Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes
Positional treeline shift is a fundamental aspect and indicator of high-mountain vegetation response to climate change. This study analyses treeline performance during the period 2005/2007 -2010/2011 in the Swedish Scandes. Focus is on mountain birch (Betula pubescens ssp. czerepanovii) along a regi...
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| Format: | Article |
| Language: | English |
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Geographical Society of Finland
2012-09-01
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| Series: | Fennia: International Journal of Geography |
| Subjects: | |
| Online Access: | https://fennia.journal.fi/article/view/5019 |
| _version_ | 1811264907729960960 |
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| author | Lisa Öberg Leif Kullman |
| author_facet | Lisa Öberg Leif Kullman |
| author_sort | Lisa Öberg |
| collection | DOAJ |
| description | Positional treeline shift is a fundamental aspect and indicator of high-mountain vegetation response to climate change. This study analyses treeline performance during the period 2005/2007 -2010/2011 in the Swedish Scandes. Focus is on mountain birch (Betula pubescens ssp. czerepanovii) along a regional climatic maritimity-continentality gradient. Treeline upshift by 3.0 yr-1 in the maritime part differed significantly from retreat by 0.4 m yr-1 in the continental part of the transect. This discrepancy is discussed in terms of differential warming-induced snow cover phenology patterns and their influence on soil moisture conditions. In the continental area, earlier and more complete melting of prior relatively rare late-lying snow patches, even high above the treeline, has progressed to a state when melt water irrigation ceases. As a consequence, soil drought sets back the vigor of existing birches and precludes sexual regeneration and upslope advance of the treeline. In the maritime area, extensive and deep snow packs still exist above the treeline and constrain its position, although some release is taking place in the current warm climate. Thereby, the birch treeline expands upslope as the alpine snow patches shrink, but continue to provide sufficient melt water throughout the summer. Treeline rise appears to have been based primarily on seed regeneration over the past few decades. This is a novelty, since prior (1915-2007) treeline advance was accomplished mainly by in situ shifts in growth form of relict krummholz birches, in some cases millennial-old, prevailing above the treeline. By the snow phenology mechanism, birch can benefit from climate warming in the maritime region, which contrasts with the situation in the continental region. This discrepancy should be accounted for in projective models. In a hypothetical case of sustained warming, the subalpine birch forest belt may expand less extensively than often assumed, although advance may continue for some time in snow rich maritime areas. |
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| id | doaj.art-915b8cb7b3e6434690f6b84b331a55ef |
| institution | Directory Open Access Journal |
| issn | 1798-5617 |
| language | English |
| last_indexed | 2024-04-12T20:13:01Z |
| publishDate | 2012-09-01 |
| publisher | Geographical Society of Finland |
| record_format | Article |
| series | Fennia: International Journal of Geography |
| spelling | doaj.art-915b8cb7b3e6434690f6b84b331a55ef2022-12-22T03:18:12ZengGeographical Society of FinlandFennia: International Journal of Geography1798-56172012-09-011901Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish ScandesLisa Öberg0Leif Kullman1Mid Sweden University, Department of Natural Science, Engineering and MathematicsUmeå University, Department of Ecology and Environmental SciencePositional treeline shift is a fundamental aspect and indicator of high-mountain vegetation response to climate change. This study analyses treeline performance during the period 2005/2007 -2010/2011 in the Swedish Scandes. Focus is on mountain birch (Betula pubescens ssp. czerepanovii) along a regional climatic maritimity-continentality gradient. Treeline upshift by 3.0 yr-1 in the maritime part differed significantly from retreat by 0.4 m yr-1 in the continental part of the transect. This discrepancy is discussed in terms of differential warming-induced snow cover phenology patterns and their influence on soil moisture conditions. In the continental area, earlier and more complete melting of prior relatively rare late-lying snow patches, even high above the treeline, has progressed to a state when melt water irrigation ceases. As a consequence, soil drought sets back the vigor of existing birches and precludes sexual regeneration and upslope advance of the treeline. In the maritime area, extensive and deep snow packs still exist above the treeline and constrain its position, although some release is taking place in the current warm climate. Thereby, the birch treeline expands upslope as the alpine snow patches shrink, but continue to provide sufficient melt water throughout the summer. Treeline rise appears to have been based primarily on seed regeneration over the past few decades. This is a novelty, since prior (1915-2007) treeline advance was accomplished mainly by in situ shifts in growth form of relict krummholz birches, in some cases millennial-old, prevailing above the treeline. By the snow phenology mechanism, birch can benefit from climate warming in the maritime region, which contrasts with the situation in the continental region. This discrepancy should be accounted for in projective models. In a hypothetical case of sustained warming, the subalpine birch forest belt may expand less extensively than often assumed, although advance may continue for some time in snow rich maritime areas.https://fennia.journal.fi/article/view/5019Swedish Scandestreelinerevisitation studyclimate warmingregenerationBetula pubescens ssp. czerepanovii |
| spellingShingle | Lisa Öberg Leif Kullman Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes Fennia: International Journal of Geography Swedish Scandes treeline revisitation study climate warming regeneration Betula pubescens ssp. czerepanovii |
| title | Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes |
| title_full | Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes |
| title_fullStr | Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes |
| title_full_unstemmed | Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes |
| title_short | Contrasting short-term performance of mountain birch (Betula pubescens ssp. czerepanovii) treeline along a latitudinal continentality-maritimity gradient in the southern Swedish Scandes |
| title_sort | contrasting short term performance of mountain birch betula pubescens ssp czerepanovii treeline along a latitudinal continentality maritimity gradient in the southern swedish scandes |
| topic | Swedish Scandes treeline revisitation study climate warming regeneration Betula pubescens ssp. czerepanovii |
| url | https://fennia.journal.fi/article/view/5019 |
| work_keys_str_mv | AT lisaoberg contrastingshorttermperformanceofmountainbirchbetulapubescenssspczerepanoviitreelinealongalatitudinalcontinentalitymaritimitygradientinthesouthernswedishscandes AT leifkullman contrastingshorttermperformanceofmountainbirchbetulapubescenssspczerepanoviitreelinealongalatitudinalcontinentalitymaritimitygradientinthesouthernswedishscandes |