Mangrove Forests

Question 1

How are mangroves distributed?

Answer 1

1. They are mainly between the Tropic of Cancer and Tropic of Capricorn. Generally at coastal areas, coast of North America, Africa, Southeast Asia, Northern Australia.
2. Mangroves thrive in tropical climates, found in sheltered coastal regions and places where rivers constantly deposit clay, silt.

Question 2

What are mangroves forests and where can they be found?

Answer 2

1. It is a woody plant or plant community which lives between the sea and the land inundated by tides.
2. They all have the ability to live in salt water, primarily in brackish water, which is a salty and fresh mix.

Question 3

What are the functions/benefits of mangroves? How are mangroves threatened?

Answer 3

1. • They serve as an important buffer
     between sea and land.
     
     • Lessen impact of intense storms.
     • Reduce erosion and increase
       sedimentation.
2. However, it is increasingly threatened as human development is most intense along coasts.

Question 4

What is Mangal and Pnuematophore?

Answer 4

1. Mangal is a community of organisms in the mangrove habitat.
2. Vertical root structures for air exchange.

Question 5

What are the living conditions in Mangals?

Answer 5

• Increasing salinity towards ocean
• Soft and waterlogged soil (Many mosquitoes)
• Less nutritious soil
• Inundation with tides

Question 6

What are halophytes and its four main species?

Answer 6

Halophytes are plants that grow naturally in saline environment.
SARB
- Sonneratia
- Avicennia
- Rhizophora
- Bruguiera

Question 7

Which area is the most frequently flooded?

Answer 7

The saline environment is more frequently flooded while the land is infrequently flooded.

Question 8

What is the structure of mangroves forests and how tolerant are they?

Answer 8

1. Bruguiera (Knee Roots) is the nearest to the land, followed by Rhizophora (Prop Roots) and lastly, Avicennia (Aerial Roots)/ Sonneratia (Aerial Roots).
2. Avicennia and Sonneratia is the most tolerant to saline environment, followed by Rhizophora and Bruguiera.

Question 9

What are the three zones? Describe them.

Answer 9

1. Coastal Zone
   - Trees are submerged deep under saltwater
   - Avicennia & Sonneratia
2. Middle Zone
   - Water level rises during high tide and roots are submerged during high tide
   - Prop Roots anchor the trees firmly to the ground as the area can be flooded during high tide
   - Rhizophora
3. Inland Zone
   -Furthest inland and away from swampy water
   - Least tolerant of saltwater
   - Knee-like roots allows further anchoring deep into the soil
   -Bruguiera

Question 10

How do the leaves adapt to the environment?

Answer 10

1. They are evergreen, have broad drip tips and a thick leathery surface to reduce water loss.
   - Opening of stomata is narrow which reduces water loss through transpiration.
2. Avicennia- Salt secretors and excess salt is secreted on underside of leaf.
   Bruguiera & Rhizophora & Sonneratia– Ultrafiltrators
   - They absorb the salt instead of secreting it.

Question 11

How do the fruits adapt to their environment?

Answer 11

1. Buoyant
   a) Seedlings contained within seed coat when it drops from plant
   b) Seed floats away
   c) Shed its coat to lodge in ideal condition for growth
   d) Stays alive in water for 3-4 days only
2. Elongated structure with sharp tips
   a) Fruits germinate when still on the parent tree
   b) Fruits drop directly on the ground to take root
   c) Sharp tips help them to anchor themselves firmly in soft muddy soil

Question 11

Describe Aerial Roots.

Answer 11

• Avicennia and Sonneratia species which grow nearest to the coast
• Breathing roots
• Allow oxygen intake
• Environment frequently flooded
• Grow upwards, stick out of the ground:
  1. To take in oxygen during low tide
  2. To used stored oxygen from the water during high tide

Question 12

Describe Prop Roots & Kneed Roots.

Answer 12

1. Prop Roots
   - Rhizophora species
   - To anchor trees firmly on muddy soil by providing a broader base which can improve support.
   - To prevent mangroves from being submerged during high tide, thus helping plants to breathe.
2. Kneed Roots
   - Bruguiera species
   - Help to provide firm support on the soft soil

Question 13

Why should mangroves be preserved?

Answer 13

1. • Since mangroves are trees and shrubs that grow in saline coastal habitats, there will be lower growth rates as a consequence of salt & air exchange
     - Once established, the roots of the mangrove plants provide a habitat for flora and animal species
2. • Mangroves provide significant value in the coastal zone as a buffer against erosion, storm and tsunamis
     - They help to hinder water flow, thereby enhancing the deposition of sediments in the area.

Question 14

Why should mangroves be cut down?

Answer 14

1. Stench
   - The stench is caused by methane which is produced by bacteria at low levels of oxygen
   - The quiet water also form breeding grounds for mosquitoes
2. Occupies precious land
   - Mangroves occupy vast areas of land, especially in the coastal area which are sought after for development
   - The area can instead be used for economic, recreational, housing purposes