A century of tree line changes in sub-Arctic Sweden shows local and regional variability and only a minor influence of 20th century climate warming
Summary (1 min read)
A century of tree line changes in sub-Arctic Sweden shows local and regional
- Twentieth century tree line changes in Swedish sub-Arctic Abstract 1 Models project that climate warming will cause the treeline to move to higher 2 elevations in alpine areas and more northerly latitudes in Arctic environments, also known as Running head.
- The lack of 446 recent tree (>2 m) establishment and the browsing scars documented in the tree rings 447 indicated that, in addition to moth herbivory, reindeer browsing is still a controlling 448 factor at these sites (Fig. 5, Table 4).
Tables
- Previous field studies on observed treeline shifts and their presumed causes in the Torneträsk area of sub-Arctic Sweden.
- Browsing damage was classified visually and for five sites also by dendrochronological analysis (the values listed in brackets).
- So as not to bias the results, Mount Nuolja (site S3), for which the two treeline sites were not randomly selected, was not included in the calculation of the mean elevational shift of the treeline in the Torneträsk area.
- Pearson correlation coefficients and R2-values (the proportion of explained variance in documented treeline shifts) obtained by forward selection of the different variables are listed at the bottom of the table.
Figure legends
- The Torneträsk study area in sub-Arctic Sweden.
- The locations of the historical transects and photo points that have been revisited to study changes in the tree line ecotone are indicated.
- The statistically-determined 30%-tree cover isoline is plotted in yellow.
- Upper photo on the left: E. Persson, bottom left: B. Mesch; upper and bottom right: R. Van Bogaert.
- Fig. 8. Tree (>2 m) establishment at the Torneträsk tree line versus summer (June- August) temperature and reindeer population numbers for the period 1800-2000.
Figures
- Historical transects and photo points that have been revisited to study changes in the tree line ecotone are indicated.
- The statistically-determined 30% tree-cover isoline is plotted in yellow.
- Upper photo: E. Persson, lower photo: S. Johnsson.
- Upper photo on the left: E. Persson, bottom left: B. Mesch; upper and bottom right: R. Van Bogaert. relation to disturbance (b) and summer temperature (c) for the period 1964-2006.
- August) temperature and reindeer population numbers for the period 1800-2000.
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"A century of tree line changes in s..." refers background in this paper
...Distinguishing human impact from natural factors is, however, one of the most difficult tasks in tree line research (Ellenberg, 1988; Hofgaard, 1997)....
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...Changes in disturbance regimes (Holtmeier & Broll, 2010), land use (Hofgaard, 1997), plant–plant interactions (Van Bogaert et al., 2009) and herbivory (Hoogesteger & Karlsson, 1992; Speed et al., 2010; Van Bogaert et al., 2010) may easily override the effect of increasing mean annual temperatures....
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157 citations
"A century of tree line changes in s..." refers background in this paper
...However, in many circumpolar and high-elevational areas the position of the tree line has not changed (Masek, 2001; Holtmeier et al., 2003; Payette, 2007; Van Bogaert et al., 2007) or has even retreated (Vlassova, 2002; Dalen & Hofgaard, 2005; Kullman, 2005; Cherosov et al., 2010)....
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146 citations
"A century of tree line changes in s..." refers background in this paper
...Changes in disturbance regimes (Holtmeier & Broll, 2010), land use (Hofgaard, 1997), plant–plant interactions (Van Bogaert et al., 2009) and herbivory (Hoogesteger & Karlsson, 1992; Speed et al., 2010; Van Bogaert et al., 2010) may easily override the effect of increasing mean annual temperatures....
[...]
..., 2009) and herbivory (Hoogesteger & Karlsson, 1992; Speed et al., 2010; Van Bogaert et al., 2010) may easily override the effect of increasing mean annual temperatures....
[...]
138 citations
"A century of tree line changes in s..." refers background in this paper
...Changes in disturbance regimes (Holtmeier & Broll, 2010), land use (Hofgaard, 1997), plant–plant interactions (Van Bogaert et al., 2009) and herbivory (Hoogesteger & Karlsson, 1992; Speed et al., 2010; Van Bogaert et al., 2010) may easily override the effect of increasing mean annual temperatures....
[...]
136 citations