Estimating Above Ground Biomass and Carbon Stocks of the Budongo Tropical Rainforest Using Polarimetric Synthetic Aperture Radar (SAR) Interferometry

Abstract

Estimation of biomass is an important means for understanding the dynamics of a forest ecosystem and the effect of forest disturbances on productivity and carbon storage of forest stands. In the recent years, there has been a growing interest in the possibility of using remote sensing to estimate carbon stocks in terrestrial systems such as tropical rainforests. Radar remote sensing is being adopted as a popular method for estimating above ground biomass over large areas because of its ability to penetrate through cloud cover and the forest canopy. The traditional approaches to estimating Carbon Stocks are labor-intensive, less accurate, and do not provide for continuous monitoring of AGB. The looming climate and the high rates of carbon emissions on a global scale call for high-quality monitoring systems to assess the amount of Carbon present in terrestrial systems. Research on carbon storage and absorption capability of forests is thus very vital, to help in formulating emission reduction strategies for sustainable development. This study seeked to use Polarimetric Synthetic Aperture Radar Interferometry to estimate Carbon stocks over the Budongo Tropical rainforest. The technique was adopted to reduce signal saturation, which is a major limitation in SAR remote sensing systems for higher biomass levels, to allow for a detailed characterization of Carbon stocks. Radar images of the study area were decomposed into higher order scattering mechanisms through polarimetric phase analysis. Thereafter, forest heights were derived by intereformetric differencing of two images of a scene acquired at different times. Field allometric measurements were used for training and validation. Above ground biomass and Carbon Stocks were then estimated through regression analysis. The findings of the study shed light on the substantial carbon storage potential of the Budongo Rainforest, with AGB estimates reaching up to 7014.39 kg/ha, and Carbon Stocks upto 3507.19 Kg/ha. These estimates demonstrate the forest's capacity as a significant carbon sink and its potential contribution to climate change mitigation efforts.