4.2.1 Peat Swamp Biodiversity
4.2.1.1 Flora
It is presumed that the two concessions and the Mendawak protection forest originally consisted of pole forest, mixed swamp forest, and riparian forest. In addition,
the southern part of the sites, close to the sea, is thought to have had native mangrove
forests along the rivers, which have already been destroyed and completely replaced
by nipa palms. As mentioned earlier, most of the forests became degraded secondary
forests, shrubs, and bushes due to various human impacts before WSL-MTI started
their activities.
Based on continuous floral field surveys, WSL-MTI has recorded 529 species,
265 genera, and 90 families in the conservation area of the concessions and the
Mendawak protection forest (unpublished data). Anderson (1963) recorded 927 species of flowering plants and ferns in the peat swamp forests of Borneo, while the
529 species recorded by WSL-MTI are by no means less than that value. At the same
time, WSL-MTI has enumerated tree species that produce fruits for animals and
birds, which also serve as potential restoration planting species.
Among tree species in the deep peat area (more than 7 m in depth), the most
frequent species were Shorea pachyphylla, Palaquium rostratum,
P. cochlearifolium, Diospyros maingayi, and Dactylocladus stenostachya. The
moderate peat (2–7 m) were Calophyllum canum, P. leiocarpum, D. pendula,
Lithocarpus blumeanus, Alseodaphne oblanceolate. The shallow peat (less than
2 m in depth) were Macaranga triloba, Cratoxylum arborescens, Nephelium
maingayi, Pometia pinnata, and Sandoricum emarginatum. The shallow peat area
is strongly influenced by logging and slash-and-burn agriculture and is primarily
composed of pioneer and secondary species, such as Macaranga spp.
Peat swamp forests are heterogeneous in forest structure and species composition
with varying peat depth, nutrient availability, and moisture conditions (Page et al.
1999). Page et al. (1999) classified tropical peatland forest types, from river’s edge to
inland, into riverine, mixed swamp, transition, low pole, tall interior, and very low
canopy forest, and compared forest structure and species composition. The relationship between forest type and peat depth has some obvious differences from the
WSL-MTI compared to those of Page et al. (1999). For example, low pole forests
occur in the deepest areas of peat and vary in species but are nearly uniform in height
(15–20 m high) and diameter (20–30 cm), and many have characteristics of stilt
roots, pneumatophores, and knee roots, while tall interior and very low canopy forest
in deep peat areas have not been observed. Other factors besides peat depth may
influence these different results. Further consideration of forest type will be given
through further analysis, as the WSL-MTI uses a method for plot setting to understand the spatial distribution rather than the commonly used transect-based plot
setting method.
As reported by Yule (2010), Pandanus spp. are distributed on the forest floor and
along rivers, sometimes vigorously growing and blocking the river’s flow. Similarly,
138
T. Kato et al.
4.2.1.1 Flora
It is presumed that the two concessions and the Mendawak protection forest originally consisted of pole forest, mixed swamp forest, and riparian forest. In addition,
the southern part of the sites, close to the sea, is thought to have had native mangrove
forests along the rivers, which have already been destroyed and completely replaced
by nipa palms. As mentioned earlier, most of the forests became degraded secondary
forests, shrubs, and bushes due to various human impacts before WSL-MTI started
their activities.
Based on continuous floral field surveys, WSL-MTI has recorded 529 species,
265 genera, and 90 families in the conservation area of the concessions and the
Mendawak protection forest (unpublished data). Anderson (1963) recorded 927 species of flowering plants and ferns in the peat swamp forests of Borneo, while the
529 species recorded by WSL-MTI are by no means less than that value. At the same
time, WSL-MTI has enumerated tree species that produce fruits for animals and
birds, which also serve as potential restoration planting species.
Among tree species in the deep peat area (more than 7 m in depth), the most
frequent species were Shorea pachyphylla, Palaquium rostratum,
P. cochlearifolium, Diospyros maingayi, and Dactylocladus stenostachya. The
moderate peat (2–7 m) were Calophyllum canum, P. leiocarpum, D. pendula,
Lithocarpus blumeanus, Alseodaphne oblanceolate. The shallow peat (less than
2 m in depth) were Macaranga triloba, Cratoxylum arborescens, Nephelium
maingayi, Pometia pinnata, and Sandoricum emarginatum. The shallow peat area
is strongly influenced by logging and slash-and-burn agriculture and is primarily
composed of pioneer and secondary species, such as Macaranga spp.
Peat swamp forests are heterogeneous in forest structure and species composition
with varying peat depth, nutrient availability, and moisture conditions (Page et al.
1999). Page et al. (1999) classified tropical peatland forest types, from river’s edge to
inland, into riverine, mixed swamp, transition, low pole, tall interior, and very low
canopy forest, and compared forest structure and species composition. The relationship between forest type and peat depth has some obvious differences from the
WSL-MTI compared to those of Page et al. (1999). For example, low pole forests
occur in the deepest areas of peat and vary in species but are nearly uniform in height
(15–20 m high) and diameter (20–30 cm), and many have characteristics of stilt
roots, pneumatophores, and knee roots, while tall interior and very low canopy forest
in deep peat areas have not been observed. Other factors besides peat depth may
influence these different results. Further consideration of forest type will be given
through further analysis, as the WSL-MTI uses a method for plot setting to understand the spatial distribution rather than the commonly used transect-based plot
setting method.
As reported by Yule (2010), Pandanus spp. are distributed on the forest floor and
along rivers, sometimes vigorously growing and blocking the river’s flow. Similarly,
138
T. Kato et al.