Mangrove forests are valuable ecosystems, but their extent and diversity are increasingly threatened
by sea-level rise and anthropogenic pressures. Here we develop a bio-morphodynamic model that
captures the interaction between multiple mangrove species and hydro-sedimentary processes
across a dynamic coastal profile. Numerical ...
Mangrove forests are valuable ecosystems, but their extent and diversity are increasingly threatened
by sea-level rise and anthropogenic pressures. Here we develop a bio-morphodynamic model that
captures the interaction between multiple mangrove species and hydro-sedimentary processes
across a dynamic coastal profile. Numerical experiments are conducted to elucidate the response of
mangrove assemblages under a range of sea-level rise and sediment supply conditions, both in the
absence and presence of anthropogenic barriers impeding inland migration. We find that
mangrove coverage can increase despite sea-level rise if sediment supply is sufficient and landward
accommodation space is available. Tidal barriers are mainly detrimental to mangrove coverage and
result in species loss. Importantly, we show that bio-morphodynamic feedbacks can cause
spatio-temporal variations in sediment delivery across the forest, leading to upper-forest sediment
starvation and reduced deposition despite extended inundation. As such, bio-morphodynamic
feedbacks can decouple accretion rates from inundation time, altering mangrove habitat
conditions and causing mangrove diversity loss even when total forest coverage remains constant
or is increasing. A further examination of bio-morphodynamic feedback strength reveals that
vegetation-induced flow resistance linked to mangrove root density is a major factor steering the
inundation-accretion decoupling and as such species distribution. Our findings have important
implications for ecosystem vulnerability assessments, which should account for the interactions
between bio-morphodynamics and mangrove diversity when evaluating the impacts of sea-level
rise on species assemblages.