Soil formation in Greyzems in Moscow district: micromorphology, chemistry, clay mineralogy and particle size distribution

Catena 34 Ž1999. 315–347

Soil formation in Greyzems in Moscow district: micromorphology, chemistry, clay mineralogy and particle size distribution R. Miedema a

a,)

, I.N. Koulechova b, M.I. Gerasimova

b

Department of Soil Science and Geology, Agricultural UniÕersity Wageningen, Wageningen, Netherlands b Faculty of Geography, Moscow State UniÕersity, Moscow, Russian Federation Received 21 May 1997; accepted 15 February 1998

Abstract Greyzems ŽGrey Forest Soils. are zonal soils of the forest–steppe, in Russia geographically situated between the ŽPodzo. Luvisols of the southern taiga forest and the ŽLuvic. Chernozems of the steppe. Greyzems are characterized by a dark mollic horizon, with uncoated Žbleached. silt and sand grains on pedfaces, and an argic horizon as diagnostic horizons. The FAO–Unesco soil map of the world shows Greyzems and Luvisols in Russia at this transition Žthe Russian soil map shows only Greyzems., while in similar geographic position in the USA and Canada the proportion of Greyzems is very small and Luvic PhaeozemsrChernozems and Albic Luvisols occupy those transitional zones of the grassland–forest interface. Three Greyzem profiles, presently under forest, and developed on loess-like mantle loams of Late Weichselian ŽValday. age in the northern forest–steppe zone of the East European plain ŽMiddle Russian Upland. were described and sampled near Pushchino, some 100 km south of Moscow. Micromorphology, particle size data, chemical data and clay mineralogy were studied. Based on the particle size distribution and the occurrence of fragments of a second humus horizon ŽSHH. the presence of two, rather similar, deposits in the solum is advocated. The following processes have been deduced from the study: Ži. decalcification and secondary accumulation of carbonates; Žii. humus accumulation, including the significance of the SHH; Žiii. clay illuviation, presumably two main phases; Živ. biological activity; Žv. degradation of the mollic A: occurrence of bleached grains; Žvi. downward migration of textural components and organic matter, in the Bt horizon along major pedfaces: occurrence of black organo-clay coatings and uncoated siltrsand grains; Žvii. gleying. The tentative sequence of these processes during Late Weichselian and Holocene times leads us to

)

Corresponding author. Fax: q31-317-482-419

0341-8162r99r$19.00 q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 4 1 - 8 1 6 2 Ž 9 8 . 0 0 1 0 5 - 2

316

R. Miedema et al.r Catena 34 (1999) 315–347

conclude that Greyzems are polygenetic. They formed as PodzoŽLuvisols. under forest, with fine clay coatings in the fine pores inside the blocky and prismatic peds, in the Late Glacial and Early Holocene. The change to tall grass steppe in the Atlanticum created a mollic horizon, that degrades when forest re-invades during the Subatlanticum. Fine clay, combined with organic matter forms black coatings on the major pedfaces. Uncoated silt and sand particles also migrate downward along those major pedfaces. Biological activity is involved in the very complex pattern of the transitional AhE and EBt horizons. Active gleying only occurs in the profile on the lowest topographic position. These latter processes are still active today. Similar soils do occur in the grassland–forest interface in North America, except where the younger age of the landscape and high CaCO3 content at shallow depth prevented their full development. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Soil formation; Greyzems; Podzoluvisols; Russia

1. Introduction Greyzems are among the least known soils in the FAO–Unesco classification system ŽFAO–Unesco, 1988.. Greyzems ŽGrey Forest Soils., are presented on soil maps of the East European plain as a narrow and irregular strip between sod–podzolic soils ŽPodzoluvisols. of the southern taiga and forest–steppe ŽLuvic. Chernozems ŽFig. 1..

Fig. 1. Location map of the study area, soils and sampling sites Žfrom 1:2.5 million soil map of Russia, sheet V..

R. Miedema et al.r Catena 34 (1999) 315–347

317

The FAO–Unesco soil map of the world shows Greyzems and Luvisols in Russia at this transition Žthe Russian soil map shows only Greyzems, Fig. 1., while in similar geographic position in the USA and Canada the proportion of Greyzems is very small and Luvic PhaeozemsrChernozems ŽArgiborollsrArgiudollsrArgiustolls—Soil Taxonomy, 1994; Leached Chernozems and Dark Gray Chernozems—Canadian System of Soil Classification, 1978. and Albic Luvisols ŽGray Luvisols—Canada; Argialbolls— USA. occupy the transitional zones of the grassland–forest interface. The ecology of this transition is summarized by Anderson Ž1983.. Anderson Ž1987. reviews the pedogenesis in the grassland and adjacent forests of the Great Plains. The argic horizon in Argiustolls is frequently questionable according to Bronger Ž1978, 1991.. Mollisols ŽChernozemsrPhaeozems. are summarized by Fenton Ž1983. and the micromorphology of selected mollic epipedons is reported by Pawluk and Bal Ž1985.. Luvisols are treated by Rust Ž1983. and their micromorphology is covered by Bullock and Thompson Ž1985.. Quoting Nygard et al. Ž1952.: ‘‘whether degraded Chernozems have evolved from Chernozems because of encroachment of forest on prairie, or have developed directly from the same kind of parent material is not known.’’ This question is still unresolved at present. These early studies had little soil data, but excellent morphological descriptions. White and Riecken Ž1955. studied Brunizems ŽChernozemsrPhaeozems. of the prairie, Gray Brown Podzolic ŽLuvisols. under forest and transitional soils. Those transitional soils were due to encroachment of deciduous trees onto the prairie, related to changing climatic conditions. Their observations are quoted: ‘‘the first visible indication of the transformation of a Brunizem into a transitional soil appears in the lower part of the A1 horizon with the introduction of gray flecks on the dark colored aggregates, accompanied by a loss of organic matter.’’ The lower organic matter content in the mineral soil might also relate to the reduced below ground inputs of organic residues once prairie has changed to forest according to Anderson Ž1987.. Foss and Rust Ž1962. studied loess derived soils ŽTypudalfsrPodzoluvisolsrGreyzems?. of Late Wisconsinan ŽWeichselian. age in SE Minnesota. They noted 10YR 3r2–3r3 matrixcolours of the peds in the A1, A2 ŽE. and AB horizons with dark gray silica coatings, platy A2 ŽE. horizons, and dark brown clay films on pedfaces consisting of clay and organic matter. Severson and Arneman Ž1973. studied in N.W. Minnesota at the forest–prairie boundary a series of profiles on medium textured, originally calcareous till of Late Wisconsinan ŽWeichselian. age with different vegetation histories. Two profiles were sampled at each site. The Udic Haploboroll ŽChernozem. had been under prairie from 8500 years BP onwards and showed a mollic A, a structure B and evidence of some removal of carbonates. The Mollic Eutroboralfs ŽDegraded ChernozemrGreyzem. had oak–savanne from 8500 years BP onwards, while the other profile had oak–savanne from 8500 to 4000 years BP and deciduous forest from 4000 years BP onwards. These soils demonstrated a more intense removal of carbonates, translocation of small amounts of organic matter with clay, that coated pedfaces and rootchannels. Porous bleached mineral grains occurred on pedfaces in the lower part of surface horizon. The depth of development and the expression of eluvialrilluvial characteristics was most expressed in the profile with present-day deciduous forest. The Typic Eutroboralf ŽGray Wooded: Podzoluvisol. had oak–savanne from 8500 to 4000 years BP, deciduous forest from

318 R. Miedema et al.r Catena 34 (1999) 315–347 Plate 1. Macromorphology of P-74. Vegetation ŽA., profile P-74 ŽB. and details of the platy AhE ŽC. and black clay–humus coatings and bleached grains in the Bt2 horizon ŽD..

319

Plate 1 Žcontinued..

