Transcript Biomes - leavingcertgeography

Geoecology
Option
2008: Q.18
 Examine
2 of the natural processes
that influence soil formation (80)
What you need to do
 Explain
how soils form
 Name 2 processes influencing soil
formation
 Explain in detail how each process
affects soil
 Refer to 2 named soil types in your
answer
2008: Q.18



Soil : loose material on earth’s surface formed by
weathering and erosion of rocks.
Formed due to a combination of factors such as
climate, relief, living organisms, parent material
and time.
E.g., latosols form in tropical wet climates and
brown earth soil form in temperate climates
where deciduous trees are present.
2008: Q.18







Climate: affects temperature and rainfall in a
region. They have important effects on soil.
Rainfall washes nutrients + humus down through
soil.
Temperature affects activity of living things.
Climate affects the vegetation that can grow in a
region. E.g.: Arctic region; few plants can survive
Vegetation is important in developing soil type,
e..g. brown earth + podzol
Climate affects weathering that takes place in a
region; colder regions > more freeze – thaw
action
Climate controls the amount of leaching in a
region
2006, q 16: Examine the factors that
influence soil characteristics.
 What
you need to do:
 Choose 3- 4 soil characteristics
 Discuss how these characteristics are
affected by soil – forming processes
 Refer to specific soils in your answer
2008: Q.18





Relief: means ‘ lay of the land’ or angle and
length of slopes.
Relief influences the amount of water that runs
off soil, how much water seeps into soil +
amount of erosion.
Steep slopes have thinner soils due to mass
movement such as soil creep and landslides.
Soils on flatter land is deeper and has more
organic content because more plants can grow.
Relief influences aspect aswell . Which in turn
affects soil quality as north facing slopes receive
less heat + light.
2006, q 16
 Characteristics
of soil: colour,
texture, structure, pH,
humus content, water content
2006, q 16




Factors affecting soil colour:
Colour of soil depends on soil – forming
processes acting upon it.
Humification tends to produce dark – coloured or
black soils. Humification is method by which dead
organic matter converted to humus by action of
fungi and bacteria.
Leaching affects soil colour as it tends to lighten
the colour of soils. It washes nutrients such as
phosphorous down through soil, leaving soil pale
and ash coloured.
2006, q 16





Factors affecting soil texture:
Soil texture is the way soil feels when rubbed in
our hands > soil can have 4 types of texture; a)
sandy, b) silty, c) clay, d) loam
Freeze – thaw action and other mechanical
weathering processes acting on sandstone rocks
can produce sandy soils. Marine action can also
produce these soils.
Granite rocks are chemically weathered by
hydrolysis. This is the action of water on feldspar
minerals in granite. The feldspar is converted to
clay which produces clay – texture soil.
Soils with a silty texture are found in areas where
river deposition has occurred.
2006, q 16









Factors affecting humus content:
Humus content is affected by factors such as climate and
relief
Climate: affects temperature and rainfall in a region. They
have important effects on soil.
Rainfall washes nutrients + humus down through soil.
Temperature affects activity of living things.
Climate affects the vegetation that can grow in a region.
E.g.: Arctic region; few plants can survive
Vegetation is important in developing soil type, e..g. brown
earth + podzol
Climate affects weathering that takes place in a region;
colder regions > more freeze – thaw action
Climate controls the amount of leaching in a region
2006, q 16





Relief: means ‘ lay of the land’ or angle and
length of slopes.
Relief influences the amount of water that runs
off soil, how much water seeps into soil +
amount of erosion.
Steep slopes have thinner soils due to mass
movement such as soil creep and landslides.
Soils on flatter land is deeper and has more
organic content because more plants can grow.
Relief influences aspect aswell . Which in turn
affects soil quality as north facing slopes receive
less heat + light.
2007, q 17: Examine the general
composition and characteristics of
any one soil type that you have
studied
 What
you need to do:
 Name the soil type you’re discussing
 Discuss composition and
characteristics giving reasons
2007, q 17
 In
this answer the composition and
characteristics of brown earth soil
will be examined
 Zonal soil: developed in response to
a climatic zone and its natural veg.
 In this case, BES have developed in
response to cool temp. oceanic and
mixed deciduous forest
2007, q 17





