Supplementary material

Table S1. Habitat variables assessed during field surveys and stereoscopic analysis of aerial photographs on our 98 sample plots (rec. = records).

Variable / Range / mean value 'grouse plot' / mean value 'non-grouse plot' / Data source / Variable description
Data based on field survey
Birch (rec.) / 0.0-108.0 / 7.7 / 2.3 / Field / Number of individuals spotted per sample plot
Mountain ash (rec.) / 0.0-126.0 / 16.5 / 3.1 / Field / Number of individuals spotted per sample plot
Alder (rec.) / 0.0-23.0 / 0.8 / 0.7 / Field / Number of individuals spotted per sample plot
Willow (rec.) / 0.0-42.0 / 3.7 / 0.3 / Field / Number of individuals spotted per sample plot
Aspen (rec.) / 0.0-21.0 / 1.0 / 0.2 / Field / Number of individuals spotted per sample plot
Amentiferous tree species (rec.) / 0.0-136.0 / 29.7 / 6.6 / Field / Number of individuals spotted per sample plot
Summary of broadleaf trees (rec.) / 0.0-146.0 / 29.7 / 6.6 / Field / Summary of birch, mountain ash, alder, willow, aspen spotted per sample plot
Fallen dead tree (rec.) / 0.0-119.0 / 28.5 / 16.8 / Field / Number of individuals crossed per sample plot
Root plate (rec.) / 0.0-64 / 7.5 / 3.1 / Field / Number of individuals crossed per sample plot
Stream (rec.) / 0.0-9.0 / 2.0 / 1.3 / Field / Number of individuals crossed per sample plot
Stand structure/vertical layers (cat.) / 1;2;3 / 2.0 / 1.4 / Field / Vertical tree diversity: 'single-storied', 'two-storied', 'three-storied' eq. 'multi-storied' Rittershofer (1994)
Data based on aerial photos
Elevation (m) / 657.2-1.319.6 / 979.3 / 951.3 / DEM / Height above sea level
Stream (m) / 0.0-4.936.6 / 944.2 / 815.7 / National Park / Footage of streams intersect sample plot
Road (m) / 0.0-1.783.6 / 644.2 / 366.4 / National Park / Footage of forest tracks intersect sample plot
Forest aisle (length) (m) / 0.0-5.420.2 / 1857,4 / 1852.2 / National Park / Footage of forest aisles intersect sample plot
Potential solar radiation (kWh/m²) / 188.4-242.7 / 223.2 / 218.7 / DEM, SAGA-GIS model / Amount of energy that is received from the sun, (Olaya 2004)
Wetness index (index) / 8.6-12.0 / 10.1 / 10.0 / DEM, SAGA-GIS model / Tendency of a cell 'soil' to produce runoff based on the TOPMODEL (Beven and Kirby 1979; Olaya 2004)
Mean patch-size (m²) / 5205.9-124.940.2 / 12,256.8 / 24842.5 / Aerial photographs / Dimension of the average patch in a sample plot
Mean borderline (m) / 218.9-11610.6 / 7,412.1 / 5576.2 / Aerial photographs / Footage of the boundaries within a sample plot calculated with the formular (sum. borderline - outline sample plot) / 2
Denuded area (m²) / 0.0-200,166.9 / 16,980.2 / 21,777.7 / Aerial photographs / Area of denuded areas
Denuded area with dead wood (m²) / 0.0-247,928.9 / 29,086.9 / 39,624.1 / Aerial photographs / Area of denuded areas covered with dead wood
Road (m²) / 0.0-13,305.9 / 2,521.4 / 2,828.3 / Aerial photographs / Area of forest tracks
Forest aisle (area) (m²) / 0.0-11,375.4 / 3,025.8 / 1,385.8 / Aerial photographs / Area of forest aisles
