生长的影响较大的环境因子要多于西部伊犁地区。  相似文献   

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