Mangroves and Deforestation Flashcards
Characteristics of the location mangroves grow in? (3-4pt)
- Mangroves have special adaptations to live in salty, oxygen-poor soil
- They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action.
- Mangroves grow in inter-tidal zones with salty, brackish to saline tidal waters.
- The soil which Mangroves grow in are muddy, water-logged and deficient in oxygen.
- They are halophytic trees (i.e. they are salt-tolerant trees that are adapted to live in harsh coastal conditions).
- Special Characteristics of Mangrove Forests:
1. Adaptations to low levels of oxygen
2. Uptaking nutrients from atmosphere
3. Limiting salt intake (halophytic trees)
4. Increasing survival of offspring
5. Limiting water loss
Horizontal Zonation of Mangroves?
- Acronym: BRAS (Bruguiera, Rhizophora, Avicennia, Sonneratia, from inland towards coastal zone, from least to most salt-tolerant)
Avicennia (3pt)
- Coastal zone
- Avicennia
→ Pencil-like roots
→ Grow up to 30cm in height
Sonneratia (3pt)
- Sonneratia (Colonise mud banks that are usually exposed at low tides)
→ Cone-shaped pneumatophores/roots (conical roots)
→ Grow up to 40-60cm in height
→ Conical roots can grow in a radius of more than 10 m.
Rhizophora (3pt)
- Middle zone
- 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
Bruguiera (2pt)
- Inland zone
- Bruguiera (Grow best in drier parts of mangrove belts where the soil is stiff clay, flooded only occasionally by the high tides)
→ 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.
Characteristics of Mangrove Forests (Adaptations) (main characteristic of mangroves - 1pt long sentence around 4 subpts in it)
Characteristics of Mangrove Forests (Adaptations)
* Mangroves are halophytic (salt-tolerant) trees that have specialised adaptive features that allow them to tolerate salty, brackish to saline tidal waters and survive in the waterlogged, anoxic muddy soil within the coastal intertidal zone.
Leaves of mangroves (1 main pt, 4 subpt)
Leaves
Salt glands within leaves – salt excretion and accumulation
* Avicennia
* secretes salt through special pores or salt glands within their leaves.
* The secreted concentrated salt solution evaporates and becomes salt crystals which are later removed by wind or rain.
* Unwanted salt is also stored in leaves which then fall off when old and remove the salt from the tree (or be removed by wind or rain).
Roots of mangroves (main point, 3 subpt)
Aerial Roots (pneumatophores) - Salt exclusion (ultrafiltration), aerial roots, wide-spreading to provide anchorage
* Aerial roots can take on different forms: the pencil-like roots, the cone-shaped roots, the prop or stilt roots and the knee-like roots.
- salt exclusion (ultrafiltration)
- wide spreading roots to improve anchorage to provide support in unstable mud
- aerial roots to take in oxygen
- Salt exclusion (ultrafiltration) (root) 2pt, 1 subpt
- Salt exclusion (ultrafiltration)
- To tolerate salt
- Rhizophora (prop or stilt roots), Sonneratia (Conical roots), Bruguiera (knee-like roots) (they don’t excrete salt in leaves – only avicennia does)
o They reduce salt intake via layers of microscopic pores in the roots and by filtering out as much as 90% of the salt found in seawater as it enters their roots.
- Wide-spreading roots to improve anchorage and to provide support in unstable mud (3pt, 2subpt)
- Wide-spreading roots to improve anchorage and to provide support in unstable mud
- All
- Prevents the tree from collapsing due to unstable ground
- Rhizophora (prop or stilt roots)
o Prop roots also help to anchor trees firmly in the muddy ground.
o Stilt roots improve stability of tree by providing a broader base and support
- Aerial roots to take in oxygen (4pt, 1-3 subpt for each - 2 1 2 3)
- Aerial roots to take in oxygen
- All
- Help in the aeration of roots to take in oxygen to thrive and prevent suffocation in the oxygen-poor (anaerobic) soil.
o ↑ surface area of root exposed to air = ↑ O2 taken in
o Soil is oxygen-poor and O2 is needed to carry out life processes (e.g. respiration)
- Aerial roots = pneumatophores
o Pneumatophores are specialised roots that act like snorkels when partially flooded and have pores called lenticels that cover their surface where oxygen exchange occurs. - Take in oxygen via lenticels on the surfaces of the roots.
o The lenticels contain substances that are hydrophobic, meaning they repel water, so when submerged, water cannot flood into the root.
o Prevents water from taking - Contain large air spaces (aerenchyma)
o To transport air
o To provide a reservoir of air during high tide when the aerial roots may be submerged.
o Ensure that the mangrove still can carry out life processes (e.g. Respiration) when it is unable to take in oxygen from the pneumatophores during high tide when the roots may be submerged.
Characteristics of aerial roots? (3-4)
- Aerial roots = pneumatophores
- Take in oxygen via lenticels on the surfaces of the roots.
- Contain large air spaces (aerenchyma)
- Aerial roots to take in oxygen
- All
- Help in the aeration of roots to take in oxygen to thrive and prevent suffocation in the oxygen-poor (anaerobic) soil.
o ↑ surface area of root exposed to air = ↑ O2 taken in
o Soil is oxygen-poor and O2 is needed to carry out life processes (e.g. respiration)
- Aerial roots = pneumatophores
o Pneumatophores are specialised roots that act like snorkels when partially flooded and have pores called lenticels that cover their surface where oxygen exchange occurs. - Take in oxygen via lenticels on the surfaces of the roots.
o The lenticels contain substances that are hydrophobic, meaning they repel water, so when submerged, water cannot flood into the root.
o Prevents water from taking - Contain large air spaces (aerenchyma)
o To transport air
o To provide a reservoir of air during high tide when the aerial roots may be submerged.
o Ensure that the mangrove still can carry out life processes (e.g. Respiration) when it is unable to take in oxygen from the pneumatophores during high tide when the roots may be submerged.
Fruits of mangroves - main characteristic (1pt)
Propagules – viviparous nature of reproduction
* Mangroves are viviparous.
- Meaning: (of a plant) reproducing from buds which form plantlets while still attached to the parent plant, or from seeds which germinate within the fruit.
Fruits of mangroves - what, how? (3-5pt, 2 subpt)
- Propagules
- Reproduce through Propagules
- the seed germinate into propagules while still attached to the parent tree.
- This helps them to grow rapidly upon falling to the soil below once they are ripe.
o increases chances of survival in the harsh environment.
o Propagules can photosynthesize while still attached to the mother tree. - Sharp end of Rhizophora anchors firmly in the mud like a javelin (Prop/Stilt roots)
- Avicennia, where fruits are buoyant, take root in coastal areas after floating in water for some time.
