Presentation on theme: "V. O. Targulian, Lomonosov Moscow State University; Institute of Geography, Russian Academy of Sciences, SELF-ORGANIZATION OF SOIL."— Presentation transcript:
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 tropical foggy 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 I T O N ECOSYSTEMECOSYSTEM SOILSOIL WEATHERING MANTLE REGOLITH ABOVEGROUND STAGE BELOWGROUND STAGE
Gas cycles n*10 -1 – 10 1 years Water cycles n*10 -1 – 10 2 years Biotic cycles n*10 -1 – 10 3 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*10 3 – 10 8 years Soil system residence time at land surface n*10 2 – 10 6 years Exogenic cycles of denudation & sedimentation n*10 2 – 10 4 years Anthropo- technogenic cycles n*10 1 – 10 4 years
Ideal model of well-developed soil & weathering mantle in humid tropics by the age of 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 DEPTHDEPTH % volume 50 INTERACTIVE COMPONENTS OF MULTIPHASE BIO-ABIOTIC SOIL SYSTEM SOLID PHASE: MINERAL AND ORGANO- MINERAL PARTICLES HUMUS LIVING BIOTA 1м1м 2 м 0 POROSITY 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 genicgenic Exogenic soil- forming potential 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
time L I t o m a t r I x n* years n* years n* years ortho para meta ortho para meta оrthо para meta ortho para meta Sapro- lite Vertical zones of multiphase soil functioning Solid phase profile labile profiles of biota, 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 phase profile heatgases solu- tions A E Bt,m sapro- lite ortho para meta time soil functioning & development climate & biota 0-time func- tioning without pedogenic horizona- 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
Soil systems behavior in time: self-development and evolution of sols
Possible fates of soil systems in geological time scale: n * 10 years time burying and new pedogenesis Continuation of life and evolution on the land surface technogenic pollution – poisoned pedogenesis denudation and pedo- new genesis
Factors of soil formation soil features Factors pedogenic processes soil features Factors processes of soil functioning pedogenic processes soil features meeting & interactio n of factors agressor s and factors acceptor s 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 microproduc ts 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-state Soil features time, years Fast processes Slow processes Soil A Soil B Soil C Progressive pedogenesisRegressive pedogenesis T0T0 T1T1 T2T2 TnTn Evolutionary model of pedogenesis (Johnson, Keller, & Rockwell, 1984) Soil features
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 10 2 – 10 6 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 & biota In humid regions biomass polar boreal temperate tropical 90 o 0o0o 45 o 90 o 45 o 0o0o biomass In arid - semihumid regions latitude polar deserts tundra-steppes semideserts deserts steppes Annual precip., t o Annual precip., t o (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 Finite Dynamically equilibrium Irrever sible Rever sible Obliterative Non- obliterative Organic matter accumulation Structuring Pedoturbations Salinization - desalinization Ca(Mg)CO 3 migration Weathering Clay formation Leaching from solum Vertical translocations of clays, Fe, Al, Si
Characteristic times of diagnostic horizons and specific pedogenic processes
diagnostic features years Characteristic times (CT) of the main diagnostic horizons and properties (WRB) Short CT n* years: Litter, Cryic, Folic, Ochric, Gleyic, Salic, Stagnic, Sulphuric, Takyric, Melanic, Plaggic 2 Medium CT n* years: Albic, Andic, Argic, Calcic, Cambic, Duric, Ferric, Fulvic, Fragic, Gypsic, Histic, Mollic, Natric, Umbric, Vertic Long CT n* years: Ferralic, Nitic Petro-(duric- plinthic- calcic-gypsic), Geric & Ferralic prop.
diagnostic features of SPP years Characteristic times of specific pedogenic processes (SPP) in soil self-development Fast SPP n* years: littering, gleyzation, stagnation, salinization, brunification, cryo-, bio- turbations, structuring, compaction, etc… 2 Medium-rate SPP n*10 3 years: mollic, umbric humification, cheluviation, andosolization, lessivage, partluvation, fersiallitization, Fe-,Si-cementation, carbonates migration etc… Slow SPP n* years: ferralitization allitization, petro- cementation, deep sapro- litization 6
diagnostic features of SPP years Characteristic times of specific pedogenic processes (SPP) related to soil absolute age Fast SPP n * years 2 Medium-rate SPP n * years Slow SPP n * years 56 young ( alluvial, volcanic, dune) soils tundra & boreal soils temperate soils tropical soils
Absolute age of soils and the real duration of the pedogenesis (taking into account the warm and frozen conditions within the each year) X 1000 years T h e H o l o c e n e s o i l a g e Warmage Frozenage 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:
«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).
MODAL DISTRIBUTION OF SOIL BIOTA AND HORIZONS-ATTRACTORS IN SOIL PROFILE О А Е В ВС ORTHО- РАRA- МЕТА- BIOTIC ZONES IN SOIL SOLID PHASE SOIL 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
7 Fertility 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