Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information
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 latitude...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-04-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/10/877/2014/cp-10-877-2014.pdf |
| _version_ | 1811242687834095616 |
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| author | J. A. Björklund B. E. Gunnarson K. Seftigen J. Esper H. W. Linderholm |
| author_facet | J. A. Björklund B. E. Gunnarson K. Seftigen J. Esper H. W. Linderholm |
| author_sort | J. A. Björklund |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-12T13:55:34Z |
| format | Article |
| id | doaj.art-2de98cb276e847409f9720b9fabe84a4 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-04-12T13:55:34Z |
| publishDate | 2014-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-2de98cb276e847409f9720b9fabe84a42022-12-22T03:30:23ZengCopernicus PublicationsClimate of the Past1814-93241814-93322014-04-0110287788510.5194/cp-10-877-2014Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood informationJ. A. Björklund0B. E. Gunnarson1K. Seftigen2J. Esper3H. W. Linderholm4Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Gotheburg, SwedenBert Bolin Centre for Climate Research, Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, SwedenRegional Climate Group, Department of Earth Sciences, University of Gothenburg, Gotheburg, SwedenDepartment of Geography, Johannes Gutenberg University, Mainz, GermanyRegional Climate Group, Department of Earth Sciences, University of Gothenburg, Gotheburg, SwedenHere 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.http://www.clim-past.net/10/877/2014/cp-10-877-2014.pdf |
| spellingShingle | J. A. Björklund B. E. Gunnarson K. Seftigen J. Esper H. W. Linderholm Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information 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 |
| title_full | Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information |
| title_fullStr | Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information |
| title_full_unstemmed | Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information |
| title_short | Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information |
| title_sort | blue intensity and density from northern fennoscandian tree rings exploring the potential to improve summer temperature reconstructions with earlywood information |
| url | http://www.clim-past.net/10/877/2014/cp-10-877-2014.pdf |
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