GeoecologyGeoecology

Option Option

2008: Q.182008: Q.18

Examine 2 of the natural processes Examine 2 of the natural processes that influence soil formation (80)that influence soil formation (80)

What you need to doWhat you need to do

Explain how soils formExplain how soils form Name 2 processes influencing soil Name 2 processes influencing soil

formationformation Explain in detail how each process Explain in detail how each process

affects soilaffects soil Refer to 2 named soil types in your Refer to 2 named soil types in your

answeranswer

2008: Q.182008: Q.18 Soil : loose material on earth’s surface formed by Soil : loose material on earth’s surface formed by

weathering and erosion of rocks.weathering and erosion of rocks. Formed due to a combination of factors such as Formed due to a combination of factors such as

climate, relief, living organisms, parent material climate, relief, living organisms, parent material and time.and time.

E.g., latosols form in tropical wet climates and E.g., latosols form in tropical wet climates and brown earth soil form in temperate climates brown earth soil form in temperate climates where deciduous trees are present.where deciduous trees are present.

2008: Q.182008: Q.18 Climate: Climate: affects temperature and rainfall in a affects temperature and rainfall in a

region. They have important effects on soil.region. They have important effects on soil. Rainfall washes nutrients + humus down through Rainfall washes nutrients + humus down through

soil.soil. Temperature affects activity of living things.Temperature affects activity of living things. Climate affects the vegetation that can grow in a Climate affects the vegetation that can grow in a

region. E.g.: Arctic region; few plants can surviveregion. E.g.: Arctic region; few plants can survive Vegetation is important in developing soil type, Vegetation is important in developing soil type,

e..g. brown earth + podzole..g. brown earth + podzol Climate affects weathering that takes place in a Climate affects weathering that takes place in a

region; colder regions > more freeze – thaw region; colder regions > more freeze – thaw actionaction

Climate controls the amount of leaching in a Climate controls the amount of leaching in a regionregion

2006, q 16: Examine the factors that 2006, q 16: Examine the factors that influence soil characteristics.influence soil characteristics.

What you need to do:What you need to do: Choose 3- 4 soil characteristicsChoose 3- 4 soil characteristics Discuss how these characteristics are Discuss how these characteristics are

affected by soil – forming processesaffected by soil – forming processes Refer to specific soils in your answerRefer to specific soils in your answer

2008: Q.182008: Q.18 Relief:Relief: means ‘ lay of the land’ or angle and means ‘ lay of the land’ or angle and

length of slopes.length of slopes. Relief influences the amount of water that runs Relief influences the amount of water that runs

off soil, how much water seeps into soil + amount off soil, how much water seeps into soil + amount of erosion.of erosion.

Steep slopes have thinner soils due to mass Steep slopes have thinner soils due to mass movement such as soil creep and landslides.movement such as soil creep and landslides.

Soils on flatter land is deeper and has more Soils on flatter land is deeper and has more organic content because more plants can grow.organic content because more plants can grow.

Relief influences aspect aswell . Which in turn Relief influences aspect aswell . Which in turn affects soil quality as north facing slopes receive affects soil quality as north facing slopes receive less heat + light.less heat + light.

2006, q 162006, q 16

Characteristics of soil: colour, Characteristics of soil: colour, texture, structure, pH, texture, structure, pH,

humus content, water contenthumus content, water content

2006, q 162006, q 16

Factors affecting soil colour:Factors affecting soil colour: Colour of soil depends on soil – forming processes Colour of soil depends on soil – forming processes

acting upon it.acting upon it. Humification tends to produce dark – coloured or Humification tends to produce dark – coloured or

black soils. Humification is method by which dead black soils. Humification is method by which dead organic matter converted to humus by action of organic matter converted to humus by action of fungi and bacteria.fungi and bacteria.

Leaching affects soil colour as it tends to lighten Leaching affects soil colour as it tends to lighten the colour of soils. It washes nutrients such as the colour of soils. It washes nutrients such as phosphorous down through soil, leaving soil pale phosphorous down through soil, leaving soil pale and ash coloured.and ash coloured.

