Estimating Mangrove Above-Ground Biomass Loss Due to Deforestation in Malaysian Northern Borneo between 2000 and 2015 Using SRTM and Landsat Images

Charissa J Wong,Normah A Besar,Joseph Tangah,Satoshi Tsuyuki,Kamlisa U Kamlun,Mui-How Phua,Daniel James

doi:10.3390/f11091018

Abstract

Mangrove forests are highly productive ecosystems and play an important role in the global carbon cycle. We used Shuttle Radar Topography Mission (SRTM) elevation data to estimate mangrove above-ground biomass (AGB) in Sabah, Malaysian northern Borneo. We developed a tree-level approach to deal with the substantial temporal discrepancy between the SRTM data and the mangrove’s field measurements. We predicted the annual growth of diameter at breast height and adjusted the field measurements to the SRTM data acquisition year to estimate the field AGB. A canopy height model (CHM) was derived by correcting the SRTM data with ground elevation. Regression analyses between the estimated AGB and SRTM CHM produced an estimation model (R2: 0.61) with a root mean square error (RMSE) of 8.24 Mg ha−1 (RMSE%: 5.47). We then quantified the mangrove forest loss based on supervised classification of multitemporal Landsat images. More than 25,000 ha of mangrove forest had disappeared between 2000 and 2015. This has resulted in a significant decrease of about 3.96 million Mg of mangrove AGB in Sabah during the study period. As SRTM elevation data has a near-global coverage, this approach can be used to map the historical AGB of mangroves, especially in Southeast Asia, to promote mangrove carbon stock conservation.

Highlights

Deforestation and forest degradation have resulted in a substantial release of greenhouse gases (GHGs) to the atmosphere, constituting approximately 10% of global emissions [1]
We examined the estimation of mangrove above-ground biomass (AGB) in Sabah, Malaysia using Shuttle Radar Topography Mission (SRTM) digital surface model (DSM)
As mangrove areas in Sabah comprises of more than half of the total area of mangrove in Malaysia, baseline information on the mangrove area and its AGB is important to the mechanism of Reduce

Summary

Introduction

Deforestation and forest degradation have resulted in a substantial release of greenhouse gases (GHGs) to the atmosphere, constituting approximately 10% of global emissions [1]. Emissions from Deforestation and Forest Degradation (REDD+) program has been negotiated under the United Nations Framework Convention on Climate Change (UNFCCC) as a viable option for reducing greenhouse-gas emissions from the land-use sector [2]. REDD+ provides financial incentives to assist in the reduction of national carbon emission rates due to deforestation and forest degradation in developing countries [3,4]. While most of the nations have focused on inland forest ecosystems especially tropical forests, the role of mangroves in climate change mitigation has gained considerable interest in recent years [5]. Mangrove forest is one of the most productive forest ecosystems in terms of its efficiency of carbon cycling and storage, as well as carbon sequestering [6,7,8]. About 58.6% of the nation’s mangrove forests are found in Sabah [16], making this state important in the REDD implementation

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