Improved dendroclimatic calibration using blue intensity in the southern Yukon

In north-western North America, the so-called divergence problem (DP) is expressed in tree ring width (RW) as an unstable temperature signal in recent decades. Maximum latewood density (MXD), from the same region, shows minimal evidence of DP. While MXD is a superior proxy for summer temperatures, there are very few long MXD records from North America. Latewood blue intensity (LWB) measures similar wood properties as MXD, expresses a similar climate response, is much cheaper to generate and thereby could provide the means to profoundly expand the extant network of temperature sensitive tree-ring (TR) chronologies in North America. In this study, LWB is measured from 17 white spruce sites ( Picea glauca) in south-western Yukon to test whether LWB is immune to the temporal calibration instabilities observed in RW. A number of detrending methodologies are examined. The strongest calibration results for both RW and LWB are consistently returned using age-dependent spline (ADS) detrending within the signal-free (SF) framework. RW data calibrate best with June–July maximum temperatures (Tmax), explaining up to 28% variance, but all models fail validation and residual analysis. In comparison, LWB calibrates strongly (explaining 43–51% of May–August Tmax) and validates well. The reconstruction extends to 1337 CE, but uncertainties increase substantially before the early 17th century because of low replication. RW-, MXD- and LWB-based summer temperature reconstructions from the Gulf of Alaska, the Wrangell Mountains and Northern Alaska display good agreement at multi-decadal and higher frequencies, but the Yukon LWB reconstruction appears potentially limited in its expression of centennial-scale variation. While LWB improves dendroclimatic calibration, future work must focus on suitably preserved sub-fossil material to increase replication prior to 1650 CE.

Download Full-text

Experiments based on blue intensity for reconstructing North Pacific temperatures along the Gulf of Alaska

Climate of the Past ◽

10.5194/cp-13-1007-2017 ◽

2017 ◽

Vol 13 (8) ◽

pp. 1007-1022 ◽

Cited By ~ 13

Author(s):

Rob Wilson ◽

Rosanne D'Arrigo ◽

Laia Andreu-Hayles ◽

Rose Oelkers ◽

Greg Wiles ◽

...

Keyword(s):

Tree Ring ◽

North Pacific ◽

Ring Width ◽

Gulf Of Alaska ◽

Climate Response ◽

Cool Period ◽

Climate Signal ◽

Latewood Density ◽

Blue Intensity

Abstract. Ring-width (RW) records from the Gulf of Alaska (GOA) have yielded a valuable long-term perspective for North Pacific changes on decadal to longer timescales in prior studies but contain a broad winter to late summer seasonal climate response. Similar to the highly climate-sensitive maximum latewood density (MXD) proxy, the blue intensity (BI) parameter has recently been shown to correlate well with year-to-year warm-season temperatures for a number of sites at northern latitudes. Since BI records are much less labour intensive and expensive to generate than MXD, such data hold great potential value for future tree-ring studies in the GOA and other regions in mid- to high latitudes. Here we explore the potential for improving tree-ring-based reconstructions using combinations of RW- and BI-related parameters (latewood BI and delta BI) from an experimental subset of samples at eight mountain hemlock (Tsuga mertensiana) sites along the GOA. This is the first study for the hemlock genus using BI data. We find that using either inverted latewood BI (LWBinv) or delta BI (DB) can improve the amount of explained temperature variance by > 10 % compared to RW alone, although the optimal target season shrinks to June–September, which may have implications for studying ocean–atmosphere variability in the region. One challenge in building these BI records is that resin extraction did not remove colour differences between the heartwood and sapwood; thus, long term trend biases, expressed as relatively warm temperatures in the 18th century, were noted when using the LWBinv data. Using DB appeared to overcome these trend biases, resulting in a reconstruction expressing 18th–19th century temperatures ca. 0.5 °C cooler than the 20th–21st centuries. This cool period agrees well with previous dendroclimatic studies and the glacial advance record in the region. Continuing BI measurement in the GOA region must focus on sampling and measuring more trees per site (> 20) and compiling more sites to overcome site-specific factors affecting climate response and using subfossil material to extend the record. Although LWBinv captures the inter-annual climate signal more strongly than DB, DB appears to better capture long-term secular trends that agree with other proxy archives in the region. Great care is needed, however, when implementing different detrending options and more experimentation is necessary to assess the utility of DB for different conifer species around the Northern Hemisphere.

