Mangrove Forests: Protection Against and Resilience to Coastal Disturbances

Background

Mangrove forests provide many ecosystem services, including habitat for fauna, enhanced water quality, carbon storage for climate change mitigation, and protection from tropical storm damage. However, mangroves are vulnerable to anthropogenic disturbances (i.e., pollution, conversion to agriculture and aquaculture, unsustainable harvesting of timber, food, fuel, medicine) and environmental stressors (i.e., tropical storms, sea level rise), which significantly decrease global mangrove forest area. The role of mangroves to mitigate storm surges is debated, since their dense vegetation attenuates wave height for waves smaller than 4 m, while waves over 4 m can uproot and destroy mangrove forests.

Goals and Methods

This review paper aims to define the role of mangrove forests in coastal protection by examining their resilience and vulnerability to coastal disturbances. The authors conducted a literature search for papers from 1950 to 2017 that discuss tropical storm mitigation, coastal resilience, and coastal protection in mangrove forests. They synthesized 90 papers that focus on case studies and mathematical models describing mangrove disturbance, resilience, and vulnerability to tropical storms.

Conclusions and Takeaways

Long-term degradation of mangroves and modifications to hydrological conditions can increase mangrove vulnerability to tropical storm surges by creating conditions that increase surge heights, flood wave velocity, and total flooded area. Despite these limitations under degraded conditions and extreme tropical storm events, mangrove forests can reduce flood extent and water level during moderate and smaller tropical storms. Mangrove restoration and coastal greenbelts are environmentally friendly and cost-effective coastal protection measures that are most effective when implemented in combination with early warning systems and enhanced community awareness, rather than as standalone interventions to decrease damage from tropical storms.