Young broadleaf forest (m²) / 0.0-75,771.5 / 6,037.7 / 3,575.1 / Aerial photographs / Area of broadleaf forest, height 0-6m
Young coniferous forest (m²) / 0.0-122,504.3 / 13,680.3 / 7,103.9 / Aerial photographs / Area of coniferous forest, height 0-6m
Young mixed forest (m²) / 0.0-58,960.4 / 4,616.9 / 2,291.8 / Aerial photographs / Area of mixed forest, height 0-6m
Middle broadleaf forest (m²) / 0.0-106,967.0 / 14,070.5 / 9,222.1 / Aerial photographs / Area of broadleaf forest, height 6-12 meter
Middle coniferous forest (m²) / 0.0-133,045.0 / 23,585.1 / 16,503.4 / Aerial photographs / Area of coniferous forest, height 6-12 meter
Middle mixed forest (m²) / 0.0-64,154.4 / 8,528.3 / 4,236.3 / Aerial photographs / Area of mixed forest, height 6-12 meter
Mature broadleaf forest (m²) / 0.0-206,196.7 / 44,436.5 / 49,963.0 / Aerial photographs / Area of broadleaf forest, height above 12 meter
Mature coniferous forest (m²) / 0.0-221,853.7 / 66,439.5 / 70,408.4 / Aerial photographs / Area of coniferous forest, height above 12 meter
Mature mixed forest (m²) / 0.0-154,436.5 / 16,871.4 / 20,952.4 / Aerial photographs / Area of mixed forest, height above 12 meter
Shannon index (index) / 0.0-2.2 / 1.53 / 1.15 / Aerial photographs / Shannon index for the individual patches
Simpson index (index) / 0.0-0.9 / 0.69 / 0.55 / Aerial photographs / Simpson index for the individual patches
Mean patch-size 'class' (m²) / 41,646.7-249,880.5 / 66,722.4 / 81,335.7 / Aerial photographs / Dimension of the average patch in a sample plot after merging
Mean borderline 'class' (m) / 0.0-10,274.7 / 5,882.7 / 4,324.3 / Aerial photographs / Footage of the boundaries within a sample plot calculated with the formula: (sum. borderline - outline sample plot) / 2, after merging
Class 0 meter (m²) / 0.0-249,880.5 / 51,614.2 / 65,615.9 / Aerial photographs / Area of the patches denuded area, denuded area with dead wood, roads, forest-aisles (area) after merging
Class 0<6 meter (m²) / 0.0-122,661.9 / 24,334.9 / 12,970.8 / Aerial photographs / Area of the patches young broadleaf forest, young coniferous forest, young mixed forest after merging
Class 6<12 meter (m²) / 0.0-171,949.8 / 46,183.9 / 29,961.8 / Aerial photographs / Area of the patches middle broadleaf forest, middle coniferous forest, middle mixed forest after merging
Class 12< meter (m²) / 0.0-247,603.1 / 127,747.4 / 141,323.8 / Aerial photographs / Area of the patches mature broadleaf forest, mature coniferous forest , mature mixed forest after merging
Shannon index 'class' (index) / 0.0-1.3 / 0.90 / 0.68 / Aerial photographs / Shannon index for the classes after merging
Simpson index 'class' (index) / 0.0-0.7 / 0.50 / 0.37 / Aerial photographs / Simpson index for the classes after merging

Table S2. Spearman correlation matrix of the 25 environmental variables which were used in backward selection, Bayesian model averaging and conditional inference model; values >0.5 are bold.

