Biomass Estimation and Mapping of Can Gio Mangrove Biosphere Reserve in South of Viet Nam Using Alos-2 Palsar-2 Data

Abstract

In this study, we used radar data from the ALOS-2 PALSAR-2 satellite to build biomass estimation models and then create a biomass map in Can Gio Mangrove Biosphere Reserve. We used the single variable regression and multivariate regression method, in which 30 sample plots for training model and 15 sample plots for validation model, the coefficient of determination (R 2 ) and root mean square error (RMSE) were used as metrics for evaluating the biomass estimates. The regression analyses showed that the HV polarization was highly related to the biomass, linear model (R 2 = 0.74; RMSE = 28.16), exponential model (R 2 = 0.69; RMSE = 28.73), and polynomial model (R 2 = 0.76; RMSE = 28.03). However, the HH polarization did not show a high relationship with the above-ground biomass, linear model (R 2 = 0.42), exponential model (R 2 = 0.46), or polynomial model (R 2 = 0.42). We also tried multiple linear regression between the parameters extracted from radar image (HH, HV, and textures) and field biomass. The coefficient of determination (R 2 ) between the biomass and two independent variables (HH and HV) was 0.79, and RMSE was 29.78. However, the model with the combination of HV variable and eight texture variables provided a better result (R 2 = 0.81; RMSE = 27.76), in other word the model could explain 81% variation of forest biomass. This model was used to produce the aboveground biomass map in Can Gio Biosphere Reserve in South of Vietnam.

Comparison of the Use of Sentinel-1 Sar and Alos-2 Palsar-2 in Mangrove Aboveground Biomass Estimation in San Juan, Batangas, Philippines

“…With that, in general, ALOS-2 PALSAR-2 still offers a greater potential for improved and effective mangrove AGB estimation compared to Sentinel-1 as supported by previous studies (Huang et al, 2018;Luong et al, 2019;Saatchi, 2019). This advantage stems from its utilization of L-band frequency, which boasts a longer wavelength capable of penetrating deeper into the vertical forest profile.…”

Characterizing Spatiotemporal Patterns of Mangrove Forests in Can Gio Biosphere Reserve Using Sentinel-2 Imagery

“…Additionally, following remotely sensed data, there is a variety of multispectral satellite imagery techniques for spectral indices performance and the determination of mangrove conditions, such as Landsat [21,22], Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) [23,24], Moderate Resolution Imaging Spectroradiometer (MODIS) [25], and Pleiades [26]. Recently, several studies have applied Landsat [27], ALOS PALSAR-2 [28], and Satellite Pour l'Observation de la Terre (SPOT) [8] combined with field observation to characterize mangrove species in the study area. Compared to other digital resource databases, Sentinel-2 provides a greater extent of the distribution of vegetation over the coastal region [29] with a high spatial resolution of 10 m, a high temporal resolution, a five day re-visit interval, and it is free of charge.…”

Seasonal Effects of Backscattering Intensity of ALOS-2 PALSAR-2 (L-Band) on Retrieval Forest Biomass in the Tropics

“…Radar remote sensing from satellites has high potential for biomass estimates at large scale because of its penetrability through clouds, applicability with night time, coverage at large scale, availability of seasonal data, and lower saturation in dense forests (Ulaby et al, 1981;Wu, 1987;Jensen, 2005;Kellndorfer et al, 2004;Ramankutty et al, 2007;Gibbs et al, 2007;Le Toan et al, 2011;Brolly & Woodhouse, 2012;Sinha et al, 2015;Luong et al, 2016;Luong et al, 2019). The long-wavelength SAR satellite is expected to have much promise for estimates of forest biomass (Ramankutty et al, 2007;FAO, 2009 The backscattering intensity of L-band and P-band SAR data have demonstrated sensitivity to structure, cover, volume, and biomass of the forests penetrating into the branches and stems of trees (Jensen, 2005;Sun et al, 2002;Balzter, 2001;Balzter et al, 2007;Luong et al, 2016).…”