Ecological Restoration of Mangrove Forests: Early Ecological Responses to Hydrological Restoration in Eastern Africa

Mangrove forests in northern Mozambique were impacted by human and natural pressures, causing channel blockage, permanent flooding, and tree die back. To address the issue, hydrological restoration was carried out in August 2024, excavating 6.88 km of channels, with impact in 38 ha of degraded mangrove. The intervention area was divided into three zones, upper, middle, and lower, based on ecological and environmental characteristics. This study reports on the monitoring carried out 4 and 10 months later. Site salinity approached optimal levels for mangrove growth, dropping by 56% in high-salinity zones, and increasing above 100% in freshwater-invaded zones. The intervention also homogenized the previously distinct upper, middle, and lower zones to more statistically similar groups (Dunn post hoc: p > 0.05). Moreover, seedling density increased from 57.1 ± 44.1 to 4864 ± 1778.6 seedlings/ha; additionally, regenerating species increased in numbers (1 to 3 mangrove species in middle zone; and 0 to 3 mangrove species in lower zone). The study also reports the dieback of competing species, Juncus kraussii and Cyperus articulates. These changes result from the improved tidal flow and general habitat conditions in the restored site. This restoration offers a model for scaling up restoration efforts across the region, where ecological restoration remains underrepresented in many mangrove restoration initiatives.