Dynamics of Hedera helix L. in Central European beech forests on limestone – Results from long-term monitoring and experimental studies

Steffi Heinrichs, Wolfgang Schmidt

Department Silviculture and Forest Ecology of the Temperate Zones, Georg-August-Universität Göttingen, Büsgenweg 1, 37077 Göttingen, Germany;

Plant Ecology

Electronic Supplementary Material (ESM)

Table A1

Annual climate data from the weather station Göttingen (173 m a.s.l.; since 1993 167 m a.s.l) for the years 1997 to 2012 measured either in the air or on the ground; annual data represent the whole calendar year, variables of winter season represent December data of the previous year and the months January and February of the calendar year. °C = mean temperature in °C; mm = precipitation sum in mm; °Cmin = minimum temperature in °C; cmmax snow = maximum snow height in cm; number of ice and frost days = days with maximum and minimum air temperature < 0 °C, respectively; number of days with snow = days with snow cover of more than 1 cm.

Annual / Winter season (December - February)
°C / mm / °C / °Cmin / Number of days with / cmmax
snow
(Air) / (Air) / (Air) / (Ground) / < -15/-20 °C
(Air) / < -15/-20°C
(Ground) / Frost / Ice / Snow
1997 / 8.9 / 580 / -0.2 / -23.7 / -27.3 / 9/2 / 13/5 / 49 / 26 / 31 / 8
1998 / 9.2 / 757 / 3.5 / -15.1 / -17.3 / 1/0 / 2/0 / 32 / 7 / 22 / 5
1999 / 9.7 / 612 / 2.0 / -15.6 / -18.2 / 1/0 / 3/0 / 44 / 15 / 24 / 15
2000 / 10.1 / 571 / 3.2 / -10.0 / -12.2 / 0/0 / 0/0 / 38 / 2 / 2 / 3
2001 / 9.2 / 646 / 2.5 / -10.7 / -12.5 / 0/0 / 0/0 / 47 / 13 / 19 / 13
2002 / 9.6 / 862 / 2.6 / -15.9 / -18.8 / 2/0 / 7/0 / 40 / 12 / 32 / 12
2003 / 9.4 / 464 / -0.3 / -15.9 / -18.1 / 1/0 / 4/0 / 59 / 27 / 20 / 12
2004 / 9.0 / 674 / 2.1 / -10.6 / -14.8 / 0/0 / 0/0 / 51 / 6 / 13 / 7
2005 / 9.2 / 585 / 1.3 / -17.2 / -20.8 / 1/0 / 2/1 / 54 / 12 / 21 / 6
2006 / 9.6 / 525 / -0.3 / -17.2 / -19.8 / 3/0 / 6/0 / 66 / 18 / 35 / 6
2007 / 10.0 / 892 / 5.0 / -9.4 / -11.9 / 0/0 / 0/0 / 21 / 3 / 6 / 3
2008 / 9.8 / 576 / 3.7 / -7.7 / -9.9 / 0/0 / 0/0 / 34 / 4 / 4 / 3
2009 / 9.3 / 640 / 0.1 / -24.1 / -29.4 / 7/2 / 8/6 / 64 / 17 / 25 / 8
2010 / 8.0 / 703 / -1.0 / -18.4 / -23.1 / 6/0 / 11/2 / 66 / 26 / 61 / 18
2011 / 9.8 / 449 / -0.1 / -17.2 / -22.8 / 3/0 / 10/2 / 66 / 32 / 39 / 24
2012 / 9.4 / 623 / 1.9 / -19.5 / -21.5 / 8/0 / 11/4 / 35 / 16 / 8 / 6

Table A2

Monthly climate values from 1997 to 2012 measured at the weather station Göttingen; for details see Table A1.

