Within-tree fluctuating asymmetry of mountain birch in subarctic Sweden
The mountain birch ecosystem forms the northern treeline in subarctic Europe. Since the treeline is extremely sensitive to temperature, stress in mountain birch can be used as an indicator of stress on the ecosystem as a whole, and in predictions of how climate change factors will influence the suba...
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| Format: | Text |
| Language: | Swedish English |
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2011
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| Online Access: | https://stud.epsilon.slu.se/3616/1/Stoneking_K_111118.pdf |
| Summary: | The mountain birch ecosystem forms the northern treeline in subarctic Europe. Since the treeline is extremely sensitive to temperature, stress in mountain birch can be used as an indicator of stress on the ecosystem as a whole, and in predictions of how climate change factors will influence the subalpine-tundra ecotone and treeline dynamics. Fluctuating asymmetry (FA) is a common technique for assessing stress in mountain birch. While no previous research has studied withintree variations of FA in mountain birch, other species have shown significant variation depending on location of the leaf within the crown, and thus leaf collection location is important to consider when sampling. The objective of this study is to determine if a relationship exists between leaf FA and location within the tree crown of mountain birch leaves across three elevation zones in subarctic Sweden. Leaves were collected from various locations within the crown with regards to height (bottom, middle, top), direction (north, east, south, west), and position (inner, outer), and at 3 elevation sites (valley, forest-limit, treeline). A nested ANOVA was used to analyze the data. The treeline site showed a higher amount of FA than the valley or forest-limit sites (P = 0.0228), but no significant difference was found between any of the within-tree leaf locations. This suggests that there is no influence from crown location on FA in the leaves of mountain birch, and therefore future studies involving FA can freely sample leaves from any location within the crown. |
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