R. Miedema et al.r Catena 34 (1999) 315–347

320

R. Miedema et al.r Catena 34 (1999) 315–347

4000 to 2000 years BP and pinerhardwood from 2000 years BP onwards. The profile had an A2 ŽE. and a B q A horizon with fine, weak platy soil structure and many distinct light gray Ž10YR 7r2. porous ped coatings in the B q A and a well expressed Bt horizon. Bleached grains, a platy A2 ŽE. horizon, a nuciform or blocky Bt with accumulations of organic matter containing clay on pedfaces were mentioned by McClelland et al. Ž1959., Mogen et al. Ž1959., Bourne and Whiteside Ž1962., Radeke and Westin Ž1963., Bailey et al. Ž1964., St. Arnaud and Whiteside Ž1964. and Redmond and Omodt Ž1967. in various states of the Great Plains. Quoting Pettapiece Ž1969. major changes in soil morphology may occur over wide transitional zones, but may also occur abruptly over a few kilometers distance. This was also mentioned by Bailey et al. Ž1964. who describe at the prairie–forest border changes from Brunizems ŽChernozemsrPhaeozems. to Gray Brown Podzolic soils ŽLuvisols. over distances from only 100 to 400 m from Forest to Prairie grooves. Santos et al. Ž1985. studied Orthic Gray Luvisols ŽCanadian System of Soil Classification, 1978. in well drained to moderately well drained positions on Late Wisconsinan ŽWeichselian. till of sandy loam to clayloam texture under forest Žaspen, mixed wood, mixed woodrspruce, aspenrspruce.. They noted strongly variable colours in the Ae ŽE. horizon and had great difficulties in distinguishing weathering coatings from illuviation coatings. Howitt and Pawluk Ž1985a,b. investigated Gray Luvisols on well drained till in Boreal forests. They noted increased pyrophosphate extractable FerAl in the Bt and they found only colloidal material in the Bt following a high rainfall event. Goldin et al. Ž1992. concluded that Bt formation in loamy glacial marine drift overlying clay-rich material in NW WA started in the Late Wisconsinan Ž12,000–11,000 years BP. and that wetrdry fluctuations favoured clay translocation. The translocation of silt in soils, first studied in detail by Arnold and Riecken Ž1964. and Arnold Ž1965. was recently summarized by Nettleton et al. Ž1994.. Freeze–thaw weakened soil aggregates in the topsoil Že.g., Sillanpaa and Webber, 1961. produce uncoated fine sand and silt grains and assumed laminar flow translocates uncoated fine sand and silt grains through larger voids of sizes between 0.5 and several millimeters Žalong pedfaces, through pedotubules.. The main feature of the area under study in Russia is a mosaic distribution of forests and steppe under the same climatic conditions ŽAkhtyrtsev, 1992; Yakusheva and Makeev, 1996.. Hence, when describing properties of grey forest soils, Russian pedologists usually emphasize the combination of ‘forest’ and ‘steppe’ features in soil morphology and chemical properties corresponding to the argic and the mollic horizons. To explain these rather incompatible features, three possible sequences, associated with vegetation changes, have been suggested in literature: Ža. Greyzems were Chernozems with a mollic A formed under steppe, that now degrades under forest Žbleached grains.

Plate 2. Micromorphology AhE and EBt horizons. A ŽPPL.rB ŽXPL.: platy to lenticular microaggregates surrounded by bleached grains ŽAhe horizon of P-74.. C ŽPPL.rD ŽXPL.: detail Ahe horizon Kolomna profile. E ŽPPL.rF ŽXPL.: laminated dark brown coating of clay–humus and bleached grains and dark brown clay–humus infillings in EBt horizon of P-74.

R. Miedema et al.r Catena 34 (1999) 315–347

321

322

R. Miedema et al.r Catena 34 (1999) 315–347

Plate 2 Žcontinued..

R. Miedema et al.r Catena 34 (1999) 315–347

Plate 2 Žcontinued..

323

324

R. Miedema et al.r Catena 34 (1999) 315–347

Plate 3. Micromorphology of BCkg and Bt horizons. A ŽPPL.rB ŽXPL.: micritic Žhypo. coating of calcite with juxtaposed thin clay–humus coating in BCkg of AL-92. C ŽPPL.rD ŽXPL.: limpid fine clay coatings, fragmented coatings and infillings in Bt1 horizon of P-74. E ŽPPL.rF ŽXPL.: the same in Bt1 horizon of P-92.

R. Miedema et al.r Catena 34 (1999) 315–347

325

Plate 3 Žcontinued..

thus leading to an argic horizon. Žb. Greyzems were ŽPodzo.Luvisols with an argic horizon formed under forest, that acquired their mollic A under steppe and that now degrade under forest Žbleached grains.. Žc. Greyzems are the result of the unique conditions of the forest–steppe zone, responsible for their morphological characteristics.

326

R. Miedema et al.r Catena 34 (1999) 315–347

Plate 3 Žcontinued..

‘Monogenetic’ hypotheses Žc. try to explain the causes of forest–steppe zone existence. Milkov Ž1950. and Ponomareva Ž1972. suggested a topographic origin of the

R. Miedema et al.r Catena 34 (1999) 315–347

327

forest–steppe. According to their ideas, which followed Dokuchaev Ž1883., forest as the eluviation-dominated type occupies the highest, most dissected, best drained spots characterized by depletion of substances Že.g., right river banks. while the steppe landscapes are restricted to lower and flat locations, not subjected to such leaching. A lithologic hypothesis was advocated by Surmach Ž1987. and Chendev Ž1994.. Forests and forest soils occupy positions with thin stratified Quaternary deposits Žloams. shallowly overlying impermeable layers. The steppe plots coincide with the areas with thick homogeneous loess-like mantle loams, having more favourable soil–water and microclimatic properties. Polygenetic hypotheses Ža and b. are based on numerous paleogeographic data ŽAlexandrovsky, 1983, 1988; Morozova, 1992.. Two alternatives are discussed: Ž1. the argic horizon was formed during the Atlantic optimum after decalcification of the initially calcareous mantle loam, and the eluvial part of this ‘Atlantic profile’ acquired mollic properties during the Subboreal; Ž2. recent eluviation has been superimposed on a soil with a mollic horizon that may be dated earlier then Atlantic. This may have been a meadow or meadow–chernozemic soil ŽGleyic PhaeozemrChernozem formed 12,500– 9300 years ago.. This hypothesis presumes the effect of the Late WeichselianrEarly Holocene cryogenesis on the soil cover structure and soil properties ŽAlifanov, 1992; Alifanov and Gugalinskaya, 1993; Alifanov, 1995.. The Greyzems in the center of the East European plain have an intricate profile with a mollic horizon, in its lower part with platy structure and bleached sand grains, and an argic horizon with distinct humus–clay coatings and bleached grains on pedfaces. Sometimes in the middle part of the profile one can find an accumulation of dark-coloured organic matter containing material known as ‘second humus horizon’ ŽSHH.. Paleoclimatologic and paleobotanical data refer the SHH formation to the Atlantic time ŽVelichko and Morozova, 1989; Velichko et al., 1996.. This opinion is confirmed by the prevailing C14 age of the SHH ŽAlexandrovsky and Chicagova, 1996.. Sokolov Ž1996. points to the possibility of rejuvenation in C14 age, as many of the SHH occur at shallow depth. He advocates a Late Glacial origin of the SHH, being the former topsoil of a Late Glacial soil. This agrees with the opinion of Alifanov Ž1992, 1995.. Morozova Ž1992. C14 dated the deepest buried SHH Žat 70–80 cm depth. in a cryogenic microdepression at 9130 years BP. This cryogenic microdepression is surrounded and underlain by an argic Bt horizon of earlier age in Late Weichselian loess-like mantle loams. Field observations and numerous literature data Ža.o., Alifanov, 1986; Alifanov et al., 1988; Makeev and Dubrovina, 1989; Alifanov, 1992, 1995. demonstrate variations in SHH morphology of Greyzems depending on their position in catenas, and in cryogenic microcatenas in particular. The SHH is conspicuous in microdepressions and may be absent in soils of paleocryogenic micro-elevations Žblocks.. The objective of this investigation was to study the soil forming processes and the sequence of events in time that have occurred since the sedimentation of calcareous loess-like mantle loams in Late Weichselian periglacial environment resulting in the development of Greyzems, possessing a dark mollic horizon, with uncoated Žbleached. silt and sand grains on structural ped surfaces, and an argic horizon as diagnostic horizons in Russia and North America.