Download Full-text

Comparison between Blue Intensity (BI) and Maximum Latewood Density (MXD) tree-ring chronologies from the North American Boreal forests

10.5194/egusphere-egu2020-21137 ◽

2020 ◽

Author(s):

Laia Andreu-Hayles ◽

Rosanne D'Arrigo ◽

Rose Oelkers ◽

Kevin Anchukaitis ◽

Greg Wiles ◽

...

Keyword(s):

High Resolution ◽

North America ◽

Tree Ring ◽

Boreal Forests ◽

Ring Width ◽

Maximum Latewood Density ◽

Latewood Density ◽

Tree Ring Data ◽

Summer Temperatures ◽

Blue Intensity

<p>Tree ring-width (TRW) and Maximum Latewood Density (MXD) series have been largely used to develop high-resolution temperature reconstructions for the Northern Hemisphere. The divergence phenomenon, a weakening of the positive relationship between TRW and summer temperatures, has been observed particularly in northwestern North America chronologies. In contrast, MXD datasets have shown a more stable relationship with summer temperatures, but it is costly and labor-intensive to produce. Recently, methodological advances in image analyses have led to development of a less expensive and labor-intensive MXD proxy known as Blue Intensity (BI). Here, we compare 6 newly developed BI tree-ring chronologies of white spruce (<em>Picea glauca</em> [Moench] Voss) from high-latitude boreal forests in North America (Alaska in USA; Yukon and the Northwestern Territory in Canada), with MXD chronologies developed at the same sites. We assessed the quality of BI in relation to MXD based on mean correlation between trees, chronology reliability based on the Expressed Population Signal (EPS), spectral properties, and the strength and spatial extent of the temperature signal. Individual BI chronologies established significant correlations with summer&#160;temperatures showing a similar&#160;strength and spatial cover than MXD chronologies. Overall, the BI tree-ring data is emerging as a valuable proxy for generating high-resolution temperature spatial reconstructions over northwestern America.</p>

Download Full-text

Blue Intensity based experiments for reconstructing North Pacific temperatures along the Gulf of Alaska

10.5194/cp-2017-26 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rob Wilson ◽

Rosanne D'Arrigo ◽

Laia Andreu-Hayles ◽

Rose Oelkers ◽

Greg Wiles ◽

...

Keyword(s):