Year / Month / Minimum temperature [°C] / Days with temperature < -15 °C / Days with temperature < -20 °C / Days with / maximum snow height [cm]
Air / Ground / Air / Ground / Air / Ground / Frost / Ice / Snow
1997 / January / -23.7 / -27.3 / 3 / 3 / 2 / 3 / 21 / 12 / 19 / 8
1997 / February / -4.0 / -6.7 / 0 / 0 / 0 / 0 / 7 / 0 / 0 / 0
1997 / March / -2.0 / -4.0 / 0 / 0 / 0 / 0 / 6 / 0 / 0 / 0
1998 / January / -12.2 / -14.8 / 0 / 0 / 0 / 0 / 13 / 3 / 8 / 3
1998 / February / -15.1 / -17.3 / 1 / 2 / 0 / 0 / 7 / 2 / 7 / 5
1998 / March / -6.0 / -7.9 / 0 / 0 / 0 / 0 / 11 / 0 / 2 / 1
1999 / January / -7.1 / -9.4 / 0 / 0 / 0 / 0 / 10 / 2 / 1 / 2
1999 / February / -15.6 / -18.2 / 1 / 2 / 0 / 0 / 14 / 6 / 15 / 13
1999 / March / -2.5 / -5.4 / 0 / 0 / 0 / 0 / 4 / 0 / 0 / 0
2000 / January / -10.0 / -11.1 / 0 / 0 / 0 / 0 / 16 / 2 / 0 / 0
2000 / February / -2.9 / -5.7 / 0 / 0 / 0 / 0 / 10 / 0 / 2 / 5
2000 / March / -1.5 / -4 / 0 / 0 / 0 / 0 / 5 / 0 / 3 / 1
2001 / January / -10.7 / -12.5 / 0 / 0 / 0 / 0 / 17 / 7 / 6 / 6
2001 / February / -6.9 / -9.1 / 0 / 0 / 0 / 0 / 16 / 3 / 6 / 12
2001 / March / -4.3 / -6.1 / 0 / 0 / 0 / 0 / 14 / 0 / 4 / 4
2002 / January / -15.9 / -18.8 / 2 / 4 / 0 / 0 / 15 / 7 / 19 / 8
2002 / February / -4.9 / -7.5 / 0 / 0 / 0 / 0 / 7 / 0 / 2 / 1
2002 / March / -5.2 / -6.9 / 0 / 0 / 0 / 0 / 8 / 0 / 0 / 0
2003 / January / -15.9 / -18.1 / 1 / 3 / 0 / 0 / 15 / 9 / 12 / 6
2003 / February / -13.7 / -17.4 / 0 / 1 / 0 / 0 / 26 / 10 / 7 / 12
2003 / March / -4.4 / -6.4 / 0 / 0 / 0 / 0 / 11 / 0 / 0 / 0
2004 / January / -7.4 / -9.8 / 0 / 0 / 0 / 0 / 20 / 5 / 4 / 7
2004 / February / -10.3 / -14.8 / 0 / 0 / 0 / 0 / 16 / 0 / 4 / 4
2004 / March / -5.2 / -6.3 / 0 / 0 / 0 / 0 / 17 / 0 / 4 / 4
2005 / January / -9.9 / -14 / 0 / 0 / 0 / 0 / 11 / 6 / 10 / 5
2005 / February / -17.2 / -20.8 / 1 / 2 / 0 / 1 / 22 / 5 / 11 / 6
2005 / March / -8.7 / -11.3 / 0 / 0 / 0 / 0 / 13 / 2 / 8 / 3
2006 / January / -17.2 / -19.8 / 3 / 5 / 0 / 0 / 28 / 10 / 7 / 4
2006 / February / -13.2 / -15.6 / 0 / 1 / 0 / 0 / 19 / 3 / 21 / 6
2006 / March / -14.9 / -16.4 / 0 / 1 / 0 / 0 / 24 / 2 / 16 / 7
2007 / January / -9.4 / -11.9 / 0 / 0 / 0 / 0 / 6 / 3 / 2 / 2
2007 / February / -4.4 / -7.0 / 0 / 0 / 0 / 0 / 11 / 0 / 4 / 3
2007 / March / -2.5 / -4.6 / 0 / 0 / 0 / 0 / 10 / 0 / 2 / 4
2008 / January / -3.7 / -5.4 / 0 / 0 / 0 / 0 / 7 / 1 / 0 / 0
2008 / February / -6.5 / -8.6 / 0 / 0 / 0 / 0 / 15 / 0 / 0 / 0
2008 / March / -4.5 / -6.4 / 0 / 0 / 0 / 0 / 11 / 0 / 5 / 3
2009 / January / -24.1 / -29.4 / 7 / 8 / 2 / 6 / 27 / 11 / 16 / 8
2009 / February / -9.3 / -11.5 / 0 / 0 / 0 / 0 / 20 / 2 / 9 / 5
2009 / March / -4.4 / -6.6 / 0 / 0 / 0 / 0 / 12 / 0 / 0 / 0
2010 / January / -18.4 / -23.1 / 4 / 6 / 0 / 2 / 28 / 12 / 31 / 18
2010 / February / -15.4 / -19.4 / 1 / 3 / 0 / 0 / 20 / 8 / 22 / 13
2010 / March / -14.4 / -18.5 / 0 / 1 / 0 / 0 / 13 / 1 / 5 / 6
2011 / January / -9.3 / -12.4 / 0 / 0 / 0 / 0 / 17 / 6 / 7 / 19
2011 / February / -10.5 / -11.7 / 0 / 0 / 0 / 0 / 19 / 4 / 2 / 2
2011 / March / -5.6 / -8.2 / 0 / 0 / 0 / 0 / 20 / 0 / 0 / 0
2012 / January / -8.5 / -10.2 / 0 / 0 / 0 / 0 / 12 / 3 / 0 / 0
2012 / February / -19.5 / -21.5 / 8 / 11 / 0 / 3 / 20 / 13 / 7 / 5
2012 / March / -2.2 / -5.2 / 0 / 0 / 0 / 0 / 5 / 0 / 0 / 0