328

R. Miedema et al.r Catena 34 (1999) 315–347

2. Materials and methods 2.1. Site conditions Three Greyzem profiles, presently under forest and developed on loess-like mantle loams of Late Weichselian ŽValday. age in the northern forest–steppe zone of the East European plain ŽMiddle Russian Upland. were described and sampled near Pushchino Ž558N, 388E., 90 km S of Moscow. These profiles were supplemented by the results of several thin sections of Greyzems of Kolomna experimental station approximately 60 km SSE of Moscow, and thin sections of a Podzoluvisol ŽSOD-1., 70 km W of Moscow ŽZvenigorod; Fig. 1.. The relief of the northern slope of the Middle Russian upland at Pushchino is rather contrasting: deeply incised gullies with steep slopes cutting the whole Quaternary sequence down to Carboniferous limestones and Jurassic clays, alternate with weakly undulating interfluves Ž220–250 m above sealevel.. The areas with polygonal paleocryogenic microrelief, consisting of blocks of 20–80 m in diameter and 0.5–3 m in height with depressions between them, of Late Weichelian ŽValday. age ŽBerdnikov, 1976; Alifanov, 1992; Alifanov and Gugalinskaya, 1993; Alifanov, 1995. are infrequent. Quaternary deposits Žtotal depth about 15 m. comprise Saalian Dnepr till; fluvioglacial Eemian coarse gravelly sands; red–brown Weichselian Moscow till everywhere superimposed by 1.5–5 m thick loess-like mantle loams of Late Weichselian ŽValday. age. The present climate is moderately continental with mean summer temperatures of q18.68C and mean winter temperatures of y9.88C. Mean annual precipitation is 520–550 mm, PrE coefficient is 0.9–1.1. Mean thickness of snow cover is 40–45 cm; average depth of soil freezing is 65 cm, although in cold winters with little snow, it may reach 120 cm depth. Approximately 60% of the area is cropland, forests are few on watersheds and are of secondary origin with birch Žand aspen. predominating over original broad-leaved species. Soil pits were located in such a way that they characterize basic positions in the paleocryogenic microcatena, although it was not so easy to find polygons because of vegetation concealing them. Pit AL-92 corresponds to a cryogenic microdepression with more hygrophilous species ŽAlifanov, 1992.. Pit P-74 ŽPlate 1. occupies the lower sloping position of a paleocryogenic block. The birch–aspen forest has a dense cover of Aegopodium podagraria, Stellaria sp., Pulmonaria obscura, Galeobdolon luteum and other herbs ŽAfanasyeva et al., 1974.. Profile P-92 is a formerly arable soil, near the right bank of the Oka river in broad-leaved forest of about 50 years old. Profiles P-74 and P-92 were classified as Haplic Greyzems, and AL-92 qualifies as Gleyic Greyzem.

Plate 4. Macromorphology and micromorphology of BtqAhb ŽSHH. horizons in AL-92 and P-74. A: macromorphology of BtqAhb horizon in AL-92. B ŽPPL.rC ŽXPL.: SHH fragments with limpid fine clay coatings in pores and surrounding the SHH fragment and a thick laminated clay–humus coatingrinfilling in a large void ŽP-74.. D ŽPPL.: macrolaminated black clay–humus coating juxtaposed on coating of siltrfine sand with humus on wall of ped with SHH remnants and other illuvial clay–humus features Žsee EF. in AL-92. E ŽPPL.rF ŽXPL.: detail of D.

R. Miedema et al.r Catena 34 (1999) 315–347

329

R. Miedema et al.r Catena 34 (1999) 315–347

Plate 4 Žcontinued..

330

331

Plate 4 Žcontinued..

R. Miedema et al.r Catena 34 (1999) 315–347

332

R. Miedema et al.r Catena 34 (1999) 315–347

The Kolomna area has similar physiographic conditions, although the paleocryogenic microrelief has not been described there. Sampling was done by Zaidelman along a catena on cropland Žgentle sloping Oka river terrace. with Haplic Greyzems on the summit and Gleyic Greyzems at the lower part of the slope. 2.2. Methods The particle size determination, the chemical analyses and the X-ray analyses of the clay fraction were carried out according to Buurman et al. Ž1996.. Thin sections Ž8 = 8 cm. were prepared according to Fitzpatrick Ž1970. and described according to Bullock et al. Ž1985.. The amount of illuviated clay was estimated in thin sections by counting 400 points at a magnification of 100 times.

3. Results 3.1. Macromorphology All three profiles have mollic epipedons Ž10YR 3r2, moist. with varying amounts of bleached grains in the lower part of the mollic. They have well expressed argic horizons and transitional subhorizons with varying proportions of Ah, E and Bt features. P-92 has a somewhat browner Ap Ž10YR 4r3 to 4r4, moist.. The AhE horizon below this Ap in P-92 has the usual colour of the mollic again Ž10YR 3r2, moist.. The structure in the mollic horizon is subangular blocky to crumb, with in the lower part fine platy structures Žespecially evident in P-74; Plate 1C.. A second humus horizon ŽSHH. in the form of a dark grey Ž10YR 3r2 to 2r2, moist. discontinuous fragmented layer is observed in P-74 and AL-92 ŽPlate 4A.. The Bt horizons have moist colours of the ped interiors of 10YR 5r4, 10YR 5r6 and 10YR 6r4. Subangular and angular blocky structure is moderate to strong in argic horizons of P-92 and P-74 and weak to moderate in AL-92; the vertical ped faces in the Bt2 of all three profiles have thick dark brown to dark grey coatings and spots with bleached sand and silt grains ŽPlate 1D.. P-74 and P-92 are well drained profiles. P-92 is noncalcareous till at least 150 cm and P-74 is noncalcareous till at least 200 cm depth. In AL-92, in the lower part of the Bt Žbelow 70 cm. and in the BCkg common distinct fine FeMn mottles occur, sometimes arranged in horizontal bands. AL-92 is a moderately well drained profile. In AL-92 in the BCkg Žat 100 cm. primary carbonates occur in the groundmass as well as fine white void coatings Žsecondary carbonates. and common large Žto 2 cm. calcaric concretions Žloess puppets. are found. 3.2. Micromorphology The micromorphological characteristics following from Russian studies on Greyzems ŽParfenova et al., 1964; Gradusov et al., 1981. have been summarized by Gerasimova et al. Ž1996.. Targulian et al. Ž1974. presented a very comprehensive study on Podzoluvisols near Moscow.

R. Miedema et al.r Catena 34 (1999) 315–347

333

Our results are illustrated in Plates 2–4 and a short general micromorphological description of the horizons is given below. 3.2.1. Mollic A horizon (Ah) The mollic Ah horizon in all tree profiles is characterized by a moderate to strong pedality with predominantly compound, mostly coprogenic aggregates. Biogenic infillings, some with fragmented clay coatings from the Bt occur regularly in the Ah and AhE horizons of all three profiles. Abundant earthworm casts are observed in the mollic of AL-92. The groundmass in all profiles is dark greyish brown due to homogeneous pigmentation by fine isotropic humus. In the Ahe horizon degradation signs Žplasma andror humus depleted zones–bleached grains. are most conspicuous in AL-92 and P-74, where they occur associated with the banded fabric of the strong platy microstructure in the lower part of the mollic ŽPlate 1C; Plate 2A,B.. Also in the Kolomna sections the bleached grains occur around microaggregates in a clearly banded fabric ŽPlate 2C,D.. Such banded fabrics are also described for Canadian boreal forest soils ŽGray LuvisolsrAlbolls. by Dasog et al. Ž1987..

Table 1 Micromorphological quantification of clay illuviation features by point counting in Greyzems ŽAL-92, P-92 and P-74. and a Podzoluvisol ŽSOD-1. Horizon

Clay and clayrhumus coatings Žvol.%.

Fragmented coatings Žvol.%.

Total illuvial coatings Žvol.%.

2–10 22–30 50–58 75–85 90–106

0.2 1.8 16.2 7.8 2.8

2.5 2.7 2.7 1.8 0.8

2.7 4.5 18.9 9.6 3.3

2–10 14–22 32–40 60–68 100–108

– – – 6.7 9.3

– 0.7 1.1 1.9 1.4

– 0.7 1.1 8.6 10.7

P-74 Ah AhE AhEBt EBt Bt1 Bt2

2–10 19–27 25–33 32–38 52–60 92–100

– – 2.4 4.8 11.3 6.1

– 0.3 2.4 2.7 2.7 1.0

– 0.3 4.8 7.5 14.0 7.1

SOD-1 AhE EBt Bt

15–23 25–33 70–78

– 1.4 12.6

0.5 4.2 2.9

0.5 5.6 15.5

AL-92 Ah AhEBt BtAhb BtŽg. BCkg P-92 Ahp Ap AhE Bt1 Bt2

Sampling depth Žcm.

