Reducing solar heat gain during winter: the role of white bark in northern deciduous trees
Deciduous tree species throughout the boreal forest of North America have lighter-coloured bark than do species restricted to more southern forests. We tested the hypothesis that light-coloured bark minimizes the thawing and freezing of cambium tissue during winter that could contribute to sunscald...
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ftcalifstateuniv:oai:scholarworks:3x816q44c 2024-09-30T14:31:39+00:00 Reducing solar heat gain during winter: the role of white bark in northern deciduous trees Timothy J. Karels Rudy Boonstra 2003 http://hdl.handle.net/10211.2/2178 English eng Arctic http://hdl.handle.net/10211.2/2178 Copyright 2003 The Arctic Institute of North America Sunscald White birch Bark colour Cambium temperatures Deciduous trees Trembling aspen Boreal forest Article 2003 ftcalifstateuniv 2024-09-10T17:06:15Z Deciduous tree species throughout the boreal forest of North America have lighter-coloured bark than do species restricted to more southern forests. We tested the hypothesis that light-coloured bark minimizes the thawing and freezing of cambium tissue during winter that could contribute to sunscald injury. During mid-winter, maximum midday cambium temperatures of south-exposed bark of white birch (Betula papyriferaMarsh.) near Timmins, Ontario, were higher for brown-painted bark (+1.6 °C) than for natural bark (-9.4 °C) and white-painted bark (-12.1 °C). Rates of temperature decrease after trees were shaded at midday were more rapid for brown-painted bark (0.06 °C/min) than for natural bark (0.03 °C/min) and white-painted bark (0.03 °C/min). When stems of white birch, trembling aspen (Populus tremuloides Michx.), yellow birch (B. alleghaniensis Britton), and largetooth aspen (P. grandidentata Michx.) were illuminated and subsequently shaded at -10 °C ambient air temperature, maximum cambium temperatures and rates of cambium cooling increased with decreasing measures of whiteness. For trembling aspen in the southwest Yukon, we found that after two years, brown-painted trees had a higher incidence (35%) of wounding that resembled sunscald injury than did white-painted trees (2.5%) and natural trees (4.5%). Therefore, we suggest that light-coloured bark reduces the risk of winter sunscald injury, probably by protecting the cambium from solar heat gain in subfreezing temperatures. This physical mechanism for reducing sunscald risk may explain why the deciduous trees at the northern limit of tree growth are those with highly reflective bark. Arctic 56(2), 168-174. (2003) 0004-0843 Article in Journal/Newspaper Arctic Yukon Scholarworks from California State University Arctic Yukon |
institution |
Open Polar |
collection |
Scholarworks from California State University |
op_collection_id |
ftcalifstateuniv |
language |
English |
topic |
Sunscald White birch Bark colour Cambium temperatures Deciduous trees Trembling aspen Boreal forest |
spellingShingle |
Sunscald White birch Bark colour Cambium temperatures Deciduous trees Trembling aspen Boreal forest Timothy J. Karels Rudy Boonstra Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
topic_facet |
Sunscald White birch Bark colour Cambium temperatures Deciduous trees Trembling aspen Boreal forest |
description |
Deciduous tree species throughout the boreal forest of North America have lighter-coloured bark than do species restricted to more southern forests. We tested the hypothesis that light-coloured bark minimizes the thawing and freezing of cambium tissue during winter that could contribute to sunscald injury. During mid-winter, maximum midday cambium temperatures of south-exposed bark of white birch (Betula papyriferaMarsh.) near Timmins, Ontario, were higher for brown-painted bark (+1.6 °C) than for natural bark (-9.4 °C) and white-painted bark (-12.1 °C). Rates of temperature decrease after trees were shaded at midday were more rapid for brown-painted bark (0.06 °C/min) than for natural bark (0.03 °C/min) and white-painted bark (0.03 °C/min). When stems of white birch, trembling aspen (Populus tremuloides Michx.), yellow birch (B. alleghaniensis Britton), and largetooth aspen (P. grandidentata Michx.) were illuminated and subsequently shaded at -10 °C ambient air temperature, maximum cambium temperatures and rates of cambium cooling increased with decreasing measures of whiteness. For trembling aspen in the southwest Yukon, we found that after two years, brown-painted trees had a higher incidence (35%) of wounding that resembled sunscald injury than did white-painted trees (2.5%) and natural trees (4.5%). Therefore, we suggest that light-coloured bark reduces the risk of winter sunscald injury, probably by protecting the cambium from solar heat gain in subfreezing temperatures. This physical mechanism for reducing sunscald risk may explain why the deciduous trees at the northern limit of tree growth are those with highly reflective bark. Arctic 56(2), 168-174. (2003) 0004-0843 |
format |
Article in Journal/Newspaper |
author |
Timothy J. Karels Rudy Boonstra |
author_facet |
Timothy J. Karels Rudy Boonstra |
author_sort |
Timothy J. Karels |
title |
Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
title_short |
Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
title_full |
Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
title_fullStr |
Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
title_full_unstemmed |
Reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
title_sort |
reducing solar heat gain during winter: the role of white bark in northern deciduous trees |
publisher |
Arctic |
publishDate |
2003 |
url |
http://hdl.handle.net/10211.2/2178 |
geographic |
Arctic Yukon |
geographic_facet |
Arctic Yukon |
genre |
Arctic Yukon |
genre_facet |
Arctic Yukon |
op_relation |
http://hdl.handle.net/10211.2/2178 |
op_rights |
Copyright 2003 The Arctic Institute of North America |
_version_ |
1811636086087090176 |