Table A3

Correlation matrix between the H. helix-cover and climatic variables. Also given are correlations between year-to-year cover changes of H. helix and climatic variables; Mean values of the four 25 m² subplots of each fertilization variant were correlated with the different climate variables; n = 16 for absolute cover values, n = 15 for year-to year-change in cover of H. helix; * p < 0.05, ** p > 0.01, *** p < 0.001; significant correlations are written in bold; for details see Table A1.

Cover Heder helix / year-to-year change in Hedera helix cover
Control / N-fertilization / P-fertilization / NP-fertilization / Control / N-fertilization / P-fertilization / NP-fertilization
Annual climatic variables
annual mean temperature [°C] / 0.215 / 0.180 / -0.103 / 0.110 / 0.244 / 0.089 / -0.026 / 0.187
annual precipitation sum [mm] / -0.013 / -0.016 / -0.086 / -0.077 / -0.044 / -0.194 / -0.120 / -0.145
mean wintertemperature [° C] / 0.003 / 0.023 / -0.191 / -0.070 / 0.089 / -0.161 / -0.070 / 0.005
annual minimum temperature in the air [°C] / 0.223 / 0.302 / 0.136 / 0.077 / 0.029 / -0.209 / -0.172 / -0.181
annual minimum temperature at the ground [°C] / 0.131 / 0.286 / 0.103 / 0.070 / -0.083 / -0.158 / -0.095 / -0.176
days with temperatures < -15 °C per winter (air) / -0.146 / -0.413 / -0.244 / -0.093 / 0.064 / -0.148 / 0.025 / 0.003
days with temperatures < -15 °C per winter (ground) / -0.085 / -0.431 / -0.288 / -0.149 / 0.044 / -0.144 / -0.151 / -0.054
days with temperatures < -20 °C per winter (air) / -0.352 / -0.299 / -0.158 / -0.176 / -0.017 / 0.068 / 0.282 / 0.150
days with temperatures < -20 °C per winter (ground) / -0.096 / -0.347 / -0.168 / -0.002 / -0.021 / -0.091 / 0.106 / 0.170
frost days per winter season / 0.156 / 0.192 / 0.369 / 0.218 / -0.046 / 0.155 / -0.022 / -0.016
ice days per winter season / -0.013 / -0.250 / -0.085 / -0.115 / 0.062 / 0.068 / -0.032 / 0.024
days with snow per winter season / -0.119 / -0.187 / -0.056 / -0.177 / -0.050 / -0.113 / -0.298 / -0.327
annual maximum snow height [cm] / 0.162 / -0.259 / -0.146 / -0.194 / 0.361 / 0.078 / -0.146 / 0.090
monthly climatic variables:
minimum temperature in the air [°C]
January / 0.296 / 0.171 / 0.004 / 0.195 / 0.283 / -0.083 / -0.161 / 0.212
February / -0.069 / -0.063 / -0.166 / -0.255 / -0.013 / -0.242 / -0.186 / -0.237
March / -0.103 / -0.352 / -0.378 / -0.280 / 0.356 / 0.280 / 0.419 / 0.561*
minimum temperature at the ground [°C]
January / 0.275 / 0.145 / -0.032 / 0.146 / 0.290 / -0.054 / -0.119 / 0.208
February / -0.068 / -0.126 / -0.254 / -0.285 / 0.039 / -0.284 / -0.234 / -0.242
March / -0.099 / -0.287 / -0.335 / -0.251 / 0.341 / 0.295 / 0.405 / 0.568*
number of frost days
January / -0.037 / 0.031 / 0.195 / 0.024 / -0.116 / 0.047 / -0.067 / -0.219
February / 0.540* / 0.499* / 0.666** / 0.647** / -0.161 / 0.096 / 0.227 / 0.161
March / 0.323 / 0.592* / 0.439 / 0.528* / -0.191 / -0.299 / -0.630* / -0.342
days with temperatures < -15°C (ground)
January / 0.031 / 0.073 / 0.269 / 0.082 / -0.287 / -0.070 / 0.122 / -0.271
February / 0.167 / -0.18 / -0.114 / 0.150 / 0.036 / 0.003 / 0.163 / 0.210
March / 0.063 / 0.216 / 0.239 / 0.149 / -0.213 / -0.289 / -0.333 / -0.600*
maximum snow height [cm]
January / 0.084 / -0.138 / 0.008 / -0.069 / -0.052 / -0.172 / -0.406 / -0.201
February / 0.082 / 0.078 / 0.236 / -0.045 / 0.298 / 0.415 / 0.507 / 0.119
March / 0.234 / 0.544* / 0.464 / 0.393 / -0.183 / -0.405 / -0.439 / -0.560*
Number of ice days
January / -0.065 / 0.024 / 0.219 / 0.007 / -0.241 / 0.001 / 0.019 / -0.219
February / 0.255 / -0.046 / 0.120 / 0.174 / 0.044 / 0.188 / 0.353 / 0.236
March / 0.105 / 0.538* / 0.470 / 0.471 / -0.304 / -0.076 / -0.273 / -0.314
Number of days with snow
January / -0.196 / -0.183 / 0.057 / -0.196 / -0.401 / -0.151 / -0.063 / -0.368
February / 0.072 / 0.262 / 0.322 / 0.227 / 0.051 / 0.103 / 0.045 / -0.211
March / 0.134 / 0.581* / 0.439 / 0.425 / -0.235 / -0.214 / -0.365 / -0.450
Days with temperatures < -20 °C (ground)
January / -0.176 / -0.193 / 0.025 / -0.044 / -0.105 / -0.049 / 0.208 / -0.025
February / 0.299 / -0.029 / -0.009 / 0.325 / 0.002 / -0.001 / 0.130 / 0.325
March / / / / / / / / / / / / / / / /

Table A4

Correlation matrix between annual climatic variables (n = 16). The winter season = December to February; * p < 0.05, ** p < 0.01, *** p < 0.001; significant correlations are written in bold; for details see Table A1.

