Uncertainty in Peat Volume and Soil Carbon Estimated Using Ground‐Penetrating Radar and Probing

Abstract

I Estimating soil C stock in a peatland is highly dependent on accurate measurement of the peat volume. In this study, we evaluated the uncertainty in calculations of peat volume using high-resolution data to resolve the threedimensional structure of a peat basin based on both direct (push probes) and indirect geophysical (ground-penetrating radar) measurements. We compared volumetric estimates from both approaches, accounting for potential sources of error, with values from the literature. Approximate uncertainty of 14 to 23% was observed in the basin volume, and the total uncertainty roughly doubled when incorporating peat properties to derive the estimated C pool. Uncertainties in final C stock values are based on the uncertainty of the basin volumes and the variability in the peat properties and range between 31 and 38%. The results indicate that the well-established ground-penetrating radar technique that is scalable to larger peatlands can be used to ohtain estimates of peat basin volumes at uncertainty levels similar to those for invasive direct probe surveys. This investigation demonstrated that ground-penetrating radar can quantify peat basin volumes at uniquely high spatial resolution without the need for extensive and invasive direct probing.

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

“…2 and 5b, respectively) and able to quantify depth of the peat-mineral soil interface at centimeter-scale resolution both vertically and laterally from a strong reflector that matched closely with coring results. This reflector resembles the peat-mineral soil interface as typically detected with GPR in boreal peatlands in North America and Europe, exemplified in several studies for those higher-latitude systems (Warner et al, 1990;Jol and Smith, 1995;Slater and Reeve, 2002;Parsekian et al, 2012;Comas et al, 2013). However, the GPR method, as used with antenna frequencies available for this study, was limited for imaging deep (i.e., 9 m or more) peat columns (i.e., Sites P1 and P2) in this study.…”

“…Due to the high water content of peat soils, the ε r(b) of peat is very high compared to inorganic mineral soils, reaching values of 50-70 depending on peat type. When ε r(b) is generally well constrained from velocity analysis, estimation of peat depth is typically accurate to within ∼ 20 cm (Parsekian et al, 2012).…”

“…Recent studies of peat thickness and peat basin volume using GPR include a variety of field sites and typically indicate discrepancies in peat volume estimates of about 20 % when compared to traditional direct methods such as coring (Rosa et al, 2009;Parsekian et al, 2012;Parry et al, 2014). Electrical resistivity imaging (ERI) has also been used in boreal systems for investigating several aspects of peatland stratigraphy and hydrogeology (Meyer, 1989;Slater and Reeve, 2002;Comas et al, 2004Comas et al, , 2011; however, no studies to our knowledge have focused on peat thickness characterization using ERI.…”

Representing northern peatland microtopography and hydrology within the Community Land Model

“…The peatlands are surrounded by gently sloping upland mineral soils that drain toward the peatland. The peat deposit in the S1-Bog is generally 2 to 4 m deep with maximum depths of 11 m (Parsekian et al, 2012). In a typical year, the peatland water table fluctuates within the top 30 cm of peat , which corresponds to peats that are least decomposed and have the highest hydraulic conductivities .…”

A comprehensive data acquisition and management system for an ecosystem-scale peatland warming and elevated CO<sub>2</sub> experiment

“…Peat depths generally range from 2 to 3 m over the experimental area but are as deep as 9 m in small pockets (Parsekian et al, 2012). The entire bog is underlain by mineral soil.…”