PhD student, University of Nottingham
Soil microbial commiunities and GHG emissions under different land use types in Malaysian peatlands:
Tropical peatlands are complex and globally important ecosystems supporting distinctive biodiversity and high carbon storage. About 68% of the carbon-rich tropical peatlands are present in South East Asia with highest cover in Indonesia and Malaysia. The microbes in peatlands play an important role in overall ecosystem function and balance. Despite the importance of microbes in tropical peatlands and their potential implications on climate change, they are understudied and are largely unknown. This project aims to find out the effect of disturbance on soil microbial communities and GHG emissions from different land use types in North Selangor Peatlands in Peninsular Malaysia. The initial results of PLFA analysis show that the phenotypic structure of microbial communities was distinct between different land use types, and showed coherent and consistent change with depth within the types. There was a characteristic and distinct shift in community structure at circa 1 metre possibly governed by the water table. The wet season measurements for CO2 and CH4 emissions were taken from November 2016 to January 2017 and the dry seasons measurement were taken at July 2017. The CO2 emissions were highest in the forest site at 913.1 mg m-2 hr-1 and lowest at the first generation oil palm (OP) at 603.1 mg m-2 hr-1. The 2nd generation intercropping sites had slightly higher emissions than the 1st generation OP site, while the emissions from 2nd generation oil palm is closer to the emissions in the forest site. The high emission in forest might be due to high autotrophic respiration matched by high primary production. The 1st generation OP and the intercropping sites retained most of the 89.8% organic content found in forest peat, but the organic content decreased with generations of mono-cropping with 2nd generation OP containing less than 50% organic matter. The CH4 emissions were under 1 mg m-2 hr-1 in all sites. The results show clear loss of carbon and increased emissions with older generations of OP mono-cropping, while the practice of inter-cropping were found to retain the peat organic content and maintain lower carbon emissions. The future work will be focused on exploring the relationship between microbial communities and the GHG emissions and their implication on climate change.
Abstract: The environmental impacts with regard to agro-based biofuel production have been associated with the impact of greenhouse gas (GHG) emissions. In this study, field GHG emissions during plantation stage of palm oil-based biofuel production associated with land use changes for oil palm plantation development have been evaluated. Three different sites of different land use changes prior to oil palm plantation were chosen; converted land-use (large and small-scales) and logged-over forest. Field sampling for determination of soil N-mineralisation and soil organic carbon (SOC) was undertaken at the sites according to the age of palm, i.e. <5 years (immature), 5-20 and >21 years (mature oil palms). The field data were incorporated into the estimation of nitrous oxide (N2O) and the resulting CO2-eq emissions as well as for estimation of carbon stock changes. Irrespective of the land conversion scenarios, the nitrous oxide emissions were found in the range of 6.47-7.78 kg N2O-N/ha resulting in 498-590 kg CO2-eq/ha. On the other hand, the conversion of tropical forest into oil palm plantation has resulted in relatively higher GHG emissions (i.e. four times higher and carbon stock reduction by >50%) compared to converted land use (converted rubber plantation) for oil palm development. The conversion from previously rubber plantation into oil palm plantation would increase the carbon savings (20% in increase) thus sustaining the environmental benefits from the palm oil-based biofuel production.
Pub.: 23 Dec '16, Pinned: 07 Nov '17
Abstract: Greenhouse gas emissions were measured from tropical peatlands of Kalimantan, Indonesia. The effect of hydrological zone and land-use on the emission of N2O, CH4 and CO2 were examined. Temporal and annual N2O, CH4 and CO2 were then measured. The results showed that the emissions of these gases were strongly affected by land-use and hydrological zone. The emissions exhibited seasonal changes. Annual emission of N2O was the highest (nearly 1.4 g N m−2y−1) from site A-1 (secondary forest), while there was no signi.cant difference in annual N2O emission from site A-2 (paddy field) and site A-3 (rice-soybean rotation field). Multiplying the areas of forest and non-forest in Kalimantan with the emission of N2O from corresponding land-uses, the annual N2O emissions from peat forest and peat non-forest of Kalimantan were estimated as 0.046 and 0.004 Tg N y−1, respectively. The emissions of CH4 from paddy field and non-paddy field were estimated similarly as 0.14 and 0.21 Tg C y−1, respectively. Total annual CO2 emission was estimated to be 182 Tg C y−1. Peatlands of Kalimantan, Indonesia, contributed less than 0.3 of the total global N2O, CO2 or CH4 emission, indicating that the gaseous losses of soil N and C from the study area to the atmosphere were small.
Pub.: 01 Jan '05, Pinned: 27 Sep '17
Abstract: The upcoming global mechanism for reducing emissions from deforestation and forest degradation in developing countries should include and prioritize tropical peatlands. Forested tropical peatlands in Southeast Asia are rapidly being converted into production systems by introducing perennial crops for lucrative agribusiness, such as oil-palm and pulpwood plantations, causing large greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change Guidelines for GHG Inventory on Agriculture, Forestry, and Other Land Uses provide an adequate framework for emissions inventories in these ecosystems; however, specific emission factors are needed for more accurate and cost-effective monitoring. The emissions are governed by complex biophysical processes, such as peat decomposition and compaction, nutrient availability, soil water content, and water table level, all of which are affected by management practices. We estimate that total carbon loss from converting peat swamp forests into oil palm is 59.4 ± 10.2 Mg of CO(2) per hectare per year during the first 25 y after land-use cover change, of which 61.6% arise from the peat. Of the total amount (1,486 ± 183 Mg of CO(2) per hectare over 25 y), 25% are released immediately from land-clearing fire. In order to maintain high palm-oil production, nitrogen inputs through fertilizer are needed and the magnitude of the resulting increased N(2)O emissions compared to CO(2) losses remains unclear.
Pub.: 18 Nov '10, Pinned: 27 Sep '17