Geoscience Reference
In-Depth Information
Table 8.2
Anderson's phasic communities (PC) of concentric forest associations within coastal basin
peat swamps of Borneo (
after
Anderson, 1961; Lee, 1991).
Forest association
Area (ha)
Descriptive characteristics
PC1.
Gonsytylus-
Dactylocladus-
Neoscrotechinia
(Mixed swamp forest)
1,174,000
Found at peat swamp margins, with structure and
physiognomy similar to lowland dipterocarp
evergreen rain forest on mineral soil; uneven canopy
with dominants attaining 40-45m; 120-150 tree species
ha
−
1
; epiphytes and climbers abundant;
Sharea albida
absent
PC2.
Shorea albida-
Gonystylu-Stenonurus
(Alan Batu forest)
127,000
Similar to PC1 but dominated by scattered, large
(
>
3.5m girth) trees of
Shorea albida
(Alan);
Stemonurus umbellatus
indicator species
PC3.
Shorea albida
(Alan Bunga forest)
76,000
Even upper canopy at 50-60m in height, dominated
by
Shorea albida
with 70-100 trees ha
−
1
of this
species alone; middle storey commonly absent;
moderately dense understorey;
Pandanus andersonii
forms dense thickets in shrub layer; herbs,
climbers and epiphytes rare
PC4.
Shorea albida-Litsea-
Parastemon
(Padang Alan forest)
41,000
Dense, even canopy at 30-40m composed of
relatively small-sized (
<
1.8m DBH) trees which
give the forest a pole-like and xeropytic appearance;
Sharea albida
density of
>
400 trees ha
−
1
;
small, prostrate shrubs (
Euthemis minor and Ficus
deltoidea var. motleyana) indicator species; herb, fens
,
epiphytes and climbers rare or absent
PC5.
Tristania-Palaquium-
Parastemon
NA
Typically found in central domes of peat swamps;
narrow transitional forest between PC4 and PC6; dense,
even, closed canopy at 15-20m with high density
(850-1,250) stems ha
−
1
) of small-sized tress;
herb layer rare or absent
PC6.
Combretacorpus-
Dactylocladus
(Padang Paya forest)
37,000
Found in central domes of peat swamps; resembles
open savannah woodland with stunted,
xeromorphic trees; patchy shrub layer present;
pitcher plants
(Nepenthes spp.)
and epiphytic and-plants
(Myrmecodia tuberosa
and
Leconopteris sinuosa)
indicator species
metres of ground water level (GWL) below the limiting value is equivalent, in terms
of settlements caused, to the surcharging effect of about 0.75 metres of conventional
ground filling.
8.3 PHYSICO-CHEMICAL PROPERTIES OF PEAT
The content of peat may differ from location to location due to factors such as the
origin of the fibres, temperature and degree of humification. Decomposition or humifi-
cation involves the loss of organic matter either in gas or in solution, the disappearance
of physical structure and the change in chemical state. As stated earlier, breakdown of
