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• V. O. Targulian, Lomonosov Moscow State University;
Institute of Geography, Russian Academy of
Sciences,
SELF-ORGANIZATION OF SOIL SYSTEMS,TIME-SCALES AND
ECOLOGICAL SIGNIFICANCE OF PEDOGENIC PROCESSES
The main goal of this presentation is to generalize some existing notions and
concepts of soil systems behavior in time, both under constant and evolving
environment, to propose some considerations and working hypothesis concerning soil self-
development, soil evolution, characteristic times of pedogenic processes and, at least, to assess the ecological significance of the WRB
diagnostic horizons/properties
Main Topics:
• Soil formation as a synergetic process of the soil system self-organization;
• Two main concepts of soil system behavior in time and their harmonization;
• Characteristic times of the WRB diagnostic horizons and specific pedogenic processes.
• Ecological significance of pedogenic processes and the main diagnostic soil horizons
The main working hypothesis of the presentation is that soil formation could be perceived as a synergetic process of the soil system self-organization
The soil formation (in its ideal model) - is a synergetic process of soil system self-organization in time, which
tends to the attractor – mature soil body in steady state;
In this process initial unsteady components and structures of the lithomatrix are transformed into new steady
components and structures of the pedomatrix (soil body, soil cover).
The pedomatrix after its formation becomes by the feedbacks a powerful regulator of the further functioning
of the soil system.
Mountain tropicalfoggy forest (Mexico)
Mountain tropical
Hystic Podzol(Mexico)
Plowed Albeluvisol, Central Russia
Calcareous Arenosols,Pacific low atolls,Cook Islands
Soil as a biospheric bio-abiotic
system on the land surface
ATMOSPHERE
S ITON
ECOSYSTEM
SOIL
WEATHERING
MANTLE
REGOLITH
ABOVEGROUND
STAGE
BELOWGROUND
STAGE
solar-
Gas cyclesn*10-1 – 101 years
Water cyclesn*10-1 – 102 years
Biotic cyclesn*10-1 – 103 years
Place of a soil on crossing of the main matter fluxes & cycles at land surface;Characteristic times of matter renewal in functioning soil system
Endogenic cycles of rocks in lithosphere n*103 – 108 years
Soil system residence time at land surface n*102 – 106 years
Exogenic cyclesof denudation &sedimentationn*102 – 104 years
Anthropo-technogenic cyclesn*101 – 104 years
Ideal model of well-developed
soil & weathering mantle in
humid tropics by the age of
105-6 years;
The total thickness of
SITON
as bio-abiotic exogenic system
O
A1
E
Bt
Mottled clay saprolite
Ortho-biotic
zone
Para-biotic
zone
Meta-biotic
zone
Soil proper as an upper part of
weathering mantle
Medium
and lower
parts of
weathering
mantle
Soil and
weathering
mantle
as in situ
formed
horizonated
body –
SITON
and as a
functioning
CRITICAL ZONE
of a landscape
Red-yellow saprolite
Coarse saprolite
Ground water
Parent rock
0 100
D
E
P
T
H
% volume50
INTERACTIVE COMPONENTS OF MULTIPHASEBIO-ABIOTIC SOIL SYSTEM
SOLID PHASE:
MINERAL AND ORGANO-
MINERAL
PARTICLES
HUMUSLIVING BIOTA
1м
2 м
0POROSITY
GASES
SOLUTIONS
Soil system functioning and soil formation
Functioning (or “life”) of the multiphase soil system starts
immediately at 0-time in the zone of multiple atmo-hydro-bio-litho- interactions within the parent
material (lithomatrix of the soil system).
Labile flux factors – “aggressors”: helio-atmo-hydro-bio; Driving forces of pedogenesis
genic
Exogenic soil-formingpotential of climate and biota - PCB
=
Static immovable site factors– “acceptors”: parent rocks,relief; litho-topo-matrix of soil system
Transformational potential of parent rocks - TPPR
Redistribution potential of relief –RPR
=
Interactions of flux and site factors and their potentials in belowground stage of ecosystem
Emergence of soil functioning multiphase system in enclosing parent material
Processes (fluxes, cycles, exchange reactions) operating in the functioning soil system are not completely closed and reversible, therefore, they produce a range of residual products of functioning (RPF): gaseous, liquid, and solid.