Prec / Tempwinter / Tempmin air / Tempmin ground / Number of Days with / maximum snow height [cm]
< -15 °C (air) / < -20 °C (air) / < -15 °C (ground) / < -20 °C (ground) / Frost / Ice / Snow
annual mean temperature [°C] / 0.077 / 0.541* / 0.433 / 0.509* / -0.464 / -0.220 / -0.427 / -0.330 / -0.445 / -0.410 / -0.641** / -0.286
annual precipitation sum [mm] (Prec) / 0.581* / 0.210 / 0.219 / -0.122 / -0.079 / -0.186 / -0.155 / -0.586* / -0.518* / -0.064 / -0.264
mean temperature winter season [°C] (Tempwinter) / 0.737** / 0.767*** / -0.601* / -0.370 / -0.709** / -0.490 / -0.919*** / -0.881*** / -0.739** / -0.557*
minimum temperature per year (air) (Tempmin air) / 0.952*** / -0.866*** / -0.678** / -0.848*** / -0.816*** / -0.537* / -0.690** / -0.561* / -0.288
minimum temperature per year (ground) (Tempmin ground) / -0.820*** / -0.688** / -0.808*** / -0.818*** / -0.637** / -0.730** / -0.628 / -0.429
days with temperatures < -15 °C (air) / 0.673** / 0.913*** / 0.907*** / 0.336 / 0.583* / 0.433 / 0.161
days with temperatures < -20 °C (air) / 0.479 / 0.823*** / 0.241 / 0.284 / 0.139 / -0.086
days with temperatures < -15 °C (ground) / 0.747*** / 0.463 / 0.781*** / 0.648** / 0.459
days with temperatures < -20 °C (ground) / 0.307 / 0.460 / 0.230 / 0.088
number of frost days / 0.740** / 0.702** / 0.584*
number of ice days / 0.730** / 0.757***
number of days with snow / 0.712**

Table A5

Correlation matrix between monthly climatic variables from January to March, n = 16; * p < 0.05, ** p < 0.01, *** p < 0.001; significant correlations are written in bold, for details see Table A1.

Minimum temperature (Air) / Minimum temperature (Ground) / Number of frost days / Days with temperatures < -15 °C / Maximum snow height [cm] / Number of ice days / Days with temperatures < -20 °C / Days with snow
January / February / March / January / February / March / January / February / March / January / February / March / January / February / March / January / February / March / January / February / March / January / February / March
Minimum temperature (Air)
January / -0.119 / 0.26 / 0.992*** / -0.101 / 0.255 / -0.736** / -0.007 / -0.013 / -0.859*** / 0.162 / -0.336 / -0.392 / -0.025 / 0.075 / -0.888*** / 0.027 / -0.145 / -0.764*** / 0.225 / / / -0.770*** / -0.238 / 0.033
February / 0.403 / -0.074 / 0.988*** / 0.457 / -0.055 / -0.602** / -0.04 / 0.007 / -0.694** / -0.276 / -0.058 / -0.492 / -0.058 / -0.01 / -0.798*** / -0.419 / 0.136 / -0.547* / / / -0.032 / -0.631** / -0.168
