Can C-Band SAR be used to estimate soil organic carbon storage in tundra?

Abstract. A new approach for the estimation of Soil Organic Carbon (SOC) pools North of the tree line has been developed based on synthetic aperture radar data (SAR). SOC values are directly determined from backscatter values instead of upscaling using land cover or soil classes. The multi-mode capability of SAR allows application across scales. It can be shown that measurements in C-band under frozen conditions represent vegetation and surface structure properties which relate to soil properties, specifically SOC. It is estimated that at least 29 PgC are stored in the upper 30 cm of soils North of the tree line. This is approximately 25 % less than stocks derived from the soil map based Northern Circumpolar Soil Carbon Database (NCSCD). The total stored carbon is underestimated since the established empirical relationship is not valid for peatlands as well as strongly cryoturbated soils. The approach does however provide the first spatially consistent account of soil organic carbon across the Arctic. Furthermore, it could be shown that values obtained from 1 km resolution SAR correspond to accounts based on a high spatial resolution (2 m) land cover map over a study area of about 7 x 7 km in NE Siberia. The approach can be also potentially transferred to medium resolution C-band SAR data such as ENVISAT ASAR Wide Swath with 120 m resolution but it is in general limited to regions without woody vegetation. Comparisons to the length of unfrozen period indicates the suitability of this parameter for modelling of the spatial distribution of soil organic carbon storage.

Download Full-text

Can C-band synthetic aperture radar be used to estimate soil organic carbon storage in tundra?

Biogeosciences ◽

10.5194/bg-13-5453-2016 ◽

2016 ◽

Vol 13 (19) ◽

pp. 5453-5470 ◽

Cited By ~ 13

Author(s):

Annett Bartsch ◽

Barbara Widhalm ◽

Peter Kuhry ◽

Gustaf Hugelius ◽

Juri Palmtag ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Land Cover ◽

Synthetic Aperture Radar ◽

Carbon Storage ◽

Synthetic Aperture ◽

Tree Line ◽

Soil Organic Carbon Storage ◽

Organic Carbon Storage ◽

Aperture Radar

Abstract. A new approach for the estimation of soil organic carbon (SOC) pools north of the tree line has been developed based on synthetic aperture radar (SAR; ENVISAT Advanced SAR Global Monitoring mode) data. SOC values are directly determined from backscatter values instead of upscaling using land cover or soil classes. The multi-mode capability of SAR allows application across scales. It can be shown that measurements in C band under frozen conditions represent vegetation and surface structure properties which relate to soil properties, specifically SOC. It is estimated that at least 29 Pg C is stored in the upper 30 cm of soils north of the tree line. This is approximately 25 % less than stocks derived from the soil-map-based Northern Circumpolar Soil Carbon Database (NCSCD). The total stored carbon is underestimated since the established empirical relationship is not valid for peatlands or strongly cryoturbated soils. The approach does, however, provide the first spatially consistent account of soil organic carbon across the Arctic. Furthermore, it could be shown that values obtained from 1 km resolution SAR correspond to accounts based on a high spatial resolution (2 m) land cover map over a study area of about 7  ×  7 km in NE Siberia. The approach can be also potentially transferred to medium-resolution C-band SAR data such as ENVISAT ASAR Wide Swath with ∼  120 m resolution but it is in general limited to regions without woody vegetation. Global Monitoring-mode-derived SOC increases with unfrozen period length. This indicates the importance of this parameter for modelling of the spatial distribution of soil organic carbon storage.

Download Full-text

Landscape-scale variability in soil organic carbon storage in the central Canadian Arctic

Canadian Journal of Soil Science ◽

10.4141/cjss-2014-018 ◽

2014 ◽

Vol 94 (4) ◽

pp. 477-488 ◽

Cited By ~ 8

Author(s):

A. Brett Campeau ◽

Peter M. Lafleur ◽

Elyn R. Humphreys

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Land Cover ◽

Carbon Storage ◽

Canadian Arctic ◽

Landscape Scale ◽

Soil Organic Carbon Storage ◽

Landscape Unit ◽

Organic Carbon Storage ◽

Up Scaling

Campeau, A. B., Lafleur, P. M. and Humphreys, E. R. 2014. Landscape-scale variability in soil organic carbon storage in the central Canadian Arctic. Can. J. Soil Sci. 94: 477–488. Arctic soils constitute a vast, but poorly quantified, pool of soil organic carbon (SOC). The uncertainty associated with pan-Arctic SOC storage estimates – a result of limited SOC and land cover data – needs to be reduced if we are to better predict the impact of future changes to Arctic carbon stocks resulting from climate warming. In this study landscape-scale variability in SOC at a Southern Arctic Ecozone site in the central Canadian Arctic was investigated with the ultimate goal of up-scaling SOC estimates with a land cover classification system. Total SOC was estimated to depths of 30 cm and 50 cm for 76 soil pits, together representing eight different vegetation communities in seven different broad landscape units. Soil organic carbon to 50 cm was lowest for the xerophytic herb community in the esker complex landscape unit (7.2±2.2 SD kg m−2) and highest in the birch hummock terrain in the lowland tundra landscape unit (36.4±2.8 kg m−2), followed by wet sedge and dry sedge communities in the wetland complex (29.8±9.9 and 22.0±2.0 kg m−2, respectively). The up-scaled estimates of mean SOC for the study area (excluding water) were 15.8 kg m−2 (to 50 cm) and 11.6 kg m−2 (to 30 cm). On a landscape scale, soil moisture content was found to have an important influence on SOC variability. Overall, this study highlights the importance of SOC variability at fine scales and its impact on up-scaling SOC in Arctic landscapes.

Download Full-text