Peatlands are the most extensive natural wetland ecosystems in South East Asia covering some 30 million ha of which 1.7 million ha are found in the coastal lowlands of Sarawak. They are well recognised for their roles as buffers against flood, reservoirs of biodiversity, water extraction; and to the human industry, as provider of timber and non-timber products.
Peatlands are carbon stores. This gives them a role in climate regulation, and thus, global importance in climate change. Socioeconomic needs coupled with limited suitable lands, however, have led to the conversion of peatlands (or peat swamp forests) to other uses, especially for agriculture.
Conversion (or reclamation) of peatland for agriculture uses involve drainage of the waterlogged peatlands. The drainage inevitably leads to surface subsidence; brought about not only by consolidation of peat materials, but also by loss of carbon through carbon dioxide (CO2) emission as the peat air contents increases. The consequence is an immediate negative impact on the environment due to excessive emission of carbon dioxide and other greenhouse gases such as nitric oxide.
Surface subsidence also sets a limit to its agricultural life and productivity. As the peat surface eventually subsides to the same level as the natural groundwater table of the surrounding areas, it leads to increased flooding frequency in settlements and agricultural areas on the peatlands. The net effect is a gradual loss of peatlands as evident from the shrinkage of peatland areas in Sabah (86,000 ha in 1989 to 46,000 ha in 1999).
A multidisciplinary research team, head by Prof. Wan Sulaiman Wan Harun is currently working on a sustainable management of tropical peatland research programme: a comprehensive study of the peatlands in Sarawak which covers the ecology and biodiversity of peat swamp forests, as well as characterisation of the peat soils and the sustainable use of the peatlands.
The research looks at the impact of peat swamp forest clearance and drainage for agriculture, and the mitigation of the impacts with particular emphasis on minimisation of surface subsidence to extend its agriculture or agronomic life, and reduce greenhouse gas emissions. This article highlights four aspects of the programme.
Natural sink for pollutants
The humic substances that made up peatland is a natural sink for pollutants. Here, a study is conducted to determine the chemical characteristics of humic substances in Sarawak's peat, and relate their molecular structural features with pollutant complexing/trapping potentials. Laboratory analyses and comparisons with data from published literatures on humic substances suggest that Sarawak's peat has a strong complexing capability.
Peat subsidence and carbon loss
The agronomic life of peatlands can be sustained/prolonged by adopting a crop mix that will maximise carbon assimilation through rapid vegetative growth, followed by appropriate surface residue management under controlled drainage. An experiment was conducted on a plantation site to explore the possible use of sago palm residues to partially offset or mitigate peat subsidence. And the findings suggest that one strategy to mitigate the impact of peat subsidence and carbon loss is to sustain high crop production levels and retain on site the maximum amount possible of the palm residues.
Large-scale planting on deep peat
Sago has traditionally been grown on mineral soils and shallow peat in a low-input production system. Large-scale (commercial) plantings of sago on deep peat face major production constraints, in particular, palms inability to develop trunks. Studies are currently being conducted to overcome the various production constraints and to gain a comprehensive and deeper understanding of the palm species as an agricultural crop.
Local community livelihood
Almost all the peatlands of Sarawak are located in populated coastal lowland. Management of the peatlands, therefore, need to include how the local communities on and around these peatlands can sustain their livelihood. A case study is being conducted to determine the socio-economic conditions and options for sustaining the livelihood of the communities living on one of the peatland areas. Strategies and recommendations are being formulated to further develop and sustain the livelihood of the local communities to prevent further degradation to the peatlands they inhabit.