Biosphere Flashcards
What is meant by “climax vegetation”? (6)
- Climax vegetation is the final stage in a vegetation succession, where vegetation cannot develop any more. It occurs when the vegetation has finally adapted to the climate, called climate climax
- Climax vegetation in Britain is deciduous woodland, whereas at the equator the climax vegetation is rainforest
- The climax vegetation will have the greatest variety of trees and plants
- It will have the greatest biomass
- It will have the tallest spices of plants
- It will have the most complex plants possible in a certain climate
Describe and give reasons for the changes in plant types likely to be observed across the transect as you move inland from the coast (16)
Embryo Dunes
- Hardy plants colonise the embryo dunes such as sea couch-grass
- Sea couch-grass can extract fresh water from salty water
- Sea couch-grass can survive strong winds
- Sea couch-grass can survive on a mobile soil
Fore Dunes
- Plants such as lyme grass colonise the fore dunes
- Lyme grass can survive with little fresh water
- Lyme grass can survive with little humus in soil
- Lyme grass can survive with salty air
Yellow Dunes
- More plants such as Marram grass colonise the yellow dunes
- Marram grass needs little moisture
- Marram grass has deep roots which anchors the plant in wind
- Marram grass leaves adjust to minimise transpiration
Grey Dunes
- In the slacks, which are the trenches in between sand dunes, reeds and rushes grow as they are generally waterlogged from being at the bottom of slopes
- The dunes nearest the yellow dune will have heather and shrubs growing on them
- As you get further away from the yellow dune, small trees such as pine and beech trees
- The dunes furthest away from the yellow dune will have climax vegetation, with oak and ash trees colonising them
Draw and annotate a diagram of Podzol soil and describe the characteristics of the soil
DIAGRAM
A
- Shallow soil due to slow weathering
- Thick, organic A horizon layer due to slow humification
- Ash grey A horizon due to iron and aluminium oxides leached out by acid rainwater
E
- Iron pan forms where a lot of iron is deposited and cements together
- Waterlogged soil here due to gleying
B
- Red brown B horizon due to abundance of minerals that have leached out of A horizon
- Horizons are clearly defined due to lack of biota mixing up soil
Describe and explain the processes which have contributed to the development of Podzol soil (7)
Weathering
• Weathering is slow due to cold, dry climate
Humification
- Humification is slow because coniferous trees have needles instead of leaves, so don’t decompose as quickly
- It is slow because these trees do not shed every year, so there is not as much material to decompose
- It is slow because the climate is cold and dry, and humification requires heat and moisture
- It is slow because there is very few biota living in the cold climate
Leaching
• Leaching is fast because the precipitation in Podzol soil areas is generally greater than the evaporation, like snowmelt
Gleying
• There is some gleying as the iron pan that forms in Podzol soil is impermeable, which water-logs the soil
Draw and annotate a diagram of Brown-Earth soil and describe the characteristics of the soil
DIAGRAM
A
- Quite shallow soil due to quite slow weathering
- Quite thick humus layer because some humification takes place
- Light brown A horizon due to calcium and manganese leached out by acid rainwater
B
- Dark brown B horizon due to abundance of minerals that have alluviated here
- Horizons often merge due to abundance of biota
Describe and explain the processes which have contributed to the development of Brown-Earth soil (7)
Weathering
• Weathering is quite slow due to mild climate, however regular precipitation does contribute to weathering
Humification
- Humification is quite fast because deciduous trees have leaves which decompose quickly
- It is quite fast because these trees shed every autumn, so there is quite a bit of material to decompose
- It is quite fast because the climate is mild and damp, which aids decomposition of leaves
- It is quite fast because there are some biota living in this climate
Leaching
• Leaching is all year round because the precipitation in Brown-Earth soil areas exceeds the transpiration
Gleying
• There is not much gleying as this soil has good drainage
Draw and annotate a diagram of Gley soil and describe the characteristics of the soil
DIAGRAM
A
- Very shallow soil due to very slow weathering
- Thick organic humus layer in A horizon because of slow humification
- The humus in the A horizon is acidic
- The A horizon is waterlogged because the soil is frozen most of the year, so is impermeable
B
- Blue Grey B horizon due to lack of oxygen, as the organisms extract oxygen from the iron in the soil, turning it this colour
- B horizon has large rock fragments because of the slow weathering
- Below the B horizon is permafrost because the summer heat does not penetrate the soil this far down
Describe and explain the processes which have contributed to the development of Gley soil (7)
Weathering
• Weathering is very slow because of the cold, dry climate of Gley soil areas
Humification
- Humification is very slow because there is little vegetation to decompose and turn unto humus
- It is very slow because the climate is very cold and dry, and decomposing vegetation requites heat and moisture
- It is very slow fast because there are very few biota living in such cold conditions
Leaching
- There is very little leaching because the soil is frozen solid for most of the year
- There is very little leaching because the subsoil is impermeable permafrost
Gleying
• There is a lot of gelling because of the poor drainage, caused by impermeable soil which water-logs the soil
