Blue intensity and density from Northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information
(2014) In Climate of the Past 10. p.877-885- Abstract
- Here we explore two new tree-ring parameters, derivedfrom measurements of wood density and blue intensity(BI). The new proxies show an increase in the interannualsummer temperature signal compared to establishedproxies, and present the potential to improve long-term performance.At high latitudes, where tree growth is mainlylimited by low temperatures, radiodensitometric measurementsof wood density, specifically maximum latewood density(MXD), provides a temperature proxy that is superior tothat of tree-ring widths. The high cost of developing MXDhas led to experimentation with a less expensive method usingoptical flatbed scanners to produce a new proxy, hereinreferred to as maximum latewood blue absorption intensity(abbreviated MXBI). MXBI... (More)
- Here we explore two new tree-ring parameters, derivedfrom measurements of wood density and blue intensity(BI). The new proxies show an increase in the interannualsummer temperature signal compared to establishedproxies, and present the potential to improve long-term performance.At high latitudes, where tree growth is mainlylimited by low temperatures, radiodensitometric measurementsof wood density, specifically maximum latewood density(MXD), provides a temperature proxy that is superior tothat of tree-ring widths. The high cost of developing MXDhas led to experimentation with a less expensive method usingoptical flatbed scanners to produce a new proxy, hereinreferred to as maximum latewood blue absorption intensity(abbreviated MXBI). MXBI is shown to be very similar toMXD on annual timescales but less accurate on centennialtimescales. This is due to the fact that extractives, such asresin, stain the wood differentially from tree to tree and fromheartwood to sapwood. To overcome this problem, and to addresssimilar potential problems in radiodensitometric measurements,the new parameters 1blue intensity (1BI) and1density are designed by subtracting the ambient BI/densityin the earlywood, as a background value, from the latewoodmeasurements. As a case-study, based on Scots pine treesfrom Northern Sweden, we show that 1density can be usedas a quality control of MXD values and that the reconstructiveperformance of warm-season mean temperatures is morefocused towards the summer months (JJA – June, July, August),with an increase by roughly 20% when also utilisingthe interannual information from the earlywood. However,even though the new parameter 1BI experiences an improvementas well, there are still puzzling dissimilarities between1density and 1BI on multicentennial timescales. As aconsequence, temperature reconstructions based on 1BI willpresently only be able to resolve information on decadalto-centennial timescales. The possibility of trying to calibrateBI into a measure of lignin content or density, similarlyto how radiographic measurements are calibrated into density,could be a solution. If this works, only then can 1BIbe used as a reliable proxy in multicentennial-scale climatereconstructions. (Less)
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https://lup.lub.lu.se/record/7515786
- author
- Björklund, Jesper ; Gunnarson, Björn ; Seftigen, Kristina ; Esper, Jan and Linderholm, Hans
- publishing date
- 2014
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Scots pine, Blue Intensity, Temperature reconstructions, Fennoscandia
- in
- Climate of the Past
- volume
- 10
- pages
- 877 - 885
- publisher
- Copernicus GmbH
- external identifiers
-
- scopus:84899689529
- ISSN
- 1814-9332
- DOI
- 10.5194/cp-10-877-2014
- language
- English
- LU publication?
- no
- id
- c8277672-ba54-483d-961f-8857f2616977 (old id 7515786)
- date added to LUP
- 2016-04-04 07:16:27
- date last changed
- 2022-03-15 06:47:29
@article{c8277672-ba54-483d-961f-8857f2616977,
abstract = {{Here we explore two new tree-ring parameters, derivedfrom measurements of wood density and blue intensity(BI). The new proxies show an increase in the interannualsummer temperature signal compared to establishedproxies, and present the potential to improve long-term performance.At high latitudes, where tree growth is mainlylimited by low temperatures, radiodensitometric measurementsof wood density, specifically maximum latewood density(MXD), provides a temperature proxy that is superior tothat of tree-ring widths. The high cost of developing MXDhas led to experimentation with a less expensive method usingoptical flatbed scanners to produce a new proxy, hereinreferred to as maximum latewood blue absorption intensity(abbreviated MXBI). MXBI is shown to be very similar toMXD on annual timescales but less accurate on centennialtimescales. This is due to the fact that extractives, such asresin, stain the wood differentially from tree to tree and fromheartwood to sapwood. To overcome this problem, and to addresssimilar potential problems in radiodensitometric measurements,the new parameters 1blue intensity (1BI) and1density are designed by subtracting the ambient BI/densityin the earlywood, as a background value, from the latewoodmeasurements. As a case-study, based on Scots pine treesfrom Northern Sweden, we show that 1density can be usedas a quality control of MXD values and that the reconstructiveperformance of warm-season mean temperatures is morefocused towards the summer months (JJA – June, July, August),with an increase by roughly 20% when also utilisingthe interannual information from the earlywood. However,even though the new parameter 1BI experiences an improvementas well, there are still puzzling dissimilarities between1density and 1BI on multicentennial timescales. As aconsequence, temperature reconstructions based on 1BI willpresently only be able to resolve information on decadalto-centennial timescales. The possibility of trying to calibrateBI into a measure of lignin content or density, similarlyto how radiographic measurements are calibrated into density,could be a solution. If this works, only then can 1BIbe used as a reliable proxy in multicentennial-scale climatereconstructions.}},
author = {{Björklund, Jesper and Gunnarson, Björn and Seftigen, Kristina and Esper, Jan and Linderholm, Hans}},
issn = {{1814-9332}},
keywords = {{Scots pine; Blue Intensity; Temperature reconstructions; Fennoscandia}},
language = {{eng}},
pages = {{877--885}},
publisher = {{Copernicus GmbH}},
series = {{Climate of the Past}},
title = {{Blue intensity and density from Northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information}},
url = {{http://dx.doi.org/10.5194/cp-10-877-2014}},
doi = {{10.5194/cp-10-877-2014}},
volume = {{10}},
year = {{2014}},
}