Tropical Mangroves

• What/Where are Mangroves found.

  • Requires calm water conditions.
  • Seedlings to take root without being washed away by strong waves.
  • Nutrients are found accumulated sediments in this area.
  • Helps sustain growth of Mangroves.
  • Found in sheltered environments such as shallow river mouth or behind islands.
• Characteristics of Mangroves.

  • Lower diversity of plant species. (e.g. Sonneratia, Avicennia, Rhizophora, Bruguiera).
  • Less dense compared to Tropical Rainforest.
  • Uniform in terms of height about 10 to 15 cm tall.
  • Some species are able to survive in higher salinity water conditions as well as tidal conditions.
  • Results in horizontal zonation determined by high and low tide levels.
  • Zonation refers to distribution of plants in specific areas according to certain conditions.
• Salt-secreting leaves.

  • Avicennia trees secretes concentrated salt solution, after evaporation becomes salt crystals.
  • Removed by rain or wind.
  • Sonneratia trees deposit excess salt in older leaves and shed them.

  
• Salt-excluding roots.

  • Bruguiera plants are able to exclude salt, only take in water.
  • Soil of coastal environment is waterlogged & poor in oxygen.
  • Soft and unstable.

  
• Various aerial roots help to adapt to the soil conditions.

  • Sonneratia has thick cone roots.
  • Avicennia has slender pencil roots.
  • Both roots grow upwards above soil level to take oxygen directly from air.

  
• These roots also help to anchor the plants to prevent being washed away by strong waves.

  • Rhizopora has prop/stilt roots that form a broad base.
  • Bruiguiera have knee-bend roots that bend upwards to emerge and bend into the soil.

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