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Table 20. Plant richness in Khe Tran
Land type Plot Tree
richness*
Number
of tree
individuals
recorded
Biodiversity and Local Perceptions |
Number
of tree
species
Mean
number
of tree
species
Number
of nontree
species
Mean
number
of nontree
species
Garden
4
6
0.25
0.00
16
12
2
1
2
46
27
37
Plantation
forest
1
5
0.00
0.30
40
40
1
3
2
25
39
33
Primary
forest
7 0.91 40 29 29 33 33
Rice field 10 n.a. 0 0 0 31 31
Secondary
forest
3
9
11
0.87
0.92
0.81
40
40
40
25
30
20
25
36
51
36
41
Shrub
land
2
8
n.a.
n.a.
0
0
0
0
0
30
24
27
*Tree richness = log sp/log count
10 10
n.a. means not applicable
7.4. Forest structure
Richness of life forms of non-tree species varied substantially among land types.
Epiphytes were present in only one secondary forest plot. Herbs, with 190 species,
were the richest non-tree life form category in all land types, especially in more
open and managed areas such as dry rice fields and gardens. Lianas, climbers and
ferns were also present in all of the land types, except rice fields (Table 22).
Secondary forests had the highest canopy, highest dbh and second lowest
furcation index, as illustrated in Figure 19 on the right. Mean height of the
secondary forest varied from 10 to 17 m with a maximum of two canopy layers,
which indicates the lack of high primary forest species. Mean height of the primary
forest was 14 m, which is in line with other survey results from this area (e.g. Le
Trong Trai et al. 2001). Canopy height in plantation forest varied between 14 and
16 m and in gardens from 6 to 10 m.
Furcation index indicates the plant height where apical dominance is no
longer a property of a single defined stem. It was recorded on a continuous scale
from 0 to 110% (the latter being a tree trunk without clear dominant stem). Some
structural features of trees may be linked to their disturbance history and MLA
experiences from, for example, Papua and Kalimantan show that apical dominance
is generally low in primary rainforests with closed canopy. An increase of value
may reflect the rate of disturbance in the forests (trees resprout after breakage) and
history of utilization of trees. As presented in Figure 19, on the right, furcation
index values in Khe Tran varied from 30 to 63. The highest value was recorded
in rubber plantation and the lowest ones in the most distant secondary forest plots
and Acacia plantation without intensive management.