Tree-ring variables as proxy-climate indicators: Problems with low-frequency signals

1996 ◽  
pp. 9-41 ◽  
Author(s):  
Keith R Briffa ◽  
Philip D Jones ◽  
Fritz H Schweingruber ◽  
Wibjörn Karlén ◽  
Stepan G Shiyatov
Keyword(s):  
Tree Ring ◽  
Low Frequency ◽  
Climate Indicators

scholarly journals Comparing selected fire regime condition class (FRCC) and LANDFIRE vegetation model results with tree-ring data

2010 ◽  
Vol 19 (1) ◽  
pp. 1 ◽  
Author(s):  
Tyson L. Swetnam ◽  
Peter M. Brown
Keyword(s):  
Tree Ring ◽  
Ponderosa Pine ◽  
Fire Regime ◽  
Reference Conditions ◽  
Low Frequency ◽  
Fire Regimes ◽  
Vegetation Types ◽  
Tree Ring Data ◽  
Map Data ◽  
Fire Regime Condition Class

Fire Regime Condition Class (FRCC) has been developed as a nationally consistent interagency method in the US to assess degree of departure between historical and current fire regimes and vegetation structural conditions across differing vegetation types. Historical and existing vegetation map data also are being developed for the nationwide LANDFIRE project to aid in FRCC assessments. Here, we compare selected FRCC and LANDFIRE vegetation characteristics derived from simulation modeling with similar characteristics reconstructed from tree-ring data collected from 11 forested sites in Utah. Reconstructed reference conditions based on trees present in 1880 compared with reference conditions modeled by the Vegetation Dynamics Development Tool for individual Biophysical Settings (BpS) used in FRCC and LANDFIRE assessments showed significance relationships for ponderosa pine, aspen, and mixed-conifer BpS but not for spruce–fir, piñon–juniper, or lodgepole pine BpS. LANDFIRE map data were found to be ~58% accurate for BpS and ~60% accurate for existing vegetation types. Results suggest that limited sampling of age-to-size relationships by different species may be needed to help refine reference condition definitions used in FRCC assessments, and that more empirical data are needed to better parameterize FRCC vegetation models in especially low-frequency fire types.

scholarly journals Low-frequency noise inδ13C andδ18O tree ring data: A case study ofPinus uncinatain the Spanish Pyrenees

2010 ◽  
Vol 24 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jan Esper ◽  
David C. Frank ◽  
Giovanna Battipaglia ◽  
Ulf Büntgen ◽  
Christopher Holert ◽  
...  
Keyword(s):  
Tree Ring ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Tree Ring Data ◽  
Spanish Pyrenees

Low-frequency divergence of tree-ring d18O variations on both sides of climatic boundary mountain of eastern China since 1980s

2020 ◽  
Author(s):  
Qiang Li ◽  
Yu Liu ◽  
Huiming Song
Keyword(s):  
Relative Humidity ◽  
Tree Ring ◽  
Time Scale ◽  
Eastern China ◽  
Sampling Site ◽  
Low Frequency ◽  
Mountain Range ◽  
Decadal Time Scale ◽  
Qinling Mountain ◽  
Significant Divergence

<p>The Qinling Mountain is the most important mountain range in eastern China, and is the geographical boundary and the climatic boundary. We investigated tree-ring d18O variations in South and North Slope of the Qinling Mountain, and found that the variations of tree-ring  d18O were significantly correlated over the past two and a half centuries (r=0.641, n=247, p<0.001). And they are negatively correlated with relative humidity and precipitation, and positively correlated with temperature. Compared with the various hydroclimate-related time series in the surrounding area, it is found that both can represent the region's long-term hydroclimate change. The consistent changes in the interannual time scale may be due to the common modulation of ENSO. However, on the decadal time scale, there have been significant divergence between the two tree-ring  d18O series since 1981 and the divergence may be caused by changes in relative humidity at the sampling site, suggesting that in the context of global warming, although the warming range is the same, but the triggered relative humidity changes are not consistent. In addition, changes in PDO may be another cause of low-frequency difference.</p>

scholarly journals Wavelet analysis of low-frequency variability in oak tree-ring chronologies from east Central Europe

2016 ◽  
Vol 8 (1) ◽  
Author(s):  
Asok K. Sen ◽  
Zoltán Kern
Keyword(s):  
Time Series ◽  
Wavelet Analysis ◽  
Central Europe ◽  
Tree Ring ◽  
Low Frequency ◽  
Wavelet Coherence ◽  
Time Interval ◽  
East Central Europe ◽  
East Central ◽  
Oak Tree