334

R. Miedema et al.r Catena 34 (1999) 315–347

3.2.2. Transitional EBt[Ahb] horizons (only present in AL-92 and P-74) and EBt horizons These are the most heterogeneous ones. Bt-microzones occur scattered throughout these horizons with characteristics similar to the underlying Bt Žwith in situ limpid fine clay coatings.. Large degraded microzones ŽE-zones. with diffuse outlines and a great number of bleached grains as well as laminated illuviation coatings of bleached grains and organo-mineral fine textured components ŽPlate 2E,F. and unsorted coatings of mixtures of organo-mineral clay and silt and fine sand dominate. The Ahb zones ŽSHH. are pigmented by black organic material, with a different morphology as the organic pigment in the mollic A. Intrapedal porosity is strongly expressed with abundant rounded channels and chambers and a low amount of incompletely decomposed plant residues. The colour Žpitch-black. and appearance of the organic matter suggests wetter accumulation conditions. These second humus horizon zones are present as small rounded aggregates with illuviation coatings Žlimpid fine clay as well as dark brown organo-mineral coatings in voids in and surrounding the Ahb fragments ŽPlate 4... Ahb fragments are most clearly expressed and larger in AL-92 than

Table 2 Particle size, chemical and clay mineralogical data of AL-92 AL-92 Horizon Depth Žcm. Org. C Ž%. Total N Ž%. CrN ratio Carbonates Ž%. pH-H 2 O pH-KCl CEC ŽcmolŽq.rkg. Clay Ž%. Silt Ž%. Sand Ž%. Base saturation Ž%. Exch. Mg 2q ŽcmolŽq.rkg. Exch. Ca2q ŽcmolŽq.rkg. Exch. Naq ŽcmolŽq.rkg. Exch. Kq ŽcmolŽq.rkg. Exch. Al 3q ŽcmolŽq.rkg. Exch. Hq ŽcmolŽq.rkg. Free Fe Ž%. Organic Fe Ž%. Organic Al Ž%. Kaolinite Illite Smectite Vermiculite Soil chlorite

Ah 0–10 2.22 0.15 14.8 y 5.1 4.3 11.8 14.8 84.1 1.1 74 0.9 7.4 0.1 0.3 0.7 0.3 0.7 0.3 0.3 qq qq q qq y

AhE 20–25 1.30 0.11 11.8 y 5.0 4.1 10.4 12.9 85.9 1.2 57 0.7 4.9 0.1 0.2 1.7 0.3 0.6 0.2 0.3 qq qq q qq y

AhEBt 25–30 1.26 0.09 14.0 y 4.8 4.0 13.1 18.7 79.9 1.4 57 1.1 6.0 0.1 0.3 3.1 0.1 0.7 0.3 0.5 qq qq q qq y

BtAhb 50–55 0.43 0.05 8.6 y 4.9 4.0 18.4 27.7 64.1 8.2 85 3.0 12.0 0.1 0.5 2.3 0.2 1.0 0.6 1.0 qq qq qq qq y

BtŽg. 75–85 0.34 0.04 8.5 y 5.5 4.5 21.5 30.1 65.1 4.8 95 3.9 16.0 0.1 0.4 0.1 0.2 0.9 0.1 0.0 qq q qq qq y

BCkg 100–105 0.20 0.03 6.7 5.5 7.6 7.4 19.2 24.2 72.6 3.2 100 3.3 15.5 0.1 0.3 0.0 0.0 0.8 0.0 0.0 q q qqq q y

R. Miedema et al.r Catena 34 (1999) 315–347

335

in P-74. Biogenic infillings occur commonly and add to the heterogeneity of these transitional horizons. 3.2.3. Argic horizon The Bt-horizons have an moderate angular blocky to prismatic microstructure. The yellowish brown groundmass is rather dense and homogenous with abundant fine channels. Practically all fine channels are lined with laminated, limpid fine clay. Fragmented coatings of limpid clay occur regularly ŽTable 1; Plate 3C–F.. Larger voids and pedfaces show dark brown laminated coatings of clay and humus ŽPlate 4., fragments thereof and dark brown unsorted coatings consisting of a mixture of clay– humus and siltrfine sand ŽPlate 2E,F.. Clay illuviation features, quantified by point counting, are presented in Table 1. In the Ah and AhE horizons the clay illuviation phenomena are all found in biogenic infillings as fragmented coatings. In the Bt horizons the proportion of biogenically translocated coatings is less than 25% of the total amount. In the lower part of the argic B, pedality becomes less well expressed Žweak coarse prismatic structure., with still

Table 3 Particle size, chemical and clay mineralogical data of P-92 P-92 Horizon Depth Žcm. Org. C Ž%. Total N Ž%. CrN ratio Carbonates Ž%. pH-H 2 O pH-KCl CEC ŽcmolŽq.rkg. Clay Ž%. Silt Ž%. Sand Ž%. Base saturation Ž%. Exch. Mg 2q ŽcmolŽq.rkg. Exch. Ca2q ŽcmolŽq.rkg. Exch. Naq ŽcmolŽq.rkg. Exch. Kq ŽcmolŽq.rkg. Exch. Al 3q ŽcmolŽq.rkg. Exch. Hq ŽcmolŽq.rkg. Free Fe Ž%. Organic Fe Ž%. Organic Al Ž%. Kaolinite Illite Smectite Vermiculite Soil chlorite

Ahp 2–10 3.18 0.23 13.8 y 5.5 5.4 15.2 13.4 81.0 5.6 88 1.6 11.3 0.1 0.4 0.0 0.1 0.6 0.1 0.1 qq qq q qq y

Ap 14–22 1.38 0.11 12.5 y 4.8 4.5 9.2 12.9 81.0 6.1 76 1.0 5.7 0.0 0.3 0.2 0.3 0.6 0.1 0.1 qq qq q qq y

AhE 32–40 0.86 0.07 12.3 y 4.9 4.5 10.9 12.1 81.8 6.1 80 1.0 7.5 0.0 0.2 0.0 0.2 0.6 0.1 0.1 qq qq q qq y

Bt1 60–68 0.36 0.04 9.0 y 4.9 4.4 15.1 21.1 69.8 9.1 91 2.0 11.3 0.1 0.4 0.4 0.3 0.9 0.1 0.1 q q qq q y

Bt2 100–108 0.22 0.03 7.3 y 4.9 4.4 16.9 26.1 67.4 6.5 91 2.8 12.0 0.1 0.4 0.3 0.3 0.9 0.1 0.0 q q qqq q y

336

R. Miedema et al.r Catena 34 (1999) 315–347

abundant intrapedal limpid clay coatings. The amount of clay illuviation phenomena in the argic horizons of the Greyzems is very high ŽMiedema and Slager, 1972.. The amount of illuviated clay in the argic of the Podzoluvisol ŽSOD-1. is similar, but in this argic horizon no organo-clay coatings were observed. The limpid clay coatings of the Podzoluvisol are very similar to the limpid clay coatings of the argic of the Greyzems, although they are somewhat more pale yellow. 3.2.4. BCkg horizon (only present in Al-92) This horizon demonstrates a crystallitic b-fabric, caused by randomly occurring sparitic grains Žprimary carbonates.. In and around voids micritic coatings and hypocoatings occur, sometimes with a juxtaposed thin clay–humus coating. Dark brown to black FeMn discrete and diffuse nodules commonly occur in the BCkg horizon ŽPlate 3A,B.. The Kolomna Greyzems are micromorphologically similar to the Pushchino Greyzems. Zones with well expressed platy microstructure are observed in the AhE horizons. In the AhE the bleached mineral grains are located as clusters around aggregates and in the groundmass. There are many, sometimes deformed, clay–humus pedofeatures in the EBt horizons. Limpid non-deformed clay coatings prevail in the

Table 4 Particle size, chemical and clay mineralogical data of P-74 P-74 Horizon Depth Žcm. Org. C Ž%. Total N Ž%. CrN ratio Carbonates Ž%. pH-H 2 O pH-KCl CEC ŽcmolŽq.rkg. Clay Ž%. Silt Ž%. Sand Ž%. Base saturation Ž%. Exch. Mg 2q ŽcmolŽq.rkg. Exch. Ca2q ŽcmolŽq.rkg. Exch. Naq ŽcmolŽq.rkg. Exch. Kq ŽcmolŽq.rkg. Exch. Al 3q ŽcmolŽq.rkg. Exch. Hq ŽcmolŽq.rkg. Free Fe Ž%. Organic Fe Ž%. Organic Al Ž%. Kaolinite Illite Smectite Vermiculite Soil chlorite

Ah 2–10 2.93 0.21 14.0 y 4.7 4.6 12.5 14.6 84.1 1.3 82 1.4 8.3 0.0 0.5 0.1 0.3 0.6 0.1 0.1 qq qq q qq y

