Table 1. Mean ± SD of cavity density, density of trees with cavity and the number of cavities per tree in different habitat types in a seasonal rainforest in tropical China. Significant differences within columns (Kruskal-Wallis ANOVA with post-hoc Dunn-Bonferroni test) are character coded.
Habitat type Cavity density
(cavities per hectare) 		Density of trees with cavity
(trees per hectare) 		No. of cavities
(cavities/tree)
Valley 102.3 ± 76.4 ab 80.9 ± 53.9 bc 0.086 ± 0.065 a
Low-slope 118.1 ± 76.1 a 95.3 ± 58.1 ab 0.091 ± 0.057 a
High-slope 129.2 ± 84.0 a 101.7 ± 55.1 a 0.081 ± 0.052 a
High-gully 117.4 ± 87.0 ab 89.4 ± 61.6 abc 0.081 ± 0.058 ab
High-plateau 85.3 ± 70.2 b 70.0 ± 55.4 c 0.063 ± 0.063 b
df 4 4 4
Statistic H = 220.420 H = 22.538 H = 18.022
P <0.001 <0.001 0.001
P values <0.05 are shown in bold.
1

Fig. 1. Proportion of cavities with (a) cavity height above ground, (b) cavity size, (c) cavity type across different habitat types in a seasonal rainforest in tropical China. The number of cavities in each category is shown.

Table 2. Mean ± SD of cavity density (cavities per hectare) across habitats in a seasonal rainforest in tropical China. Significant differences within rows (Kruskal-Wallis ANOVA with post-hoc Dunn-Bonferroni test) are character coded.
Variable Valley Low-slope High-slope High-gully High-plateau df H P
(a): Cavity height
  <2 m 49.8 ± 49.6 b 62.9 ± 54.7 ab 69.9 ± 53.9 a 54.7 ± 53.2 ab 52.2 ± 50.6 ab 4 13.841 0.008
  2–4 m 24.3 ± 28.6 ab 20.6 ± 24.9 ab 26.1 ± 27.7 a 22.9 ± 27.2 ab 16.1 ± 27.4 b 4 10.866 0.028
  4–6 m 11.8 ± 20.4 14.0 ± 19.4 12.4 ± 22.0 11.4 ± 20.4 7.2 ± 14.1 4 6.237 0.182
  6–8 m 7.0 ± 15.3 b 8.5 ± 17.2 ab 9.8 ± 17.9 ab 14.0 ± 20.9 a 3.6 ± 10.3 b 4 17.605 0.001
  8–10 m 4.8 ± 14.0 4.7 ± 13.9 4.5 ± 11.7 5.5 ± 11.4 2.2 ± 7.2 4 4.016 0.404
  ≥10 m 4.6 ± 13.3 7.4 ± 17.3 6.5 ± 17.1 8.9 ± 21.2 3.9 ± 13.5 4 4.745 0.314
(b): Cavity size
  2–5 cm 45.9 ± 46.7 44.5 ± 39.4 53.1 ± 44.4 52.1 ± 47.9 36.4 ± 38.6 4 8.360 0.079
  5–15 cm 47.9 ± 46.3 ab 60.2 ± 47.7 a 60.7 ± 55.4 a 47.5 ± 51.2 ab 39.7 ± 42.9 b 4 15.060 0.005
  15–30 cm 7.5 ± 14.6 10.2 ± 19.7 12.1 ± 22.6 13.6 ± 23.8 8.1 ± 13.9 4 3.433 0.488
  30–60 cm 0.9 ± 4.7 b 2.5 ± 8.4 ab 2.5 ± 8.5 ab 4.2 ± 10.5 a 1.1 ± 6.4 ab 4 11.445 0.022
  ≥60 cm 0.2 ± 2.1 0.8 ± 4.5 0.8 ± 4.5 0.0 ± 0.0 0.0 ± 0.0 4 6.970 0.138
(c): Cavity type
  butt hollow 7.5 ± 15.2 b 10.2 ± 16.7 b 22.8 ± 30.8 a 16.5 ± 26.9 ab 15.0 ± 25.4 ab 4 24.231 <0.001
  trunk main 60.0 ± 48.5 ab 63.2 ± 52.5 ab 62.9 ± 51.1 a 57.2 ± 45.5 ab 43.9 ± 44.7 b 4 11.271 0.024
  trunk top 13.2 ± 21.3 16.2 ± 24.8 20.2 ± 23.2 21.6 ± 33.3 12.5 ± 18.8 4 9.724 0.065
  crack 16.4 ± 25.2 ab 23.1 ± 26.7 a 19.7 ± 24.3 ab 16.5 ± 25.3 ab 11.4 ± 21.6 b 4 15.341 0.004
  branch middle 2.5 ± 8.1 3.3 ± 13.0 1.4 ± 8.7 4.2 ± 11.5 1.4 ± 5.8 4 6.283 0.179
  branch end 1.8 ± 7.1 1.1 ± 5.2 2.0 ± 6.8 0.4 ± 3.3 0.8 ± 4.5 4 3.993 0.407
  bayonet 0.9 ± 4.7 1.1 ± 5.2 0.3 ± 2.6 0.8 ± 4.6 0.3 ± 2.6 4 3.118 0.538
P values <0.05 are shown in bold.
