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BIOSPHERE Summary of What You Must Know You should be able to: describe and explain the effect of physical factors – climate , relief , drainage , parent material , soil biota and vegetation on soil formation. - PowerPoint PPT Presentation
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BIOSPHERE
Summary of What You Must Know
You should be able to:
describe and explain the effect of physical factors – climate, relief, drainage, parent material, soil biota and vegetation on soil formation.
draw annotated diagrams to describe the properties of podzols, brown earth soils and gley soils, referring to horizons, colour and texture.
recognise the type of soil shown in a profile diagram, and describe the features which help to identify the soil type.
compare and contrast the appearance and soil forming factors of two of the three soil types.
explain the series of soils found in a soil catena.
explain fully what is meant by the term climax vegetation.
describe and explain the changes in the types of plants (succession) to be found across a coastal sand dune transect, referring to the names of specific plants.
explain the changing environmental factors that they must adapt to.
Slide 25
Slide 30
The Biosphere
The Living environment
This consists of plants, animals, insects, micro-organisms and people.
The Non-living environment
This consists of
Water (rain or stored in the soil). Air – provides oxygen and carbon dioxide which is essential for life. Solar energy – provides heat and light. Rocks – the lithosphere – provides nutrients Soil – varies in depth, acidity, nutrients and fertility
Slide 19
The Biosphere – where life is found 3m below to 30m above the ground. It comprises water areas, both salt and fresh and all land. An Ecosystem – a natural system in which life of plants and animals are clearly linked to one another and to the non-living environment through food chains.
Ecosystems vary in size from extensive areas of rainforest to a micro system under a stone.
All ecosystems depend on two basic processes:
• A flow of energy (heat and light)• The recycling of nutrients within the system
Ecosystems will remain in balance unless conditions change such as climate or through human interference.
Slide 20
Soils
Soil is the function of climate (water and temperature), organisms (bacteria, insects, plants etc.), parent material (rock under the soil), relief (steepness) and time.
Factors affecting soil formation
Soil Formation
Climate
Drainage
Relief
Vegetation
Soil Biota
Parent Material
Slide 28
Classification of soils:
When precipitation exceeds evaporation water washes down through the soils carrying minerals with it. These soils are called pedalfers and include podzols and brown earth soils.
Hard pan – a resistant layer in the soil at or below the surface. Usually caused by illuviation (deposition of minerals, humus and other materials) after leaching of the upper horizons. Hard pans can be formed of clay humus or a compound of Calcium, iron and silicon.
Soil formation – a profile
A
B
C
Horizons
Organic matter Humus
Translocation
Hard pan
Bed rock
Slide 38
Slide 47
When describing any soil you must mention the impact of climate, vegetation, parent material, soil biota, drainage and relief on its development
Brown Forest Soils
Slide 31
Plentiful supply of deciduous vegetation – mildly acidic humus.
Moderate leaching occurs leading to a thin iron pan whenever leaching is more active.
Warm temperatures lead to more biotic activity and decomposition. This makes the horizons merge more gradually.
Soil is free draining so there is less likelihood of a hard pan layer.
Gentle sloping land has good drainage and moderate leaching.
This is the most fertile of the three soils we study and it can support agriculture which allows greater human development and higher population density.
Podzol Slide 32
High levels of precipitation plus spring snowmelts leads to a great deal of water flushing through the soil causing rapid leaching of minerals and the formation of a thick iron pan.
The Iron pan impedes drainage.
Pine cones and needles result in very acidic humus.
Soil horizons more clearly defined as there is little mixing due to restricted action of soil biota (this is a result of the cold climate).
Cold climate also leads to slow breakdown of plant materials.
Highlands: High precipitation and short growing season.
Steep slopes – downward movement of water increases leaching and iron pan formation.
Tundra/Gley Soils
Slide 33
Gleys have damp waterlogged soils due to inadequate drainage resulting from permafrost layer found below the surface. Because there is waterlogging there is a lack of oxygen in the soil.