2006, q 162006, q 16 Factors affecting soil texture:Factors affecting soil texture: Soil texture is the way soil feels when rubbed in Soil texture is the way soil feels when rubbed in

our hands > soil can have 4 types of texture; a) our hands > soil can have 4 types of texture; a) sandy, b) silty, c) clay, d) loamsandy, b) silty, c) clay, d) loam

Freeze – thaw action and other mechanical Freeze – thaw action and other mechanical weathering processes acting on sandstone rocks weathering processes acting on sandstone rocks can produce sandy soils. Marine action can also can produce sandy soils. Marine action can also produce these soils.produce these soils.

Granite rocks are chemically weathered by Granite rocks are chemically weathered by hydrolysis. This is the action of water on feldspar hydrolysis. This is the action of water on feldspar minerals in granite. The feldspar is converted to minerals in granite. The feldspar is converted to clay which produces clay – texture soil.clay which produces clay – texture soil.

Soils with a silty texture are found in areas where Soils with a silty texture are found in areas where river deposition has occurred.river deposition has occurred.

2006, q 162006, q 16 Factors affecting humus content:Factors affecting humus content: Humus content is affected by factors such as climate and Humus content is affected by factors such as climate and

reliefrelief Climate: Climate: affects temperature and rainfall in a region. They affects temperature and rainfall in a region. They

have important effects on soil.have important effects on soil. Rainfall washes nutrients + humus down through soil.Rainfall washes nutrients + humus down through soil. Temperature affects activity of living things.Temperature affects activity of living things. Climate affects the vegetation that can grow in a region. Climate affects the vegetation that can grow in a region.

E.g.: Arctic region; few plants can surviveE.g.: Arctic region; few plants can survive Vegetation is important in developing soil type, e..g. brown Vegetation is important in developing soil type, e..g. brown

earth + podzolearth + podzol Climate affects weathering that takes place in a region; Climate affects weathering that takes place in a region;

colder regions > more freeze – thaw actioncolder regions > more freeze – thaw action Climate controls the amount of leaching in a regionClimate controls the amount of leaching in a region

2006, q 162006, q 16

Relief:Relief: means ‘ lay of the land’ or angle and means ‘ lay of the land’ or angle and length of slopes.length of slopes.

Relief influences the amount of water that runs Relief influences the amount of water that runs off soil, how much water seeps into soil + amount off soil, how much water seeps into soil + amount of erosion.of erosion.

Steep slopes have thinner soils due to mass Steep slopes have thinner soils due to mass movement such as soil creep and landslides.movement such as soil creep and landslides.

Soils on flatter land is deeper and has more Soils on flatter land is deeper and has more organic content because more plants can grow.organic content because more plants can grow.

Relief influences aspect aswell . Which in turn Relief influences aspect aswell . Which in turn affects soil quality as north facing slopes receive affects soil quality as north facing slopes receive less heat + light.less heat + light.

2007, q 17: Examine the general 2007, q 17: Examine the general composition and characteristics of composition and characteristics of

any one soil type that you have any one soil type that you have studiedstudied

What you need to do:What you need to do: Name the soil type you’re discussingName the soil type you’re discussing Discuss composition and Discuss composition and

characteristics giving reasonscharacteristics giving reasons

2007, q 172007, q 17

In this answer the composition and In this answer the composition and characteristics of brown earth soil characteristics of brown earth soil will be examinedwill be examined

Zonal soil: developed in response to Zonal soil: developed in response to a climatic zone and its natural veg.a climatic zone and its natural veg.

