| |
There
are a total of 89,542 habitat polygons identified on
the final habitat map. The number of polygons derived
for individual habitat types ranged widely from 12 for
Seagrass Bed to 19,072 for Mixed Shrubland. The majority
of other vegetation habitats (except for Fung Shui Forest,
Montane Forest and Plantation or Plantation/Mixed Forest)
had their polygon numbers > 8,000. Enormous variation
in the size of individual polygons was noted for all
habitat types. The smallest difference in polygon size,
102 times (ie the largest polygon is 102 times the smallest
one), was recorded for Seagrass Bed whilst the biggest
difference was observed for Intertidal Mudflat (ie 1011
times). Landfill showed the largest mean polygon size
(26.5 ± 40.5 ha) and there is only one other
category, ie Modified Watercourse, which had its mean
polygon size > 15 ha. The majority of the other habitat
types showed a mean polygon size of < 3 ha. Standard
deviation is particularly high for Grassland, Other
and Intertidal Mudflat which showed at least 13 times
the mean and almost ten times for Lowland Forest and
Mangrove.
The
large number of polygons identified for the natural
vegetation habitats, including Lowland Forest, Mixed
Shrubland, Baeckia Shrubland, Shrubby Grassland and
Grassland, and the generally small average size of polygons
suggested that the habitats are largely patchy and fragmented
in distribution. The relatively low number of polygons
(< 50) mapped for Fung Shui Forest, Seagrass Bed,
Quarry and Landfill indicated that these habitats are
of limited distribution in Hong Kong.
| Table
9.3a Mean, Minimum and Maximum Area of Polygon Mapped
for Each Habitat Type and Their Total Numbers Identified
on the Habitat Map |
|
Habitat
Category
|
No.
of Polygons
|
Total
Area (ha) |
Minimum
Area of Polygon (10-4ha) |
Maximum
Area of Polygon (ha) |
Mean
Area of Polygon (ha) |
Standard
Deviation (ha)
|
| Grassland |
15,382 |
26,081.3 |
0.01 |
1979.1 |
1.7 |
22.8 |
| Other |
8,921 |
18,819.9 |
0.67 |
4771.4 |
2.1 |
59.4 |
| Lowland
Forest |
8,088 |
18,225.4 |
0.63 |
1016.5 |
2.3 |
21.6 |
| Mixed
Shrubland |
19,072 |
16,477.7 |
0.004 |
484.1 |
0.86 |
5.9 |
| Shrubby
Grassland |
10,736 |
8,702.8 |
0.04 |
108.5 |
0.81 |
3.5 |
| Baeckia
Shrubland |
10,621 |
5,976.9 |
0.35 |
120.4 |
0.56 |
2.7 |
| Cultivation |
4,572 |
4,381.0 |
0.01 |
63.7 |
0.96 |
3.0 |
| Modified
Watercourse |
186 |
2,827.0 |
102.1 |
1201.0 |
15.2 |
101.6 |
| Fishpond/Gei
Wai |
2,281 |
1,835.7 |
0.07 |
61.1 |
0.80 |
2.1 |
| Intertidal
Mudflat |
710 |
1,563.9 |
0.00001 |
722.1 |
2.2 |
29.7 |
| Bare
Rock or Soil |
3,230 |
1,440.0 |
0.60 |
37.5 |
0.45 |
1.4 |
| Freshwater/Brackish
Wetland |
1,556 |
1,030.5 |
0.07 |
32.4 |
0.66 |
1.8 |
| Rural
Industrial Storage/Containers |
1,859 |
1,007.7 |
107.9 |
17.8 |
0.54 |
1.2 |
| Golf
Course/Urban Park |
187 |
1,006.7 |
246.4 |
170.2 |
5.4 |
17.3 |
| Natural
Watercourse |
1,565 |
783.4 |
1.3 |
30.4 |
0.50 |
1.4 |
| Landfill |
15 |
397.7 |
450.8 |
126.7 |
26.5 |
40.5 |
| Mangrove |
201 |
326.5 |
132.3 |
220.7 |
1.6 |
15.6 |
| Quarry |
27 |
228.9 |
269.3 |
60.8 |
8.5 |
16.1 |
| Sandy
Shore (spatial) |
145 |
206.4 |
428.1 |
24.6 |
1.4 |
2.8 |
| Plantation
or Plantation/Mixed Forest |
67 |
180.0 |
131.7 |
44.6 |
2.7 |
7.9 |
| Fung
Shui Forest |
42 |
111.7 |
352.2 |
11.9 |
2.7 |
2.8 |
| Montane
Forest |
67 |
59.6 |
152.2 |
12.4 |
0.89 |
1.8 |
| Seagrass
Bed |
12 |
41.1 |
446.1 |
14.9 |
3.4 |
5.0 |
| Total: |
89,542 |
111,711.8 |
|
|
|
|
Note:
As Rocky Shore, Artificial Rocky/Hard Shoreline and
the majority of Sandy Shore habitats are represented
as a linear component on the habitat map, spatial calculation
for these habitats was not applicable.
|
|