ICESat/GLAS Data as a Measurement Tool for Peatland Topography and Peat Swamp Forest Biomass in Kalimantan, Indonesia

Uwe Ballhorn,Juilson Jubanski,Florian Siegert

doi:10.3390/rs3091957

Uwe Ballhorn, Juilson Jubanski + Show 1 more

Open Access

https://doi.org/10.3390/rs3091957

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Abstract

Indonesian peatlands are one of the largest near-surface pools of terrestrial organic carbon. Persistent logging, drainage and recurrent fires lead to huge emission of carbon each year. Since tropical peatlands are highly inaccessible, few measurements on peat depth and forest biomass are available. We assessed the applicability of quality filtered ICESat/GLAS (a spaceborne LiDAR system) data to measure peatland topography as a proxy for peat volume and to estimate peat swamp forest Above Ground Biomass (AGB) in a thoroughly investigated study site in Central Kalimantan, Indonesia. Mean Shuttle Radar Topography Mission (SRTM) elevation was correlated to the corresponding ICESat/GLAS elevation. The best results were obtained from the waveform centroid (R2 = 0.92; n = 4,186). ICESat/GLAS terrain elevation was correlated to three 3D peatland elevation models derived from SRTM data (R2 = 0.90; overall difference = −1.0 m, ±3.2 m; n = 4,045). Based on the correlation of in situ peat swamp forest AGB and airborne LiDAR data (R2 = 0.75, n = 36) an ICESat/GLAS AGB prediction model was developed (R2 = 0.61, n = 35). These results demonstrate that ICESat/GLAS data can be used to measure peat topography and to collect large numbers of forest biomass samples in remote and highly inaccessible peatland forests.

Highlights

Peatlands store huge amounts of carbon as peat consists of dead, incompletely decomposed plant material that has accumulated over thousands of years in waterlogged environments that lack oxygen
ICESat/GeoScience Laser Altimeter System (GLAS) capable of penetrating the dense peat swamp forest cover and to measure the peat surface topography? (2) How accurate is the Shuttle Radar Topography Mission (SRTM) digital elevation model in comparison to ICESat/GLAS measurements on peatlands? (3) How accurate are 3D peatland elevation models derived from SRTM data? (4) How accurate are ICESat/GLAS measurements of peat swamp forest canopy heights compared to airborne Light Detection and Ranging (LiDAR) measurements? (5) Is it possible to derive a peat swamp forest Above Ground Biomass (AGB) prediction model from ICESat/GLAS data based on airborne LiDAR and forest inventory data?
The ICESat/GLAS data is referenced to a consistent geodetic reference frame, so that its horizontal and vertical geolocation accuracy and its ability to resolve the height distribution of elevations within the laser footprint, provides a set of accurate control points which can be used to investigate the vertical accuracy of the SRTM digital elevation model [53]

Summary

Introduction

Peatlands store huge amounts of carbon as peat consists of dead, incompletely decomposed plant material that has accumulated over thousands of years in waterlogged environments that lack oxygen. Peatland is usually covered by forests and current estimates indicate that the total area of tropical peatland is in the range of 30–45 million ha (approximately 10–12% of the total global peatland resource); about 16.8–27.0 million ha are found in Indonesia [1]. This is one of the largest near-surface pools of terrestrial organic carbon [1,2,3,4]. In particular drainage and forest clearance disturb the hydrological stability [3] and make these otherwise waterlogged ecosystems susceptible to fire [11]

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