Tree Ring ◽

North Pacific ◽

Large Scale ◽

Ring Width ◽

Gulf Of Alaska ◽

Cool Period ◽

Latewood Density ◽

Ocean Atmosphere ◽

Blue Intensity

Abstract. Climate in the Gulf of Alaska (GOA) reflects large-scale ocean-atmosphere variability of the North Pacific climate system. Ring-width (RW) records from the GOA have yielded a valuable long-term perspective for North Pacific changes on decadal to longer time scales in prior studies, but express a broad winter to late summer seasonal response. Similar to the highly climate-sensitive maximum latewood density (MXD) proxy, the Blue Intensity (BI) parameter has recently been shown to correlate well with year-to-year warm-season temperatures for a number of sites at northern latitudes. Since BI records are much less expensive and labor intensive to generate than MXD, such data hold great potential value for future tree-ring studies in the GOA and other regions at mid-to-high latitudes. Here we highlight the potential for improving tree-ring based reconstructions using combinations of RW and BI-related parameters (latewood BI (LWB) and delta BI (DB)) from an experimental sub-set of samples from eight mountain hemlock (Tsuga mertensiana) sites along the GOA. This is the first such study for the hemlock genus using BI data. We find that using either LWB or DB can improve the amount of explained temperature variance by > 10 % compared to RW alone although the optimal target season changes to June–September, which may have implications for studying ocean-atmosphere variability in the region. However, one challenge in building these BI records is that resin extraction did not remove colour differences between the heartwood and sapwood, so long term trend biases, expressed as relatively warm temperatures in the 18th century, were noted when using the LWB data. Using DB appeared to overcome these trend biases resulting in a reconstruction expressing 18th–19th century temperatures ca. 0.5 °C cooler than the 20th/21st centuries. This cool period agrees well with previous dendroclimatic studies and the glacial advance record in the region. Continuing BI measurement in the GOA region must focus on sampling more trees per site (> 20) and more sites to overcome site specific factors effecting climate response while sub-fossil material will extend the reflectance records back over 1000 years. DB appears to capture long term secular trends that agree with other proxy archives in the region but great care is needed when implementing different detrending options. Finally, more experimentation is needed to assess the utility of DB for different conifer species around the Northern Hemisphere.

Download Full-text

Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information

Climate of the Past ◽

10.5194/cp-10-877-2014 ◽

2014 ◽

Vol 10 (2) ◽

pp. 877-885 ◽

Cited By ~ 53

Author(s):

J. A. Björklund ◽

B. E. Gunnarson ◽

K. Seftigen ◽

J. Esper ◽

H. W. Linderholm

Keyword(s):

Tree Ring ◽

Wood Density ◽

Lignin Content ◽

Warm Season ◽

Summer Temperature ◽

Latewood Density ◽

Radiographic Measurements ◽

Temperature Reconstructions ◽

June July ◽

Blue Intensity

Abstract. Here we explore two new tree-ring parameters, derived from measurements of wood density and blue intensity (BI). The new proxies show an increase in the interannual summer temperature signal compared to established proxies, and present the potential to improve long-term performance. At high latitudes, where tree growth is mainly limited by low temperatures, radiodensitometric measurements of wood density, specifically maximum latewood density (MXD), provides a temperature proxy that is superior to that of tree-ring widths. The high cost of developing MXD has led to experimentation with a less expensive method using optical flatbed scanners to produce a new proxy, herein referred to as maximum latewood blue absorption intensity (abbreviated MXBI). MXBI is shown to be very similar to MXD on annual timescales but less accurate on centennial timescales. This is due to the fact that extractives, such as resin, stain the wood differentially from tree to tree and from heartwood to sapwood. To overcome this problem, and to address similar potential problems in radiodensitometric measurements, the new parameters Δblue intensity (ΔBI) and Δdensity are designed by subtracting the ambient BI/density in the earlywood, as a background value, from the latewood measurements. As a case-study, based on Scots pine trees from Northern Sweden, we show that Δdensity can be used as a quality control of MXD values and that the reconstructive performance of warm-season mean temperatures is more focused towards the summer months (JJA – June, July, August), with an increase by roughly 20% when also utilising the interannual information from the earlywood. However, even though the new parameter ΔBI experiences an improvement as well, there are still puzzling dissimilarities between Δdensity and ΔBI on multicentennial timescales. As a consequence, temperature reconstructions based on ΔBI will presently only be able to resolve information on decadal-to-centennial timescales. The possibility of trying to calibrate BI into a measure of lignin content or density, similarly to how radiographic measurements are calibrated into density, could be a solution. If this works, only then can ΔBI be used as a reliable proxy in multicentennial-scale climate reconstructions.

Download Full-text

Blue Intensity for dendroclimatology: The BC blues: A case study from British Columbia, Canada

The Holocene ◽

10.1177/0959683614544051 ◽

2014 ◽

Vol 24 (11) ◽

pp. 1428-1438 ◽

Cited By ~ 33

Author(s):

Rob Wilson ◽

Rohit Rao ◽

Miloš Rydval ◽

Cheryl Wood ◽

Lars-Åke Larsson ◽

...

