1

Fig. 1. The location of the study area (QFCERN: Qingyuan forest CERN).

Table 1. The basic information for the images used in this analysis.
Year Image Type Source Spatial Resolution
2002 Satellite image SPOT 5 Panchromatic 2.5 m; Multispectral 10.0 m
2003 Satellite image SPOT 5 Panchromatic 2.5 m; Multispectral 10.0 m
2011 Satellite image SPOT 5 Panchromatic 2.5 m; Multispectral 10.0 m
2014 Satellite image KOMPSAT-3 Panchromatic 0.7 m; Multispectral 2.8 m
Table 2. Overall accuracy and Kappa coefficients in different years detected by satellite images. Image interpretation data were compared with ground survey data.
Year Overall accuracy (%) Kappa coefficient
2002 78 0.62
2003 73 0.68
2011 86 0.72
2014 82 0.70
Table 3. The mean tree heights of five regions divided by forest types, ages and slopes.
Forest type Age / Slope Mean tree height
Larch plantation 20 years old 18 m
Larch plantation 30 years old 21 m
Larch plantation 40 years old 23 m
Secondary forest south, southeast, east, northeast slopes 19 m
Secondary forest north, northwest, west, southwest slopes 17 m
2

Fig. 2. The spatial patterns of gaps and vacant lands before (A) and after (B) the wind/snowstorm.

Table 4. General characteristics of gaps and vacant lands before and after the wind/snowstorm and the flood disturbances.
Characteristic Wind/snowstorm Flood
Before (2002) After (2003) Before (2011) After (2014)
Gap Fraction (%) 3.64 5.1 3.14 2.71
Mean size (m2) 121 130 106 78
Density (ha–1) 2.97 3.94 3.0 3.5
GNNI 0.81 0.77 0.65 0.56
Vacant land Fraction (%) 0.26 0.27 0.22 1.10
Mean size (m2) 4488 4052 3780 4656
Number 8 8 8 32
GNNI = gap nearest neighbor index
3

Fig. 3. Relationship between slope and area ratio of gaps induced by wind/snowstorm to total gaps, x: the upper limit of the slope classes, y: the area ratio of new gaps to total gaps.

4

Fig. 4. Relationship between altitude and area ratio of gaps induced by wind/snowstorm to total gaps, x: the upper limit of the altitude classes, y: the area ratio of new gaps to total gaps.

5

Fig. 5. The number and area percentages of gap in large, medium and small classes before and after the wind/snowstorm disturbance, x: gap size classes (divided by the ratio of gap diameter to the mean height of gap border trees, 0.23–0.73, 0.74–1.73 and 1.74–3.23 for small, medium and large gaps).

6

Fig. 6. The spatial patterns of gaps and vacant lands before (A) and after (B) the flood.

7

Fig. 7. Relationship between slope and area ratio of gaps induced by flood to total gaps, x: the upper limit of the slope classes, y: the area ratio of new gaps to total gaps.

8

Fig. 8. Relationship between altitude and area ratio of gaps induced by flood to total gaps, x: the upper limit of the altitude classes, y: the area ratio of new gaps to total gaps.

9

Fig. 9. The number and area percentages of gap in large, medium and small classes before and after the flood disturbance, x: gap size classes (divided by the ratio of gap diameter to the mean height of gap border trees, 0.23–0.73, 0.74–1.73 and 1.74–3.23 for small, medium and large gaps).