Spatial Distribution of Tropical Rainforests and Mangroves Flashcards
What is natural vegetation
Plant life which covers parts of the world’s land areas and develops without human interference
Climate of a given location determines the type of natural vegetation found there
Different types of natural vegetation
Temperate grassland
Temperate deciduous forest (shed leaves before every winter to conserve water)
Mediterranean forest
Tropical rainforest
Tundra
Temperate coniferous forest
Desert
Tropical grassland
What is climate
Average weather conditions of a place over a long period of time (>30yrs)
What is Tropical Climate
Experienced between the Tropic of Cancer and the Tropic of Capricorn
Annual rainfall of 2000mm per year on average (as high as 4500mm)
Rainfall throughout the year and temperature is high
Natural vegetation like tropical rainforests and mangroves are found
Recieve abundant sunlight
Suitable for plant growth
What are tropical rainforests
Main type of natural vegetation oudn in parts of the world experiencing tropical climate
Found in: Central&South America, West and Central Africa, South and Southeast Asia (Near Equator)
Evergreen: Constant green appearance
—Do not shed all leaves at particular time of year
—Continuously grow new leaves to replace older ones that fall off
Favourable climate conditions: large variety of plant species
3 main layers of tropical rainforest
Emergent
Canopy
Undergrowth
What is emergent layer in tropical rainforest
Crown of plants which grow 30m and beyond
What is the canopy layer
20 to 30m in height
Grow very close to one another: crowns interlock to form a thick and near-continuous mass of branches and leaves
Prevents 97-98% of sunlight from reaching the forest floor
What is the undergrowth layer
Beneath canopy layer: very little sunlight able to reach this area: not many plants grow here (except smaller growing in shade and seedlings of taller plants)
Amount of vegetation is sparse
Undergrowth plants grow upwards very quickly and fill up the gaps where there is sunlight
Adaptations developed by plants in tropical rainforests
Broad leaves
Waxy Leaves
Drip tips
buttress roots
Broad leaves adaptation explanation:
Large surface area
Absorb as much sunlight as possible to make food for survival and growth
Waxy leaves adaptation explanation:
Surface glossy appearance
Reduce amount of water vapour lost to the atmosphere during transpiration (due to high temperatures of tropical rainforests)
drip tips adaptation explanation:
Allow rainfall that drops on the leaf’s surface to flow off easily [Frequent rainfall so leaves can dry quickly, preventing fungi and bacteria to grow on them]
Buttress roots adaptation explanation:
Keep tall plants upright and prevent from toppling over
Grow up to 5m above ground surface
Rest fi the roots do not extend deeply beneath the ground’s surface
Nutrienst are concentrated in the topmost layer of rainforest soil (released when dead leaves and branches that have fallen on the ground surface and decomposed)
Shallow underground roots: absorb nutrients as quickly as possible
What are mangroves
Along narrow strips of the world’s coast
Concentrated largely within the tropics
70% of coastline is covered by mangroves
Grow in water that has higher salinity taht normal water: lack of competition from other plants which are unable to grow in such conditions)
Where are mangroves found
Experience tropical climate (not able to withsatnd freezing conditions)
Grow best when average air and water temperature does not fall below 20 degrees: cannot survive far north or south tropics
Calm water so seedlings can take root without getting washed away by strong waves
—Encourage the accumulation of fine sediments containing nutrients which mangrove plants require to grow)
Only found in sheltered environments along or very close to the coast, such as shallow river mouths or behind islands
Characteristics of mangroves
Evergreen
Much lower diversity of plant species than rainforest
Can tolerate longer periods of flooding thsu found closer towards the low tide level
Density of trees significantly lower than rainforests, hence less competition for sunlight
Coastal environment difficult for plants to survive in, mangrove need as much energy from the sun as possible
Cannot tolerate shady conditions
Uniform in height
Mangrove forest tend to exhibit a horizontal zonation largely determined by low and high tide. Zonation refers to distribution of plants in specific areas according to certain parameters, each characterised by its dominant species
High tide: Duration of flooding is shorter
Low tide: Duration of flooding is longer
How have plants in mangroves adapted to their environment
Salt-secreting leaves
Salt-excluding roots
Aerial roots
Salt secreting leaves adaptation explanation
Enable plant to remove salt from saline water that their roots have absorbed
Removal fo salt in this manner prevents salt from building up within the plant
Salt excluding leaves adaptation explanation
Deny intake of salt using roots
Aerial roots adaptation explanation
Soil found in coastlal environment is flooded for several hours of the day by tide. Soil is waterlogged and poor in oxygen, soft and unstable
Grow partially above soil surface, enables them to take in oxyegn directly from the airwhen they are exposed during low tide. Able to survive in oxygen-poor soil
Anchor mangrove plants to the soft soil, preventing them from being uprooted and washed away by strong winds
