A scientific research project into greenhouse gas emissions on tropical peatland landscapes has published its initial findings on methane (CH4) gas emissions in Riau province, Sumatra, Indonesia.
The study found that tropical peatlands are significant CH4 sources and likely have a greater impact on global atmospheric concentrations than previously thought, while also establishing new links between ground water levels and methane emissions across different land use types.
The research, among the first of its kind to assess CH4 emissions in tropical peatlands using the eddy covariance technique, is the result of a two-year intensive monitoring program of methane emissions across natural and plantation forests in Riau, Sumatra, carried out by a group of international scientists from Indonesia, the UK, Finland and the U.S. The full study can be viewed here.
The aim of the study, which was supported by APRIL Group, is to build on the current understanding of emission factors in tropical peatland landscapes and to enhance knowledge of the relationship between the management of tropical landscapes and greenhouse gas emissions.
Led by Dr. Chandra Deshmukh, Greenhouse Gas Monitoring Manager, APRIL Group, the peer reviewed study found that groundwater levels control variables in methane emissions, and that higher methane emissions from natural forest may be attributed to higher groundwater levels. As groundwater levels decline, methane emissions also decrease, according to the study.
The measurement of methane emissions was carried out using the eddy covariance technique, drawing on data from two 40-m and 48-m flux towers situated in plantation and natural forest areas. The flux towers provide high frequency measurements every 30 minutes, with each tower covering an area of more than 200 hectares.
The eddy covariance technique is designed to calculate the net exchange or the balance between the removals and emission of methane between ecosystems and the earth’s atmosphere. The results are then used to quantify the imbalance between the net methane exchanges between natural forest and Acacia crassicarpa plantations.
The publication of this study is the first part of a comprehensive series of research publications from APRIL’s peatland science research jointly with the Independent Peat Expert Working Group on greenhouse gas exchanges on tropical peatland landscapes that will also focus on carbon dioxide and nitrous oxide emissions.
Understanding methane emissions is an important aspect of the research project because it is one the most potent greenhouse gases and extremely efficient at trapping radiation and warming the atmosphere. A kilogram of CH4 warms the planet 84 times more than a kilogram of CO2 over a 20-year period after being released to the atmosphere*. Methane is produced from natural processes, such as decomposition in low-oxygen conditions as well as human activities such as farming and horticulture.
The new findings contribute to the understanding of methane emissions in tropical landscapes, filling an important research gap, according to Professor Fahmuddin Agus, co-author and member of the Indonesian Soil Research Institute: “Tropical peatlands are a known source of methane to the atmosphere, but their contribution to atmospheric methane is poorly understood.”
“This work fills critical knowledge gaps in our science on tropical peatland methane cycling. Our results show that tropical peatlands probably have a greater impact on global atmospheric methane concentrations than previously thought,” he said.
Professor Susan Page, of the University of Leicester, one of the co-authors of the study, said: “We found that the annual methane emissions from the natural forest were around twice as high as those of the acacia plantation.”
The results of the study are among the first eddy covariance methane exchange data reported for tropical peatland globally and should help to reduce the uncertainty in the estimation of CH4 emissions from important peatland ecosystems, according to Professor Chris Evans, of the UK Centre for Ecology and Hydrology.
“It will also help provide a more complete estimate of the impact of land-cover change on tropical peat, and to develop science-based peatland management practices that help to minimize greenhouse gas emissions.”
Dr. Deshmukh was supported by a team of international scientists, including: Prof. Page; Prof. Agus; Prof. Evans; Prof. Supiandi Sabiham, Bogor Agricultural University; Prof. Ari Lauren, University of Eastern Finland; Prof. Ankur Desai, University of Wisconsin-Madison; and Prof. Vincent Gauci, University of Birmingham.
The team also received essential support from a team of APRIL researchers, which included: Dr. Sofyan Kurnianto; Yogi Suardiwerianto; Dony Julius; Adibtya Asyhari; Ari Susanto; and Nardi.
*IPCC AR5, Chapter 8, Table 8.7
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