Biosphere Revision Material for Miss T’s class

Make sure you revise from the summary notes and from your jotter… if you revise just from this PowerPoint you won’t pass!

End of unit test is on Thursday 3/09/2009

Good luck!

Basically, you need to know…

• Vegetation Succession – Pioneer climax vegetation.

• Soil Characteristics and Processes- what is soil made from and what elements (things) shape, change the soil over time.

• Sand Dune succession. • Soil Profiles (Podzol, Brown-earth and Gley soil)-

make sure you can draw/label them! • Soil Catena.

Vegetation succession • Succession is the steady change of plants over

time, e.g. moss, lichens, weed, small plants, shrubs and then trees.

You need to know what happens to a piece of land that has been destroyed by forest fire or volcanic activity .. Brand new piece of land that just formed due to under water volcanic activity (Iceland is a real life example).

You need to be able to answer exam question like:

Describe the main events that takes place at each stage of vegetation succession. (12)

Use page 2 of the summary notes to help you!

Succession stages

1. The improved soil attracts other larger and more complex species.

2. All plants are competing for light, nutrients and water. Survival of the fittest.

3. New species change the environment. They continue to improve the soil – attracting more new species to settle.

4. As this process of succession continues the number of species and it’s size (height) increase.

There are three succession stage you need to be aware of: 1, Pioneer 2, Secondary succession stage, and finally 3, Climax vegetation. At each stage different things happen to the land and soil but four things I have listed below happen at all stages.

What is soil???

Soil is the thin layer of loose material which covers much of the Earth’s land surface. Soil is mostly broken-down rock fragments and rotting organic matter.

It takes up to 400 years for 1cm of soil to form, and between 3000 and 12000 years to produce sufficient depth for farming.

Composition of a typical soil(Characteristics)

For more information see summary notes page 4

Composition of a typical soil (Characteristics)

• Mineral matter – from the physical and chemical composition of the parent material.

• Water occupies the “void”- the gaps between soil particles. Too little water has a negative effect on biota and rates of decomposition

• Air fills the space between the particles. Air is needed for biotas. Amount of in air depends on the type of material found in soil.

• Organic matter/humus. Essential for soil fertility, boosts soil nutrient level.

• Biota- living animal and plants. Help decomposition of organic matter. They mix and bind the soil together.

Soil Processes- read summary notes page 5-6

Sand Dune Succession(remember Troon/Ayre trip?)

An aerial view of a sand dune system

youngest dunes

oldest dunes

Vegetation Successions in Coastal Dune Belts(Psammoseres)

Strandline/Embryo Dune

• Along the line next to the sea plants have to cope with difficult conditions including the drying effect of the wind and high levels of salt from the sea. • There is also very little humus in the

soil.

Fore-dune

At the fore-dune the salt content begins to decrease and some humus develops from the decay of the sea couch grass.

Marram grass begins to grow.

The leaves of the marram grass can curl up to reduce moisture loss.

The marram grass, which has long tap roots to find water, can survive being buried by wind-blown sand.

Yellow dune and grey dune At the main dune the marram grass thrives

and form a thin layer of humus which allows other plants such as dandelions and sea spurges to grow.

With time the soil becomes damper and richer to enable mosses, lichens and flowering plants to grow.

Oldest dune

The climax vegetation is on the oldest dunes which lie farthest from the sea where salt level are lower and there is more humus in the soil.

The climax vegetation can take many forms including grasses, heathers and pine trees. The type of vegetation depends on the amount of calcium carbonate in the soil.

Dune slack Water sometimes collects

behind the back of dunes. These damp hollows are called dune slacks.

Marsh plants and small willow trees sometimes grow in the slacks.

Study diagram “vegetation succession on coastal dune area”. Describe and explain the changes in the type of plants to be found across the sand dune transect.

12 marks

Psammosere: summary of stages

Podzol soils are ________soils which are found in ________latitudes under ________forests. Cones and _______from the coniferous trees help to form a very ________ humus.

Podzol soils are infertile soils which are found in northern latitudes under coniferous forests. Cones and needles from the coniferous trees help to form a very acidic humus.

Melting snow in _______ releases water which causes heavy leaching- _________ are removed from the ______ leaving a very sterile soil. The leaching of ____ and aluminium oxides results in the formation of an iron or ________ at the top of the B-Horizon. This can impede drainage and result in __________ in the A-Horizon.

Melting snow in Spring releases water which causes heavy leaching- nutrients are removed from the topsoil leaving a very sterile soil. The leaching of iron and aluminium oxides results in the formation of an iron or hard pan at the top of the B-Horizon. This can impede drainage and result in water-logging in the A-Horizon.

_____ rainfall and low _________ restrict the action of soil organisms such as ______ which, if present, will help to _____ down the soil and improve its ____________.

