Building barriers Elucidating the sediment trapping properties of mangroves and their relevance for ecosystem service provision

Abstract

Mangrove forests in the tropics and subtropics provide a plethora of ecosystem services, among which mitigation of coastal erosion and protection against coastal disturbances and extreme weather events. These forests are however continuously under threat of degradation as the result of direct human actions and the consequences of climate change, especially noting sea level rise. As a way to escape this degradation and continue providing these ecosystems services, mangrove forests are able to expand or migrate. A major factor influencing their capacity to do this is their ability to influence sediment dynamics and consequently stimulate sedimentation. This review therefore aimed to show the ways in which mangroves facilitate this process. Here we start by describing the functional anatomy of mangroves for sediment trapping, together with the conditions necessary for mangrove forest migration. Once these theoretical foundations are established, we highlight a number of experimental studies, both in field and lab settings that have aimed to uncover the biophysical properties of mangroves that underlie sediment trapping, as well as remote sensing studies that describe the influence of sediment capture on mangrove forest migration in various geographical contexts. Subsequently, we describe how this experimental and remote sensing data has been used to create several models that are able to predict how mangrove ecosystems will develop under the influence of various bio-geomorphological factors. Next, we note some Building with Nature projects that have intended to restore degraded mangrove forests by applying the acquired theoretical knowledge of sediment trapping. We then envision the future of mangrove forests, where their survival is influenced by both environmental factors and human (in)actions. In summary, we note that comprehensive understanding of mangrove forests and the complexities regarding their context-dependence, in combination with sustainable usage are crucial in ensuring that these forests are able to provide their ecosystem services far into the future.