Mangroves are like nature’s multitaskers: they are not only plants, they also manage entire coastal ecosystems! With their tangled roots, they stop erosion and organise feasts for fish and birds. If only they could talk, they would probably give us lessons on how to be more efficient and sustainable!
Mangroves, plants or ecological associations?
Mangroves are a plant formation consisting of mainly woody plants of different species.
These formations develop on the shallow shorelines of tropical sea coasts, particularly in the periodically tidal zone.
These are halophilous, i.e. salt-loving, plants that have adapted to live in brackish environments, where fresh water from rivers mixes with salt water from the sea.
The term ‘mangrove’ is often misused as a common name for some representative species of this plant formation; in fact, there are about 80 species such as the red mangrove, which has large aerial roots, the yellow mangrove with bean-shaped fruits, the white mangrove with salt glands at its base, and the black mangrove with dark green and silver leaves.
In summary, mangroves are both a type of plant with unique adaptations to live in brackish environments and an ecological association that creates viable habitats and protects coastlines.
Mangroves are estimated to cover an area of about 150,000 km² worldwide, with the majority located in Asia. Only 6.9% of mangroves fall under existing protected area networks.
Ecological associations and functions
Mangroves grow along shorelines and near river estuaries and are an outstanding example of plants protecting coastlines.
These forests form a complex and vital ecosystem for many benthic species; they provide habitats and breeding areas for a wide range of organisms, such as fish, crustaceans, molluscs and birds.
Their intricate rootsstabilise the soil, preventing beach erosion; they stabilise the soil, protecting the coastline from storms and storm surges. They also act as a natural barrier against rogue waves and sea currents, minimising negative impacts on coastal communities.
These plants have the ability to trap plastic waste, functioning as natural barriers that limit its dispersion. They act as grids, blocking the material both in and out.
Other types of pollutants also undergo sedimentation and degradation, accelerated by root microorganisms, resulting in improved water quality.
One hectare of mangrove forest can absorb as much carbon as four hectares of rainforest. This is because the water also captures carbon from the decomposition of leaves, flowers and fruit that fall from the branches, thus also contributing to the formation of new soil.
Case studies
A study by the University of Pisa highlighted the fundamental role of plants in dune systems in limiting plastic pollution.
The research analysed the composition, coverage and distribution of marine litter and its relationship with vegetation cover in the protected area of the Migliarino San Rossore Park (Pisa). Results show that coastal dunes with dense vegetation cover can trap litter and thus play a relevant role in the spatio-temporal dynamics of coastal litter.
German study, CREC (Coastal Research Network on Environmental Changes), looked at locations in Australia, Brazil, Mexico, South Africa and the United States.
Their intricate roots have been shown to act as a natural barrier against waves and sea currents. They reduce energy by up to 66%, reduce erosion by up to 50%, sequestering carbon dioxide by up to 1.5 tonnes per hectare per year.
These studies demonstrate the importance of mangroves not only for coastal protection, but also for biodiversity conservation and climate change mitigation.
Play for the planet!