Y2 Geography: Mangrove Forests

Name the 3 sections of the mangrove forest from sea to land, and what types of trees are found in each section.

Coastal zone - Avicennia and Sonneratia

Middle zone - Rhizophora

Inland zone - Bruguiera

Where can mangroves be found?

• Found in tropical climate sone between 23.5ºN and 23.5ºS of the equator

• grow at the interface between land and sea

What is the climate of a mangrove forest? Include amount of rainfall and temperatures.

• Very wet - > 2000mm of rainfall per year

• Uniformly high temperatures - 20ºC - 35ºC

What are the characteristics of the vegetation in a mangrove forest?

• Halophytic (salt-tolerant) trees, shrubs and other plants grow in the brackish and saline tidal waters of the intertidal coastal zone

• Contain a salt filtration system and a complex root system

• Evergreen

Name one characteristic of the water in a mangrove forest.

It has a high salt content.

Name two characteristics of soil of a mangrove forest.

• salty

• Oxygen-poor

Name three ways to secrete salt and which species of mangrove secrete salt each way.

• Contain glands that allow them to secrete excess salt, salt removed by wind/rain

  • Avicennia

• Salt is transferred to leaves which store it then fall off from the tree when it grows old

  • Sonneratia

• Does not secrete salt - instead uses Ultrafiltration at the root level to exclude salt

  • Rhizophora, Bruguiera

Name 3 adaptations of the leaves in the mangrove forest.

• broad

• Has drip tips

• Is thick and leathery

How do broad leaves help plants in the mangrove forest?

• Greater surface area with the sun

• absorbs more sunlight

• Greater rate of photosynthesis

How do drip-tips help plants in the mangrove forest?

• allow rain to flow off quickly

• Prevents fungus from growing on the leaves

• Prevents infection and prevents disease from killing the plants

How do thick and leathery leaves help the plants in the mangrove forest?

• prevent water loss

• Soil in the mangrove is very waterlogged and lacks water

• Helps the plants to survive better

Name the 5 types of roots in a mangrove forest.

• pneumatophores

• Prop roots

• Stilt roots

• Kneed roots

• Plank roots

Explain how pneumatophores look like (the two different types as well) and how they function.

• pencil-like and grow up to 30cm - Avicennia

• Cone-shaped and grow up to 40-60cm - Sonneratia

• Stick out of the soil

• Enable the mangrove roots to take in oxygen from the atmosphere

Explain the difference between prop roots and stilt roots and what they function for.

• prop roots prop trees up when the trees reach the mud (trunk touches ground)

• stilt roots arch out from the trunk down to reach the ground for support (where the trunk does not touch the ground)

• Both function to support the tree

Explain how kneed roots look like.

• emerge from the ground then loop back in

• has a knobbly bump at the highest point that resembles a knee

Explain how plank roots look like.

• horizontal roots that grow vertically upwards on the upper side for the entire length

• roots are wavy, plank-like structures which radiate outwards from trunk base

State the adaptation of mangrove seeds and why the adaptation is needed.

• mangrove seeds are viviparous

  • Seeds germinate into propagule while still attached to the parent tree

  • increases the chances of survival in the harsh environment 

  • allows the parent tree to supply water and necessary nutrients for the seeds to germinate and develop into seedlings

  • These seeds are also buoyant and float in the water for quite sometimes before rooting themselves on suitable soil

• This is needed because

  • because of the unconducive environment for seeds to germinate (with saline water and unconsolidated saline soil that has little or no oxygen)

Name the 4 different species of mangrove.

Bruguiera

Rhizophora

Avicennia

Sonneratia

Name the characteristics of Bruguiera.

• grows in the inland zone of the mangrove

• Does not secrete salt, uses ultrafiltration at the root level

• Kneed roots

• Low level of salt-tolerance

Name the characteristics of Rhizophora.

• grows in the middle zone of the mangrove

• Does not secrete salt - instead uses ultrafiltration at the root level

• Stilt roots

• Medium level of salt-tolerance

Name the characteristics of Avicennia.

• grows in the coastal zone of the mangrove

• Secretes salt through glands on the leaves

• Pneumatophore roots - pencil-like that grow up to 30cm

• High level of salt-tolerance

Name the characteristics of Sonneratia.

• grows in the coastal zone of the mangrove

• Secretes salt through transferring salt to leaves which age and fall off

• Pneumatophore roots - cone-shaped that grow up to 40-60cm

• High level of salt-tolerance