Imaging tropical peatlands in Indonesia using ground-penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization

[摘要] Current estimates of carbon (C) storage in peatland systems worldwideindicate that tropical peatlands comprise about 15% of the global peat carbonpool. Such estimates are uncertain due to data gaps regarding organic peatsoil thickness, volume and C content. We combined a set of indirectgeophysical methods (ground-penetrating radar, GPR, and electricalresistivity imaging, ERI) with direct observations using core sampling and Canalysis to determine how geophysical imaging may enhance traditional coringmethods for estimating peat thickness and C storage in a tropical peatlandsystem in West Kalimantan, Indonesia. Both GPR and ERI methods demonstratedtheir capability to estimate peat thickness in tropical peat soils at a spatialresolution not feasible with traditional coring methods. GPR is able tocapture peat thickness variability at centimeter-scale vertical resolution,although peat thickness determination was difficult for peat columnsexceeding 5 m in the areas studied, due to signal attenuation associatedwith thick clay-rich transitional horizons at the peat–mineral soilinterface. ERI methods were more successful for imaging deeper peatlandswith thick organomineral layers between peat and underlying mineral soil.Results obtained using GPR methods indicate less than 3% variation inpeat thickness (when compared to coring methods) over low peat–mineral soilinterface gradients (i.e., below 0.02°) and show substantial impacts inC storage estimates (i.e., up to 37 MgC ha⁻¹ even for transects showing adifference between GPR and coring estimates of 0.07 m in average peatthickness). The geophysical data also provide information on peat matrixattributes such as thickness of organomineral horizons between peat andunderlying substrate, the presence of buried wood, buttressed trees ortip-up pools and soil type. The use of GPR and ERI methods to image peatprofiles at high resolution can be used to further constrain quantificationof peat C pools and inform responsible peatland management in Indonesia andelsewhere in the tropics.

[学科分类] 地球化学与岩石