Work on peatlands in the Philippines is in its infancy, there having been very few targeted studies on peat areas. Andriesse (1988) undertook some surveys of peatlands in the mid 1980s, including parts of the Agusan Marsh and the Visayas. The IPAS surveys in 1991 briefly described peatland near Bunawan in the Agusan Marsh, whilst surveys during the consultation workshops for this project in November and December 2005 yielded more information on additional areas of peatland in the Agusan Marsh and the Leyte Sab-a Basin peatland. This included a possible peat dome at Caimpugan in the Agusan Marsh, the first peat dome to be described for the Philippines. However, these have mostly been brief studies and there has been very little or no work on the flora and fauna of the peatlands, nor their hydrology or pedology. There is little doubt that there are other areas of peatlands waiting to be described.
Distribution and Status of Peatlands
There are two areas in the Philippines where substantial areas of peat have been found: the Agusan Marsh and the Leyte Sab-a Basin. There has been a lack of targeted surveys for peatlands, but information indicates that there are almost certainly other areas. The location of these areas is shown in Figure 1.
The Sab-a Basin is a west-east elongated basin close to the north coast of Leyte separated from it by a metamorphic ridge. The total area is c. 3,088 ha of which 44% has been reclaimed for agriculture. The remaining unutilised peatland (1,740 ha) in the eastern half of the basin consists of small remnant areas of swamp forest and sedge/grass peat swamp (ADB 2000). The two smaller peat basins in the area Daguitan (210 ha) and Kapiwaran (430 ha) have mostly been converted to agricultural land.
The Agusan Marsh may hold the largest area of peatland in the Philippines. At present, there is no reliable estimate of the area and distribution of peat within Agusan Marsh. Two areas of peatland within the marsh have been confirmed – one just to the north of Bunawan, the vegetation of which has mostly been cleared and burned, and the other to the west of Caimpugan, which exhibits the characteristics of a peat dome, the forest of which is mostly intact except close to the Hibong River. There may be other areas of peat within the marsh, especially in Terminalia copelandii/ Metroxylon sagu forests in the northwest portion of the marsh.
Peat may also be present in the following areas:
- Ligawasan Marsh in Mindanao, the largest marshland area in the Philippines
- Dolongan area in Basey, Western Samar (Bureau of Soils, 1975. Soil Survey of Samar Provinces, Philippines. Reconnaissance Soil Survey and Soil Erosion Survey)
- Southern Leyte (Whitmore1984) as cited in Draft Philippine Plant Conservation Strategy.
- Mt. Pulag in Northern Luzon (Leonard Co, pers. comm.)
- Surigao del Norte, Northeastern Mindanao (areas overlying ultramafic rocks) (Edwino Fernando, pers. comm.)
- Naujan Lake, Mindoro Oriental: herbaceous marshland adjacent to the west of the lake (Arne Jensen pers. comm.)
- Pangasinan floodplains
Value of peatlands
a. Hydrology and Water Regulation
Many peatlands are very important for reducing flood peaks and for maintenance of base flows in rivers during dry periods, the peat acting as a sponge, absorbing water during wet periods and releasing it slowly. This service is particularly important in the Agusan Marsh, which is situated in the middle reaches of the Agusan River, not on the coastal plains. The value of the peatland in the marsh in reducing flood peaks in downstream areas with important settlements is likely to be substantial. The contribution to dry season base flows in the Agusan River and maintenance of groundwater levels is also probably high. Likewise, the peatland in the Leyte Sab-a Basin has the capacity to absorb and hold a lot of water during the rainy season, releasing it slowly to maintain base flows in the outflow rivers. Both peatlands are also probably significant in preventing penetration of saline water up rivers due to this contribution to minimum flows in the rivers during dry periods.
b. Carbon Storage
Although the Philippines has relatively little peatlands compared to other countries, the peatlands of the Philippines still have an important role to play in the storing and sequestration of carbon from the atmosphere. Despite this small area, it seems that much of the peatlands in the Philippines is still intact and is actively accumulating carbon from the atmosphere.
c. Biodiversity Values
The limited information available suggests that biodiversity values of Philippine peatlands are high. Considering the high level of endemism of the Philippine flora, the botanical survey of peatland areas may yield undescribed species. Moreover, at the ecosystem level of biodiversity, there seems to be a unique vegetation assemblage on the Caimpugan peat dome, which is different from the vegetation community found on peat domes in nearby northwest Borneo.
There have been no faunal surveys in Philippine peatlands, although wild boar and deer are found in the Agusan Marsh. The endemic Philippine Tarsier has been reported from the Leyte Sab-a Basin peatlands, which also hosts a resident Little Egret population.
d. Aesthetic Values
High scenic values are found in identified Philippine peatlands, including the striking forests of Lanipao (Terminalia copelandii) in both the Agusan Marsh and the Leyte Sab-a Basin. Both peatlands are surrounded by uplands, from which impressive views of the peatlands can be gained.
e. Socio-Economic Values
Peatlands are also important to local communities as a source of wood like timber and firewood for domestic needs and non wood products like the Frimbistylis globulosa, locally known as “tikog” for mat making and other livelihood purposes. Important peatlands in both Agusan and Leyte Sab-a have been drained and converted to agriculture.
Management Issues and Threats Related to Peatlands
Main problems faced in management of peatlands
Since peat is a fairly rare soil type in the Philippines, there is a fundamental lack of awareness of what peat is, its properties and appropriate management strategies for peatlands in all sectors, from local people to NGOs and government agencies. Linked to this, there is very limited capacity for managing peatlands wisely and no national institutional framework for managing peatlands.
This means that there is a great danger that peatlands may be degraded through activities which do not take into account the special properties of peat. For example, areas of peatland in the Leyte Sab-a Basin and the Agusan Marsh have been cleared for agriculture, but have been abandoned after a few years due to poor yields. In addition, the Agusan Marsh faces substantial migration from other parts of the Philippines, with these farmers being familiar only with agriculture on mineral soils. Land clearance activities are increasing in the Agusan Marsh and may pose a threat to intact peatlands. There is substantial clearing of land immediately to the west of the Caimpugan peat, which may threaten the unique vegetation communities by a combination of fire and lowering of the water table.
Large scale development projects including irrigation components also pose a threat to the Agusan Marsh and the Leyte Sab-a Basin. In the basin, some peatlands have been converted to agriculture by the defunct Leyte Sab-a Development Authority. Likewise, the Department of Agrarian Reform (DAR) continues to issue Certificate of Land Ownership Agreement (CLOAs) over the remaining peatlands. In the Agusan Marsh, 4,000 ha of the marsh may be declared as Alienable and Disposable for the purposes of irrigation. It is not clear whether this is in a peatland area. With these two examples, it is clear that peatlands may be converted to agriculture without any kind of land suitability assessment, which makes the identification of peatland areas in the Philippines all the more urgent.
These threats make it imperative that peatlands are identified and mapped so that appropriate development strategies can be implemented.
Without the ASEAN Peatland Management Initiative (APMI), there is little likelihood that issues on peatlands conservation and sustainable use would have been addressed in the Philippines. The Philippines can benefit greatly from the experience and knowledge gained by other countries in ASEAN in the sustainable management of peatlands, so that information exchange and cooperation with relevant authorities in these other countries is highlighted as a priority in the National Action Plan (NAP).