- A new study shows mangroves in Tacloban, the Philippine city hit hardest hit by Typhoon Haiyan in December 2013, have expanded beyond pre-storm levels.
- This recovery was driven by community-led reforestation efforts from 2015-2018, when residents planted 30,000 Rhizophora mangrove seedlings across 4 hectares (10 acres) of Cancabato Bay.
- Satellite image analysis and modeling reveal how the forest was destroyed by Haiyan and how it later withstood 2019’s Typhoon Phanfone.
- However, experts warn that the recovering mangroves may be threatened by an ongoing project to build a causeway across the bay, which could generate pollution and physical disturbances.
Mangroves in the Philippine city of Tacloban, the area hit hardest by one of the most powerful typhoons ever recorded, have recovered and even expanded beyond their pre-disaster extent, thanks largely to community-led reforestation. But scientists caution that ongoing coastal development could threaten the recovering forests.
In a recently published study, Hiroshi Takagi, a professor at the Institute of Science Tokyo, examined mangrove recovery in the Paraiso neighborhood in the innermost part of Tacloban’s Cancabato Bay. He used satellite imagery to track the decline and rebound of mangrove canopy following the devastation wrought by Typhoon Haiyan (known in the Philippines as Typhoon Yolanda) in November 2013. He also applied wind, wave and storm surge modeling to assess the extent of typhoon-induced impacts on the forest.
His modeling showed that Haiyan generated storm surges of 4.7 meters (15.4 feet), waves up to 1.3 meters (4.3 feet), and wind gusts of around 148 kilometers per hour (92 miles per hour) — strong enough to flatten the area’s mature Rhizophora apiculata mangrove trees. Satellite images also revealed a sharp drop in vegetation after the storm and minimal coastal recovery in the following three years. Growth began accelerating around 2018, and by 2023, the mangrove area had expanded even beyond pre-Haiyan levels, reaching an estimated 3.6 hectares (8.9 acres) compared to about 1.9 hectares (4.7 acres) before the storm.
This rebound corresponded with reforestation efforts carried out between 2015 and 2018, when residents, assisted by NGOs and the Philippine and Japanese governments, planted some 30,000 seedlings across about 4 hectares (10 acres). Prior to Haiyan, the site included mangrove palms (Nypa fruticans) planted through earlier coastal rehabilitation efforts, but these were uprooted by the storm’s surge. Following the disaster, the community introduced deeper-rooted R. apiculata, and Asiatic mangroves (Rhizophora mucronata), which have since thrived in the bay’s calm, sheltered environment.
The study notes that the planted mangroves “appeared to have withstood” Typhoon Phanfone (known locally as Ursula), which struck in December 2019, “with minimal damage,” offering an indication of early storm resilience.
Takagi told Mongabay in an email that the results demonstrate how quickly mangroves can recover under suitable conditions. “This study provides a concrete example that even when a mangrove forest is devastated by a powerful typhoon, it can recover in a relatively short time with effective afforestation efforts,” he said.
While old-growth mangrove stands provide superior coastal protection and a wide range of ecosystem services, Takagi noted that young mangroves also gain resilience within a relatively short period. “After one to two years from planting, they can endure typhoons of average strength,” he said, referring to< similar findings from sites impacted by Typhoon Haishen in Japan in 2020 and Typhoon Ragasa in Macau this year.
Takagi recommended early action in post-disaster zones. “It is advisable to carry out replanting as early as possible after everyday life is restored and debris has been removed,” he said.
Importance of community stewardship
Beyond biophysical factors, Takagi emphasized the central role of local involvement. “I believe community-led mangrove planting and maintenance efforts are indispensable for mangrove conservation,” he said.
He noted that successful projects can attract additional partners. “If a project proves as successful as the Paraiso mangrove initiative, secondary stakeholders, such as local governments and companies, will take notice and may consider providing further support to the community,” he said.
Takagi also said collaboration between residents and researchers improves outcomes. “A way to strengthen this positive mechanism is for the community to work with scientists and researchers, enabling them to share their experiences with wider audiences nationally and internationally, supported by scientific evidence,” he said.
Residents later established the Paraiso Mangrove Eco-Learning Park, which the study describes as a community-driven environmental education initiative emerging from the reforestation effort.
Potential risks from coastal development
The study didn’t assess potential impacts of ongoing coastal development projects, but it underscored the importance of stable sediment conditions, clean water, and low hydrodynamic disturbance — factors that large coastal structures can affect.
This is particularly relevant to the ongoing $81 million Tacloban City Causeway Project, a 2.56-kilometer (1.59-mile) road embankment and reclamation structure across Cancabato Bay that proponents say will protect the city from storm surges and reduce travel time from downtown to the airport.
The project has drawn opposition from activists and scientists.
Eduardo Mangaoang, director of the Regional Climate Change Research and Development Center at Visayas State University, warned of its potential impacts on the recovering Paraiso mangroves. “I am not in full detail of the causeway project but I am sure pollution in near future will badly affect the recovering patches of mangrove stand,” he said.
He added that construction activity may create physical disruption, and pointed to species sensitivity: “There are important mangrove species that are sensitive to polluted water, e.g. Rhizophoras, which I suppose will be badly affected,” he said.
In his study, Takagi concluded that the findings can help guide successful mangrove reforestation in typhoon-prone regions. He said the approach used in Tacloban after Haiyan is applicable to other tropical cyclone-exposed areas with extensive mangrove forests, including countries across Asia, Oceania and the Caribbean.
Banner image: Paraiso Mangrove Eco Learning Park, Tacloban City. Image by Patrickroque01 via Wikimedia Commons (CC BY-SA 4.0).
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Citations:
Takagi, H. (2025). Mangrove forest recovery a decade after Super Typhoon Haiyan. Journal of Environmental Management, 395, 127840. doi:10.1016/j.jenvman.2025.127840
Takagi, H. (2023). Survival of young planted mangroves in a calm bay environment during a tropical cyclone. Nature-Based Solutions, 4, 100082. doi:10.1016/j.nbsj.2023.100082
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