Formation, accumulation, and differentiation of solid RPF in the soil system are the essence of soil formation as in situ development of the soil body (pedomatrix) from the parent material (lithomatrix);
Soil formation (pedogenesis) is the “irreversible time-arrow” of the soil system functioning.
Relation between multiphase processes of soil system functioning and specific pedogenic
processes of formation solid phase pedogenic features
timeL
I t
o m
a t
r I
x
n*101-2
yearsn*103-4 years
n*105-6 years
ortho
para
meta
ortho
para
meta
оrthо
para
meta
ortho
para
meta Sapro-lite
Vertical zones of multiphase soil functioning
Solid phase profile
labileprofiles ofbiota, gases,
solutions,heat
Relationship between functioning of soil system and formation of solid phase soil body
We need to distinguish the multiphase soil system functioning and the solid phase soil body self-organization (self-development) in time:
--multiphase soil system functioning on the land surface is potentially endless process, if not interrupted by denudation or burying,
--solid phase soil body self-organization is potentially self-terminated process, as any synergetic process tending to attractor.
litho-matrix
biota
soild phaseprofile
heat gasessolu-tions
A
E
Bt,m
sapro-lite
ortho ortho ortho ortho
para para para para
meta meta meta meta
time
soil functioning & developmentclimate & biota
0-time
func-tioningwithoutpedogenichorizona-tion
functioning with pedogenic horizonation
solid phase record of long-term functioning
steady state soil body
functioning within steady state
soil body
time
solid phase soil body
present day horizonation of soil functioning
regulates soil functioning
MODEL OF SOIL SELFDEVELOPMENT
feedbacks
feedbacks
Soil systems behavior in time:self-development and
evolution of sols
Possible fates of soil systems in geological time scale: n*10 years4-6
0-time
burying and new pedogenesis
Continuation of “life” and evolution on the land surface
technogenic pollution – “poisoned” pedogenesis
denudationand
pedo-new
genesis
Factors of soil formation soil featuresFactors pedogenic processes soil features
Factors processes of soil functioning pedogenic processes soil features
“meeting” &
interaction of
factors “agressor
s” and factors
“acceptors”
multiphase bio-abiotic interactions
in soil system; in situ labile
horizonation of gases, liquids,
biota and heat in
parent rock;
start of soil system
functioning
fast cycling and renewal
of labile components
(gases, solutions,
biota);
formation & surviving of solid phase
microproducts of soil functioning
selection, accumulation & differentiation of solid phase microproducts
within a soil system;
formation of pedogenic soil macrofeatures,
horizons & profiles;
soil memory
Vertical and lateral
diversity of soil bodies and covers
in space and time
Emerging and functioning of multiphase soil system in solid
phase parent materials
Formation and evolution of pedogenic solid phase structure of soil system in space and
time
Steady-state model of soil development
(Dokuchaev, Jenny, Rode, Yaalon)
Steady-stateSoilfeatures
time, years
Fastprocesses
Slowprocesses
101 102 103 104 105
Soil A
Soil B
Soil C
Progressive pedogenesis Regressive pedogenesis
T0T1 T2 Tn
Evolutionary model of pedogenesis(Johnson, Keller, & Rockwell, 1984)
Soilfeatures
Finity of soil self-development
in constant environment:Under the constant environment, soil development is self-terminated process directed towards the steady state, because all specific pedogenic processes are either self-terminated due to depletion of initial resources, or come to dynamic equilibrium with the environment.
Infinity of soil evolution
in the changing environment: Under the evolving environment without strong erosion and deep burying, soil evolution is an endless process, because specific pedogenic processes are changing following the driving changes of the environment.
Why soil system can approach the steady state?
Self-terminating pedogenic processes
Soil features
Carbonate leaching
time Leaching of bases
from silicates
Dynamically-equilibrium pedogenic processes
Soil features
0
Humus (formation vs decomposition)
Structure
0
Clay formation
Texture differentiation
Primary silicates decomposition
time
Biogenic elements
Soil features steady state of system
Fast pedogenic processes
Slow pedogenic processes
time, yrs.
precipit.
temperature, Possible changes of climate and biota during 102 – 106 years
time, years b.p.
