eoh(geogelec)_pwp_c3
Post on 13-Nov-2014
115 Views
Preview:
TRANSCRIPT
1
Earth: Our Home Geography Elective
Chapter 3
Types
of
Natural Vegetation
2
You will learn:
• to describe the global distribution of different types of forests
• to describe the characteristics of different types of forests
• to compare the ways in which different types of forests adapt to the environment
3
What is Natural Vegetation?
• Natural vegetation refers to plants that grow naturally in a place with little or no human interference.
• It plays an important role in a forest ecosystem by providing food and shelter for the animals and native people that live in the forest.
4
Major types of natural vegetation
Tropical rainforest Temperate deciduous forest
Coniferous forest
Grassland biome
Grasses constitute the main plants in a grassland biome. It has few varieties of plants.
Tropical grassland Temperate grassland
Desert biome
The vegetation in a desert biome consists of mainly sparse vegetation, such as scrubs and tough grasses in the hot desert, and mosses and lichens in the cold desert. It has very few varieties of plants.
Hot desert vegetationCold desert vegetation
(tundra)
Forest biome
The vegetation in a forest biome consists of mainly trees. It generally has many varieties of plants.
5
Distribution of Natural Vegetation
• Climate is a major factor in influencing the distribution of natural vegetation.
• There are 3 climatic types..
Very low temperatures, often below 0ºC. Very low annual precipitation, below 250 mmPolar region
Temperate region
Tropical region
Tropical region
Temperate region
Polar region
Low to modern temperatures, ranging from 0°C to 34°C, depending on the season. Moderate annual precipitation, 300 mm to 1 000mm High temperatures throughout the year, 20°C to 30°C. High
precipitation, above 1 000 mm
6
Distribution of Natural Vegetation
• Temperature and precipitation can influence plant growth.
• Plant growth is more abundant in areas where temperatures are consistently above 20C than in areas where temperatures fall below 6C.
7
Distribution of Natural Vegetation
• Water is required by plants to make food. • Thus, different types of natural vegetation
forests are found in different parts of the world.- forests --- high precipitation at above
1 000mm per year. - grasslands --- moderate precipitation
between 200mm to 1 000mm per year.- hot desert vegetation or tundra --- no or
little precipitation at less than 250 mm per year.
8
Distribution of Natural Vegetation
9
Tropical forests are a cradle of biodiversity. It has been estimated that half of the plant and animal life forms that live on this planet are found in this environment, even though tropical forests cover only six percent of the earth’s surface. Source: The Tropical Rainforest by Francesco Petretti, Journey Editions, 1998, Italy.
10
Tropical Rainforest
• Tropical rainforests- found in places that experience tropical equatorial climate- high temperatures, about 27C - high amount of rainfall, above 1 500mm throughout the year- examples of tropical rainforests are Amazon Basin in South America, Congo Basin in Africa and parts of Southeast Asia
11
Tropical Rainforest
• Structure of the forest
- 5 layers:- Emergent layer, 30m to 50m
- Canopy layer, 15m to 30m
- Understorey layer, 6m to 15m
- Shrub layer, grow up to 6m
- Undergrowth layer, grow up to 5m
12
Tropical RainforestEmergent layer 50 m
Tall trees, called emergents, reach a height of 30 m to 50 m. Their crowns appear above the canopy layer. These trees have tall, thick and straight trunks.
30 m
Canopy layer
The trees in this layer reach a height of 15 m to 30 m. Their wide, shallow and umbrella-shaped crowns form a continuous leaf cover, called a canopy, as they prevent sunlight from penetrating into the lower layers of the forest. 15 m
Understorey layer
The trees here have narrower, oval-shaped crowns because most of the sunlight is blocked by the canopy. These trees grow where gaps in the canopy allow sunlight to pass through. Their heights range from 6 m to 15 m. Young trees of the emergent and canopy layers are also found in this layer.
6 m
Shrub layer
Tree saplings and woody plants are found in this layer. They may grow up to 6 m high.
5 m
Undergrowth layer
The undergrowth or forest floor is made up of grasses, ferns, mosses and fungi. Plant growth is sparse because very little sunlight reaches this layer. Plants in this layer reach a maximum height of 5 m.