AhE 19–27 2.06 0.16 12.9 y 4.3 4.2 10.1 14.7 84.5 0.8 59 0.9 4.7 0.1 0.3 1.6 0.3 0.7 0.2 0.1 qq qq q qq y

AhEBt 25–33 1.01 0.08 12.6 y 4.1 3.8 13.0 17.6 79.1 3.3 56 1.5 5.5 0.1 0.2 4.0 0.1 0.7 0.3 0.5 qq qq q qq y

EBt 32–38 0.67 0.07 9.6 y 4.3 3.9 13.0 19.5 77.3 3.2 70 2.1 6.6 0.1 0.3 2.7 0.2 0.8 0.4 0.6 qq qq q qq y

Bt1 52–60 0.34 0.04 8.5 y 4.2 4.0 15.8 29.4 66.9 3.7 82 3.5 8.9 0.1 0.5 4.3 0.1 1.0 0.2 0.1 q q qq q y

Bt2 92–100 0.22 0.03 7.3 y 4.6 4.3 18.8 32.7 65.3 2.0 91 4.9 11.5 0.2 0.6 1.6 0.3 0.9 0.1 0.1 q q qqq q y

R. Miedema et al.r Catena 34 (1999) 315–347

337

argic Bt horizon. In the EBt and Bt horizons bleached grains occur to a depth of 70 cm as cappings in void infillings and as lamina in fine clay–humus coatings. 3.3. Analytical data (Tables 2–4) 3.3.1. Particle size distribution Particle-size data testify to an advanced textural differentiation with a clear accumulation of clay in the Bt horizons. The micromorphology proves that a major part of the accumulation is due to clay illuviation. Below 50 cm the amount of smectite is increasing and the amounts of kaolinite, illite and vermiculite are decreasing. This increased smectite content may be related to clay translocation Žpreferential movement of fine sized smectites—Soil Taxonomy, 1994; Jongmans, personal communication, 1998.. The sand content with depth in all three profiles demonstrates an increase around 50–60 cm depth, decreasing again to greater depth. The increased sand contents occur in association with increased clay contents of the Bt. The silt content of the upper 50–60 cm is very high in all three profiles with values ranging from 77.3% to 85.9%. Below 50 cm the silt contents in all three profiles range from 64.1% to 69.8%. This suggests a deposit from 0 to 50 cm depth that has a very high silt content, relatively low sand contents and 12% to 15% clay. The present clay content will be lower than the original clay content of the sediment due to eluviation of fine clay Žmicromorphology.. The clay mineralogy of the upper 50 cm is also distinctly different from that below. This might also suggest that the presumed upper deposit is an accumulation of previously eluviated material from the surroundings Žsolifluctionreolian?..

Fig. 2. Climate in the Late Weichselian and Holocene in the study area in Russia Žfrom Khotinskiy, 1986..

338

R. Miedema et al.r Catena 34 (1999) 315–347

3.4. Chemical data The mollic horizon in the three profiles has organic carbon contents from 2.2% to 3.2% decreasing with depth to 0.9% to 1.3%. The subsoil has values from 0.2% to 0.4%. The CrN ratio is highest in the top 10 cm of the profiles Ž13.8–14.8., ranges from 12.3 to 14.0 in the remainder of the mollic and drops to very low values of 6.7–7.3 in the deepest samples around 100 cm depth. This suggests the incorporation of well decomposed forest litter in the mollic, and translocation of nitrogen enriched organic matter to the subsoil. The SHH remnants in P-74 and AL-92 do not show increased organic carbon contents. pH-H 2 O values of the 0–10 cm topsoil samples Ž4.7–5.5., then drop to 4.1–4.9 in the subsoil. The exchangeable acidity values of the 0–10 cm samples are low, compared to those between 10 and 50 cm depth. Exchangeable Ca2q and Mg 2q are clearly higher in the 0–10 cm samples, which also explains the higher base saturation in that layer. These elevated exchangeable divalent cations are due to cycling through litter addition from the forest. AL-92 and P-74 have the lowest pH values of the subsurface horizon, with base saturation as low as 56% to 60% and corresponding appreciable amounts of exchangeable acidity Žnotably Al 3q .. P92 has the highest subsurface pH and almost no exchangeable acidity. This could be due to former arable use. In the non-calcareous deeper subsoils of all three profiles the base saturation increases to 80% to 90%. In AL-92 and P-92 the exchangeable acidity in these layers is very small. But in P-74 the pH-H 2 O remains low and exhangeable acidity high even at base saturations of 80% to 90%. The deepest sampled subsoil ŽBCkg. of AL-92, which contains primary and secondary carbonates, has a pH-H 2 O of 7.6 and a base saturation of 100%. In the other two profiles no carbonates were found till 130 cm depth ŽP-92. and 200 cm ŽP-74.. The CEC data demonstrate the relation with clay and organic matter content. The values reflect the decreasing organic matter content with depth, as well as the increasing clay contents in the EBt and Bt horizons. The CEC values agree well with the clay mineralogy. The increasing free iron content with depth, which is decreasing again in the deepest samples, is related to the translocation of fine clay with some iron to the argic B-horizon. This correlates well with the quantitative data on clay illuviation in Table 1. Interesting are the trends observed in pyrophosphate extractable organic Fe and Al. The profiles AL-92 ŽTable 2. and P-74 ŽTable 4. show a clear increase in organic Fe and Al with depth, followed by a decrease in the deeper subsoil. This points to the translocation of complexes of organic matter and clay chelated with FerAl. This agrees with the results of Howitt and Pawluk Ž1985a.. In P-92 ŽTable 3. this phenomenon is not found, which is caused by the former agricultural use of this soil. 4. Discussion 4.1. Parent material homogeneity and the SHH The formation of the SHH, present in two of our three studied soils, in Greyzems and Podzoluvisols in the European and Siberian southern taiga and forest–steppe zone, has

R. Miedema et al.r Catena 34 (1999) 315–347

339

been described and interpreted repeatedly by many researchers Ža.o., Lebedeva, 1969; Akhtyrsev, 1979; Dolgova et al., 1979; Alexandrovsky, 1983; Akhtyrtsev and Akhtyrtsev, 1986; Alifanov, 1986; Karavaeva et al., 1986; Chichagova and Cherkinskiy, 1988; Bagnavets, 1989; Dubrovina and Kulinskaya, 1989; Gerasimova et al., 1992; Morozova, 1992; Gerasimova et al., 1996; Makeev and Yakusheva, 1996; Velichko et al., 1996.. The black colour of the pigmenting organic matter and the mullranmoor type of humus present in the rounded and lenticular fragments of the SHH in AL-92 and P-74 agrees with earlier descriptions. We consider the presence of remnants of a SHH in AL-92 and P-74, in agreement with Sokolov Ž1996., as proof for two deposits. These two deposits can also be noted in the slightly different particle size distribution, not only in AL-92 and P-74, but also in P-92, where direct evidence of a SHH lacks. The different clay mineralogy can also in part be attributed to two deposits. The oldest mantle loam deposit occurs very widespread and from the Late Weichselian period. Cryogenic microrelief has been found by many authors Ža.o., Berdnikov, 1976; Alifanov, 1992; Morozova, 1992; Alifanov, 1995.. Sokolov Ž1996., reviewing the various hypotheses to explain the SHH and the texture differentiated profiles, concluded that the SHH has to be the buried Ah of the Late Weichselian to early Holocene soil profile. The SHH would then be present in the microlows of the cryogenic microrelief which also explains its lateral disappearing and changes to peaty material. The micromorphological characteristics of the organic matter in the SHH points to a relatively wet accumulation. Assuming that the overlying deposit is related to the cryogenic microrelief, this solifluction deposit might date from the outgoing Late WeichselianrPreboreal period. Some C14 ages ŽMorozova, 1992—third humus horizon; Alifanov, 1992. of relatively deep SHH support this timing. Frequently younger C14 dates of SHH ŽAtlanticum. are reported Ž5150 to 7000 years BP: Alexandrovsky, 1983; Alifanov, 1986; Chichagova and Cherkinskiy, 1988; Morozova, 1992—SHH.. Sokolov Ž1996. arguments that these dates are far too young, because rejuvenation takes place with humus from the recent vegetation. Organic matter moves down the profile as clay–humus chelates ŽTables 2 and 4., but a number of the dated SHH are from depths between 50 and 80 cm, however. If we must assume that the Atlanticum dating of the SHH is correct, then, based on the well established climatic changes in the Holocene in this part of Russia ŽFig. 2., another possibility for this surface deposit would be the Subboreal-1 period between 4600 and 4200 years BP. 4.2. Decalcification The absence of carbonates in the well drained P-92 Žtill at least 130 cm. and P-74 Žtill at least 200 cm. soils indicates considerable decalcification, assuming that the original mantle loam was calcareous. Whether the supposed surface deposit was originally calcareous is not known. The presence of primary and secondary carbonates in the moderately well drained Al-92 indicates that in certain landscape positions decalcification has not been so deep. Secondary calcite precipitates occurs in and around voids. Decalcification precedes clay translocation ŽPlate 3A,B.. Rapid decalcification can occur in the Late WeichselianrPreboreal period when local hydromorphic soil conditions and

