TY - JOUR
T1 - Empirical relationships between AIRSAR backscatter and LiDAR-derived forest biomass, Queensland, Australia
AU - Lucas, Richard M.
AU - Cronin, Natasha
AU - Lee, Alex
AU - Moghaddam, Mahta
AU - Witte, Christian
AU - Tickle, Phil
PY - 2006/2/15
Y1 - 2006/2/15
N2 - To evaluate the use of multi-frequency, polarimetric Synthetic Aperture Radar (SAR) data for quantifying the above ground biomass (AGB) of open forests and woodlands, NASA JPL AIRSAR (POLSAR) data were acquired over a 37 x 60 km area west of Injune, central Queensland, Australia. From field measurements recorded within 32 50 x 50 m plots, AGB was estimated by applying species-specific allometric equations to stand measurements. AGB was then scaled-up to the larger area using relationships established with Light Detection and Ranging (LiDAR) data acquired over 150 (10 columns, 15 rows) 500 x 150 m cells (or Primary Sampling Units, PSUs) spaced 4 x 4 km apart in the north- and east-west directions. Large-scale (1 : 4000) stereo aerial photographs were also acquired for each PSU to assess species composition. Based on the LiDAR extrapolations, the median AGB for the PSU grid was 82 Mg ha - 1 (maximum 164 Mg ha- 1), with the higher levels associated with forests containing a high proportion of Angophora and Callitris species. Empirical relationships between AGB and SAR backscatter confirmed that C-, L- and P-band saturated at different levels and revealed a greater strength in the relationship at higher incidence angles and a larger dynamic range and consistency of relationships at HV polarizations. A higher level of saturation (above ∼50 Mg ha- 1) was observed at C-band HV compared to that reported for closed forests which was attributable to a link between foliage projected cover (FPC) and AGB. The study concludes that L-band HV backscatter data acquired at incidence angles approaching or exceeding 45° are best suited for estimating the AGB up to the saturation level of ∼80-85 Mg ha- 1. For regional mapping of biomass below the level of saturation, the use of the Japanese Space Exploration Agency (JAXA) Advanced Land Observing Satellite (ALOS) Phase Arrayed L-band SAR (PALSAR) is advocated.
AB - To evaluate the use of multi-frequency, polarimetric Synthetic Aperture Radar (SAR) data for quantifying the above ground biomass (AGB) of open forests and woodlands, NASA JPL AIRSAR (POLSAR) data were acquired over a 37 x 60 km area west of Injune, central Queensland, Australia. From field measurements recorded within 32 50 x 50 m plots, AGB was estimated by applying species-specific allometric equations to stand measurements. AGB was then scaled-up to the larger area using relationships established with Light Detection and Ranging (LiDAR) data acquired over 150 (10 columns, 15 rows) 500 x 150 m cells (or Primary Sampling Units, PSUs) spaced 4 x 4 km apart in the north- and east-west directions. Large-scale (1 : 4000) stereo aerial photographs were also acquired for each PSU to assess species composition. Based on the LiDAR extrapolations, the median AGB for the PSU grid was 82 Mg ha - 1 (maximum 164 Mg ha- 1), with the higher levels associated with forests containing a high proportion of Angophora and Callitris species. Empirical relationships between AGB and SAR backscatter confirmed that C-, L- and P-band saturated at different levels and revealed a greater strength in the relationship at higher incidence angles and a larger dynamic range and consistency of relationships at HV polarizations. A higher level of saturation (above ∼50 Mg ha- 1) was observed at C-band HV compared to that reported for closed forests which was attributable to a link between foliage projected cover (FPC) and AGB. The study concludes that L-band HV backscatter data acquired at incidence angles approaching or exceeding 45° are best suited for estimating the AGB up to the saturation level of ∼80-85 Mg ha- 1. For regional mapping of biomass below the level of saturation, the use of the Japanese Space Exploration Agency (JAXA) Advanced Land Observing Satellite (ALOS) Phase Arrayed L-band SAR (PALSAR) is advocated.
KW - Biomass
KW - Forests
KW - Incidence angle
KW - Polarization
KW - Saturation
KW - Synthetic aperture radar
UR - http://www.scopus.com/inward/record.url?scp=31344454624&partnerID=8YFLogxK
U2 - 10.1016/j.rse.2005.10.019
DO - 10.1016/j.rse.2005.10.019
M3 - Article
SN - 0034-4257
VL - 100
SP - 407
EP - 425
JO - Remote Sensing of Environment
JF - Remote Sensing of Environment
IS - 3
ER -