Ideal model of soil and
weathering mantle
self-development
compared with
possible
environment changes
during this time
Soil-forming potential of climate & biotaIn humid regions
biomass
polar
boreal
temperate
tropical
90o 0o45o
90o 45o 0o
biomass
In arid - semihumid regions
latitude
latitude
polar desertstundra-steppes
semideserts
deserts
steppes
Annualprecip., to
Annualprecip., to
(sub)tropical
savannas
rainforcement of weathering and pedogenesis
developing & obliterating soil evolution
weakening of weathering & pedogenesis
inheriting & superimposing soil evolution
Two main models of soil evolution
Individual pedogenic processes (IPP) in soil self-development and evolution
IPP groups FiniteDynamically equilibrium
Irreversible
Reversible
ObliterativeNon-
obliterative
Organic matter accumulation - + - + + - Structuring - + - + + - Pedoturbations - + - + + + Salinization - desalinization - + - + + - Ca(Mg)CO3 migration - + - + + - Weathering + - + - - + Clay formation + - + + - + Leaching from solum + - + - - + Vertical translocations of
clays, Fe, Al, Si + - + - - +
Characteristic times of diagnostic horizons and
specific pedogenic processes
diagnosticfeatures
10 10 10 10 10 10 10 10 100-1 1 2 3 4 5 6 7 years
Characteristic times (CT) of the main diagnostic horizons and properties (WRB)
Short CTn*10 -10
years:
Litter, Cryic,Folic, Ochric,Gleyic, Salic,
Stagnic, Sulphuric, Takyric, Melanic,Plaggic
-1 2Medium CT
n*103 -104 years:
Albic, Andic, Argic, Calcic, Cambic,
Duric, Ferric, Fulvic, Fragic, Gypsic,
Histic, Mollic, Natric, Umbric, Vertic
Long CTn*105 -106
years:Ferralic, NiticPetro-(duric-
plinthic-calcic-gypsic),
Geric & Ferralic prop.
diagnosticfeaturesof SPP
10 10 10 10 10 10 10 10 100-1 1 2 3 4 5 6 7 years
Characteristic times of specific pedogenic processes (SPP) in soil self-development
Fast SPPn*10 -10
years:littering ,
gleyzation,stagnation,salinization,
brunification,cryo-, bio-turbations,structuring,compaction,
etc…
-1 2
Medium-rate SPPn*103 years:mollic, umbric humification, cheluviation,
andosolization,lessivage,
partluvation,fersiallitization,
Fe-,Si-cementation,carbonates migration
etc…
Slow SPPn*104 -10
years:ferralitization
allitization,petro-
cementation,deep sapro-
litization
6
diagnosticfeaturesof SPP
10 10 10 10 10 10 10 10 100-1 1 2 3 4 5 6 7 years
Characteristic times of specific pedogenic processes (SPP) related to soil absolute age
Fast SPPn*10 -10
years
-1 2
Medium-rate SPP
n*10 3-104 years
Slow SPPn*10 -10
years
5 6
young ( alluvial, volcanic, dune) soils tundra & boreal soils
temperate soilstropical soils
• Absolute age of soils and the real duration of the pedogenesis (taking into account the warm and frozen conditions within the each year)
0 1 2 3 4 5 6 7 8 9 10
X 1000 years
T h e H o l o c e n e s o i l a g e
WarmWarm
““age”age”
FrozenFrozen
““age”age”
arctic
tundra
boreal permafrost
temperate seasonally freezing
subtropics & tropics
Interactions of the specific pedogenic processes
Direct linkages(SPP chronochains, which are rather clear)
Fast SPP Medium-rate SPP
Slow SPP
Feedbacks (SPP time bombs, which are often latent)
There are the main areas of synergetic interactions in soil systems
Ecological significance of WRB diagnostic horizons
Diagnostic horizons (WRB) are perceived as attractors of the soil system development:
Diagnostic horizons (WRB) are perceived as attractors of the soil system
development:
«Good» attractors are those states of the soil horizons, upon reaching which the horizons become more favorable for biota than in their previous states (in terms of biological productivity, biodiversity, and reproduction).
«Bad» attractors are those states of the soil horizons, upon reaching which the horizons become less favorable for biota than in their previous states (in terms of biological productivity, biodiversity, and reproduction).