There is a lot of partially decomposed material due to the restricted level of biotic action. This is the result of a very short summer with low temperatures and the waterlogged soils.
Horizons are poorly defined due the movement caused by constant freezing and thawing.
Parent material is obvious within the B horizon. The vegetation is dominated by mosses and lichens
which produce acidic humus. Large areas of flat land increase the drainage problems.REMINDER:
When describing any soil you must mention the climate, vegetation, soil biota, relief and the impact of each on
the development of the soil.
Soil catena showing variations in soil processes and effects along a slope
Slide 36
Brown EarthBrown Earth Podzol Podzol GleyGley
Climate Climate Milder warmer Milder warmer climate leads to climate leads to increased biotic increased biotic activity and activity and decomposition.decomposition.
Moderate Moderate leaching occurs leaching occurs leading to thin iron leading to thin iron pan in some pan in some places where places where leaching is more leaching is more active.active.
High levels of High levels of precipitation and precipitation and spring snow melt spring snow melt leads to downward leads to downward movement of water movement of water and consequent and consequent leaching of mineralsleaching of minerals
Hard iron pan forms Hard iron pan forms and impedes and impedes drainage.drainage.
Cold temps. result Cold temps. result in slow breakdown of in slow breakdown of plant materials and plant materials and leads to a thick black leads to a thick black humus. humus.
Soils are damp and Soils are damp and waterlogged due to waterlogged due to inadequate drainage inadequate drainage resulting from resulting from permafrost. permafrost. Waterlogging leads to Waterlogging leads to lack of oxygen in soils.lack of oxygen in soils.
Constant freeze thaw Constant freeze thaw means horizons are means horizons are poorly defined and poorly defined and parent material is found parent material is found in the B horizon. in the B horizon.
VegetationVegetation A plentiful supply A plentiful supply of plant material of plant material (esp. from (esp. from deciduous leaves) deciduous leaves) leads to slightly leads to slightly acidic humus acidic humus
Acidic humus Acidic humus caused by nature caused by nature of the needles and of the needles and cones from pine cones from pine trees. trees.
Mosses and lichens Mosses and lichens dominate vegetation dominate vegetation leading to acidic humus leading to acidic humus
Biosphere: Summary Notes
Brown EarthBrown Earth Podzol Podzol GleyGley
Bio activity Bio activity (organisms) (organisms)
Horizons merge Horizons merge more gradually due more gradually due to increased action to increased action of biota.of biota.
Climate severely Climate severely limits soil bio limits soil bio activity so horizons activity so horizons are clearly defined are clearly defined
Because summer Because summer is so short and cold is so short and cold there is a very there is a very restricted biotic restricted biotic action. This results action. This results in lots of partially in lots of partially decomposed decomposed material in the soil. material in the soil.
Relief and Relief and drainagedrainage
Gentle slopes Gentle slopes lead to good lead to good drainage and drainage and restricts leaching.restricts leaching.
Less likelihood of Less likelihood of hard pan so soil is hard pan so soil is free draining free draining
Higher areas have Higher areas have more precipitation more precipitation and a shorter and a shorter growing season.growing season.
Steep slopes Steep slopes cause downward cause downward flushing of water flushing of water and increases and increases leaching and hard leaching and hard pan formation. pan formation.
Much flat land Much flat land which increases which increases drainage problems. drainage problems.
Summary Notes
Ecosystems
The non-living environment includes:
Water: rain or water stored in the soilAir: provide oxygen and carbon dioxide which are essential for life.Rocks: provide the nutrients for the soil.Soil: these vary in depth, nutrients and fertility.Solar energy: the sun is the earth’s primary source of energy and provides light and heat.
