Forest Soils &
Vegetation Development
SOILS = f (?????)
SOILS = f (cl, r, o, p, t, …..H)
1
2
How would you solve this equation???
OR
How would you design the research to solve
this equation????
3
This is called a ???
Climofunction
4
Eg:
S1 =
S2 =
S3 =
S4 =
f(cla,pa,ra,oa,ta,..,)
f(clb,pa,ra,oa,ta,..,)
f(clc,pa,ra,oa,ta,..,)
f(cld,pa,ra,oa,ta,..,)
Quantitative
research!
5
Can this type
of research
be
accomplished???
6

Chronosequence???
7
Qualitative
research!! ???
Maybe
Quantitative now
Eg:
S1 =
S2 =
S3 =
S4 =
f(cl1.0,p1.0,r1,0,o1.0,t1,..,)
f(cl1.1,p1.2,r1.2,o1.2,t2,..,)
f(cl1.1,p1.3,r1.5,o1.2,t3,..,)
f(cl1.2,p1.1,r1.0,o1.0,t4,..,)
8
Soils or
some soil
property
may be
described as
‘mature’ or
in
‘equilibrium’
or
t1
‘STEADY
STATE’
when:
9
Is steady state
common in
ecosystems??
The change in
SOILS
or
soil parameters
is called??
(pedogenesis)
10
Pedogenic processes involve:




additions of organic & mineral materials to the
soil as solids, liquids & gases
(eg, littering, cumulization)
losses of those from the soil
(eg, leaching, erosion)
translocations of materials from one point to
another within the soil
(eg, eluviation, illuviation, podzolization)
transformations of mineral & organic
substances within the soil
(eg, decomposition, mineralization)
11


Processes affect soil development
Processes affect vegetation
BUT!


Soil affects processes, AND
Vegetation affects processes
SO
12
SOILS affect Vegetation
And
 Vegetation affects SOILS

AND
 HUMANS affect both!!
13
Forest Soils &
Vegetation Development
So with MANAGEMENT
we can affect both
Vegetation
AND
SOILS
14
Soil Physical Properties
affect tree growth

????
15
Texture

Sandy soil?

Clayey soil?

Loams just right?

Ameliorate poor texture?
• OM?
• ???
16
Structure

Moderates effects of texture
• Water percolation
• Aeration
• Bulk density



OM?
Coatings of Fe or CaCO3, salts
???
17
Bulk Density



Root penetration
Affects pore volume -water, air, ???
Management affects BD?
• negative, positive??
18
Color



Depicts OM, moisture, parent
material, salts, ??
Affects temperatures
Indirectly, if OM, it affects nutrients,
moisture, etc???
19
Temperature

Affects soil organisms, chemistry,
weathering of minerals
20
Water



Adhesion
Cohesion
Water potential
• Matric – attraction btwn water & soil
particles
• Osmotic – soluble salts, important in dry
soils
• Gravitational – water in large pores
(saturated-field capacity)


Field capacity – after saturated soil
drains
Permanent wilting point -
21
U.S. Soil Taxonomy
Soil Orders
23
Major Soil Types in Forest Regions
Major Forest Types
Most Common Soil Orders
Boreal
Gelisols, Spodosols,
Histosols, Inceptisols
Temp conifer, mixed,
hardwood, & montane
Alfisols, Inceptisols, Ultisols,
Spodosols, Entisols, Mollisols
Tropical rain forests,
monsoon forests,
dry forest
Ultisols, Inceptisols, Oxisols,
Andisols
24
Processes:


1a. Eluviation
Movement of material out of a
portion of a soil profile as in an albic
horizon (E)
1b. Illuviation
Movement of material into a portion
of soil profile as in an argillic (Bt) or
spodic (Bs or Bhs) horizon
26
Processes:


2a. Leaching
General term for washing out or
eluviating soluble materials from the
solum
2b. Enrichment
General term for addition of material
to a soil body
Processes:


3a. Erosion
Removal of material from the surface
layer of a soil
3b. Cumulization
Aeolian, hydrologic & human-made
additions of mineral particles to the
surface of a soil solum [also urbic,
garbic, spolic?]
Processes:


4a. Decalcification
Reactions that remove (or move out)
CaCO3 from one or more soil horizons
4b. Calcification
Processes including accumulation of
CaCO3 in Ck & possibly other
horizons (Bk)
Processes:


5a. Salinization
Accumulation of soluble salts (eg
SO4’s & Cl’s of Ca, Mg, Na or K) in
salic (Bz) (salty) horizons
5b. Desalinization
Removal of soluble salts from salic
soil horizons
Processes:


6a. Alkalization or solonization
Accumulation of Na ions on the
exchange sites in a soil
6b. Dealkalization or solodization
Leaching of Na ions & salts from a
natric (Btn) horizon
Processes:


7a. Lessivage
Mechanical migration of small mineral
particles from the A to the B horizon producing
a clay enriched B horizon (ie, argillic = Bt)
7b. Pedoturbation
Biologic, physical (freeze-thaw & wet-dry
cycles) churning & cycling of soil materials,
thereby homogenizing the solum in varying
degrees. Eg
Processes:
7b. Pedoturbation - Eg

faunal pedoturbation - animals

floral pedoturbation - plants (eg, tip overs)

congellipedoturbation - freeze-thaw

argillipedoturbation - mass wasting

movements by expansion of clays

aeropedoturbation - mix soil gases (after rain)

aquapedoturbation - mix soil H2O (upwelling

currents)

crystalpedoturbation - mix crystal growth

seismipedoturbation
Processes:


8a. Podzolization
Chemical migration of Al & Fe &/or OM
resulting in the concentration of Si (ie,
silication) in the layer eluviated (Bs, Bhs)
8b. Desilication or ferrallitization,
ferritization, allitization
Chemical migration of Si out of the soil solum
and thus increase the concentration of
sesquioxides in the solum (goethite, gibbsite,
etc), with or without formation of ironstone
(laterite; hardened plinthite) and concretions
[laterization]
Processes:


9a. Decomposition
Breakdown of mineral & organic
materials
9b. Synthesis
Formation of new particles of
mineral & organic species
Processes:


10a. Melanization
Darkening of light-colored mineral initial
unconsolidated materials by admixture of OM
(as in a dark A or mollic or umbric horizon)
10b. Leucinization
Paling of soil horizons by disappearance of
dark organic materials either through
transformation to light-colored ones or through
removal from the horizons
Processes:



11a. Littering
Accumulation on the mineral soil surface of
organic (plant & faunal) litter and associated
humus to a depth of less than 30 cm
(Oi & Oe)
11b. Humification
Transformation of raw organic material into
humus (Oe & Oa)
11c. Mineralization
Release of oxide solids through
decomposition of OM
Processes:
(cont’d)


11d. Ripening
Chemical, biological & physical changes in
organic soil after air penetrates previously
waterlogged material (eg, polder construction)
11e. Paludization
Processes regarded by some workers as
geogenic rather than pedogenic, including the
accumulation of deep (> 30cm) deposits of
OM as in mucks & peats - Histosols
Processes:


12a. Braunification, rubification,
ferrugination
Release of iron from primary minerals and the
dispersion of particles of iron oxide in
increasing amounts; their progressive oxidation
or hydration, giving the soil mass brownish,
reddish brown, and red colors, respectively
12b. Gleization
Reduction of iron (Fe+3  Fe+2) under
anaerobic “waterlogged” soil conditions, with
the production of bluish to greenish gray
matrix colors, with or without yellowish brown,
brown, and black mottles, and ferric and
manganiferous concretions
Processes:


13a. Loosening
Increase in volume of voids by activity of
plants, animals, & humans and by freeze-thaw
or other physical processes and by removal of
material by leaching
13b. Hardening
Decrease in volume of voids by collapse &
compaction & by filling of some voids with fine
earth, carbonates, silica & other materials