March / 0.301 / 0.431 / 0.986*** / -0.585* / -0.38 / -0.588* / -0.476 / 0.002 / -0.891*** / -0.437 / -0.273 / -0.726** / -0.493 / -0.158 / -0.804*** / -0.005 / 0.146 / / / -0.488 / -0.772*** / -0.754***
Minimum temperature (Ground)
January / -0.054 / 0.302 / -0.740** / -0.048 / -0.05 / -0.873*** / 0.163 / -0.345 / -0.448 / -0.028 / 0.056 / -0.898*** / 0.021 / -0.186 / -0.798*** / 0.222 / / / -0.806*** / -0.273 / 0.029
February / 0.482 / -0.084 / -0.617* / -0.043 / -0.014 / -0.656** / -0.301 / -0.068 / -0.528* / -0.111 / -0.048 / -0.782*** / -0.447 / 0.135 / -0.507* / / / -0.083 / -0.651** / -0.19
March / -0.570* / -0.412 / -0.515* / -0.474 / -0.08 / -0.902*** / -0.474 / -0.333 / -0.686** / -0.484 / -0.251 / -0.792*** / -0.031 / 0.085 / / / -0.52* / -0.812*** / -0.689**
Number of frost days
January / 0.232 / 0.287 / 0.786*** / -0.116 / 0.656** / 0.550* / 0.174 / 0.302 / 0.817*** / 0.019 / 0.33 / 0.585* / -0.23 / / / 0.625** / 0.489 / 0.316
February / 0.312 / 0.233 / 0.296 / 0.272 / 0.243 / 0.448 / 0.171 / 0.275 / 0.682** / 0.403 / 0.077 / 0.299 / / / 0.068 / 0.452 / 0.228
March / 0.156 / -0.305 / 0.452 / 0.35 / -0.154 / 0.607* / 0.22 / -0.186 / 0.459 / -0.091 / -0.281 / / / 0.019 / 0.262 / 0.571*
Days with temperatures < -15 °C
January / -0.126 / 0.540* / 0.407 / 0.119 / 0.118 / 0.816*** / 0.047 / 0.247 / 0.739** / -0.234 / / / 0.740** / 0.45 / 0.125
February / 0.089 / -0.205 / 0.182 / -0.126 / -0.17 / 0.781*** / 0.073 / -0.133 / 0.922*** / / / -0.126 / 0.261 / -0.094
March / 0.345 / 0.328 / 0.728** / 0.504* / 0.195 / 0.658** / 0.073 / -0.126 / / / 0.453 / 0.807*** / 0.686**
Maximum snow height [cm]
January / 0.108 / 0.079 / 0.620* / 0.097 / 0.1 / 0.298 / -0.298 / / / 0.696** / 0.194 / -0.106
February / 0.215 / 0.175 / 0.568* / 0.175 / -0.065 / -0.039 / / / 0.158 / 0.667** / 0.079
March / 0.179 / -0.123 / 0.624** / -0.18 / -0.19 / / / 0.09 / 0.542* / 0.827***
number of ice days:
January / 0.105 / 0.332 / 0.623** / -0.225 / / / 0.829*** / 0.373 / 0.151
February / 0.154 / -0.105 / 0.645** / / / 0.082 / 0.457 / -0.108
March / -0.082 / 0.092 / / / 0.224 / 0.679** / 0.843***
Days with temperatures < -20 °C:
January / -0.142 / / / 0.540* / 0.096 / -0.224
February / / / -0.252 / 0.029 / -0.086
March / / / / / /
Days with snow:
January / 0.33 / -0.05
February / 0.550*
March