Controls on ecosystems
The organism within an ecosystem are controlled by two main factors:
1. Environmental factors (non-living environment)2. Competition (from other plants)
Succession
The change of community (plants and animals) and habitat over the years as a result of changing environmental conditions often brought about by the community. Slide 20
Environmental conditions
Each species has its own preferred set of environmental conditions. Under these conditions the species will flourish. Obviously if these conditions differ markedly from the optimum the species will be unable to survive and will be replaced (competition).
Competition
Ecosystems are rarely composed of single species. The number and variety present is determined by the suitability of the environmental conditions, species diversification and the ability of species to compete for energy and nutrients.
The Nutrient Cycle
Soil
Nutrients lost through leaching (down) or capillary action (up)
Nutrients added by weathering of parent rock
Litter: surface layer of
vegetation
Biomass = weight of living material (plants
and organisms)
Nutrients taken up by plants and organisms
Nutrients released as plants and leaves
decompose
Trees and animals die
Slide 23
All ecosystems go through stages or seres when a different set of plants grow in thearea. A sere is a process of succession.
Climax vegetation
An empty area of ground will always be colonised by plant species. The plants arriveas seeds or spores.
The arrival and development of the vegetation is influenced by:
1. Climatic factors2. Soil type3. Biota4. Time5. Competition from other plants
The first set of plants to arrive is the pioneer community. These first colonisers tend to
be simple, hardy, low lying, lacking in diversity and unable to compete with otherspecies as the ecosystem develops.
Over the years the pioneer community is succeeded by other plants more suited tothe new environment (natural selection). After many years climax vegetation isreached.
Slide 37
Climax vegetation
Climax vegetation is the final stage in the possible development of natural vegetation of a region or area. This is when the composition of the plant community is relatively stable and in balance with the existing environmental conditions which are normally determined by climate and soil. In sand dunes the climax vegetation is made up of pine and oak trees and flowering plants.
Sand Dune Succession: psammosere
Stage 1: At and behind the strandline, sea couch and sea rocket colonise. These are pioneer plants. It is a hostile environment (saline and strong winds) in which few plants can survive.An embryo gradually forms as the vegetation semi-stabilises the sand (through roots etc) and encourages a slight build up to form a dune.
Stage 2: 20 metres or so from the strandline are the yellow dunes (formerly embryo dunes). Here the marram grass grows as it has adapted to harsh conditions and salinity. The marram grass stabilises the dunes which continues to grow higher. The marram grass roots go deep to reach the water table.
Slide 38
Slide 41
Stage 3: As the marram grass begins to die (conditions have become less suitable for marram) and a humus forms. Therefore soils begin to form. Conditions have become suitable for plants like dandelions.
Stage 4: Soil becomes richer in nutrients and plants such as birdsfoot trefoil colonise the fixed dune. The dune succession now reaches its climax vegetation with flowering plants, pine and oak trees growing.
Stage 5: Between some of the dunes ridges are low lying depressions called dune slacks. They are often covered in water from October till April submerging plants and creating very wet conditions. Rushes and sedges grow here.
Factors which affect changes in the soil
The embryo and yellow dune soils have a higher salt content and are therefore more alkaline.
The sandy texture of the soil means rapid drainage therefore there is a lot of leaching. Rainwater will remove the salt in the soil in the semi – fixed and fixed dunes (further away from sea spray). pH gets more acidic so different plants can now colonise.
With the addition of humus water retention will improve further away from the coast so the soil is wetter. The Humus encourages a decrease in pH.
Vegetation type depends on calcium carbonate. Where sand and shell fragments are found in high proportion rich grasslands flourish.
Slide 40
Mineral matter (inorganic): minerals derived from parent material by physical and chemical weathering. Usually dissolved by water in the soil.
Organic material (humus): derived from decaying roots, leaves, needles and remains of dead animals.
Air and Water: co-exist and occupy the spaces in the soil called voids.
Organisms: the life in the soil. Living organisms include worms, fungi and bacteria, called biota. They assist in the decay of plants and they mix the soil by their movement.
