Karin M. Viergever

Monitoring the World's Savanna Biomass by Earth Observation

Abstract Savannas constitute approximately 40% of the tropics and occur primarily in developing countries. Their net primary productivity rates are third only to tropical and temperate forests. Due to their high carbon sequestration potential savannas are likely to become important areas under Kyoto Protocol initiatives for removing CO2 from the atmosphere. They are, however, prone to human pressure. It is therefore important that accurate methods for the estimation of savanna biomass are developed which can be repeated for monitoring purposes. The paper examines research conducted to evaluate the use of Synthetic Aperture Radar (SAR) for estimating the biomass of the woody vegetation within a savanna in Belize, Central America. Results show that established SAR methods for estimating biomass for closed canopy forest are not directly transferable to the non-continuous cover woodlands that frequently occur in savanna areas. This has important implications for Earth observation satellites launched for the purpose of global biomass estimation.

Backscatter and interferometry for estimating above-ground biomass of sparse woodland: A case study in Belize

Tropical savannas cover 20% of the Earths land surface and are important ecosystems in the global carbon cycle due to their high productivity. This paper evaluates the use of SAR for estimating above-ground biomass of the woody vegetation in heterogeneous tropical savanna woodland in Belize, Central America. Single-pass shortwave InSAR data used are X-band (Intermap) and C-band (AIRSAR and SRTM). L- and P-band SAR backscatter data are from AIRSAR. Results show that SAR backscatter has a relatively low correlation to above ground biomass in the sparse savanna woodlands. Retrieved canopy heights from both X- and C-band InSAR give a better representation of the spatial distribution of AGB, but cannot be used to estimate biomass directly due to the heterogeneity of the canopy.

Sar Interferometry For Estimating Above-Ground Biomass Of Savanna Woodlands In Belize

Tropical savannas cover 20% of the Earths land surface and are important ecosystems in the global Carbon cycle due to their high productivity. This paper evaluates the capability of different shortwave synthetic aperture radar interferometry (InSAR) data for estimating above-ground biomass of the woody vegetation in heterogeneous tropical savanna woodland in Belize, Central America. Single-pass InSAR data used are X-band (Intermap) and C-band (AIRSAR and SRTM). Results show that retrieved canopy heights from both X- and C-band InSAR are indicative of general patterns of tree height, but the details remain inaccurate due to the heterogeneity of the canopy. Scattering phase centers for C-band are generally higher than for X-band over sparse woodlands, whereas dense tropical forest areas yield higher X-band scattering phase centers.

backscatter and interferometry for estimating above- ground biomass intropical savanna woodland

Tropical savannas cover 15% of the Earths land surface and are important ecosystems in the global Carbon cycle due to their high productivity. SAR interferometry and backscatter are investigated for estimating biomass in a tropical savanna in Belize, Central America. Single-pass InSAR data used are C-band (AIRSAR) and X-band (Intermap); SAR backscatter data used are fully polarimetric L and P band (AIRSAR). Results show that both C-band and X-band InSAR show a clear trend in vegetation patterns although both underestimate vegetation heights due to the heterogeneity of the vegetation cover. The scattering phase centre is lowered more for the X-band due to larger ground- level contribution. High P and L-band backscatter values are observed for areas containing high biomass vegetation, but also for leafy palmetto that have relatively low biomass.

Airborne Synthetic Aperture Radar for Estimating Above-ground Woody Biomass in Tropical Savanna Woodland: A Case Study in Belize

The capability of synthetic aperture radar (SAR) for estimating above-ground woody biomass in tropical savanna woodland is investigated, primarily through the estimation of canopy height from SAR interferometry (InSAR). The study area is a heterogeneous savanna woodland. Radar data used are AIRSAR C-band SAR interferometry (InSAR) and fully polarimetric L and P band SAR and Intermap Technologies Xband InSAR data. Results show that although X and C-band DSMs are indicative of general vegetation patterns, the height retrieval remains inaccurate due to the heterogeneity of the savanna woodland canopy. Initial results also show that L-hv and P-hv backscatter is dominated not only by high biomass areas, but also by areas of leafy palmetto. Keywords-biomass estimation, tree height, tropical savanna woodland;heterogeneous, digital surface model (DSM); AIRSAR, Intermap Technologies.