Table 1. Number of stands, plots and total area in the 182 surveyed tracts. Arithmetic mean values with one SE of the mean within brackets.
  Total per stand per tract
Stands (no) 450   2.5 (0.09)
Plots (no) 2052 4.6 (0.17) 11.3 (0.51)
Area (ha) 2134 4.7 (0.22) 11.7 (0.64)
1

Fig. 1. Frequencies of tracts with different average cover of Scots pine (a), birch (b) and RAW (c) browse. Values on the x-axis denote class upper limits, except for the 0-class. RAW = rowan, aspen, willows.

2

Fig. 2. Akaike relative weights for independent variables (normalized to sum up to 1.0 for each species) in multiple regressions explaining recent browsing damage by moose to Scots pine, birch and aspen. The proportion of the total variance explained by all variables combined (Adj. R2) are given above each bar. RAW = rowan, aspen, willows.

Table 2. Summary of regression models used to explain recent moose damage to Scots pine, birch and aspen at the tract level. All independent variables except site index were [log10 (n + 1)] transformed before analysis.
Variables df Coeff. SE p
Scots pine        
Intercept 1 –0.314 0.461 0.497
Moose index 1 1.068 0.328 0.001
Site index 1 0.042 0.018 0.025
Scots pine cover 1 –0.461 0.116 <0.001
Birch cover 1 0.005 0.146 0.970
RAW cover 1 0.100 0.202 0.621
Error 167      
Total 173      
F   8.735   <0.001
Birch
Intercept 1 –0.400 0.588 0.497
Moose index 1 1.793 0.410 <0.001
Site index 1 0.038 0.023 0.100
Scots pine cover 1 0.135 0.144 0.351
Birch cover 1 –0.158 0.198 0.424
RAW cover 1 –0.295 0.243 0.226
Error 162      
Total 168      
F   6.550   <0.001
Aspen
Intercept 1 4.178 1.963 0.042
Moose index 1 1.503 1.277 0.249
Site index 1 –0.058 0.068 0.408
Scots pine cover 1 –1.513 0.546 0.010
Birch cover 1 –1.715 0.592 0.007
RAW cover 1 0.272 0.707 0.703
Error 26      
Total 32      
F   3.785   0.010
Note: RAW = rowan, aspen, willows
3

Fig. 3. Proportion of Scots pine with recent browsing damage depending on the height-relation between birch and Scots pine. When the relation is >1.0, birch is overtopping pine. Tracts with both birch and Scots pine are included in the analysis (n = 154). Vertical bars show ± one S.E. of the mean.

Table 3. Independent variables included and ΔAICc values for predicting recent moose browsing damage on Scots pine, birch and aspen.
Species Moose index Site index Forage cover ΔAICc
Scots pine Birch RAW  
Scots pine X X X     0
X X X   X 1.72
X X X X X 3.72
Birch X         0
X       X 0.61
X X     X 0.75
X X X   X 2.24
X X X X X 3.57
Aspen     X X   0
X   X X   0.94
X X X X   2.10
X X X X X 3.92
Note: RAW = rowan, aspen, willows