0 m
13
Tropical Rainforest• Characteristics of the 5 layers
Emergent layer - trees have tall, thick and straight trunksCanopy layer- tree crowns inter-lock- presence of epiphytes & lianas, and parasitic plantsUnderstorey layer- trees with narrower crowns- presence of parasitic plantsShrub layer- tree saplings & woody plants foundUndergrowth layer- sparse due to lack of sunlight that reaches the forest
floor
14
Tropical Rainforest• Characteristics
- a wide diversity of plant species- 750 species of trees and 1 500 species of other plants in 1 hectare- the high temperature and rainfall throughout the year enables it to support a large variety of plants
• Density- extremely dense- density is due to high temperature and rainfall that encourage abundant vegetation growth
15
Tropical Rainforest• Characteristics & Adaptations
Leaves
- are evergreens
- due to high rainfall throughout the year, trees do not shed leaves at the same time
- are waxy with drip tips
- to allow rainwater to drain off easily
16
Tropical Rainforest
• Characteristics & Adaptations
Flowers & fruits
- are colourful & sweet-smelling
- to attract insects for pollination and animals for seed dispersal
17
Quick Quiz
• Can you identify the flower?
18
Quick Quiz
• It is a type of Rafflesia, a spectacular plant found in the tropical rainforest.
• There are 15 to 19 species of Rafflesia.
• Rafflesia is known to produce the largest individual flower on earth.
19
Tropical rainforest
• Characteristics & AdaptationsBark & branches- thin and smooth branches- does not need protection against cold or dry conditions- branches are found at the uppermost one-third of the trunks to get as much sunlight as possible
Roots- shallow and spreading- nutrients are found at topsoil due to high decomposition
- buttress roots (of some tall trees)- support weight of trees.
20
Tropical Monsoon Forest • Tropical monsoon forest
- found in the tropics
- high temperatures, about 26C
- high amount of rainfall, above 1 500mm throughout the year, but with distinct wet and dry seasons
- located in South Asia, Southeast Asia,southern China and northern Australia
21
Tropical Monsoon Forest• Distribution
22
Tropical Monsoon Forest
• Structure of the forest
- 3 layers:
- Canopy layer, 25m to 30m
- Understorey layer, about 15m
- Undergrowth layer
23
Tropical Monsoon Forest 30 m
Canopy layer
Trees can grow to 25 to 30 m
in height. They are more
spread out than those in a
tropical rainforests, plants such
as creepers, vines, epiphytes
and parasitic plants are found
within this layer.
15 m
Understorey layer
The trees in the understorey
are about 15 m in height.
6 m
Undergrowth
Bamboo thickets and grasses
grow densely here during the
wet season. They are
dense during the dry season.
0 m
24
Tropical Monsoon Forest
• Characteristics of the 3 layersCanopy layer- more spread out than those in tropical rainforest- presence of epiphytes & lianas, and parasitic plants
Understorey layer- consists of shorter trees about 15m in height
Undergrowth
- bamboo thickets and grasses grow densely here during the wet season but are less dense during dry season
25
Tropical Monsoon Forest
• CharacteristicsDiversity of plant species- about 200 species in 1 hectare- less species compared to tropical rainforest due to inconsistent rainfall
Density- plant growth is abundant but less dense than tropical rainforest
26
Tropical Monsoon Forest
• Characteristics & Adaptations
Leaves
- are deciduous
- shed leaves during the dry season to minimise loss of water through transpiration
- waxy with drip tips to allow rainwater to drain off easily
27
Tropical Monsoon Forest
• Characteristics & AdaptationsBark & branches- thick & coarse
- protects the trunk from heat and dryness during the dry season- withstand extreme heat from natural - forest fires- branches found around middle of trunks as trees grow less dense than tropical rainforest
28
Tropical Monsoon Forest
• Characteristics & Adaptations
Roots
- deep tap roots
- to tap water sources deep under the ground as rainfall is irregular throughout the year
29
Tropical forests in a glance
• What are the similarities between the tropical rainforest and the tropical monsoon forest?
• What are the differences?
