Cassie Freund – In 2020, the Indonesian government set a goal of restoring 600,000 hectares, or nearly 1.5 million acres, of mangrove ecosystems by 2024. Progress toward that goal has been slow: Indonesia's Peatland and Mangrove Restoration Agency (BRGM) reported it had restored 34,911 hectares (86,267 acres) in 2021, more than its stated 30,000-hectare (74,000-acre) target for the year, but still a small percentage of the larger goal. Now, the 600,000-hectare target faces another challenge. A recently published countrywide map of suitable areas for mangrove restoration shows that just 193,367 hectares (477,820 acres) of mangroves, 30% of the target area, is actually suitable for restoration.
The idea behind this new study, led by Sigit Sasmito of the National University of Singapore and Mohammad Basyuni of the University of North Sumatra and published in the journal Nature Ecology & Evolution, was simple. "We were triggered by the fact that there was a big plan to restore 600,000 hectares of mangrove in Indonesia, so we were curious about where to find the land," said co-author Daniel Murdiyarso, principal scientist at CIFOR-ICRAF.
Mangrove restoration is much more complex than simply planting seedlings; whether those seedlings will grow depends on the substrate, hydrology and history of the area they've been planted in, and whether they will persist in the long term is linked to the land tenure status of where they're growing. And, according to Planet Indonesia executive director Adam Miller, planting is not necessarily even the most effective restoration method.
"Research and best practices have shown us that the priority should be on enabling natural recruitment of mangroves, rather than manually replanting them," he told Mongabay. In sum, predicting where restored mangroves will flourish requires understanding the biological, geological and governance factors involved.
Sasmito and Basyuni's team did just that, compiling countrywide data to identify areas of high, medium and low opportunity for mangrove restoration. Just 9% of potential restorable land, they discovered, are high-opportunity areas, with nearly 60% classified as low-opportunity. The most promising areas for restoration are concentrated in five provinces: the Bornean provinces of East, North and West Kalimantan, and the Sumatran provinces of South Sumatra and Riau.
While there's a large disparity between the extent of potentially restorable mangrove area in the new map and the BRGM's goal, the agency's priority provinces generally matched the regions classified by Sasmito and Basyuni's analysis as high-opportunity locations. According to Murdiyarso, their publication captured the BRGM's attention, and he was invited to a "full house" meeting with the agency.
"The good thing about this is that we are invited to work closer with them, to help [with] fine-tuning where these areas are, and what kind of priority they need," he said. Murdiyarso is also part of a WhatsApp group of Indonesian mangrove and conservation experts, many of whom have offered their assistance with restoration in their local regions.
Restoring hundreds of thousands of hectares of Indonesian mangroves would bring numerous benefits to coastal communities and help the country make progress on at least six of the U.N. Sustainable Development Goals. The Kubu Raya mangrove forests in West Kalimantan, parts of which Sasmito and Basyuni's analysis identified as medium-opportunity areas for restoration, are illustrative of these benefits.
"Communities in Kubu Raya draw on the mangroves for a variety of fishery and non-timber-based products," Miller said. Planet Indonesia works with village-level forest management institutions in Kubu Raya to manage and monitor village mangrove management strategies, which include no-take zones and temporary fisheries closures.
Successful mangrove restoration in Kubu Raya and across the country could secure healthy fisheries for coastal communities and improve fisheries-based economies, thereby reducing poverty and hunger, and improving health and well-being for 74 million people. Restoring 193,367 hectares of mangrove ecosystems by 2025 would also contribute to the sequestration of an estimated 22 million metric tons of carbon dioxide equivalent by 2030 and the conservation of hundreds of animal species.
While it remains unclear exactly how many hectares of mangroves the BRGM will restore in the coming two years, it does appear Indonesia is serious about improving its mangrove ecosystems. This new map, and the research group's work with the agency to translate it into priority areas on the ground, is an important piece of the puzzle that proponents say should bring the country closer to achieving its restoration goals.
Sasmito, S. D., Basyuni, M., Kridalaksana, A., Saragi-Sasmito, M. F., Lovelock, C. E., & Murdiyarso, D. (2023). Challenges and opportunities for achieving sustainable development goals through restoration of Indonesia's mangroves. Nature Ecology & Evolution, 7(1), 62-70. doi:10.1038/s41559-022-01926-5