In this case, BES have developed in In this case, BES have developed in response to cool temp. oceanic and response to cool temp. oceanic and mixed deciduous forestmixed deciduous forest

2007, q 172007, q 17 Composition of BES:Composition of BES: BES contain all materials> mineral matter, air, BES contain all materials> mineral matter, air,

water, living things, humus.water, living things, humus. BES contain mineral matter that has developed in BES contain mineral matter that has developed in

response to mechanical and chemical weathering response to mechanical and chemical weathering > freeze thaw action in uplands and sheltered > freeze thaw action in uplands and sheltered lowlands. lowlands.

BES contain air and water held in the pore spaces BES contain air and water held in the pore spaces btwn grains. Water comes from moderate btwn grains. Water comes from moderate amounts of rainfall.amounts of rainfall.

Organic matter and humus present in BES Organic matter and humus present in BES because cool, temperate oceanic climate is mild; because cool, temperate oceanic climate is mild; BES contains lots of living thingsBES contains lots of living things

2007, q 172007, q 17 Characteristics of BES:Characteristics of BES: Texture: loam texture. Loam have roughly equal mix of Texture: loam texture. Loam have roughly equal mix of

sand, silt and clay particles. BES developed on variety of sand, silt and clay particles. BES developed on variety of parent rock such as limestone, slate and sandstoneparent rock such as limestone, slate and sandstone

Humus content: High because of action of humification. Soil Humus content: High because of action of humification. Soil – forming process dominant in cool temperate oceanic – forming process dominant in cool temperate oceanic climates.climates.

pH: Varies from mildly acidic to mildly alkaline. Due to pH: Varies from mildly acidic to mildly alkaline. Due to moderate rainfall that only mildly leaches soil.moderate rainfall that only mildly leaches soil.

Structure: BES have a crumb structure, where peds are Structure: BES have a crumb structure, where peds are clumped together in round grains or crumbs. Crumb soil clumped together in round grains or crumbs. Crumb soil structures develop in soils with lots of living things.structures develop in soils with lots of living things.

Colour: BES are uniformly brown due to being well mixed by Colour: BES are uniformly brown due to being well mixed by plant roots and animal activity. High humus content.plant roots and animal activity. High humus content.

2007, q 172007, q 17

Variations of BESVariations of BES Acidic BES: developed in upland Acidic BES: developed in upland

areas 500m + in altitudeareas 500m + in altitude Shallow BES: limestone areas such as Shallow BES: limestone areas such as

BurrenBurren Podzolised BES: Developed where Podzolised BES: Developed where

podzolisation has occurred in low – podzolisation has occurred in low – lying areas.lying areas.

BiomesBiomes

Tropical RainforestTropical Rainforest

Vegetation: Emergent LayerVegetation: Emergent Layer

Emergent layer consists of tops of Emergent layer consists of tops of tallest trees, from 40m to 80mtallest trees, from 40m to 80m

Trees have small, pointed leavesTrees have small, pointed leaves Trees have straight smooth trunksTrees have straight smooth trunks Root system shallowRoot system shallow

Emergent SpeciesEmergent Species

– Hummingbird

Squirrel Monkey

Scarlet Macaw

Vegetation: CanopyVegetation: Canopy

Canopy upper parts of trees which Canopy upper parts of trees which grow below emergentgrow below emergent

Canopy found 20-40m above groundCanopy found 20-40m above ground

Canopy SpeciesCanopy Species

ToucanToucan

HornbillHornbill

OrangutanOrangutan

Vegetation: UnderstoreyVegetation: Understorey

Dark environment under canopyDark environment under canopy Plant growth limitedPlant growth limited Short, leafy, mostly non – flowering Short, leafy, mostly non – flowering

shrubsshrubs

Understorey: SpeciesUnderstorey: Species

JaguarsJaguars

BeetleBeetle

LizardLizard

Forest FloorForest Floor

Teeming with animal lifeTeeming with animal life Less than 1% of light that strikes top Less than 1% of light that strikes top

of forest reaches forest floorof forest reaches forest floor Few plants growFew plants grow