30
Tropical forests in a glance
• Similarities
- both forests are dense
- leaves are waxy with drip-tips
31
Tropical forests in a glance
• Differences diversitydiversity
densitydensity
leavesleaves
bark & bark & branchesbranches
rootsroots
32
AnswersTropical rainforest Differences in
terms of Tropical monsoon forest
more diversity less
denser density less dense
evergreen leaves deciduous
Smooth, thin bark
Branches at top one-third
bark & branches Thick bark
Branches around middle of tree
shallow roots deep tap roots
33
Quick Quiz
• What do you think the feature with the shape of a heart is?
34
Quick Quiz
• It’s actually a picture of the mangrove forest in New Caledonia, an island near Australia in the southern Pacific Ocean.
• The sand is clearly seen because the saltiness of the soil has discouraged plant growth.
• Source: The Earth from the Air for Children by Yann Arthus-Bertrand, 2002, Thames & Hudson, UK.
35
Mangrove forests
• Found mainly in areas experiencing tropical climate, along sheltered coastal regions and places where rivers constantly deposit clay and silt.
36
Mangrove Forests• Structure
- grows to a height of 2m to 40m
- horizontal zones of mangrove species
Coastal area
Avicennia and Sonneratia trees are
common in this zone, which is the
nearest to the coast. They have adapted
to growing in salt water, as the coastal
zone is flooded with seawater during
high tide. The trees have breathing
roots or aerial roots.
Middle zone
Rhizophora trees are common in this
zone. They have prop roots or stilt roots.
Inland zone
Bruguiera trees grow further inland, as
they are the least tolerant of salt water.
They have knee-like roots.
High tide
Low tide
37
Mangrove Forests
• Characteristics & Adaptations- four main species which are known as halophytes - Avicennia, Sonneratia, Rhizophora, Bruguiera- dense & luxuriant
Leaves- evergreen- salt secretors- ultrafiltrators
38
Mangrove Forests• Characteristics & Adaptations
Flowers - generally colourful to attract insects to pollinate
Fruits- buoyant so that waves and currents can carry them
away- elongated with sharp tips to anchor in soft muddy soil
39
Mangrove Forests
• Characteristics & Adaptations
Roots
- aerial roots that are exposed
- allow them to take in oxygen
- prop roots
- anchor the trees firmly in the muddy soil
40
Coniferous Forests
• Coniferous forest
- found in places that experience a cool continental climate
- experiences seasons
- temperatures range from -40C to 21C
- low amount of precipitation, usually in the form of snow, 300mm to 635mm in a year
- located in Alaska, northern Canada, northern USA, northern Scandinavia & Russia
41
Coniferous Forests
• Distribution
42
Coniferous Forest
• Structure
- no distinct layers
- generally uniform in height, about 20m to 30m
- trees grow close together
- little undergrowth
43
Coniferous forests
• Characteristics & AdaptationsDiversity- few species as not many trees can adapt to
the climate- the trees grow in pure standsDensity- forest are not dense as the climate does not
support dense vegetation growth
44
Coniferous Forest
• CharacteristicsLeaves- evergreen- retain leaves so that photosynthesis can take place whenever temperature rises above 6 C - needle-like with small surface area to reduce water loss due to transpiration- store water for use in winter
45
Coniferous Forest
• Characteristics & AdaptationsFlowers & Fruits- trees bear female and male cones- female cones produce seeds- male cones produce pollen- cones can be dispersed by wind or animals after pollination
46
Coniferous forest
• Characteristics & AdaptationsBark and branches- thick bark - to protect from long, cold winters- flexible branches that slope downwards - to enable snow to slide off easilyRoots- shallow, spreading roots- enable trees to absorb water easily from soil surface when snow melts
47
Importance of Forests
• Support diversity of plants and animals.
• Natural habitats for animals.
• Provide us with resources.
• Home to some natives.
• Part of our natural heritage.
48
Learning Outcomes
•Global distribution of tropical rainforests, Global distribution of tropical rainforests, tropicaltropical monsoon forests, mangroves and monsoon forests, mangroves and coniferous forests.coniferous forests.•Characteristics and adaptations of tropical Characteristics and adaptations of tropical rainforests, tropical monsoon forests, rainforests, tropical monsoon forests, mangroves and coniferous forests.mangroves and coniferous forests.•SkillsSkills-- Compare and contrast the characteristicsCompare and contrast the characteristics of different forests.of different forests.
top related