Keyword(s):

British Columbia ◽

Tree Ring ◽

Large Scale ◽

Ring Width ◽

Frequency Information ◽

Maximum Latewood Density ◽

Latewood Density ◽

Summer Temperatures ◽

Two Parameters ◽

Blue Intensity

Maximum latewood density (MXD) is a strong proxy of summer temperatures. Despite this, there is a paucity of long MXD chronologies in the Northern Hemisphere, which limits large-scale tree-ring-based reconstructions of past temperature which are dominated by ring-width (RW) data – a weaker temperature proxy at inter-annual time-scales. This paucity likely results from the relative expense of measuring MXD and the lack of laboratories with the facilities to measure it. Herein, we test the ability of a relatively new, less expensive, tree-ring parameter, Blue Intensity (BI), to act as a surrogate parameter for MXD. BI was measured on Engelmann spruce samples from British Columbia where MXD had previously been measured to allow direct comparison between the two parameters. Signal strength analyses indicate that 8 MXD series were needed to acquire a robust mean chronology while BI needed 14. Utilising different detrending methods and parameter choices (RW + MXD vs RW + BI), a suite of reconstruction variants was developed. The explained variance from the regression modelling (1901–1995) of May–August maximum temperatures ranged from 52% to 55%. Validation tests over the earlier 1870–1900 period could not statistically distinguish between the different variants, although spectral analysis identified more lower frequency information extant in the MXD-based reconstructions – although this result was sensitive to the detrending method used. Ultimately, despite the MXD-based reconstruction explaining slightly more of the climatic variance, statistically robust reconstructions of past summer temperatures were also derived using BI. These results suggest that there is great potential in utilising BI for dendroclimatology in place of MXD data. However, more experimentation is needed to understand (1) how well BI can capture centennial and lower frequency information and (2) what biases may result from wood discolouration, either from species showing a distinct heartwood/sapwood boundary or from partly decayed sub-fossil samples.

Download Full-text

Is temperature still the most limiting factor for growth in northern boreal forests?

The Holocene ◽

10.1177/09596836211011661 ◽

2021 ◽

pp. 095968362110116

Author(s):

Jeroen DM Schreel

Keyword(s):

Tree Ring ◽

Boreal Forests ◽

Ring Width ◽

Temperature Fluctuations ◽

Limiting Factor ◽

Tree Ring Width ◽

Climate Reconstructions ◽

Latewood Density

Over the last few decades – at a range of northern sites – changes in tree-ring width and latewood density have not followed mean summertime temperature fluctuations. This discrepancy sharply contrasts an earlier correlation between those variables. As the origin of this inconsistency has not been fully deciphered, questions have emerged regarding the use of tree-ring width and latewood density as a proxy in dendrochronological climate reconstructions. I suggest that temperature is no longer the most limiting factor in certain boreal areas, which might explain the observed divergence.

Download Full-text

A Preliminary Reconstruction of Rainfall in North-Central China since A.D. 1600 from Tree-Ring Density and Width

Quaternary Research ◽

10.1006/qres.1994.1056 ◽

1994 ◽

Vol 42 (1) ◽

pp. 88-99 ◽

Cited By ~ 91

Author(s):

Malcolm K. Hughes ◽

Wu Xiangding ◽

Shao Xuemei ◽

Gregg M. Garfin

Keyword(s):