340

R. Miedema et al.r Catena 34 (1999) 315–347

marshy vegetation were widespread. Decalcification is a still ongoing process due to the leaching regime of the present-day climate in this region. 4.3. Translocation of clay and other textural components Micromorphologically a strong fine clay translocation is evident and this is supported by the clay distribution with depth. The decalcified soil material and Late Glacial through Holocene environmental condition Žalternating freezing and thawing andror drying and wetting. favour the translocation of clay ŽMc Keague, 1983.. The presence of limpid fine clay coatings in fine pores inside the peds of the Bt and the presence of clay–humus coatings in large channels through the peds and planar voids separating the blocky and prismatic peds suggests at least two phases in illuviation. The present-day translocation involves clay, humus and other textural components Žsiltrfine sand. as evidenced from the character of the thick, laminated coatings ŽPlate 2E,F. and the trends with depth of organic FerAl ŽTables 2 and 4.. It is associated with the preferential water movement along the peds in the Bt. The humus is derived from the degradation of the mollic horizon. Accumulations of translocated textural components may also be in the form of accumulations of uncoated silt and fine sand grains, located on pedfaces till deep in the Bt or in large pores. A complex variety of organic matter containing textural accumulations is found in the intermediate EBt horizons. Such translocations take place from the completely saturated topsoil after springmelt. When the topsoil is dry in summer, sudden wetting by thunderstorms may also trigger the translocation of textural components with humus. The limpid fine clay coatings originate from an older process. This type of illuviation must postdate the SHH as such coatings occur in and around the fragments of the SHH. The coatings are strikingly similar with the coatings in the Podzoluvisol, studied for comparison. In that soil under forest no clay–humus coatings were observed, although some authors have observed that they do occur on major prismatic pedfaces in the subsoil around 1 m depth. Most Russian researchers are of the opinion that the texture differentiation of the profile was formed principally during the first half of the Holocene Ža.o., Dolgova et al., 1979; Akhtyrtsev and Akhtyrtsev, 1986; Karavaeva et al., 1986; Bagnavets, 1989; Dubrovina and Kulinskaya, 1989; Gerasimova et al., 1992; Morozova, 1992. or even formed almost synsedimentary ŽMakeev and Dubrovina, 1989; Sokolov, 1996.. Walker Ž1966. found that in Iowa, USA, where presently Luvic Chernozemsr Phaeozems occur, initially scarce coniferous forest stabilized the landscape from 13,000 to 10,500 years BP. Conifers changed to mixed forest with hardwood dominating from 10,500 to 8000 years BP. From 8000 to 3000 years BP the warm, dry herbaceous maximum occurred, followed by oak invading prairie subclimax from 3000 years BP to the present time. The last 1000 years the agricultural landscape took shape. The Russian literature on the evolution of the vegetation of forest–steppe in the centre of the Russian plain Žpresently with Greyzems soils. mentions the following succession ŽFig. 2.: tundra–steppe with pine forest islands Žfrom 14,000 to 12,500 years BP; Dryas-3.; birch forest–steppe with some pine and grass cover with periglacial

R. Miedema et al.r Catena 34 (1999) 315–347

341

elements Žfrom 12,500 to 10,300; Dryas-3 to Allerod.; forest–steppe with spruce and pine forest, meadows and swamps Ž10,300 to 9300 years BP; Preboreal.; pine–birch forests and steppe plots with Artimisia and herbs Ž9300 to 8000 years BP; Boreal.; increasing share of herbal steppe and introduction of broad-leaved species in forests Ž8000 to 6000 years BP; Atlanticum-1.; oak dominated broadleaved forest patches in complexes with grass–cereal steppe Ž6000 to 4500 years BP; Atlanticum-2.; decreasing of forest areas, formation of Festuca steppe Ž4500 to 2500 years BP; Subboreal.; expansion of forests, meadow–steppe Ž2500 to 1000 years BP; Subatlanticum 1 and 2.; agricultural landscape Ž1000 years BP till present.. 4.4. Accumulation of humus (present mollic horizon) The present mollic horizon is characterized by the dark greyish brown colour, high organic matter content and strong subangular blocky to crumb structure and, in the lower part, platy pedality ŽPlate 1C.. The organic matter occurs as blackish brown mull humus and pigments the groundmass. The organic pigment of the SHH is pitchblack due to its less well drained formation Ž‘anmoorig’.. About the time of formation of the mollic horizon all Russian and North American studies agree: the Atlantic period ŽHypsithermal. with its improved climate ŽFig. 1.. The thermal optimum in the Hypsithermal is reached early in the Atlanticum Žaround 8000 BP. in the Northern Hemisphere ŽVan Vliet-Lanoe, ¨ personal communication.. Some deviating opinions exist in literature: Bork Ž1983. agrees with the theory of Rohdenburg and Meyer Ž1968. that in Southeast Lower Saxony a Chernozem mollic horizon developes on loess under dense semi-deciduous forest in the early Holocene ŽPreboreal through early Atlanticum., followed by progressive degradation under semideciduous forest of the mollic Ždecalcification, brunification, clay illuviation. in the Neolithic period Ž6900–3700 BP.. We find it hard to believe that under unchanged climatic and vegetation conditions the pedogenesis would shift from the formation of a chernozemic mollic horizon to dynamics leading to the argic horizon characteristic for Luvisols. Bork states that the mollic is eroded in agriculturally used sites. These sites experience a natural reforestation: however, no new mollic horizon is formed. Weir et al. Ž1971. demonstrated in England that on Late Weichselian ŽDevensian. loess a Luvisol with a fully developed argic horizon exists under colluvium of 5000 BP. Van Vliet-Lanoe¨ Ž1990. refers to studies Že.g., Langohr and Sanders, 1985. timing the formation of a fully developed argic horizon already in Late Weichselian times. Recently, Rogaar et al. Ž1993. reported on Phaeozem and Luvisol development related to relief and climate in Rheinhessen, Germany. They concluded that in the most continental lower parts of the landscape the formation of the mollic horizon of the calcaric Phaeozem Žwhich does not have an argic horizon. under steppe started early in the Holocene and continued till recent. In the forest profile at a higher elevation with more precipitation, under forest a Luvisol was formed without a mollic horizon. The authors argue that decalcification, weathering and clay translocation took place in Late Weichselian to Early Holocene times. Their intermediate Phaeozem profile demonstrated decalcification, weathering and weak clay translocation prior to the formation of the overlying mollic horizon.

342

R. Miedema et al.r Catena 34 (1999) 315–347

Havinga Ž1990. concludes that a not very open forest was the natural vegetation on the Chernozems on loess in the dry and warm climate region in Eastern Austria and that roughly it was during the Subatlanticum that, due to human activity, the forest gave way to steppe. Havinga’s pollenspectra, however, covering the Holocene from Boreal times onward, demonstrate large amounts of grass and herb pollen throughout that whole time period. Our conclusion would be that the landscape was a kind of forest stepperparkland. Degradation features in the mollic of our Greyzems are indicated by zones at the periphery of platy aggregates in Ah, AhE and transitional horizons, impoverished in clay and organic matter, thus leaving the characteristic uncoated quartz grains of silt and fine sand size behind. The fine textured materials and the organic matter jointly illuviate as discussed above. These degradation features occur when forest re-invades ŽSubatlanticum. over larger areas or in increasing forest grooves in the forest steppe or parkland environment Ža.o., Walker, 1966; Alifanov, 1986; Akhtyrtsev and Akhtyrtsev, 1986; Karavaeva et al., 1986; Anderson, 1987; Bagnavets, 1989; Dubrovina and Kulinskaya, 1989; Gerasimova et al., 1992; Morozova, 1992; Gerasimova et al., 1996; Velichko et al., 1996.. The liberated quartz silt and fine sand grains may also be translocated with turbulent flow and are redeposited in the transitional horizons as well as on the prismatic and blocky faces along the preferential flowpaths ŽLangohr and Sanders, 1985; Nettleton et al., 1994.. 4.5. Biological actiÕity Bioturbation by earthworms, as evidenced by many channels and infillings, coprogenic granular structure and high porosity, is an important present-day process in all three profiles. AL-92 demonstrates the highest bioturbation which is logical in view of its landscape position. The bioturbation, presumably by grass roots and insects, of early Holocene times is especially visible in the numerous fine channels in the interiors of peds in the Bt and BC horizons. The amount of animal reworking of the illuviation coatings is high in the top 50 cm, but less than 25% by volume in the Bt and BCk horizons ŽTable 1.. 4.6. Gleying AL-92 shows evidence of active gleying with coating, hypocoatings and nodules of FeMn in the lower BtŽg. and BCkg horizons. This is in line with its moderately well drainage position. In the other two profiles signs of active gleying are lacking, although the occasional ferric nodule is present throughout the soil.

