Geography-Mangroves

Aerial Roots

• To avoid suffocation in the oxygen-poor (anaerobic) soil, trees have roots that take in oxygen from the air. They can take on different forms: the pencil-like or conical roots, the prop or stilt roots and the knee-like roots

Pencil-like Roots

• short roots, which grow up to 30 cm in height, called Pneumatophores

• Most Salt Tolerant

Prop/Stilt Roots

• Branched, looping roots arise from the trunk and lower branches. At this stage, they are known as prop roots. They become stilt roots only when the bottom of the trunk becomes upside down conical and may even lose contact with the ground. The stilt roots improve the stability of the tree by providing a broader base and support in the soft and unstable mud. They also help in aeration as they are exposed for at least most of the day between tides.  

• Wide spreading roots help improve anchorage in unstable mud. Stilt roots improve stability by providing a broader base and support.

• Salt Tolerant

Knee-like Roots

• emerge from the ground then loop back in, often with a knobbly bump at the highest point of the loop that resembles a knee.

• Least Salt Tolerant

Bruguiera

• Bruguiera sends out knee-like roots, that emerge from the ground then loop back in, often with a knobbly bump at the highest point of the loop that resembles a knee.

• Least Salt Tolerant

Rhizophora

• Stilt roots arching out from their trunk down to the ground for extra support and air absorption.

• Prop roots from branches to prop them up when the roots reach the mud.

• Salt Tolerant

Avicennia

• has pencil-like roots, which grow up to 30cm in height

• Most Salt Tolerant

Sonneratia

• develop cone-shaped pneumatophores which may reach a height of 40-60cm.

• Most Salt Tolerant

Pneumatophores

• They are roots that grow vertically up from the underground root system

• They are specilaised roots that act like snorkels when partially flooded and have pores called lenticels that cover their surface where oxygen exchange occurs.

Lenticels

• Contain substances that are hydrophobic, meaning they repel water, so when submerged, water cannot flood into the root

Plank Roots

• Found in Nyireh Bunga (Xylocarpus granatum),

• Horizontal roots grow vertically upwards on the upper side for the entire length.

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

Horizontal Zonation

• Inland, Middle, Coastal

• Adapt to the Saline and Muddy Coastline

Mangrove Forests

• Found in tropical climate zone between 23.5°N and 23.5°S of equator

• “Rainforests by the sea” - grow at the interface between land and sea

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

• Have special adaptations to live in salty, oxygen-poor soil

• Contain a salt filtration system and a complex root system

• Little variation in temperature

• High precipitation throughout the year

• Evergreen Leaves

• Photosynthesise throughout the year

Mangrove Characteristics

Special Characteristics

1. Adaptations to low levels of oxygen

2. Uptaking nutrients from atmosphere

3. Limiting salt intake

4. Increasing survival of offspring

5. Limiting water loss

Leaves

• Evergreen

• Are broad to absorb sunlight and have drip tips to allow rain to flow off quickly

• Thick and leathery to prevent water loss

• Contain glands to allow them to secrete excess salt (Avicennia does this the best)

• Salt is stored in old leaves which them fall off and remove salt from the tree (Sonneratia)

Ultrafiltration

• Used Non-salt secretors like Sonneratia, Rhizophora and Bruguiera at root level to exclude salt

Aerenchyma

Aerenchyma are large air spaces that transport air and provide a reservoir of air during high tide, when the aerial roots may be submerged.

Fruits

• viviparous nature of reproduction

• The mangroves reproduce through propagules; the seeds germinate while still on the tree. This helps them to grow rapidly upon falling to the soil below once they are ripe.

• Avicennia, where fruits are buoyant, take root in coastal areas after floating in water for some time.

Provisioning Services

Regulating Services

• Regulates Climate, Air quality and water quality

• Carbon Equastor

Cultural Services

Supporting Services

Salt Accumulation

• All the salt is stored in some of the older leaves those leaves would wither, letting all the salt get out

• Best done by Sonneratia

Salt Excretion

• The leaves excrete salt using special pores and glands, which let the salt escape

• Done by Avicennia

Causes of Deforestation

• Logging

• Transport Infrastructure Development

• Cattle Ranching

• Soy Bean Farming

Effects of Deforestation