Tree Ring ◽

Spectral Power ◽

Singular Spectrum Analysis ◽

Ring Width ◽

Central China ◽

North Central ◽

Ring Density ◽

Maximum Latewood Density ◽

Documentary Sources ◽

Latewood Density

AbstractMay-June (MJ) and April-July (AJ) precipitation at Huashan in north-central China has been reconstructed for the period A.D. 1600 to 1988 using tree-ring density and width fromPinus armandii. MJ precipitation (based on ring width and maximum latewood density) calibrated and cross-validated against local instrumental data more strongly than AJ precipitation (based only on ring width). A major drought was reconstructed for the mid- and late 1920s, confirmed by local documentary sources. This drought (culminating in 1929) was the most severe of the 389-yr period for MJ and second most severe for AJ, after an event ending in 1683. Neither reconstruction shows much spectral power at frequencies lower than 1 in 10 yr, but both show concentrations of power between 2.1 and 2.7 yr and 3.5 to 9 yr. There are significant correlations between the two reconstructions and a regional dryness/wetness index (DW) based on documentary sources, particularly at high frequencies. These correlations are focused in the 7.6- to 7.3-, 3.8- to 3.6-, and 2.5-yr periods. Using singular spectrum analysis, quasiperiodic behavior with a period close to 7.2 yr was identified in the MJ precipitation reconstruction and in the DW index based on documents.

Download Full-text

Tree-Ring Records of Near-Younger Dryas Time in Central North America—Preliminary Results from the Lincoln Quarry Site, Central Illinois, Usa

Radiocarbon ◽

10.1017/s0033822200035980 ◽

2004 ◽

Vol 46 (2) ◽

pp. 933-941 ◽

Cited By ~ 6

Author(s):

Irina P Panyushkina ◽

Steven W Leavitt ◽

Alex Wiedenhoeft ◽

Sarah Noggle ◽

Brandon Curry ◽

...

Keyword(s):

North America ◽

Tree Ring ◽

Environmental Changes ◽

Ring Width ◽

Younger Dryas ◽

Late Glacial ◽

Radiocarbon Dates ◽

Initial Sampling ◽

Central Illinois ◽

A Site

The abrupt millennial-scale changes associated with the Younger Dryas (YD) event (“chronozone”) near the dawn of the Holocene are at least hemispheric, if not global, in extent. Evidence for the YD cold excursion is abundant in Europe but fairly meager in central North America. We are engaged in an investigation of high-resolution environmental changes in mid-North America over several millennia (about 10,000 to 14,000 BP) during the Late Glacial–Early Holocene transition, including the YD interval. Several sites containing logs or stumps have been identified and we are in the process of initial sampling or re-sampling them for this project. Here, we report on a site in central Illinois containing a deposit of logs initially thought to be of YD age preserved in alluvial sands. The assemblage of wood represents hardwood (angiosperm) trees, and the ring-width characteristics are favorable to developing formal tree-ring chronologies. However, 4 new radiocarbon dates indicate deposition of wood may have taken place over at least 8000 14C yr (6000–14,000 BP). This complicates the effort to develop a single floating chronology of several hundred years at this site, but it may provide wood from a restricted region over a long period of time from which to develop a sequence of floating chronologies, the timing of deposition and preservation of which could be related to paleoclimatic events and conditions.

Download Full-text

Phenotypic Correlations among Growth and Selected Wood Properties in White Spruce (Picea glauca (Moench) Voss) †

Forests ◽

10.3390/f10070589 ◽

2019 ◽

Vol 10 (7) ◽

pp. 589 ◽

Cited By ~ 1

Author(s):

Cyriac S. Mvolo ◽

Ahmed Koubaa ◽

Jean Beaulieu ◽

Alain Cloutier ◽

Maurice Defo ◽

...

Keyword(s):