Table 3. Rayleigh test of orientation of cavities in each habitat in a seasonal rainforest in tropical China.
Habitat No. of cavities Mean orientation Z-value P 95% confidence intervals
Valley 474 95.8° 0.050 0.951 –
Low-slope 342 110.9° 3.651 0.026 110.9 ± 47.4°
High-slope 388 49.4° 1.711 0.181 –
High-gully 218 327.7° 3.604 0.027 327.7 ± 51.7°
High-plateau 229 341.7° 4.078 0.017 341.7 ± 44.3°
P values <0.05 are shown in bold.
Table 4. Summary of generalized linear mixed models relating density of cavity types to fixed effects. Likelihood ratio test statistics (χ2), probabilities (P), semi-partial marginal determination coefficients (Rm2 [%]) are displayed. Model parameters were considered significant at 5% and are highlighted in bold.
Model Tree species richness RMS DBH Topographical spatial variability
χ2 P Rm2 (%) χ2 P Rm2 (%) χ2 P Rm2 (%)
All density 43.405 <0.001 4.127 20.029 <0.001 1.092 133.937 <0.001 22.57
 Density
  Cavity height
   <2 m 33.484 <0.001 3.325 6.807 0.009 0.442 142.781 <0.001 24
   2–4 m 10.833 0.001 2.702 10.922 0.001 3.437 59.892 <0.001 14.927
   4–6 m 2.434 0.119 0.8 0.631 0.427 0.212 17.582 <0.001 9.023
   6–8 m 0.787 0.375 0.437 0.23 0.632 0.124 43.973 <0.001 27.256
   8–10 m 0.032 0.857 0.164 0.059 0.809 0 9.046 0.003 8.544
   ≥10 m 0.447 0.504 0.251 0.194 0.659 2.072 66.813 <0.001 56.919
  Cavity size
   2–5 cm 4.911 0.027 1.161 1.19 0.275 0.214 136.22 <0.001 29.075
   5–15 cm 23.278 <0.001 2.828 6.374 0.012 0.359 74.336 <0.001 14.437
   15–30 cm 13.004 <0.001 3.634 15.984 <0.001 1.987 50.465 <0.001 21.799
   30–60 cm 4.617 0.032 3.326 1.602 0.206 0.493 19.456 <0.001 34.47
  Cavity type
   Butt hollow 18.32 <0.001 4.863 3.036 0.081 0.068 39.474 <0.001 15.029
   Trunk main 11.469 0.001 1.978 0.098 0.754 0.012 91.989 <0.001 18.33
   Trunk top 23.692 <0.001 4.062 0.673 0.412 0.818 43.873 <0.001 14.039
   Crack 5.898 0.015 0.349 5.561 0.018 0.529 35.16 <0.001 11.306
   Branch middle 18.724 <0.001 0.391 14.611 0 1.401 51.162 0.001 55.476
   Branch end 5.412 0.02 4.444 2.02 0.155 4.951 12.815 0.541 31.914
RMS DBH, root mean square diameter of trees at breast height in a given subplot.