Forest Floor: SpeciesForest Floor: Species

TapirTapir

AnteaterAnteater

LeavesLeaves High Level Rainfall > Plants have High Level Rainfall > Plants have

made adaptationsmade adaptations

Drip tips Drip tips Grooved leavesGrooved leaves Oily coatingsOily coatings Large leaves to absorb lightLarge leaves to absorb light

Roots and TrunksRoots and Trunks Emergents grow fast to absorb lightEmergents grow fast to absorb light

‘‘Stilt’ roots for supportStilt’ roots for support

Smooth, thin barkSmooth, thin bark EpiphytesEpiphytes

Parasitic PlantsParasitic Plants

Live off nutrients of Live off nutrients of host planthost plant

Lianas catch a host Lianas catch a host tree and take lift to tree and take lift to lightlight

Poison Arrow FrogPoison Arrow Frog

SlothsSloths

Flying FoxesFlying Foxes

Deforestation and intensive Deforestation and intensive agriculture in Brazilagriculture in Brazil

Deforestation and intensive Deforestation and intensive agriculture in Brazilagriculture in Brazil

Causes of deforestation in Brazil:Causes of deforestation in Brazil: Intensive agricultureIntensive agriculture LoggingLogging Demand for wood as fuelDemand for wood as fuel Construction of large dams / Construction of large dams /

reservoirs drown forestreservoirs drown forest Mining and industry clear forestMining and industry clear forest Government – organised colonisation Government – organised colonisation

schemes clear forestschemes clear forest

Underlying social and economic Underlying social and economic conditions in Brazilconditions in Brazil

1.1. Overpopulation and poverty in Overpopulation and poverty in Brazil creates political difficultiesBrazil creates political difficulties

2.2. Government wants to open up Government wants to open up rainforest to take advantage of rainforest to take advantage of timber and mineral wealthtimber and mineral wealth

3.3. Beef producers require more landBeef producers require more land

4.4. Industry requires more powerIndustry requires more power

DeforestationDeforestation Timber companies given rights to remove forest Timber companies given rights to remove forest

and sell timber abroadand sell timber abroad Licences given to mining companies to clear Licences given to mining companies to clear

forests and mine for metalsforests and mine for metals Roads are being built across the Amazon Roads are being built across the Amazon

rainforest to allow access to logging companiesrainforest to allow access to logging companies New capital city, Brasilia, built from scratch New capital city, Brasilia, built from scratch

during 50s and 60s in heart of Amazonduring 50s and 60s in heart of Amazon Over 125 new HEP dams have been built in the Over 125 new HEP dams have been built in the

Brazilian rainforest areaBrazilian rainforest area January 2000: Brazilian government announced January 2000: Brazilian government announced

plans for Avanca Brasil > €30m plan to develop plans for Avanca Brasil > €30m plan to develop much of Amazon rainforestmuch of Amazon rainforest

Impact of agriculture on biomeImpact of agriculture on biome

Effects of intensive agriculture:Effects of intensive agriculture: DeforestationDeforestation Destruction of natural habitat: soils Destruction of natural habitat: soils

damaged due to intensive agriculture, damaged due to intensive agriculture, animals and plants cant survive in the animals and plants cant survive in the plantations plantations

Introduction of exotic speciesIntroduction of exotic species

Impact of clearance on people and Impact of clearance on people and wildlifewildlife

Suggested that some Amazonian Indians Suggested that some Amazonian Indians may have been murdered for resistancemay have been murdered for resistance

Area of natural habitat has been severely Area of natural habitat has been severely reducedreduced

Many species of plant have been lost > Many species of plant have been lost > serious concern as some contain serious concern as some contain chemicals that could 1 day cure illnesseschemicals that could 1 day cure illnesses

Increase in global warmingIncrease in global warming

Impact on Brazilian soilsImpact on Brazilian soils

When forest is cleared, nutrient cycle When forest is cleared, nutrient cycle is destroyedis destroyed

Soil then becomes baked hard which Soil then becomes baked hard which cannot support plant growthcannot support plant growth

Useless for farmingUseless for farming