Greenhouse gas exchange of tropical peatlands - A review

This article presents data on greenhouse gas (ghg) exchange of tropical peat soils with emphasis on changes in emissions of gases during and following the conversion of native tropical peatlands to plantations of oil palm and other crops. the relevant ghgs are carbon dioxide (co2),methane (ch 4) and nitrous oxide (n2o). establishment of plantations on peat requires drainage,which,even if controlled,results in peat aeration and subsidence. subsidence is mainly due to natural consolidation,often augmented by mechanical compaction,and is manifested as increased bulk density. aeration causes carbon to be released as co2. methods for distinguishing and quantifying these processes are discussed. exchanges of ch4 and n2o are also changed by plantation development and are influenced by management practices but the quantities involved are small and in some cases peat soils even act as a sink and not a source,of these gases. there are seasonal changes in the ghg fluxes related to both water table depth and rainfall,and emissions of ch4 and n2o can be promoted by nitrogen application. ghg exchange of reclaimed peat is dominated by co2 despite the higher global warming potential of ch4 and n2o. methods for estimating co2 fluxes are reviewed and their shortcomings are examined. the importance of adequately distinguishing between emission sources,e.g. root and microbial respiration when evaluating carbon fluxes at the surface of peat soils is emphasised.