AbstractThis study investigates the low-frequency (interannual and longer period) variability in three hydroclimatic records from east Central Europe. Two of these records consist of climate proxies derived from oak-tree rings in Bakta forest, and Balaton Highlands in Hungary, for the time interval 1783-2003. The third record consists of homogenized instrumental precipitation data from Budapest, Hungary, from 1842 to 2003. Using wavelet analysis, the three time series are analyzed and compared with one another. It is found that all three time series exhibit strong interannual variability at the 2-4 years timescales, and these variations occur intermittently throughout the length of each record. Significant variability is also observed in all the records at decadal timescales, but these variations persist for only two to three cycles. Wavelet coherence among the various time series is used to explore their time-varying correlation. The results reveal significant coherence at the 2-4 years band. At these timescales, the climatic variations are correlated to the tree-ring signal over different time intervals with changing phase. Increased (decreased) contribution of large-scale stratiform precipitation offers a potential explanation for enhanced (faded) coherence at the interannual timescale. Strong coherence was also observed occasionally at decadal timescales, however these coherences did not appear uniformly. These results reinforce the earlier assertion that neither the strength nor the rank of the similarity of the local hydroclimate signals is stable throughout the past two centuries.

A fistful of shells: amplifying sclerochronological and palaeoclimate signals from molluscan death assemblages

2009 ◽  
Vol 146 (6) ◽  
pp. 917-930 ◽  
Author(s):  
S. HELAMA ◽  
J. K. NIELSEN ◽  
M. MACIAS FAURIA ◽  
I. VALOVIRTA
Keyword(s):  
Sample Size ◽  
Tree Ring ◽  
Small Sample Size ◽  
Low Frequency ◽  
Small Sample ◽  
Pearl Mussel ◽  
Climate Signal ◽  
Growth Variability ◽  
Low Frequency Variability ◽  
The Individual

AbstractA growing body of literature is using sclerochronological information to infer past climates. Sclerochronologies are based on series of skeletal growth records of molluscs that have been correctly aligned in time. Incremental series are obtained from a number of shells to assess the temporal control and improve the climate signal in the final chronology. Much of the sclerochronological theory has been adopted from tree-ring science, due to the longer tradition and more firmly established concepts of chronology construction in dendrochronology. Compared to tree-ring studies, however, sclerochronological datasets are often characterized by relatively small sample size. Here we evaluate how effectively palaeoclimatic signal can be extracted from such a suite of samples. In so doing, the influences of the very basic methods that are applied in nearly every sclerochronological study to remove the non-climatic growth variability prior to palaeoclimatic interpretations, are ranked by their capability to amplify the desired signal. The study is performed in the context of six shells that constitute a bicentennial growth record from annual shell increments of freshwater pearl mussel. It was shown that when the individual series were detrended using the models set by the mean or the median summary curves for ageing (that is, applying Regional Curve Standardization, RCS), instead of fitting the ageing mode statistically to each series, the resulting sclerochronology displayed more low-frequency variability. Consistently, the added low-frequency variability evoked higher proxy–climate correlations. These results show the particular benefit of using the RCS method to develop sclerochronologies and preserve their low-frequency variations. Moreover, calculating the ageing curve and the final chronology by median, instead of mean, resulted in an amplified low-frequency climate signal. The results help to answer a growing need to better understand the behaviour of the sclerochronological data. In addition, we discuss the pitfalls that may potentially disrupt palaeoclimate signal detection in similar sclerochronological studies. Pitfalls may arise from shell taphonomy, water chemistry, time-variant characters of biological growth trends and small sample size.

