Mangroves are bridges between terrestrial and marine ecosystems. - photo: damedias/ stock.adobe.com
Mangroves are salt-tolerant trees or shrubs that grow along tropical and subtropical coastlines and river deltas. They are famous for their branched root systems that provide stability in muddy soils and brackish waters. The term “mangrove” not only belongs to one singular species, but rather a whole plant community encompassing around 80 different species of trees and shrubs worldwide. Together with various evergreen palms, shrubs and ferns, and a variety of animal species, mangrove trees form distinct ecosystems. Those ecosystems also carry the name “mangrove” or “mangrove forest”.
Mangrove species are true survival artists. As they grow along shores and river deltas, they are constantly exposed to extreme heat, salinity, anaerobic soil conditions, storm surges, coastal erosion and many other factors that limit plant growth. Over millions of years, mangrove species have developed sophisticated adaptations to withstand these difficult environments.
Mangroves can be found along the tropical and subtropical coasts near the equator on nearly all continents. A distinction is made between the western and eastern mangrove families. While the western mangroves thrive on the coasts of the Americas and western Africa, the eastern mangroves occur on the coasts of eastern Africa and South to Southeast Asia. The largest occurrence of mangroves is found in Southeast Asia, particularly in Indonesia. The archipelago encompasses the largest mangrove area in the world, accounting to around 22% of all mangrove forests worldwide.
Mangrove biomes are bridges between terrestrial and marine ecosystems, and are true all-rounders. They provide many vital ecosystem services, such as:
Mangrove conservation and restoration benefit millions of people and help fight the climate crisis. - photo: haddadToni
The salt-tolerant mangroves thrive where conditions would be deadly for most other plant species.- photo: NABU/ Martin Baumann
Mangrove species are diverse. For example, they form very different seeds. Here, our partners from ASITY Madagascar hold two different types of mangrove seeds found in one of our project regions. - photo: haddadToni
Mangroves grow aerial roots in different variations. - photo: jalvarezg/ stock.adobe.com
Mangroves are disappearing at alarming rates: In many places they are being cleared, for example for aquaculture ponds in Indonesia. - photo: NABU/ Martin Baumann
Together with its international partners, NABU protects and restores mangroves in Africa and Southeast Asia. - photo: NABU/ Martin Baumann
Globally, mangroves are diminishing at an alarming rate. Historically, wherever humans settled along tropical coasts in large numbers, mangroves were logged to make space for farmland, ports and other infrastructure, or to fulfil needs for timber and charcoal. In recent decades, the rise of fish and shrimp aquacultures has led to extensive destruction and degradation of mangroves. Some countries and regions already lost more than half of their mangroves. Although this trend has slowed down slightly in recent years, the climate crisis and its many consequences, such as rising sea levels and more severe tropical cyclones, add to the list of threats to these unique ecosystems. Tragically, mangroves would be important allies to mitigate and adapt to climate change, as they store enormous amounts of carbon and reduce the damage by extreme climate events like hurricanes.
NABU is joining hands with coastal communities, NGOs, academia, local stakeholders and government agencies to ensure the protection of remaining mangroves, identify areas suitable for restoration and develop concepts for the sustainable use of natural resources from mangroves to secure livelihoods.
Mangroves and their ecosystem services are indispensable for Indonesia's coastal communities. However, the country experiences alarming rates of mangrove loss. In Sulawesi, we support mangrove conservation and identify areas suitable for restoration. more →
The protected area Mahavavy-Kinkony in Madagascar suffers from degradation of its coastal ecosystems. NABU and ASITY Madagascar joined forces supporting communities for restoring ecosystems, improving livelihoods and responding to the impacts of climate change. more →
Mangrove trees developed specific adaptations to survive the salinity of seawater, the scorching tropical heat of the sun and the constant cycle of the tides. To prevent the harmful effects of salt water on their metabolic processes, large parts of the salt ions are already filtered through the roots. Further, salt is stored in the vacuoles of the cells or excreted through salt glands in the leaves. As the water-saturated mud soils are very poor in oxygen, above-ground aeration systems in the form of stilt roots ensure the oxygen supply to belowground plant tissue. Furthermore, the seeds of many mangrove species already germinate on the mother tree till the tree sheds the seedlings and float upright on the water surface for up to a year until they get stuck in the mud and take root.
Mangrove trees can grow for up to 100 years, protecting the coasts from erosion, waves, tidal currents, and storms, providing food and shelter for a plethora of species and supporting the livelihood of around 120 million of people. However, climate change, logging and extensive agri- and aquaculture threaten the survival artists. Around a quarter of the world's mangroves have already been destroyed - an alarming development that must be stopped and reversed. Conserving and restoring mangroves is crucial to protect livelihoods and fight the global biodiversity and climate crisis.
Just like the trees in any forest, mangrove trees take up CO₂ from the atmosphere and use the carbon to build up leaves, stems, and roots. Depending on geographical region, structure and age of the mangrove forest, the amount of carbon stored in biomass above and below the ground can vary widely, but is usually in the range of 100-200 tonnes of carbon per hectare. This is comparable to most forest types in temperate climates.
What makes mangrove ecosystems such important allies in our efforts to mitigate the climate crisis, however, is their ability to lock away enormous amounts of carbon in their soils. Fallen leaves and branches are constantly buried by crabs or other animals and covered by sediments from rivers and the sea. Due to the (mostly) waterlogged, i.e. oxygen-poor and saline conditions, the buried plant tissue decomposes very slowly. When new organic material is added quicker than old material is decomposed, soil carbon can accumulate over long periods. This soil carbon stock usually surpasses the biomass carbon stock by a factor of three to five, and values of more than 1000 tonnes of carbon per hectare locked away in mangrove biomass and soil have been measured in several mangrove ecosystems around the globe. When mangroves are destroyed, for example by converting them into aquaculture ponds, most of this carbon is mobilized and released as CO₂ back into the atmosphere. The numbers are truly mind-boggling: destroying only one hectare of carbon-rich mangroves can cause the same CO₂ emissions as driving a mid-size gasoline car 500 times (!) around the entire planet.
An ecosystem is a complex of living organisms. NABU focuses on restoring ecosystems to their original state and important regulatory functions such as carbon sequestration. Ideally that's done by creating conditions in which the ecosystem can recover on its own. more →
Climate change and biodiversity loss are the most pressing challenges to humanity and people start to realize they are both sides of the same coin. NABU stands with science. We demand and support all efforts to reach a net-zero-carbon economy globally. more →
