Source: DTE
Subject: Environment
Context: A recent study reveals that 10–15% of the Sundarbans is losing its resilience due to critical slowing down, a phenomenon where the ecosystem takes longer to recover from climate stress.
About Mangroves:
What They Are?
- Mangroves are a unique group of salt-tolerant trees and shrubs that grow in the intertidal zones of tropical and subtropical sheltered coastlines. Often called oceanic forests or tidal forests, they thrive in conditions that would kill most other plants—namely high salinity, extreme tides, and oxygen-poor (anaerobic) soil.
Habitat and Distribution:
- Location: Found in the intertidal regions between land and sea, primarily in tropical and subtropical latitudes (between 25 degree N and 25 degree S).
- Condition: They require slow-moving waters that allow fine sediments to accumulate.
- The Sundarbans: Located at the delta of the Ganga, Brahmaputra, and Meghna rivers, it is the only mangrove forest in the world inhabited by tigers.
Conservation Status:
- UNESCO World Heritage Site: The Sundarbans (shared by India and Bangladesh) is recognized for its exceptional biodiversity.
Key Characteristics:
Mangroves have evolved remarkable extremophile traits to survive:
- Pneumatophores (Blind Roots): Since the soil is underwater and lacks oxygen, mangroves have vertical roots that grow upward out of the mud to breathe air directly from the atmosphere.
- Stilt and Buttress Roots: These specialized roots provide structural stability in the soft, shifting mud and help the trees withstand heavy wave action and cyclones.
- Vivipary (Live Birth): Seeds germinate while still attached to the parent tree. Once they develop into a seedling (propagule), they drop into the water, floating until they find mud to take root in.
- Salt Management:
- Excretion: Some species have special glands on their leaves to secrete excess salt.
- Exclusion: Others have ultra-filtration systems in their roots that prevent salt from entering in the first place.
- Succulent Leaves: Many mangroves have thick, fleshy leaves that store water, similar to desert plants, to manage the physiological drought caused by high salt levels.
Significance:
- Mangroves act as a natural bio-shield, absorbing the energy of storm surges, tsunamis, and cyclones, protecting inland human settlements.
- They are Blue Carbon giants, storing up to four times more carbon per hectare than typical terrestrial tropical forests.