5. Conclusions and synthesis Based on the literature and data of our profiles we hypothesize the following sequence of events during the Late Weichselian and Holocene time. In the Late Weichselian paleocryogenic microrelief formed. During the interstadials ŽBøllingrAl-

R. Miedema et al.r Catena 34 (1999) 315–347

343

lerød?. in the Late Weichselian hydromorphic humus accumulation occurred, presently preserved as fragments of the SHH Žor third humus horizon like in depression soils studied by Morozova Ž1992... We believe that Sokolov Ž1996. is right to suppose that the C14 age of many SHH is Žfar. too young due to rejuvenation by more recent humus, either by its rather shallow position or by present-day downward movement of chelated humus–clay as demonstrated in our profiles. In the same Late Weichselian substantial decalcification already has occurred Že.g., Slager et al., 1976; Miedema, 1992.. Furthermore a presumably substantially if not fully decalcified surface deposit Žsolifluctionreolian?. was laid down on top of the fragments of SHH in the paleocryogenic microlows. Probably already synsedimentary, but certainly upon climate warming in Late Weichselian interstadial periods and in the Preboreal the substrate was subjected to bioturbation by plant roots and burrowing fauna. Bioturbation Ža.o., by earthworms. has continued throughout the whole Holocene in the studied profiles. Texture differentiation may have happened already synsedimentary as, e.g., Sokolov Ž1996. beliefs, but limpid fine clay translocation has continued during Preboreal and Boreal times under forest that changed composition in time. This fits the vegetation reconstruction in both Russia and the USA During the warm and relatively humid Atlanticum the present-day mollic horizon has been formed under the herbal steppe with sparse broadleave forest grooves. The Subboreal-1 period from 4600 to 4200 years BP presents a problem. The temperature lowering would allow deep seasonal freezing ŽVan Vliet-Lanoe, ¨ 1985. and cryogenic processes with the formation of microhighs and microlows. In the microlows an hydromorphic humus accumulation may have occurred, now preserved as SHH. This would fit the C14 dates of literature, supposing they are correct and not rejuvenated. Solifluction may have truncated part of the mollic topsoil from the cryogenic microhighs and its deposition in cryogenic microlows buried the SHH. The Subboreal-2 from 4200 to 3200 years BP demonstrated considerable warming and mollic development continued on the microhighs and in the solifluction deposits in the microlows. Texture differentiation continued, certainly when in the Subatlanticum forests re-invade and degradation of the mollic under forest liberates clay–humus chelated with Fe and Al that illuviates along preferential flowpaths of water. In this liberation freezingrthawing in the present continental climate plays clearly a role as evidenced by the platy structure around 30 cm depth and the loss of organic matter from the exteriors of these platy peds ŽFig. 1C; Fig. 2A–D.. Part of the uncoated quartz grains of silt and fine sand size, left behind in the Ah and AhE horizons, illuviates along the same preferential flowpaths given occasional high energy water transport. This phase of still ongoing texture differentiation is characterized by thick, often clearly laminated dark greyish brown illuviation phenomena with even layers of uncoated siltrfine sand ŽPlate 2E,F.. Shifting of zones due to climatic changes in the Holocene is responsible for the changes over kilometers wide transitional zones. Persisting forest grooves in steppe and grassy spots in forests may cause GreyzemrŽPodzo.Luvisols alternations within 1 km ŽBailey et al., 1964; Pettapiece, 1969; Gerasimova et al., 1992, 1996.. The influence of the agricultural use of the last 1000 years has not been studied, although profile P-92 presumably has been used for agriculture. This shows up in the presence of an Ahp and Ap horizon and somewhat modified chemical characteristics, but no clear micromorphological evidence has been observed.

344

R. Miedema et al.r Catena 34 (1999) 315–347

Acknowledgements We wish to thank our colleagues Alifanov for help in selecting the profile locations and discussions in the field, Zaidelman for the thin sections of the Kolomna profiles, Lychagin for help with the fieldwork and Gontcharenko for participation in thin sections description. Miedema is grateful to his colleagues Ransom, Mermut, Protz, Norton and Franzmeier who demonstrated and discussed soils in similar landscapes in the USA and Canada.

References Afanasyeva, E.A., Gorbunov, N.I., Karmannov, I.I., Kokovina, I.P., Muzychkin, E.T., Grin, G.S., Kissel, V.D., Polupan, N.I., Ivanov, V.F., Molchanov, R.T., Nazarov, A.G., 1974. Guide to soil excursion. The East European plain. Forest steppe and steppe zones. Tour 1. Xth International Congress of Soil Science. Publishing House ‘Nauka’, Moscow, 87 pp. Akhtyrsev, B.P., 1979. Genesis of Grey Forest soils. Sov. Soil Sci. 11, 521–531. Akhtyrtsev, B.P., 1992. On the evolution of the Gray Forest soils in the middle Russian forest–steppe. Pochvodedenie 3, 5–18. Akhtyrtsev, B.P., Akhtyrtsev, A.B., 1986. Holocene soil evolution on Middle Russian forest–steppe zone. Evolution and Age of USSR Soils. Puschino, pp. 163–173. Alexandrovsky, A.L., 1983. Holocene Soil Evolution on the East European Plain. Publishing House ‘Nauka’, Moscow, 150 pp. Alexandrovsky, A.L., 1988. The evolution of the East European soils at the forest–steppe boundary. Natural and Anthropogenic Soil Evolution. Pushchino, pp. 82–94. Alexandrovsky, A.L., Chicagova, O.A., 1996. Radiocarbon Age of East European Forest–Steppe Holocene Paleosols XIV INQUA Congress, Berlin, Germany, InquarISSS Paleopedology Commission Newsletter No. 12, 14. Alifanov, V.M., 1986. Gray Forest soils in the centre of the Russian plain. Historical–genetical analysis. Evolution and Age of USSR Soils. Pushchino, pp. 155–162. Alifanov, V.M., 1992. Paleocryogenesis and present-day soil genesis. Abstract of Doctoral thesis, Moscow State University, 47 pp. Alifanov, V.M., 1995. Paleocryogenesis and Present-day Soil Formation. Pushchino, 320 pp. Alifanov, V.M., Gugalinskaya, L.A., 1993. Paleocryogenesis in the Russian plain and soil cover structure. Pochvovedenie 7, 65–75. Alifanov, V.M., Gugalinskaya, L.A., Kovda, I.V., 1988. History of the soils in the centre of the Russian plain. Pochvovedenie 9, 76–84. Anderson, R.C., 1983. The eastern prairie–forest transition—an overview. In: Brewer, R. ŽEd.., Proceedings of the 8th North American Prairie Conference. Dept. of Biology, Western Michigan University, Kalamazoo, MI, pp. 86–92. Anderson, D.W., 1987. Pedogenesis in the grassland and adjacent forests of the Great Plains. Adv. Soil Sci. 7, 53–93. Arnold, R.W., 1965. Multiple working hypothesis in soil genesis. Soil Sci. Soc. Am. J. 29, 717–725. Arnold, R.W., Riecken, F.F., 1964. Grainy gray ped coatings in some Brunizem soils. Iowa Acad. Sci. Proc. 71, 350–360. Bagnavets, O.S., 1989. On the history of soil formation in the Holocene in the northern part of the Pre-Volga upland. In: Anthropogennic and Natural Evolution of Soils and the Soil Cover. Pushchino, Moscow, pp. 237–239. Bailey, L.W., Odell, R.T., Boggess, W.R., 1964. Properties of selected soils developed near the forest–prairie border in East-Central Illinois. Soil Sci. Soc. Am. J. 28, 257–264.

