Journal of Biogeography
SUPPORTING INFORMATION
Spring frost and growing season length co-control the cold range limits of broad-leaved trees
Chris Kollas, Christian Körner and Christophe F. Randin
Appendix S1 Validation of linear models on the second year of measurement for Sorbus aucuparia in the Western Swiss Alps (West) and for
the species Sorbus aucuparia, Tilia platyphyllos, Fraxinus excelsior and Acer pseudoplatanus in the Eastern Swiss Alps (East). Observed daily
temperatures (y-axis) are plotted against predicted daily temperatures for mean, minimum and maximum temperatures. The coefficient of
determination (Corr.), the P-value (P-val), the maximum deviation (Max.delta) and the root mean square error (RMSE) are provided along with
the line of perfect match (Perf. match).
1
2
3
Validation of linear models built to predict minimum (Tmin), mean (Tmean) and maximum (Tmax) temperatures at the species limit in the Western
Swiss Alps (West) and in the Eastern Swiss Alps (East). Numbers show correlations (r and associated P-values) and root mean square errors
(RMSE) between predicted temperatures by linear models based on first-year data and measured in situ during the second year.
Tmin
r
Sorbus aucuparia
(West)
Tilia platyphyllos
(East)
Fraxinus excelsior
(East)
Acer pseudoplatanus
(East)
Sorbus aucuparia
(East)
P
Tmean
RMSE (K)
r
P
Tmax
RMSE (K)
r
P
RMSE (K)
0.989
< 0.001
1.1
0.99
< 0.001
1.1
0.979
< 0.001
1.7
0.987
< 0.001
1.2
0.989
< 0.001
1.2
0.968
< 0.001
2.2
0.988
< 0.001
1.1
0.992
< 0.001
0.9
0.978
< 0.001
1.7
0.973
< 0.001
1.7
0.976
< 0.001
1.7
0.963
< 0.001
2.4
0.990
< 0.001
1.1
0.996
< 0.001
0.7
0.986
< 0.001
1.4
4
Appendix S2 Crown temperature deviations (on-siteTCrown, in K) from 2-m air temperature (on-siteTAir) in the forest during the growing season,
the non-growing season and the whole year. Temperature deviations are shown for monthly absolute minimum and monthly mean minimum
temperatures. Numbers show the means and standard errors (standard deviation divided by the root of sample size) of data for four sites per
region.
Western Swiss Alps
Growing
season1
Δon-siteTCrown–on-siteTAir
1
Absolute minima
Mean minima
-0.3±0.1
-0.5±0.1
Nongrowing
season
-1.0±0.1
-0.6±0.1
Eastern Swiss Alps
Full year
Growing
season
-0.7±0.1
-0.6±0.0
-0.6±0.1
-0.6±0.1
Growing season refers to the months May to September.
5
Nongrowing
season
-1.1±0.1
-0.8±0.1
Southern Sweden
Full year
Growing
season
-0.9±0.1
-0.7±0.0
-0.3±0.1
-0.1±0.1
Nongrowing
season
-0.7±0.2
-0.3±0.1
Full year
-0.6±0.1
-0.2±0.1
Appendix S3 Monthly mean minimum temperatures and monthly mean temperatures at broad-leaved tree species limits in three regions:
Western Swiss Alps (West), Eastern Swiss Alps (East) and southern Sweden (North). Numbers represent means across 50 years (1961–2010).