Composition of BES:
BES contain all materials> mineral matter, air,
water, living things, humus.
BES contain mineral matter that has developed in
response to mechanical and chemical weathering
> freeze thaw action in uplands and sheltered
lowlands.
BES contain air and water held in the pore spaces
btwn grains. Water comes from moderate
amounts of rainfall.
Organic matter and humus present in BES
because cool, temperate oceanic climate is mild;
BES contains lots of living things
2007, q 17






Characteristics of BES:
Texture: loam texture. Loam have roughly equal mix of
sand, silt and clay particles. BES developed on variety of
parent rock such as limestone, slate and sandstone
Humus content: High because of action of humification. Soil
– forming process dominant in cool temperate oceanic
climates.
pH: Varies from mildly acidic to mildly alkaline. Due to
moderate rainfall that only mildly leaches soil.
Structure: BES have a crumb structure, where peds are
clumped together in round grains or crumbs. Crumb soil
structures develop in soils with lots of living things.
Colour: BES are uniformly brown due to being well mixed
by plant roots and animal activity. High humus content.
2007, q 17
 Variations
of BES
 Acidic BES: developed in upland
areas 500m + in altitude
 Shallow BES: limestone areas such
as Burren
 Podzolised BES: Developed where
podzolisation has occurred in low –
lying areas.
Biomes
Tropical Rainforest
Vegetation: Emergent Layer
Emergent layer consists of tops of
tallest trees, from 40m to 80m
 Trees have small, pointed leaves
 Trees have straight smooth trunks
 Root system shallow

Emergent Species
–
Hummingbird
Squirrel Monkey
Scarlet Macaw
Vegetation: Canopy
Canopy upper parts of trees which
grow below emergent
 Canopy found 20-40m above ground

Canopy Species
Toucan
Hornbill
Orangutan
Vegetation: Understorey
Dark environment under canopy
 Plant growth limited
 Short, leafy, mostly non – flowering
shrubs

Understorey: Species
Jaguars
Beetle
Lizard
Forest Floor
Teeming with animal life
 Less than 1% of light that strikes top
of forest reaches forest floor
 Few plants grow

Forest Floor: Species
Tapir
Anteater
Leaves

High Level Rainfall > Plants have
made adaptations
Drip tips
 Grooved leaves
 Oily coatings
 Large leaves to absorb light

Roots and Trunks

Emergents grow fast to absorb light

‘Stilt’ roots for support
Smooth, thin bark
 Epiphytes

Parasitic Plants


Live off nutrients of
host plant
Lianas catch a host
tree and take lift to
light
Poison Arrow Frog
Sloths
Flying Foxes
Deforestation and intensive
agriculture in Brazil
Deforestation and intensive
agriculture in Brazil
Causes of deforestation in Brazil:
 Intensive agriculture
 Logging
 Demand for wood as fuel
 Construction of large dams /
reservoirs drown forest
 Mining and industry clear forest
 Government – organised colonisation
schemes clear forest
Underlying social and economic
conditions in Brazil
1.
2.
3.
4.
Overpopulation and poverty in
Brazil creates political difficulties
Government wants to open up
rainforest to take advantage of
timber and mineral wealth
Beef producers require more land
Industry requires more power
Deforestation






Timber companies given rights to remove forest
and sell timber abroad
Licences given to mining companies to clear
forests and mine for metals
Roads are being built across the Amazon
rainforest to allow access to logging companies
New capital city, Brasilia, built from scratch
during 50s and 60s in heart of Amazon
Over 125 new HEP dams have been built in the
Brazilian rainforest area
January 2000: Brazilian government announced
plans for Avanca Brasil > €30m plan to develop
much of Amazon rainforest
Impact of agriculture on biome
Effects of intensive agriculture:
 Deforestation
 Destruction of natural habitat: soils
damaged due to intensive agriculture,
animals and plants cant survive in the
plantations
 Introduction of exotic species
Impact of clearance on people and
wildlife




Suggested that some Amazonian Indians
may have been murdered for resistance
Area of natural habitat has been severely
reduced
Many species of plant have been lost >
serious concern as some contain
chemicals that could 1 day cure illnesses
Increase in global warming
Impact on Brazilian soils
When forest is cleared, nutrient cycle
is destroyed
 Soil then becomes baked hard which
cannot support plant growth
 Useless for farming
