SFR/FTY 111/112 - Forests Through Time:
Forest Soils
By: William H. Livingston, School of Forest Resources, University of Maine
Samantha Langley-Turnbaugh, Dept. Env. Sci. & Policy, University of Southern Maine
Readings& Web Sites:
Pages 26-30, 415-435 in Kricher, J.C. 1998. A Field Guide to Eastern Forests, North
America. Houghton Mifflin Co., NY. 488 p.
Pages 3-50, 99-104, 153-154, 162 in Harpstead, M.I., T.J. Sauer, and W.F. Bennett.
1997. Soil Science Simplified, 3rd Ed. Iowa State Univ. Press, Ames. 210 p.
I.
Introduction
II.
What is soil?
A. Surface layer of the earth
B. Natural materials
C.
Supports plant life
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
Used in large amounts
Used in small amounts
From air and water
From soil
From soil
Carbon (C)
Nitrogen (N)
Manganese (Mn)
Hydrogen (H)
Phosphorus (P)
Boron (B)
Oxygen (O)
Potassium (K)
Molybdenum (Mo)
Calcium (Ca)
Copper (Cu)
Magnesium (Mg)
Zinc (Zn)
Sulfur (S)
Chlorine (Cl)
Iron (Fe)
III.
What Makes Soil?
A. Interaction of abiotic and biotic factors in the environment.
B.
C.
Because environment differs from location to location, soils differ from location to
location
Particle size
1.
Sand (0.05mm to 2mm)
2.
Clay (<0.002 mm)
3.
Silt (0.002 to 0.05 mm)
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
4.
D.
Loam - mixture of all three
Parent Material
1.
Materials underlying soil
2.
Five categories
a)
Minerals and rocks
b)
E.
F.
Glacial deposits
c)
Wind blown deposits (silt)
d)
Water-body deposits (silt/clay)
e)
Organic deposits (mucky organic)
Climate
1.
Factors that affect break-down of mineral components
2.
Affect which life forms can live in area.
3.
Water dissolves and carries minerals to lower layers in soils - soil development
Living organisms
1.
Vegetation
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
G.
H.
2.
Bacteria and fungi
3.
Animals
Topography - the lay of the land
1.
Hilly - variable water dynamics
2.
Flat - uniform soils
Time
1.
All factors interact over time
2.
Soil develops
3.
IV.
Soil "age" actually refers to soil development - dependent on all factors
Characterizing Soils
A. Soil Profile - layers or "horizons"
1.
Organic horizon develops on top
2.
Most have 3 mineral horizons"
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
B.
V.
Major Soil Types
1.
Primitive/immature
2.
Volcanic
3.
Desert
4.
Grassland
5.
Organic
6.
Southern forest
7.
Northern conifer
8.
Northern hardwood
Maine's Forest Soils
A. Typical characteristics of "Spodosols"
1.
Cool, humid climate
2.
Coniferous vegetation (acidic foliage)
3.
Well developed O horizons
4.
Narrow A horizon (cold)
5.
E horizon between A and B horizon
6.
B horizon
7.
Parent material from granite
8.
Drainage determines how well trees can grow
a)
Poor drainage in many areas
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
b)
VI.
Good drainage associated with;
Nitrogen fixation
A. Fourth most needed nutrient
B.
Special bacteria are needed to convert gaseous N to water soluble N
1.
A little in soil.
VII. Conclusion
A. Soils and climate determine which plants will be present
B. Soil characteristics determined by multiple factors (parent material, climate,
topography, vegetation, time)
C. Maine's soils favor growth of forests.
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SFR/FTY 111/112 - Forests Through Time:
Forest Soils
Terms
Soil
Organic
Inorganic
Minerals
Anchorage
Nutrients
Parent material
Sand
Clay
Silt
Loam
Glacial deposits
Topography
Soil profile
Soil age
0 horizon
A horizon
B horizon
C horizon
E horizon
Primitive/immature
soil
Volcanic soil
Desert soil
Grassland soil
Organic soil
Sourthern forest soil
Northern conifer soil
Northern hardwood
soil
Spodosols
Leaching
Organic acids
Granite
Poor drainage
Good drainage
Nitrogen fixation
N-fixing bacteria
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