BIOSPHERE Summary of What You Must Know You should be able to:

1. 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, brownearth soils and gley soils, referring to horizons, colour and texture. • recognise the type of soil shown in a profile diagram, and describe thefeatures 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. Slide 25 Slide 30

2. The Biosphere Core • 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

3. 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

4. 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 Relief Climate Vegetation Soil Formation Drainage Soil Biota Parent Material Slide 28

5. Soil formation – a profile Horizons A Organic matter Humus Translocation B Hard pan C Bed rock 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.

6. 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

7. Natural vegetation — deciduous forest vegetation provides deep leaf litter, which is broken down rapidly in mild/warm climate providing nutrients. • Trees have roots which penetrate deep into the soil, ensuring the recycling of minerals back to the vegetation. • Moderate leaching occurs leading to a thin iron pan whenever leaching is more active. In lower rainfall areas no iron pan can form. • soil biota break down leaf litter producing mildly acidic mull humus. They also ensure the mixing of the soil, aerating it and preventing the formation of distinct layers within the soil.

8. South-facing slopes with a greater amount of sunshine and higher temperatures increase the rate of humus production. • Soil colour varies from dark brown in A horizon to lighter • brown in B horizon where humus content is less obvious. Texture is loamy and well-aerated in the A horizon but lighter in the B horizon. • The C horizon is derived from a range of parent material, with limestone producing lighter-coloured alkaline soils, clay producing dark coloured soils. • 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.

9. Podzol Slide 32

10. 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. • Yellowish/ grey colour in the top soil due to leaching and a the lack of minerals from the parent material. • The Iron pan impedes drainage causing waterlogging and reduced bioactivity in the top soil. • Pine cones and needles and a lack of other vegetation result in a very thin acidic humus (mor). • 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, thin acidic humus.

11. greater altitude results in temperatures and the growing season being reduced and an increase in precipitation. This high precipitation and short growing season restricts the bioactivity (soil biota) to a short period of the year. • Steeper slopes tend to produce thinner soils due to gravity. These steeper slopes mean more downward movement of water which increases leaching forming an iron pan. • Parent material – may be fluvioglacial sands or till or acidic parent rock which determines the nature of the C horizon

12. Tundra/Gley Soils Slide 33

13. Gleys have damp waterlogged soils due to inadequate drainage resulting from permafrost layer found below the surface. Because of this 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 in addition to the permafrost increase the drainage problems and form large tundra ponds in summer . REMINDER: When describing any soil you must mention the climate, vegetation, soil biota, reliefand the impact of each on the development of the soil.

14. Soil catena showing variations in soil processes and effects along a slope Slide 36

15. Summary Notes

16. Summary Notes

17. 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 Slide 2 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.

18. Slide 29

19. TIME Slide 4 HUMAN INFLUENCE • 400 yrs for 10mm of soil to form Affects soil development by • 1000 yrs for 1mm in extreme conditions • Adding fertiliser • 3,000 – 12,000 yrs for farming soil • Breaking up horizons by ploughing, draining or irrigating land • Horizons develop when soil reaches maturity PARENT MATERIAL determines soil • Depth • Accelerating or controlling soil erosion • Texture (coarse or fine) Soil • Drainage (permeability) • Nutrient content RELIEF/TOPOGRAPHY • Colour • Altitude: soils are thinner higher up CLIMATE • Determines rate of weathering • Aspect: Northern Hemisphere south-facing slopes are warmer and drier. SOIL BIOTA • Precipitation affect type of vegetation • Nutrient cycle/recycling • Dictates leaching or capillary action • Bacteria and fungi decompose dead plants and animals • Slope angle affects drainage and soil depth • Temperature determines length of growing season and humus supply • Worms and termites aerate the soil

20. Slide 1

21. Distribution of 3 Major Soil Types: Brown Earths, Podzols and Gleys. Arctic Circle Gley Soil Gley Soil Podzol Brown Earth Podzol Brown Earth Tropic of Cancer Equator Tropic of Capricorn Slide 1

22. Brown Earth Profile Slide 6

23. Slide 7 Podzol Profile

24. Slide 34 Gley Soil Profile

25. Waterlogged Tundra in summer Gley Soil Profile Slide 8

26. A B Which soil type is which? C

27. Simplified stages in soil formation

28. 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