Species
Region
Jan
min*/
mean1
(°C)
Feb
min/
mean
(°C)
Mar
min/
mean
(°C)
Apr
min/
mean
(°C)
May
min/
mean
(°C)
Jun
min/
mean
(°C)
Sorbus aucuparia
West
East
-6.9/-4.8
-6.7/-4.5
-7.1/-5
-7/-4.5
-5.7/-3.5
-5.1/-2.5
-3.2/-1.1
-2.2/0.3
1.2/3.5
2/4.8
4.6/7.3
5.1/8
7/10.1
7.4/10.3
7.2/10
7.4/10
4.7/7.1
4.9/7.3
1.6/3.6
2/4.2
-3.4/-1.5
-3.1/-1.1
-6/-3.9
-5.9/-3.8
Acer
pseudoplatanus
West
East
North
-4.5/-1.9
-6.7/-4.1
-4.5/-2
-4.7/-2.1
-6.9/-4.1
-5.1/-2.3
-3.3/-0.6
-5.1/-2.1
-2.7/0.5
-0.8/1.8
-2.3/0.8
1/4.9
3.5/6.2
1.9/5.4
5.9/10.3
6.8/9.9
4.9/8.7
10.1/14.6
9.2/12.7
7.1/11.1
12.2/16.6
9.3/12.6
7.1/10.8
11.9/15.8
6.9/9.7
4.7/7.9
8.4/11.9
3.8/6.3
1.8/4.7
4.8/7.5
-1.1/1.4
-3.1/-0.6
0.5/2.8
-3.6/-1
-5.9/-3.4
-3.1/-0.6
Fagus sylvatica
West
East
North
-2.8/-0.5
-5.3/-3.3
-7.2/-3.5
-3/-0.8
-5.5/-3.3
-7.8/-3.5
-1.6/0.7
-3.7/-1.3
-4.8/-0.1
0.9/3.1
-0.9/1.6
-0.6/4.9
5.1/7.6
3.3/6.1
4.3/10.8
8.5/11.3
6.4/9.5
8.8/15
10.9/14
8.6/11.8
10.9/16.8
11/13.9
8.6/11.5
10.4/15.8
8.6/11.1
6.1/8.7
6.8/11.3
5.5/7.7
3.3/5.5
3.1/6.6
0.6/2.7
-1.7/0.2
-1.7/1.5
-1.9/0.4
-4.5/-2.5
-6/-2.2
Fraxinus excelsior
West
East
North
-3/-0.7
-2.6/-0.2
-7.7/-4.4
-3.2/-0.9
-2.8/-0.2
-8.3/-4.3
-1.8/0.6
-1/1.7
-5.3/-0.7
0.7/3
1.7/4.5
-1.1/4.5
4.9/7.4
5.8/8.9
3.8/10.8
8.3/11.1
8.7/12.2
8.2/15.2
10.7/13.9
10.9/14.4
10.4/17.2
10.8/13.8
10.9/14.1
9.9/16.1
8.4/11
8.5/11.4
6.2/11.4
5.3/7.5
5.7/8.3
2.5/6.4
0.4/2.6
0.9/3.2
-2.2/1
-2.1/0.2
-1.9/0.5
-6.4/-3
Prunus avium
West
East
North
-3/-0.7
-2.6/-0.2
-5.3/-3
-3.2/-0.9
-2.8/-0.2
-5.8/-2.9
-1.8/0.6
-1/1.7
-3.1/0.2
0.7/3
1.7/4.5
0.6/4.7
4.9/7.4
5.8/8.9
4.9/10.2
8.3/11.1
8.7/12.2
8.9/14.1
10.7/13.9
10.9/14.4
10.8/15.7
10.8/13.8
10.9/14.1
10.4/14.8
8.4/11
8.5/11.4
7.1/10.7
5.3/7.5
5.7/8.3
3.8/6.4
0.4/2.6
0.9/3.2
-0.4/1.7
-2.1/0.2
-1.9/0.5
-4.2/-1.8
Tilia platyphyllos
West
East
-2.1/0.5
-2.8/-0.2
-2.3/0.2
-3.1/-0.2
-0.9/1.8
-1.3/1.7
1.5/4.2
1.4/4.5
5.8/8.8
5.4/8.9
9.1/12.6
8.3/12.1
11.5/15.4
10.4/14.3
11.6/15.3
10.4/14
9.2/12.4
8/11.3
6.1/8.9
5.3/8.3
1.3/3.8
0.6/3.1
-1.2/1.4
-2.1/0.5
Quercus petraea
West
East
North
-2.1/0.5
-2.6/-0.2
-3.7/-1.6
-2.3/0.2
-2.8/-0.2
-4.2/-1.9
-0.9/1.8
-1/1.7
-2/0.7
1.5/4.2
1.7/4.5
1.3/5
5.8/8.8
5.8/8.9
5.8/10.3
9.1/12.6
8.7/12.2
9.7/14.4
11.5/15.4
10.9/14.4
11.5/16.3
11.6/15.3
10.9/14.1
11.3/15.6
9.2/12.4
8.5/11.4
8.1/11.8
6.1/8.9
5.7/8.3
4.8/7.5
1.3/3.8
0.9/3.2
0.9/3
-1.2/1.4
-1.9/0.5
-2.4/-0.3
*Monthly mean of daily minima.
1
Monthly mean temperature.
6
Jul
min/
mean
(°C)
Aug
min/
mean
(°C)
Sep
min/
mean
(°C)
Oct
min/
mean
(°C)
Nov
min/
mean
(°C)
Dec
min/
mean
(°C)