Environmental Engineering Reference
In-Depth Information
The planted wood species provided special habitats for understory communities to develop. Table 11.6
lists the average height,
H
, cover, number of species,
S
, and number of shrubs and herb species in the
canopy habitats. There were only a few shrub species in the canopy habitat of
Leucaena leucocephala
forest.
Rhododendron sp.
and
Jatropha curcas
appeared after 10 in years
Leucaena leucocephala
forest,
but only one shrub species
Ricinus communis
was found after 20 years in
Leucaena leucocephala
forest.
As a comparison, 12 shrub species was found in the canopy habitat of
Pinus yunnanensis
forest.
Dominant shrub species were
Qnerous
,
Hypericum acmosepalum
,
Neolitsea aurata
, and
Kerria japonica
.
Figure 11.74 shows the comparison of the understory communities after 20 years
Leucaena leucocephala
forest and 20 years
Pinus yunnanensis
forest. The
Pinus yunnanensis
forest had developed into three
layers vegetation with 12 shrub species and 22 herb species. The
Leucaena leucocephala
forest consisted
of only 1 shrub species and 4 herb species.
Fig. 11.73
Forest cover as a function of tree age for four planted species of trees
T
able 11.6
Understory communities of the four planted wood species
Tree layer
Shrub layer
Herb layer
Planted wood
species
Age
(yr)
H
(m)
D
(cm)
Cover
(%)
Density
(n/hm
2
)
H
(m)
NS
Cover
(%)
H
(m)
Cover
(%)
S
3
3.1
1.4
32
2600
0.3
5
2
6
0.10
25
7
Eucalyptus spp.
8
21
16.4
40
1000
1.5
18
5
10
0.45
93
12
14
22
18.5
50
1100
1.3
23
6
15
0.45
93
14
4
9.2
2.6
40
5600
0.25
20
1
4
0.10
20
11
Acacia mearnsii
7
11
8.3
75
3200
1.1
31
4
7
0.05
6
9
8
11.5
9.1
80
2900
0.6
23
5
6
0.15
9
7
4
5.5
1.9
30
3700
0
0
0
0
0.10
22
5
Leucaena
leucocephala
10
14
3.64
80
2200
1.5
10
2
4
0.50
88
8
20
16
4.5
70
6000
1.4
2
1
2
0.05
0.7
4
4
3
1.93
35
3400
0.2
7
2
1
0.15
30
8
Pinus yunnanensis
14
4.5
5.63
60
2000
0.5
94
7
11
0.15
18
13
20 15.2 17.8 65 1400 2.5 136 12 26 0.20 46 22
Note
:
H
is the average height of plants;
D
is the average diameter of trees;
N
is the number of shrub at eachs site in
200 m
2
, and
S
is the number of species of shrubs or grasses
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