Table A6

Model selection statistics for the three best linear regression models for each fertilization variant with a maximum number of estimated parameters of k = 5. The following variables were included into the regression models: the number of frost days in February (Feb), the number of frost days in March (Mar), the snow height in February (in cm), the number of days < -15 °C on the ground in February, the number of days < -15 °C on the ground in March. The Akaike’s Information Criterion (with correction for a finite sample size; AICc) and the difference in AICc relative to the best fitted model (∆AICc) are given. The best model per fertilization variant is highlighted in bold.

Fertilization variant
Control / N-fertilization / P-fertilization / NP-fertilization
Model / k / AICc / ∆AICc / k / AICc / ∆AICc / k / AICc / ∆AICc / k / AICc / ∆AICc
Absolute cover of H. helix
Frost days (Feb) / 3 / 46.863 / 0.0 / 3 / 47.786 / 2.3 / 3 / 42.984 / 0.0 / 3 / 43.684 / 0.8
Frost days (Mar) / 3 / 45.466 / 0.0
Snow height (Feb) + Frost days (Feb) / 4 / 49.760 / 2.9 / 4 / 42.918 / 0.0
Frost days (Feb) + Frost days (Mar) / 4 / 46.140 / 0.7 / 4 / 44.817 / 1.8 / 4 / 43.701 / 0.8
Frost days (Feb) + Days -15 °C (ground/Mar) / 4 / 43.214 / 0.2
Days -15°C (ground/Feb)+Frost days (Feb)+ Days -15°C (ground/Feb) x Frost days (Feb) / 5 / 49.444 / 2.6
Year-to-year change in cover of H. helix
Snow height (Feb) / 3 / 48.319 / 2.2 / 3 / 46.877 / 0.2
Days -15 °C (ground/Mar) / 3 / 49.020 / 2.9 / 3 / 43.012 / 0.0
Frost days (Mar) / 3 / 48.313 / 1.7 / 3 / 42.132 / 0.5
Snow height (Feb) + Days -15 °C (ground/Mar) / 4 / 46.646 / 0.0 / 4 / 44.123 / 1.1
Frost days (Feb) + Frost days (Mar) / 4 / 41.673 / 0.0
Days -15 °C (ground/Mar) + Frost days (Mar) / 4 / 45.861 / 4.2
Days -15 °C (ground/Mar) + Frost days (Feb) / 4 / 44.128 / 1.1
Snow height (Feb) + Frost days (Feb) + Snow height (Feb) x Frost days (Feb) / 5 / 46.149 / 0.0