Dr. Shailendra Mishra | Asian School of the Environment, Nanyang Technological University, Singapore.
Abstract
Southeast Asian peatlands are undergoing degradation through drainage and deforestation, accompanied with forest fires. This is occurring at unprecedented rates for agriculture and human settlement purposes. Exposure of carbon-rich peat to air has resulted in enhanced microbial-mediated peat oxidation emitting high levels of potent greenhouse gases (GHGs). Peat oxidation results in land subsidence, thus, increasing the risk of flooding that can affect the livelihoods of millions of people. Peatland restoration of drained peatlands by revegetation and rewetting is being planned on a large scale, as a strategy to reduce fire incidences as well
as mitigate CO2 emissions. However, the immediate consequences of saturating dry peat on greenhouse gas emissions, that result from carbon decomposition are not well understood.
The overall aim of my study is to provide an in-depth understanding of how land-use change and peat management practices affect the below-ground ecology and physicochemical processes leading to peat oxidation and release of GHGs. Firstly, we used molecular marker–based approaches (microbial and metabolic profiles) that revealed the profiles were most influenced by variations in water table and land-use patterns, followed by age of drainage and peat thickness in that order. Towards the revegetation efforts, we found that plantations with mixed cropping had the least subsidence rates (a proxy for peat oxidation) when compared to
monoculture plantation. This pattern is linked with release of diverse exudates from different crops, supporting high below-ground and metabolic diversity in mixed crop plantation. We link this mechanism as a reallocation of carbon-substrates on the root exudates, rather than peat carbon stock. Secondly, we conducted a study to unravel the consequences of drying and wetting on peat carbon decomposition. We show from both controlled microcosms and field studies, that anoxic decomposition from water-saturated peat accounts for nearly 70-80% of CO2 productions. The mechanism behind the continued peat decomposition, even in the wet period associated with high anoxia, was linked with increased nutrient availability (of both
carbon and nitrogen) due to ’priming’ affect.
The overall findings of this study will be useful in peatland management by providing a basis to focus early efforts on hydrological interventions and improving sustainability of oil palm plantations by adopting mixed cropping practices. By adopting these ecological-driven technological solutions, we aim to perform socio-economic analysis in future that can reveal the benefits for the livelihood of people affected by the land-use change in the region.
About me:
Dr. Shailendra Mishra has been working in the area of peatland research since 2009. He uses genomics-derived framework to explain the complexity of below-ground ecosystems by combining meta-omics (metagenomics and metabolomics) with associated metadata (geochemical and physiological data) using multivariate statistical methods. His research interest in the peatland ecosystem is aimed at developing an in-depth understanding of peatoxidation processes due to microbiome functioning, which leads to high greenhouse gas emissions from tropical peatlands. Currently, he is working as a Research Scientist (Fellow)
under Prof David Wardle’s group at Asian School of the Environment, Nanyang Technological University (NTU), Singapore, where he aims to understand the linkages of below- and aboveground processes in tropical peatlands across SE Asian region.