Low rainfall and low temperature restrict the action of soil organisms such as worms which, if present, will help to break down the soil and improve its composition.

Fertility of the soil can be improved by _______ and adding lime (to make it less____) but podzols are of limited value for _______and only the hardiest of crops, such as potatoes and ____, can be grown.

Fertility of the soil can be improved by drainage and adding lime (to make it less acidic) but podzols are of limited value for farming and only the hardiest of crops, such as potatoes and oats, can be grown.

Calcium hydroxide Ca(OH)2

Characteristics of Brown Earths

• Free draining• Brown/reddish brown• Deciduous woodland• Litter rich in nutrients• Intense biological

activity e.g. earthworms• Mull humus

Brown Earth Profile

• A-topsoil dark coloured enriched with mull humus, variable depth

• B - subsoil with distinctive brown/red brown colours

• Lightening in colour as organic matter/iron content decreases with depth

Brown Earth: Soil forming factors

• Relatively warm, dry• Climate

• Generally low lying• Topography

• Vegetation/organisms • Broadleaf woodland, mull humus, indistinct horizons

• Rapid decomposition• Often earthworms and

other mixers

• Variable soil texture• Parent material

• Since end of last ice age c10,000 years

• Time

Help create a good and well aggregated, aerated and fertile crumb structured soil

Organisms in Brown Earths

Thin section of soil showing enchytraeid faecal material

False colour SEM of mixture of soil fungi and bacteria

Earthworm activity is important in soil mixing

Uses of Brown Earths

• Amongst the most fertile soils in Scotland

• Used extensively for agriculture e.g. winter vegetables

• Fertilisers required to maintain nutrient levels under agriculture

• Occurring on gently undulating terrain - used extensively for settlement and industry

• Sheltered sites suit growth of trees

Test yourself: Brown Earths

Write down 3 characteristics of a brown earth

Draw a sketch profile of a brown earth labelling the different horizons with the correct letters

Gley Soil Profile

Gley

Gley-from the Russian word; glei= compact bluish grey

Characteristics of Gley soils

• Poorly drained• Periodic or permanent waterlogging • Lack of oxygen in pore space = anaerobic conditions• Chemical reduction occurs prior to translocation• Grey or bluish grey colour to subsoil• Where gleying is intermittent, orange/yellow

coloured mottling can occur• Horizons generally rich in organic matter intergrading

into peat deposits - peaty gley to peat

Gley profile

• O - organic layer

• Bg - B horizon with evidence of gleying

• Cg - C horizon with evidence of gleying

Orange/yellow mottles

Gley: Soil forming factors

• Since end of last ice age 10,000 years ago

• Time

• Where groundwater high/ impermeable layer below

• Topography

• Relatively warm• Precipitation greater than

evaporation - leaching

• Climate

• Anaerobic organisms found• Vegetation/organisms

• Parent material • Variable - coastal sand to glacial till

Anaerobic organisms in gleys

Uses of Gleys

When drained, the better gley soils can be used for agriculture; usually productive grassland for dairy or beef cattle

In their natural state they support wet plant species and are used for rough grazing and forestry

Mottling

Test yourself: Gley

What does “anaerobic” mean?

Where in a landscape would you find a gley?

Soil revision ideas

• Draw out each of the 3 soil profiles with and without labels e.g. on a separate index card for each soil

• Shade/highlight the soil characteristics in one colour and soil processes in another

• Make photocopies of the profile without labels and practice labelling it when revising

• Write out some one word answer questions such as those on the following slides

• Test yourself using past paper questions

Test yourself - 10 questionsone word answers

• Name of the zone that material moves out of in a podzol

• Type of humus found in brown earths• The term used for a downward movement of

minerals in a soil caused by precipitation being greater than evaporation

• F refers to ….. in a soil profile• The h in Ah refers to ...

Test yourself - 10 questionscontinued

• The type of vegetation found above a podzol• Typical colour of the sub soil in a Gley• In Brown Earths the horizons are often indistinct due

to the activity of ….• The acidic humus found in a podzol is known as …..• The iron pan in a podzol is a zone of ...

Question 6: Biosphere

• Describe the different properties (horizons, colour, texture, drainage) of the two soils shown.

• Explain the differences in their formation.

SQA past questions2006

Study Reference Diagram Q6 which shows soil profiles for a podzol and a brown earth

PODZOLBROWN EARTH

Reference Diagram Q6

(Selected soil profiles)

Marks 14

Question 6: Biosphere

(i) Describe the characteristics of the soil, including horizons, colour, texture and drainage.

SQA past questions2007

Study Reference Diagram Q6A which shows two soil profiles.

PODZOL GLEY

Reference Diagram Q6A (Selected soil

profiles)

Marks 6