1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 / 17 / 18 / 19 / 20 / 21 / 22 / 23 / 24 / 25
Mountain ash / 1 / 0.695 / 0.487 / 0.458 / 0.197 / -0.030 / 0.230 / 0.223 / 0.261 / -0.356 / 0.131 / 0.034 / -0.089 / 0.146 / -0.102 / -0.232 / 0.393 / 0.269 / 0.263 / -0.027 / -0.173 / 0.011 / -0.228 / -0.167 / 0.139
Amentiferous trees / 2 / 0.693 / 0.379 / 0.119 / 0.171 / -0.024 / 0.327 / 0.314 / -0.341 / 0.098 / 0.077 / -0.140 / 0.239 / -0.036 / -0.183 / 0.365 / 0.447 / 0.185 / 0.083 / -0.179 / 0.065 / -0.104 / -0.185 / 0.197
Willow / 3 / 0.252 / 0.113 / 0.316 / -0.168 / 0.263 / 0.361 / -0.126 / -0.010 / -0.006 / -0.149 / 0.339 / 0.113 / -0.060 / 0.423 / 0.107 / -0.024 / 0.101 / -0.135 / 0.210 / 0.058 / -0.114 / 0.288
Fallen dead trees / 4 / 0.596 / -0.100 / 0.449 / 0.119 / -0.175 / -0.514 / 0.185 / -0.034 / 0.401 / -0.252 / -0.341 / -0.309 / 0.059 / 0.280 / 0.076 / -0.072 / -0.256 / -0.101 / -0.426 / -0.311 / -0.317
Root plates / 5 / -0.072 / 0.388 / -0.036 / -0.198 / -0.310 / 0.052 / 0.008 / 0.191 / -0.075 / -0.196 / -0.208 / 0.027 / 0.164 / -0.017 / -0.136 / -0.134 / -0.059 / -0.148 / -0.208 / -0.184
Stand structure / 6 / -0.318 / 0.060 / 0.187 / 0.120 / 0.038 / -0.064 / -0.275 / 0.391 / 0.158 / 0.223 / 0.115 / -0.111 / -0.079 / 0.242 / 0.042 / 0.257 / 0.160 / 0.089 / 0.397
Elevation / 7 / -0.177 / -0.147 / -0.355 / -0.039 / -0.044 / 0.352 / -0.210 / -0.276 / -0.225 / 0.020 / 0.085 / 0.080 / -0.238 / 0.094 / -0.307 / -0.512 / -0.198 / -0.286
Stream (length) / 8 / -0.014 / -0.295 / 0.112 / 0.072 / -0.195 / 0.249 / -0.051 / 0.003 / 0.273 / 0.283 / 0.146 / 0.112 / -0.074 / 0.042 / 0.023 / -0.059 / 0.277
Road (length) / 9 / 0.074 / 0.009 / 0.057 / -0.197 / 0.283 / 0.293 / 0.040 / 0.278 / -0.104 / -0.053 / 0.251 / -0.043 / 0.172 / 0.143 / 0.086 / 0.313
Forest aisle (length) / 10 / -0.077 / -0.063 / -0.223 / 0.101 / 0.410 / 0.372 / -0.226 / -0.345 / -0.236 / 0.058 / 0.188 / 0.132 / 0.366 / 0.245 / 0.099
Potential solar radiation / 11 / -0.036 / -0.127 / 0.051 / -0.274 / 0.186 / 0.128 / -0.073 / 0.126 / 0.238 / 0.080 / 0.045 / -0.165 / -0.189 / 0.137
Wetness / 12 / -0.015 / -0.060 / 0.005 / -0.022 / 0.051 / 0.019 / -0.067 / -0.101 / -0.106 / -0.154 / 0.043 / -0.078 / -0.058
Mean patch size / 13 / -0.627 / -0.259 / -0.282 / -0.141 / -0.058 / -0.044 / -0.204 / -0.162 / -0.144 / -0.275 / -0.121 / -0.611
Mean border line / 14 / 0.216 / 0.440 / 0.269 / 0.121 / 0.008 / 0.286 / 0.147 / 0.228 / 0.123 / 0.050 / 0.793
Road (area) / 15 / -0.021 / -0.087 / -0.188 / -0.151 / 0.164 / 0.018 / 0.221 / 0.398 / 0.094 / 0.130
Forest aisle (area) / 16 / -0.136 / -0.096 / -0.162 / 0.123 / 0.229 / 0.155 / 0.135 / 0.053 / 0.291
Young broadleaf / 17 / 0.102 / 0.163 / 0.154 / -0.155 / -0.038 / -0.194 / -0.122 / 0.345
Young conifers / 18 / 0.099 / -0.056 / -0.047 / -0.124 / -0.147 / -0.197 / 0.030
Young mixed forest / 19 / 0.031 / -0.161 / -0.086 / -0.225 / -0.088 / 0.133
Middle broadleaf / 20 / -0.007 / 0.245 / -0.139 / 0.152 / 0.437
Middle conifers / 21 / 0.239 / -0.101 / 0.079 / 0.244
Middle mixed forest / 22 / -0.005 / 0.187 / 0.369
Mature conifer / 23 / -0.043 / 0.014
Mature mixed / 24 / 0.253
Shannon Index / 25