Context: A study was conducted to explore changes in mangrove forest diversity under a broad range of sea-level rise rates and sediment supply conditions, both in the absence and presence of a tidal barrier like a dike / seawall that obstructs inland migration.
More about the study published in Environmental Research Letters
- Methodology: The researchers conducted simulations for a period of 330 years.
- The first 30 years were used as an adaptation period during which mangroves could settle, allowing the analysis of mangrove assemblage dynamics over the remaining 300 years.
- The model tracked key forest characteristics, including tree density, type of species, stem diameter, tree height and associated biomass.
- Focus was on changes in total forest coverage and species distribution.
- Significance: The study helps to understand mangrove species zonation linked to a dynamic coastal profile, differences in lateral accommodation space (coastal progradation and landward migration) and mangrove properties like root density.
Key Findings of the study
- Alarming rate: Mangroves forests are being threatened at an increasing pace:
- River dams negatively impact the supply of mud that raises mangrove soils.
- The space required for mangroves survival is increasingly getting occupied by buildings and seawalls.
- Tidal barriers have proven to be disastrous for mangrove coverage and can result in species loss.
- Sign of hope: But mangrove coverage can increase despite sea-level rise if sediment supply is sufficient and land accommodation space available.
- Mangroves depend on a steady supply of sediment flowing down from rivers.
- But the delivery of sediment from most rivers reduced over the past three decades.
- Mangroves are various large extensive types of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics - mainly between latitudes 25 N and 25 S.
- Mangroves are salt tolerant trees (halophytes) adapted to live in harsh coastal conditions.
- They contain a complex salt filtration system and complex root system to cope with salt water immersion and wave action.
- They are adapted to the low oxygen (anoxic) conditions of waterlogged mud.
Image Source: DTE