Mangrove’s response to cyclone Eline (2000): What is happening 14 years later

• We assessed changes in a cyclone impacted mangrove forest 14 years later.
• We identified changes in NDVI and in forest structure.
• Forest has not recovered after 14 years.
• Mangrove forests resilience should be increased in face of climate changes.

This study assesses the impact of severe cyclones on a mangrove forest and the response over a 14 year period. SPOT images from pre- and post-cyclone years were used to assess changes in area and in the Normalized Difference Vegetation Index (NDVI) in a cyclone impacted mangrove forest in central Mozambique. Forest structure and condition were evaluated in the field 11 years after the cyclone, sampling both the protected creek and exposed seaward mangroves. Transects perpendicular to the coast line were set across impact zones, covering high-, mid- and less-impacted zones. Quadrats (10 × 10 m) were set along each transect, and adult trees within were identified to species, Diameter at Breast Height (DBH) measured, height estimated, and life condition (living or dead) indicated. Regeneration was assessed in 5 × 5 m quadrats. Cyclone Eline impacted on 47.8% of the mangrove forest area, as shown by reduced NDVI in 2000 after the cyclone. Field sampling results indicate substantial recovery in creek forests; while seaward mangroves had 100% mortality in Rhizophora mucronata dominated areas. This species is sensitive to defoliation and sedimentation and unable to sprout. Only mid- and less-impacted zones had high densities of juveniles. Species with high regenerating success were R. mucronata, Ceriops tagal and Avicennia marina. Sheltered creek mangroves were able to recover but changes in sedimentation prevented recovery in the exposed seaward sites. This study highlights the need to understand the response of mangroves to cyclones, considering increased frequency with climate changes. Higher frequency of cyclones might prevent recovery, threatening the forest and associated coastal protection. However increased forest resilience can be gained with proper management.