BIOL 4120: Principles of Ecology Lecture 5: Terrestrial Environment - PowerPoint PPT Presentation

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BIOL 4120: Principles of Ecology Lecture 5: Terrestrial Environment

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5.1 Soil is the foundation of all life. 5.2 Formation of soil. 5.3 Physical properties of soil. 5.4 Soil horizons. 5.5 Soil water holding capacity ... – PowerPoint PPT presentation

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Title: BIOL 4120: Principles of Ecology Lecture 5: Terrestrial Environment


1
BIOL 4120 Principles of Ecology Lecture 5
Terrestrial Environment
  • Dafeng Hui
  • Office Harned Hall 320
  • Phone 963-5777
  • Email dhui_at_tnstate.edu

2
  • Topics for this class
  • 5.1 Soil is the foundation of all life
  • 5.2 Formation of soil
  • 5.3 Physical properties of soil
  • 5.4 Soil horizons
  • 5.5 Soil water holding capacity
  • 5.6 Soil ion exchange capacity
  • 5.7 Soil classification
  • 5.8 Light distribution in plant canopy

3
5.1 Soil is the foundation upon which all
terrestrial life depends
  • Before life invaded the land from the sea, there
    was probably little that looked like soil today
  • Dust like Mars Little organic matter
  • A few microorganisms.
  • Soil is medium for plant growth the basis of all
    terrestrial life. Without soil, there would be no
    plants, no soil microorganism and no land animals
  • Plants obtain many of their water and nutrients
    from soil and it provides an place to attach to.

4
Definition of soil
  • Soil is hard to define because it is so complex
  • Soil is a natural product formed and synthesized
    by the weathering of rocks and the action of
    living organism.
  • Soil is a collection of natural bodies of earth,
    composed of mineral and organic matter and
    capable of supporting plant growth.
  • The stratum below vegetation and above hard rock

5
  • Soil is a living system made up of a three
    dimensional matrix (length, width, and depth) and
    of minerals and organic matter, and organisms
  • plants, both roots and stems
  • Bacteria
  • Fungi
  • Algae
  • Small animals
  • Larger animals

6
5.2 Formation of soil
  • Starting Point weathering of rocks and their
    minerals.
  • Mechanical and Chemical Weathering
  • Mechanical interaction of several forces
  • Water
  • Wind
  • Temperature
  • Creates loose material
  • Sorted and moved
  • Chemical
  • Acids produced by lichens and mosses
  • Addition of organic matter (dead plants and
    animal tissues)
  • Oxidization
  • etc

7
Five interrelated factors
  • Five factors are involved in the formation of
    soil
  • Parent Material
  • Igneous rock
  • Sedimentary rock
  • Metamorphic rock
  • Climate
  • Temperature Rainfall
  • Wind Elevation
  • Latitude
  • Biotic Factors
  • Living organisms (plants, animals, bacteria,
    fungi).
  • Degradation by living organisms
  • Topography
  • Water runoff
  • Draining
  • Erosion
  • Time
  • Weathering, accumulation, decomposition and
    mineralization take time
  • Initial differentiation can be within 30 years

8
5.3 Soils show a great deal of variation
  • Color
  • No direct effect on how soil function
  • Allows classification
  • Red
  • Possibly oxides
  • Black
  • Possible high organic content
  • Texture
  • Variation in size and shape of soil particles
  • Gravel
  • gt2mm
  • Sand
  • 0.05mm to 2mm
  • Silt
  • 0.002mm to 0.05mm
  • Clay
  • lt0.002mm

Soil texture is percentage of sand, silt and
clay. (Texture chart)
9
  • Structure
  • Space for roots etc
  • Pore space
  • Amount of water held
  • Rate of water movement
  • Aeration
  • Compaction
  • Aggregation
  • Depth
  • Depends on
  • Slope
  • Weathering
  • Parent material
  • Vegetation
  • Grasslands are deep
  • Forests are shallow

10
5.4 Soil has horizontal layers
Soil profile Layers or horizons
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5.5 Moisture holding capacity is an essential
feature of soils
  • Soil can become saturated if all pores filled
  • All water is hold by soil particulars, at field
    capacity (FC)
  • Capillary water is usually present
  • Extracted by plants
  • Wilting point (WP)
  • Plant no long extract water
  • Available water capacity (AWC)
  • All affected by soil texture
  • Sand
  • Lower capacity
  • Clays
  • Higher capacity

13
Water content at different soils
14
5.6 Ion exchange capacity is important to soil
fertility
  • Soil soluble nutrients are charged particles,
    ions.
  • Cations positively charged (Ca2, Mg2, NH4)
  • Anions negatively charged (NO3, PO34)
  • Ions are attached to soil particles, so do not
    leach out of the soil.
  • Ion exchange capacity total number of charged
    sites on soil particles in a standard volume of
    soil.

