Carbon sequestration potential in the rehabilitated mangroves in Indonesia

Mangrove ecosystem provides important services for coastal communities. Unfortunately, this ecosystem has undergone physical pressures for decades, including land conversion for shrimp aquaculture. Rehabilitation of the degraded mangroves offers an effective solution for bringing back mangrove functions, including carbon sequestration capacity. This study aims to quantify carbon stock (CS) and sequestration rate of a rehabilitated mangrove ecosystem in Indonesia, particularly in Banten Province. We compared sediment CS and carbon accumulation rate (CAR) of a rehabilitated mangrove in Ciseukeut, Panimbang, with a natural mangrove in Cilintang, the Ujung Kulon National Park. The sediment CS to a depth of 1 m in a rehabilitated mangrove in Ciseukeut was higher than in a natural mangrove in Cilintang, constituting 364 Mg C ha−1 and 126 Mg C ha−1, respectively. However, CAR showed the opposite pattern, in which a natural mangrove showed an almost two-fold higher rate (0.50 ± 0.42 Mg C ha−1 year−1) than that of a rehabilitated mangrove (0.27 ± 0.20 Mg C ha−1 year−1). Local hydrogeomorphological conditions play a role in affecting sediment CS and CAR in both sites. Enhancing hydrological modification can promote CAR, especially in an abandoned pond like in Ciseukeut. This study provided a knowledge base for suitable mangrove rehabilitation in the future that supports the Indonesian government's commitment to rehabilitating ca. 600,000 ha of degraded mangroves in Indonesia. Furthermore, the study also provides the first investigation of potential blue carbon for the world's natural heritage of the Ujung Kulon National Park.