July 6, 2020
Coastal ecosystems like mangroves absorb carbon dioxide (CO2) called blue or organic carbon. When such ecosystems are damaged, this may lead to adverse effects to the environment.
Healthy coastal ecosystems can help reduce hazards during natural disasters, according to a joint research of Filipino and Japanese researchers from the University of the Philippines (UP) Diliman and Tokyo Institute of Technology. Thus, said researchers recently proposed a new mangrove vegetation index to facilitate easy and rapid mapping of mangroves from satellite images.
A scientific paper on the Mangrove Vegetation Index (MVI) was released this June and is published in the International Society for Photogrammetry and Remote Sensing (ISPRS) Journal via ScienceDirect, a global database of scientific and medical journals.
"A mangrove mapping index derived from free satellite images is crucial for regular monitoring of our mangrove forests, especially when it is integrated in online mapping platforms like Google Earth Engine," said Alvin Baloloy, Senior Researcher at UP Diliman. "We have recently simplified a mangrove index that will support rapid and accurate mapping of mangroves that will not only be useful in our study sites in the Philippines and Japan but also in other mangrove-rich countries."
The MVI is a mangrove-specific index or measure that distinguishes mangrove areas from other vegetation. The MVI value increases with higher probability of an area being classified as mangroves.
The MVI analyzed the characteristics of mangrove and non-mangrove sites in the Philippines and in Japan and was incorporated in IDL (a scientific programming language) and Google Earth Engine.The study developed and implemented two automated platforms: an offline IDL-based MVI Mapper and an online Google Earth Engine-based MVI mapping interface. These platforms can be used to identify and measure areas with mangroves. The latter was used in generating the latest mangrove extent map of the Philippines - with an estimate of 227,808 hectares for year 2019.
A hectare of mangroves can provide more than USD 3,200 worth of direct flood reduction benefits per year, according to a 2017 World Bank policy brief on Valuing the Protection Services of Mangroves in the Philippines.
Mangrove extent maps derived using the new MVI were close to previous estimates derived from more complex techniques and were more than 90% accurate.
The MVI is one of the outcomes of an ongoing five-year research project of Japan International Cooperation Agency (JICA) and Japan Science and Technology Agency (JST). Called the Comprehensive Assessment and Conservation of Blue Carbon Ecosystems and their Services in the Coral Triangle or BlueCARES project, the research aims to help policy makers develop scientific-based conservation measures or Blue Carbon Strategy to preserve and improve coastal ecosystems.
The development of the MVI also utilized field data from the IAMBlueCECAM Program, the BlueCARES counterpart program in the Philippines. IAMBlueCECAM stands for Integrated Assessment and Modelling of Blue Carbon Ecosystems for Conservation and Adaptive Management. The program is funded by the Philippine Council for Industry, Energy and Emerging Technology Research and Development (PCIEERD).
"We aim to leverage our findings to support a Blue Carbon Strategy to help mitigate the impact of extreme weather and other threats to coastal environments and ensure a future worthy for the next generation," said Dr. NADAOKA Kazuo, Japanese Chief Technical Advisor of the BlueCARES project. The Blue Carbon Strategy refers to the policy framework on blue carbon conservation that can be implemented at the national and local levels.
The BlueCARES study sites include Busuanga Island, northern and eastern coast of Panay Island, Samar, Leyte, Bolinao, and Boracay Island in the Philippines; Japan's Yaeyama Islands in Okinawa; and Berau-Derawan Islands, Northern Sulawesi Peninsula, Nusa Penida Islands, Karimunjawa Islands, and Northern Coast of Java Island in Indonesia.
BlueCARES is the first trilateral initiative under JICA's Science and Technology Research Partnership for Sustainable Development (SATREPS) that promotes research to address socio-economic issues. In the Philippines, past SATREPS initiatives included coastal conservation study, extreme weather monitoring, leptospirosis prevention and control, childhood pneumonia, and earthquake and volcano monitoring.