15
Soils have an excess of negative charged sites
  • Cationic exchange dominant (colloids)
  • Cation exchange capacity (CEC) total of
    negatively charged sites, located on the leading
    edges of clay particles and SOM.
  • Concentration and affinity

Al3 gt H gt Ca2 gt Mg2 gt K NH4 gt Na
16
Soils have an excess of negative charged sites
  • Change in pH affects binding capacity for ions
  • Immovable
  • Hydrogen (H)
  • Aluminum (Al)
  • Removable in order
  • Calcium (Ca)
  • Magnesium (Mg)
  • Potassium (K)
  • Ammonium (NH4)
  • Sodium (Na)

17
Process of cation exchange in soils
In soils with high Mg or Ca, K is lacking,
why?
18
5.7 Basic Soil Formation Processes Produce
Different Soils
  • Regional differences in geology, climate, and
    vegetation give rise to characteristically
    different soils
  • The broadest level of soil classification is soil
    order

19
  • There are twelve orders of soil
  • Entisol
  • Mollisol
  • Alfisol
  • Andisol
  • Aridisol
  • Inceptisol
  • Histosol
  • Oxisol
  • Vertisol
  • Spodosol
  • Ultisol
  • Gelisol

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5.7 Soils vary with climate and vegetation
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Ultisols
  • Ultisol
  • Warm climate soil
  • Redish or yellowish
  • Low nutrient content
  • Laterization when PPT greatly exceeds ET in warm
    climates, water rapidly percolated through soil
    and into groundwater. Soluble soil nutrients are
    constantly leached out of soils, leaving behind
    the less soluble ions (Al and Fe) which give
    soil color (whitish for Al and red for Fe) and H
    make soil acidic and nutrient poor.

24
Salinization (Aridisol)
  • Salinization in very dry climates and when loss
    of soil moisture due to ET exceeds PPT, water
    leaves the soil through the surface. The minerals
    (NaCl) dissolved move upward from the groundwater
    and result in a salt crust on the surface of the
    soil.
  • Irrigation of dryland can result salinization.
    This becomes a problem in US southwest,
    Australia, Northern Africa, China, and major
    areas of dryland irrigation.

25
5.8 Light distribution within plant canopy
  • Influencing factors
  • Vegetation types
  • Leaf area index (LAI)
  • Leaf angles

26
  • Plant cover dramatically changes the light
    environment underneath it
  • types of plants making up the cover can have an
    effect (small portion reach ground)
  • Deciduous forest 1 to 5
  • Coniferous forest 10 to 15
  • Tropical rain forest 0.25 to 2

27
Total LAI315/78.54
28
  • Effect of leaf angle on leaf area index and light
    penetration

29
  • Season also affects the light penetration
  • The ground under a deciduous forest will undergo
    a seasonal cycle affected by leaf loss
  • The ground under a coniferous forest will undergo
    a seasonal cycle unaffected by leaf loss
  • The ground under a tropical rainforest will
    neither have a seasonal cycle or an effect from
    leaf drop

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31
Quantifying Ecology Beers Law and the
Attenuation of Light
  • The greater the surface area of leaves, the less
    light will penetrate the canopy and reach the
    ground
  • The attenuation (vertical reduction) of light
    through a stand of plants is estimated using
    Beers law

32
Beers Law
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35
The End
36
Basic Soil Formation Processes Produce Different
Soils
  • Laterization is a process common to soils found
    in humid environments in the tropical and
    subtropical regions ? heavy leaching of nutrients
  • Calcification occurs when evaporation and water
    uptake by plants exceed precipitation ?
    deposition and buildup of alkaline salts (CaCO3)
    in the subsoil
  • Salinization occurs in very dry climates or
    coastal regions as a result of salt spray ? salt
    deposits near the soil surface

37
  • Podzolization occurs in cool, moist climates
    where coniferous vegetation (pine forests)
    dominates ? acidic soil enhances leaching of
    cations, iron, and aluminum from the topsoil
  • Gleization occurs in areas with high rainfall or
    in areas of poor drainage ? organic matter is
    slowly decomposed and accumulates in the upper
    layers of soil

38
Padilla and Pngnaire (2007, Functional Ecology.
Mediterranean Woody seedling)
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