Other characteristics and adaptations of MANGROVES

Distribution:

Swampy coastal areas of tropical regions of West Africa, Southeast Asia ( Peninsular Malaysia, Singapore), Australia.

Soil : muddy, water-logged, deficient in oxygen ,salty or brackish water.

Climate:

• High mean annual temperature of 27°C
• Uniform throughout the year
• Small annual temperature range: 2 °C
• Heavy annual rainfall of 1500mm to 3000 mm
• Conventional rain that is frequent throughout the year
• No distinct wet or dry season

Mangroves have had to physically adapt their leaves, roots,and their reproductive methods in order to survive in a harsh, dynamic environment of soft, low- oxygen soils and varying salinity( Amount of salt in the water)..

Leaves:

• Thick and leathery to reduce excessive transpiration
• tough and evergreen to keep moisture in.


• Have special glands to secrete salt ( Salt secretors- Eg. Avicennia)


• Some store in old leaves which will drop off ( Ultrafiltrators)


• For example: Rhizophora and Sonneratia species.


• Have drip tips and waxy texture of leaves that remove excess water.


• turn automatically to reduce the surface area of the leaves exposed to the hot sun,in order to reduce water loss through evaporation.

As mangroves grow in sand or mud that is saturated with water, their ability to exchange gases through their root system is reduced.

Roots:

Thus, as mentioned before, some have:

• Breathing roots, which is an aerial root system above ground to help roots take in oxygen
• Pencil- like roots which protrude through mud up to 30 cm
• For example: Avicennia
• Knee-like roots that grow upwards and turn downwards into the soil
• For example: Bruguiera trees


• Prop roots that grow from trunks, anchor firmly into the muddy ground


• For example: Rhizophora
• Roots provide structural support in the soft soils.

Flowers and fruits:

• Flowers- Colourful to attract insects to pollinate its flowers
• Fruits germinate on trees (Eg. Rhizophora). When seedling falls, sharp end anchors firmly in mud
• Buoyant.
• Float for some time before taking root in some coastal areas ( Eg. Avicennia trees)
• The tide acts as the dispersal to avoid crowding of young plants

Structure/ layers:

• 15m tall
• Trees vary in height from 2- 40 m
• Average eight: 15m
• No distinct vertical layering
• Grow close together and form dense thickets
• Have a close appearance with little sunlight reaching the forest floor.

Diversity of plant species:

• Dense and luxuriant, because of the high temperatures and rainfall
• There are 4 main species:
• Avicennia
• Sonneratia
• Rhizophora
• Bruguiera
  
• Others: Sea hibiscus ,Nipah palm
  
• Provide valuable resources:

1. Food
2. Medicine
3. Firewood
4. Charcoal
5. Construction materials