A comparison of two tree-ring-index standardization techniques

1992 ◽  
Vol 22 (12) ◽  
pp. 1922-1928 ◽  
Author(s):  
J.O. Murphy ◽  
J.G. Palmer
Keyword(s):  
Tree Ring ◽  
Low Frequency ◽  
Polynomial Functions ◽  
Spectral Profile ◽  
Biological Growth ◽  
Climatic Variations ◽  
Highly Correlated ◽  
Index Standardization ◽  
Statistical Indicators ◽  
Mean Sensitivity

A comparison is made between two tree-ring index chronologies that are based on the same set of site ring measurements but use two different standardization techniques. Both polynomial functions and 50-year Gaussian filtering procedures have been employed to represent the biological growth curve, thereby essentially detrending the resulting ring-index chronologies. It is established that although both approaches generate highly correlated time series at lag 0, significant differences exist in the autocorrelation functions, mean sensitivity values, and spectral amplitudes at the low frequency end of the spectrum. The exclusion of these periodicities is of concern, as they are normally associated with longer term climatic variations as well as site influences. Consequently, the nature of the descriptive statistical indicators generally considered, especially the spectral profile, should be established in conjunction with possible standardization options. Also, it would be prudent to appraise existing chronologies, on the same basis, prior to undertaking any dendrochronological applications.

scholarly journals Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings

2010 ◽  
Vol 6 (3) ◽  
pp. 379-400 ◽  
Author(s):  
C. Corona ◽  
J. Guiot ◽  
J. L. Edouard ◽  
F. Chalié ◽  
U. Büntgen ◽  
...  
Keyword(s):  
Tree Ring ◽  
Regional Growth ◽  
Low Frequency ◽  
Warming Trend ◽  
High Elevation ◽  
Ice Age ◽  
European Alps ◽  
Linear Calibration ◽  
Late 20Th Century ◽  
Short Tree

Abstract. This paper presents a reconstruction of the summer temperatures over the Greater Alpine Region (44.05°–47.41° N, 6.43°–13° E) during the last millennium based on a network of 38 multi-centennial larch and stone pine chronologies. Tree ring series are standardized using an Adaptative Regional Growth Curve, which attempts to remove the age effect from the low frequency variations in the series. The proxies are calibrated using the June to August mean temperatures from the HISTALP high-elevation temperature time series spanning the 1818–2003. The method combines an analogue technique, which is able to extend the too short tree-ring series, an artificial neural network technique for an optimal non-linear calibration including a bootstrap technique for calculating error assessment on the reconstruction. About 50% of the temperature variance is reconstructed. Low-elevation instrumental data back to 1760 compared to their instrumental target data reveal divergence between (warmer) early instrumental measurements and (colder) proxy estimates. The proxy record indicates cool conditions, from the mid-11th century to the mid-12th century, related to the Oort solar minimum followed by a short Medieval Warm Period (1200–1420). The Little Ice Age (1420–1830) appears particularly cold between 1420 and 1820 with summers that are 0.8 °C cooler than the 1901–2000 period. The new record suggests that the persistency of the late 20th century warming trend is unprecedented. It also reveals significant similarities with other alpine reconstructions.

Forest dynamics and the growth decline of red spruce and sugar maple on Bolton Mountain, Vermont: a comparison of modeling methods

2008 ◽  
Vol 38 (10) ◽  
pp. 2635-2649 ◽  
Author(s):  
Daniel G. Gavin ◽  
Brian Beckage ◽  
Benjamin Osborne
Keyword(s):  
Tree Ring ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Low Frequency ◽  
Growth Patterns ◽  
Red Spruce ◽  
Forest Plot ◽  
Progressive Decline ◽  
Growth Decline ◽  
Branch Dieback

Montane forests in the northeastern United States have experienced symptoms of declining vigor, such as branch dieback and increased mortality, over the last half-century. These declines have been attributed to the cumulative impacts of acid deposition, but reconstructing these declines from tree-ring records has proved difficult because of confounding factors that affect low-frequency growth patterns, including climate and natural growth trajectories following disturbance. We obtained tree-ring records of red spruce ( Picea rubens Sarg.) and sugar maple ( Acer saccharum L.) from three elevations on Bolton Mountain, Vermont, and applied traditional dendroclimatological analyses that revealed a profound declining growth–climate correlation since ca. 1970 for sugar maple but much less so for red spruce. We then applied a new multifaceted statistical approach that conservatively detrends tree-ring records by minimizing the influences of tree size, age, and canopy disturbances on radial growth. In contrast with the traditional analysis, this approach yielded chronologies that were consistently correlated with climate but with important exceptions. Low-elevation sugar maple suffered distinct episodes of slow growth, likely because of insect defoliators, and also a progressive decline since ca. 1988. Red spruce experienced subdecadal episodes of decline that may be related to freeze–thaw events known to injure foliage but showed no evidence of a progressive decline. This analysis was supported by a forest plot resurvey that indicated major declines in these species.

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