«Good» attractors--diagnostic horizons (WRB) ecologically favorable for biota :
1. Mollic
2. Umbric
3. Chernic
4. Melanic
5. Histic (eutrophic)
6. Hortic
7. Terric
8. Andic
9. Cambic
10. Calcic
11. Nitic
12. Vitric
13. Ochric (?)
«Bad» attractors--diagnostic horizons (WRB) ecologically unfavorable for biota:
1. Albic
2. Argic
3. Cryic
4. Duric
5. Ferralic
6. Ferric
7. Fragic
8. Gypsic
9. Natric
10. Petrocalcic
11. Petroduric
12. Petrogypsic
13. Petroplinthic
14. Plinthic
15. Salic
16. Spodic
17. Sulfuric
18. Takyric
19. Vertic
20. Yermic
21. Abrupt texture
22. Alic properties
23. Geric properties
24. Gleyic properties
25. Stagnic properties
26. Permafrost
MODAL DISTRIBUTION OF SOIL BIOTA AND HORIZONS-ATTRACTORS IN SOIL PROFILE
ОА
Е
В
ВС
ORTHО-
РАRA-
МЕТА-
BIOTIC ZONES IN SOIL
SOLID PHASESOIL PROFILE
«GOOD» ATTRACTORS
«BAD» АТТRACTORS
Conclusions:1. Soil formation in the broad sense is a synergetic process of
the soil system in situ self-organization during its functioning in time and space.
2. Soil formation, sensu stricto, is the transformation of the solid-phase lithomatrix of the soil system into the pedomatrix (soil body, soil cover).
3. Soil system functioning and soil formation are intimately linked but basically different processes: the former is infinite in time, if not interrupted by external factors; the latter, as any self-organization process, is finite in time and tends to reach its attractor (the steady state).
.
4. Soil formation consists of the set of specific pedogenic processes (SPP), which have different characteristic times and rates to reach their individual steady states, i.e. their attractors.
5. SPP could be subdivided into three groups according to their characteristic times: fast SPP, medium-rate SPP and slow SPP, interacting in each soil body.
6. Partial steady states could be reached by faster SPP on the background of slower proceeding SPP, so the direct and feedback synergetic interactions among the different SPP are acting during pedogenesis; the complete steady state is implemented, when the slowest SPP is realized in the soil system.
7. Real duration of active pedogenesis in cold soils is shorter in 3-5 times than their absolute age, so no these soils have reached complete steady state but only partial steady states by fast and medium rate SPP.
.
8. All the diagnostic soil horizons (WRB) are perceived as more or less stable and «mature» attractors of soil self-development. They are separated into «good» and «bad» attractors with respect to biota.
9. «Good» attractors include 13 out of 39 diagnostic horizons and properties (33%). They are mainly shaped by biotic fluxes and cycles, which are comparable to or exceed abiotic fluxes and cycles in their power and capacity. In this case, biota transforms and improves the environment rather than adapts to it.
10. «Bad» attractors include 26 out of 39 diagnostic horizons
and properties (67%). They are shaped by the mutual action of biotic and abiotic fluxes and cycles under the predominance of abiotic ones. In this case, biota adapts to the environment rather than transforms it.
FEW WORDS
TO PROVOKE
THE DISCUSSION
Soil formation - the myths and reality
• Gaia hypothesis (Lovelock, 1989, 1991): biota conducts all processes on the Earth surface, transforms and regulates abiotic environment rather than adapts to it.
• Soil formation is the transformation of parent material by biota with an obligatory consequent increase in its fertility and ecological suitability (Williams, 1930, 1945; Ponomareva, 1975; Van Breeman, 1990).
• Fertility is the main specific property of soil (widespread opinion).
Is it true?
• Soil formation is a global, complex, bio-abiotic process inherent in biosperic planet; it comprises innumerable interactions of biotic
and abiotic fluxes and cycles, which create various specific pedogenic processes (SPP);
• These SPP have different capacities, rates and opposing trends, therefore they build soil bodies as resultant systems with very
complex and discrepant set of soil horizons and features;
• Global pedogenesis is not purposeful, ruled only by biota, harmonious process, on the contrary, it is very contradictory bio-abiotic process in time and space, which can cause positive as well
as negative results for land biota;
• Such understanding of soil formation allows us to assess the role of soil systems in the biosphere more sensibly and to avoid an
overestimated “biospheric euphoria”
7Fertility is a distinctive but not absolutely specific
feature of soil;
Fertility is also the ingraine feature of all bio-abiotic Earth systems including atmosphere and hydrosphere, terrestrial and marine ecosystems
and the biosphere as a whole;
Soil fertility has his own specificity among these systems:
it is “long-term stored” fertility in a form of stable solid phase soil composition and arrangement,
it is “inertial” fertility long-term accumulated in situ within a soil system
THANK YOU FOR YOUR ATTENTION