SELF-ORGANIZATION OF SOIL SYSTEMS, TIME-SCALES AND ECOLOGICAL SIGNIFICANCE OF PEDOGENIC PROCESSES • V. O. Targulian, Lomonosov Moscow State University; Institute of Geography, Russian Academy of Sciences, firstname.lastname@example.org
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 tropical foggy forest (Mexico)
Mountain tropical Hystic Podzol (Mexico)
Calcareous Arenosols, Pacific low atolls, Cook Islands Plowed Albeluvisol, Central Russia
Soil as a biospheric bio-abiotic system on the land surface
ATMOSPHERE E C O S Y S T E M ABOVEGROUND STAGE S O I L S ITON BELOWGROUND STAGE WEATHERING MANTLE REGOLITH
Water cycles n*10-1 – 102 years Gas cycles n*10-1 – 101 years Biotic cycles n*10-1 – 103 years Exogenic cycles of denudation & sedimentation n*102 – 104 years Anthropo- technogenic cycles n*101 – 104 years Soil system residence time at land surface n*102 – 106 years Endogenic cycles of rocks in lithosphere n*103 – 108 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
O A1 E Bt Mottled clay saprolite Ortho-biotic zone Para-biotic zone Meta-biotic zone Soil and weathering mantle as in situ formed horizonated body – SITON and as a functioning CRITICAL ZONE of a landscape 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 Soilproper as an upper part of weathering mantle Medium and lower parts of weathering mantle Red-yellow saprolite Coarse saprolite Ground water Parent rock
0 LIVING BIOTA 100 50 HUMUS % volume 0 POROSITY D E P T H GASES SOLID PHASE: MINERAL AND ORGANO- MINERAL PARTICLES SOLUTIONS 1м 2 м INTERACTIVECOMPONENTS OF MULTIPHASE BIO-ABIOTIC SOIL SYSTEM
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 = Exogenic soil-forming potential of climate and biota - PCB Interactions of flux and site factors and their potentials in belowground stage of ecosystem genic Emergence of soil functioning multiphase system in enclosing parent material 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 =
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
Solid phase profile time ortho ortho ortho оrthо para para para para L I t o m a t r I x n*105-6 years n*101-2 years n*103-4 years meta meta Sapro- lite meta meta labile profiles of biota, gases, solutions, heat Vertical zones of multiphase soil functioning 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.
climate & biota present day horizonation of soil functioning soild phase profile soil functioning & development solu- tions time heat gases 0-time biota A ortho ortho ortho ortho E functioning within steady state soil body functioning with pedogenic horizonation func- tioning without pedogenic horizona- tion Bt,m para para para para litho- matrix steady state soil body solid phase record of long-term functioning sapro- lite meta meta meta meta time solid phase soil body regulates soil functioning MODEL OF SOIL SELFDEVELOPMENT
technogenic pollution – “poisoned” pedogenesis burying and new pedogenesis Possible fates of soil systems in geological time scale: n*10 years 4-6 Continuation of“life” and evolution on the land surface 0-time denudation and new pedo- genesis
Factors of soil formation soil featuresFactors pedogenic processes soil featuresFactors processes of soil functioning pedogenic processes soil features “meeting” & interaction of factors “agressors” and factors “acceptors” fast cycling and renewal of labile components (gases, solutions, biota); formation & surviving of solid phase microproducts of soil functioning 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 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 Soil features Steady-state model of soil development (Dokuchaev, Jenny, Rode, Yaalon) Slow processes Fast processes time, years 102 103 104 105 101 Progressive pedogenesis Regressive pedogenesis Soil features Soil A Soil B Evolutionary model of pedogenesis (Johnson, Keller, & Rockwell, 1984) Soil C T2 Tn T1 T0
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 processesare changing following the driving changes of the environment.
Why soil system can approach the steady state? Self-terminating pedogenic processes Soil features Clay formation Texture differentiation Carbonate leaching Primary silicates decomposition Leaching of bases from silicates 0 time Dynamically-equilibrium pedogenic processes Soil features Humus (formation vs decomposition) Structure Biogenic elements 0 time
Soil features Ideal model of soil and weathering mantle self-development compared with possible environment changes during this time steady state of system Fast pedogenic processes Slow pedogenic processes time, yrs. Possible changes of climate and biota during 102 – 106 years temperature, precipit. time, years b.p.
Soil-forming potential of climate & biota In humid regions Annual precip., to tropical biomass temperate boreal polar 45o 0o 90o latitude In arid - semihumid regions Annual precip., to steppes biomass semideserts savannas tundra-steppes (sub)tropical polar deserts deserts 90o 45o 0o latitude
Two main models of soil evolution rainforcement of weathering and pedogenesis developing & obliterating soil evolution weakening of weathering & pedogenesis inheriting & superimposing soil evolution
Individual pedogenic processes (IPP) in soil self-development and evolution
Characteristic times of diagnostic horizons and specific pedogenic processes
Long CT n*105 -106 years: Ferralic, Nitic Petro-(duric-plinthic-calcic-gypsic), Geric & Ferralic prop. Medium CT n*103 -104 years: Albic, Andic, Argic, Calcic, Cambic, Duric, Ferric, Fulvic, Fragic, Gypsic, Histic, Mollic, Natric, Umbric, Vertic Short CT n*10 -10 years: Litter, Cryic, Folic, Ochric, Gleyic, Salic, Stagnic, Sulphuric, Takyric, Melanic, Plaggic -1 2 -1 0 1 2 3 4 5 6 7 10 10 10 10 10 10 10 10 10 Characteristic times (CT) of the main diagnostic horizons and properties (WRB) diagnostic features years
Characteristic times of specific pedogenic processes (SPP) in soil self-development Slow SPP n*104 -10 years: ferralitization allitization, petro-cementation, deep sapro-litization 6 Medium-rate SPP n*103 years: mollic, umbric humification, cheluviation, andosolization, lessivage, partluvation, fersiallitization, Fe-,Si-cementation, carbonates migration etc… Fast SPP n*10 -10 years: littering , gleyzation, stagnation, salinization, brunification, cryo-, bio-turbations, structuring, compaction, etc… -1 2 -1 0 1 2 3 4 5 6 7 10 10 10 10 10 10 10 10 10 diagnostic features of SPP years
Characteristic times of specific pedogenic processes (SPP) related to soil absolute age Slow SPP n*10 -10 years 5 6 Medium-rate SPP n*10 3-104 years Fast SPP n*10 -10 years -1 2 -1 0 1 2 3 4 5 6 7 10 10 10 10 10 10 10 10 10 diagnostic features of SPP years young ( alluvial, volcanic, dune) soils tundra & boreal soils temperate soils tropical soils
T h e H o l o c e n e s o i l a g e • 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 arctic tundra Frozen “age” Warm “age” boreal permafrost temperate seasonally freezing subtropics & tropics
Interactions of the specific pedogenic processes Direct linkages (SPP chronochains, which are rather clear) Medium-rate SPP Fast SPP Slow SPP Feedbacks (SPP time bombs, which are often latent) There are the main areas of synergetic interactions in soil systems
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 becomemore 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 :
«Bad» attractors--diagnostic horizons (WRB) ecologically unfavorable for biota:
MODAL DISTRIBUTION OF SOIL BIOTA AND HORIZONS-ATTRACTORS IN SOIL PROFILE О ORTHО- «GOOD» ATTRACTORS А Е РАRA- В «BAD» АТТRACTORS МЕТА- ВС SOLID PHASE SOIL PROFILE BIOTIC ZONES IN SOIL
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