Response of Mangroves to Late Holocene Sea-Level Change: Palaeoecological Evidence from Sumatra, Indonesia

This study was conducted with aim to reconstruct the late Holocene mangrove history and to investigate if mangroves can be resilient to current and projected sea-level rise (SLR). The palynological record from a sediment core in the Mendahara Ilir region (MI) in Sumatra was compared with available sea level reconstructions from sites close to MI (Malacca Strait and Singapore). The palynological results show that the mangrove swamp forest was already present in MI ca. 2300 years ago. At time, the sea-level was estimated to be ca. 2 m higher than the present level, thus indicating persistence of mangroves in MI for the current global increase scenario of more than 1 m SLR by 2100. However, the estimated rate of change from the MI core are ca. 2.2 mm/yr. These values are much lower than current (5.0 mm/yr) and future (7 mm/yr) estimates. Thus posing a threat on the resilience and the capacity to adapt of the mangrove swamp forest. Additionally, the palynological results indicate that the mangrove swamp forests were quickly moving seaward and landward following regression and transgression phases in MI. Without a clear inland free path, such migration will be impeded under current and future projections of SLR.