Types of parent material
• Solid bedrock
• Alluvium
• River terrace gravel
• Wind blown sand (loess)
• Glacial till
What does soil contain?
Slide 25
(Inorganic)
Ecosystems can vary enormously in scale:
Ecosystems can vary enormously in scale:
• Small, or micro scale, e.g. under a leaf or stone
• Medium scale, e.g.. a woodland, a sand dune, a salt marsh
• Large, or global scale, e.g.. Tropical rainforests, hot deserts
Slide 13
Ecosystems depend upon two basic processes:Ecosystems depend upon two basic processes:1. A continuous flow of energy, the main source being sunlight.
• Sunlight is taken in by the green leaves of plants.
• It is then converted, by a process known as photosynthesis, into a form of energy which can pass through the ecosystem in the food chain.
Slide 21
The food chain
Snowy Owl
Lemming
Slide 23
2.The recycling of nutrients: carbon, nitrogen, phosphorus and potassium.
Slide 3
Slide 15
As they burrow through the soil, earthworms drag dead leaves and other organic matter down to the
lower levels, and break them down into humus
This earwig and her babies are among the thousands of insects and other
small animals that live in soil.
Dung beetle feeding on animal dung and so help to
break down plant and animal matter.
Slide 2
Slide 27
Slide 29
Soil
TIME
• 400 yrs for 10mm of soil to form
• 1000 yrs for 1mm in extreme conditions
• 3,000 – 12,000 yrs for farming soil
• Horizons develop when soil reaches maturity
PARENT MATERIAL
• Depth
• Texture (coarse or fine)
• Drainage (permeability)
• Nutrient content
• Colour
CLIMATE
• Determines rate of weathering
• Precipitation affect type of vegetation
• Dictates leaching or capillary action
• Temperature determines length of growing season and humus supply
SOIL BIOTA
• Nutrient cycle/recycling
• Bacteria and fungi decompose dead plants and animals
• Worms and termites aerate the soil
RELIEF/TOPOGRAPHY
• Altitude: soils are thinner higher up
• Aspect: Northern Hemisphere south-facing slopes are warmer and drier.
• Slope angle affects drainage and soil depth
HUMAN INFLUENCE
Affects soil development by
• Adding fertiliser
• Breaking up horizons by ploughing, draining or irrigating land
• Accelerating or controlling soil erosion
determines soil
Slide 4
Slide 1
Equator
Tropic of Cancer
Tropic of Capricorn
Arctic Circle
Podzol
Podzol
Brown Earth Brown Earth
Gley Soil Gley Soil
Distribution of 3 Major Soil Types: Brown Earths, Podzols and Gleys.
Slide 1
Slide 5
Brown Earth Profile
Slide 6
Podzol Profile
Slide 7
Gley Soil Profile
Slide 34
Gley Soil Profile
Waterlogged Tundra in summer
Slide 8
AB
C
Which soil type is which?
Simplified stages in
soil formation
Slide 5
HYPOTHESES: The sequence of soil profiles found in western Britain
1. Soil depth will decrease as gradient increases.
2. Soil moisture will decrease as gradient increases.
3. Soil acidity will be highest where gradient is lowest and leaching predominates.
4. Soil texture will be sandier where slope gradient is greatest and clay particles have been washed down-slope.
5. Organic content will be highest where slope gradient is lowest and soil depth greatest.
6. Soil acidity will be positively related to vegetation density.
Slide 10
Pioneer community (first plants to colonise an area)
Climax vegetation ( final stage in the
succession)
The complete process, from bare ground to climax vegetation, is called a plant succession or sere
Slide 16
Vegetation succession across a Coastal Sand Dune - psammosere
Vegetation across a grey dune and a dune slackEmbryo and fore-
dunes
Slide 17
Lime grass
Sea rocket
Slide 43
Marram grass
Slide 42
How Marram Grass stabilises sand dunes Slide 17
Birdsfoot trefoil
Cotton Grass
Spruce
Slide 18
Slide 32