P&E CS - Podsol and Tropical Red latisol

Where is tropical red latosol found?

• 5º N and S of the equator - tropical equatorial rainforest biome

• supports half of all living organisms on earth

How is the latosol able to accommodate the level of growth in tropical climates?

• world’s most predictable climate - hot wet and humid without seasons

• promotes perfect growing all year round for plants

• this means deciduous trees can lose their leaves at any point providing constant supply of leave litter which rapidly decomposes into nutrient rich hummus

• so lower layers being infertile has no impact

Why is the clearing of the forest detrimental for TRL?

• when cleared the readily available supply of hummus is halted and TRL becomes quickly exhausted of nutrients

• then is exposed to excessive leaching of nutrients and to erosion by gullying in heavy convectional rainfall.

What is the impact of populations that live in tropical equatorial forests?

• for decades people have been able to live sustainably but more recently deforestation has been on a massive scale by feeling, bulldozing and burning (once covered 15% of earth but has been reduced by 6%)

• population growth and economic development have been linked to this with increased need for:

  • land for settlement

  • land for agriculture

  • hardwood timber

  • access to mineral extraction

How can soils be classified?

zonal system - divides world’s soils into 3 major categories

• zonal = mature soils reflecting climatic conditions

• intrazonal = reflect the dominance of other factors such as parent rock

• azonal = generally immature and skeletal, poorly developed

What is the composition from surface to underground of tropical red latosol?

1. think hummus layer quickly broken down giving soil grey-red colour with many active decomposers

2. a layer of rapid leaching of silica and dissolved salts - build up of iron and aluminium oxide gives soil dark red colour.

3. some silica is re-deposited deeper in the soil giving it a yellowish colour and clays are produced due to chemical weathering

4. bedrock and parent material.

how deep can TRL be?

up to 30m

where is podsol found?

• it is the zonal soil of the taiga - continuous belt of subarctic climate across north america and eurasia

• also found in other areas of cool climates such as heathland and moorland of the UK

what vegetation is podsol associated with?

prolonged harsh winters and cool summers ristrict the vegetation to boreal coniferous forests (evergreen)

• spruce

• pine

• fir

What is the role of moisture in areas of podsol?

areas of boreal forest don’t receive a large amount of precipitation but podsolisation processes requires downward movement of water

• participation despite being low exceeds rate of evapotrans due to cool temp

• coniferous trees shelter the ground from drying winds

• therefor infiltration and percolation can still occur.

What are the characteristics of podsol

has a very poor nutrient cycle as coniferous evergreens do not take up many nutrients (aren’t returned to the ground in the form of litter) - hence a poor layer of hummus

• accumulation of a hard-pan of iron beneath zone of leaching (highest point of the water table)

• clear differentiation in layers (horizons), unlike tropical latosol, indicating less mixing agents such as earthworms and ants

what agricultural practices in the UK are associated with podsol?

upland sheep farming and heather moorland management for breeding grouse for shooting

• small areas of surface heather burnt in 10-15 year rotation

• provides feeding areas for grouse with unburnt nesting areas nearby

• grouse shooting generates £150 million annually so is important to the UK’s rural economy

What agricultural practices in North America and Eurasia are associated with podsol?

• lie beneath the NA and eurasian taiga biomes where hunting moose, caribou and brown bear is no longer sustainable without legal protection

• this is due to deforestation resulting in loss of habitats

• logging in NA is now managed but still occurs meaning taiga is slowly disappearing

What is the composition from surface to underground of Podsol?

1. thick black layer of acid hummus with dark staining beneath due to washing down of hummus (few organisms in the soil due to acidic conditions)

2. Below is a bleached layer more sand as finer materials are washed downwards

3. waterlogging may occur above the hard pan or iron formed with layers of aluminum beneath

4. layer of accumulated clays stained by iron oxides

5. bedrock

How deep is podsol generally?

normally won’t exceed 1m