Physical Properties ◽

Picea Glauca ◽

Radial Growth ◽

Juvenile Wood ◽

Wood Properties ◽

Mature Wood ◽

Ring Density ◽

Tracheid Length ◽

Latewood Density ◽

Anatomical Properties

We examined phenotypic relationships among radial growth-related, physical (i.e., related to wood density), and anatomical (i.e., related to tracheid dimensions) wood properties in white spruce (Picea glauca (Moench) Voss), in order to determine the strength and significance of their correlations. Additionally, principal component analysis (PCA) was used to establish if all of the properties must be measured and to determine the key properties that can be used as proxies for the other variables. Radial growth-related and physical properties were measured with an X-ray densitometer, while anatomical properties were measured with a Fiber Quality Analyzer. Fifteen wood properties (tracheid length (TL) and diameter (TD), earlywood tracheid length (ETL) and diameter (ETD), latewood tracheid length (LTL) and diameter (LTD), ring width (RW), ring area (RA), earlywood width (EWW), latewood width (LWW), latewood proportion (LWP), ring density (RD), intra-ring density variation, earlywood density (EWD), and latewood density (LWD)) were assessed. Relationships were evaluated at intra-ring and inter-ring levels in the juvenile wood (JW) and mature wood (MW) zones. Except for a few cases when mature tracheid diameter (TD) was involved, all intra-ring anatomical properties were highly and significantly correlated. Radial growth properties were correlated, with stronger relationships in MW compared to JW. Physical properties were often positively and significantly correlated in both JW and MW. A higher earlywood density coupled with a lower latewood density favored wood uniformity, i.e., the homogeneity of ring density within a growth ring. Managing plantations to suppress trees growth during JW formation, and enhancing radial growth when MW formation starts will favor overall wood quality. In order, RW-EWW-RA, TL-ETL-LTL, and RD-EWD-LWP are the three clusters that appeared in the three wood zones, the whole pith-to-bark radial section, the juvenile wood zone, and the mature wood zone.

Download Full-text

Siberian tree-ring and stable isotope proxies as indicators of temperature and moisture changes after major stratospheric volcanic eruptions

Climate of the Past ◽

10.5194/cp-15-685-2019 ◽

2019 ◽

Vol 15 (2) ◽

pp. 685-700 ◽

Cited By ~ 7

Author(s):

Olga V. Churakova (Sidorova) ◽

Marina V. Fonti ◽

Matthias Saurer ◽

Sébastien Guillet ◽

Christophe Corona ◽

...

Keyword(s):

Tree Ring ◽

Global Climate ◽

Sunshine Duration ◽

Ring Width ◽

Volcanic Eruptions ◽

Climate Dynamics ◽

Global Climate Models ◽

Added Value ◽

Latewood Density ◽

The Impact

Abstract. Stratospheric volcanic eruptions have far-reaching impacts on global climate and society. Tree rings can provide valuable climatic information on these impacts across different spatial and temporal scales. To detect temperature and hydroclimatic changes after strong stratospheric Common Era (CE) volcanic eruptions for the last 1500 years (535 CE unknown, 540 CE unknown, 1257 CE Samalas, 1640 CE Parker, 1815 CE Tambora, and 1991 CE Pinatubo), we measured and analyzed tree-ring width (TRW), maximum latewood density (MXD), cell wall thickness (CWT), and δ13C and δ18O in tree-ring cellulose chronologies of climate-sensitive larch trees from three different Siberian regions (northeastern Yakutia – YAK, eastern Taimyr – TAY, and Russian Altai – ALT). All tree-ring proxies proved to encode a significant and specific climatic signal of the growing season. Our findings suggest that TRW, MXD, and CWT show strong negative summer air temperature anomalies in 536, 541–542, and 1258–1259 at all studied regions. Based on δ13C, 536 was extremely humid at YAK, as was 537–538 in TAY. No extreme hydroclimatic anomalies occurred in Siberia after the volcanic eruptions in 1640, 1815, and 1991, except for 1817 at ALT. The signal stored in δ18O indicated significantly lower summer sunshine duration in 542 and 1258–1259 at YAK and 536 at ALT. Our results show that trees growing at YAK and ALT mainly responded the first year after the eruptions, whereas at TAY, the growth response occurred after 2 years. The fact that differences exist in climate responses to volcanic eruptions – both in space and time – underlines the added value of a multiple tree-ring proxy assessment. As such, the various indicators used clearly help to provide a more realistic picture of the impact of volcanic eruption on past climate dynamics, which is fundamental for an improved understanding of climate dynamics, but also for the validation of global climate models.

Download Full-text