R. Miedema et al.r Catena 34 (1999) 315–347

345

Berdnikov, V.V., 1976. Paleocryogenic Microrelief in the Centre of the Russian Plain. Publishing House ‘Nauka’, Moscow, 124 pp. Bork, H.R., 1983. Die Holozane Beispiele aus dem Sudost¨ Relief- und Bodenentwicklung in Lossgebieten. ¨ ¨ lichen Niedersachsen. Catena Supplement 3: Bodenerosion, Holozane ¨ und Pleistozane ¨ Bodenentwicklung, 1–93. Bourne, W.C., Whiteside, E.P., 1962. A study of the morphology and pedogenesis of a medial Chernozem developed in loess. Soil Sci. Soc. Am. J. 26, 484–490. Bronger, A., 1978. Climatic sequences of steppe soils from Eastern Europe and the USA with emphasis on the genesis of the ‘argillic horizon’. Catena 5, 33–51. Bronger, A., 1991. Argillic horizons in modern loess soils in an ustic soil moisture regime? Comparative studies in forest–steppe and steppe areas from Eastern Europe and the USA. Dev. Soil Sci. 15, 41–90. Bullock, P., Thompson, M.L., 1985. Micromorphology of alfisols. In: Douglas, L.A., Thompson, M.L. ŽEds.., Soil Micromorphology and Soil Classification. SSSA Spec. Publ. 15, pp. 17–48. Bullock, P., Fedoroff, N., Jongerius, A., Stoops, G., Tursina, T.V., 1985. Handbook for Soil Thin Section Description. Waine Research Publications, Wolverhampton, 152 pp. Buurman, P., van Lagen, B., en Velthorst, E.J., 1996. Manual for Soil and Water Analysis. Backhuys Publishers Leiden, The Netherlands, 314 pp. Canadian System of Soil Classification, 1978. Canadian Soil Survey Committee, Subcommission on Soil Classification. Can. Dep. Agric. Publ. 1646, Supply and Services Canada, Ottawa, 164 pp. Chendev, Y.G., 1994. Natural and anthropogenic evolution of soils in the central forest–steppe: factors and trends ŽBelgorod region.. Abstract Doctoral Thesis, Moscow State University, 25 pp. Chichagova, O.A., Cherkinskiy, A.E., 1988. Radiocarbon Investigations in Geography. Printing House ‘Nauka’, Moscow, 79 pp. Dasog, G.S., Mermut, A.R., Acton, D.F., 1987. Micromorphology and submicroscopy of illuviated mineral particles in boreal clay soils of Saskatchewan. Geoderma 40, 193–208. Dokuchaev, V.V., 1883. Russian Chernozem. In: Collection of Scientific Papers, 1949, Vol. 3. Moscow, 538 pp. Dolgova, L.S., Gerasimova, M.I., Badenko, S.V., Goryacheva, E.S., Dianova, T.M., Titelman, I.Z., 1979. The soils with two humus horizons in the Moscow region. In: Methodology and Methods in Soil and Landscape–Geochemic Investigation. Moscow State University, pp. 3–16. Dubrovina, I.V., Kulinskaya, E.V., 1989. On microstructure and genesis of Gray Forest soils of Vladimir opol’ie. Bulletin of Docuchaev Soil Institute 51, 56–57. FAO–Unesco, 1988. Soil map of the world, revised legend. World Soil Resources Report 60, FAO, Rome, 140 pp. Fitzpatrick, E.A., 1970. A technique for the preparation of large thin sections of soils and unconsolidated materials. In: Osmondn, D.A., Bullock, P. ŽEds.., Micromorphological Techniques and Applications. Soil Survey of England and Wales, Rothamsted Experimental Station, Harpenden, UK. Technical monograph 2, 3–13. Fenton, T.E., 1983. Mollisols. In: Wilding, L.P., Smeck, N.E., Hall, G.F. ŽEds.., Pedogenesis and Soil Taxonomy. II. The Soil Orders. Elsevier, Amsterdam, pp. 125–163. Foss, J.E., Rust, R.H., 1962. Soil development in relation to loessial deposition in Southeastern Minnesota. Soil Sci. Soc. Am. J. 26, 270–274. Gerasimova, M.I., Gubin, S.V., Shoba, S.A., 1992. Micromorphological Features of the USSR. Zonal Soils. Pushchino, 215 pp. Gerasimova, M.I., Gubin, S.V., Shoba, S.A., 1996. In: Miedema, R. ŽEd.., Soils of Russia and Adjacent Countries: Geography and Micromorphology. Van Gils, Wageningen, The Netherlands, 204 pp. Goldin, A., Nettleton, W.D., Engel, R.J., 1992. Pedogenesis in outwash and glacial marine drift, Northwestern Washington. Soil Sci. Soc. Am. J. 56, 1545–1552. Gradusov, B.P., Urusevskaya, I.S., Shoba, S.A., 1981. Micromorphological properties and cay mineralogy of Gray Forest soils of the Russian plain. Vestnik Moscow State University, Biology series 2, pp. 16–28. Havinga, A.J., 1990. Eine palynologische Untersuchung zur holozane ¨ Vegetationsabfolge im Tschernosemge¨ bied Ostosterreichs. Verh. Zool.-Bot. Ges. Osterreich 127, 83–94. ¨ Howitt, R.W., Pawluk, S., 1985a. The genesis of a Gray Luvisol within the Boreal Forest region: I. Static pedology. Can. J. Soil Sci. 65, 1–8.

346

R. Miedema et al.r Catena 34 (1999) 315–347

Howitt, R.W., Pawluk, S., 1985b. The genesis of a Gray Luvisol within the Boreal Forest region: II. Dynamic pedology. Can. J. Soil Sci. 65, 9–19. Karavaeva, N.A., Cherkinskiy, A.E., Goryachkin, S.V., 1986. Second Humus Horizon: An Approach to Genetic–Evolutional Systematization. Advances in Soil Science, Moscow, pp. 167–173. Khotinskiy, N.A., 1986. Interaction of forest and steppe according to a paleogeographical study of the Holocene. In: Evolution and Age of Soils of the USSR. Pushchino, pp. 46–53. Langohr, R., Sanders, J., 1985. The Belgian loess belt in the last 20,000 years: evolution of soils and relief in the Zonien forest. In: Boardman, J. ŽEd.., Soils and Quaternary Landscape Evolution. John, Chichester, UK, 359–372. Lebedeva, I.I., 1969. Nature of the illuvial horizon of Light Grey Forest soils and moraine loams. Sov. Soil Sci. 6, 10–19. Makeev, A.O., Dubrovina, I.V., 1989. Geography and morphology of the second humus horizon and soil cover evolution in Vladimir opol’e. In: Anthropogenic and Natural Evolution of Soils and the Soil Cover. Pushchino, pp. 209–211. Makeev, A.O., Yakusheva, T.E., 1996. Buried soil horizons in the profile of surface soils of the Russian plain. InquarISSS Paleopedology Commission Newsletter No. 12 ŽMay., 21. McClelland, J.E., Mogen, C.A., Johnson, C.A., Schroer, F.W., Allen, J.S., 1959. Chernozems and associated soils of eastern North Dakota: some properties and topographic relationships. Soil Sci. Soc. Am. J. 23, 51–56. Mc Keague, J.A., 1983. Clay skins and argillic horizons. In: Bullock, P., Murphy, C.P. ŽEds.., Soil Micromorphology, Vol. I. AB Academic Publishers, Berkhamsted, UK, pp. 367–388. Miedema, R., 1992. Processus de formation des sols tardi-glaciaires et holocenessur les terrasses alluviales du ` Rhin aux Pays Bas. Science du Sol 30, 149–168. Miedema, R., Slager, S., 1972. Micromorphological quantification of clay illuviation. J. Soil Sci. 23, 309–315. Milkov, F.N., 1950. Forest–Steppe of Russian Plain. Moscow, 180 pp. Mogen, C.A., McClelland, J.E., Allen, J.S., Schroer, F.W., 1959. Chestnut, Chernozem and associated soils of western North Dakota. Soil Sci. Soc. Am. J. 23, 56–60. Morozova, T.D., 1992. Age of relic signs in forest–steppe soils. Soil Genesis, Geography and Evolution. Publishing House ‘Nauka’, Moscow, pp. 153–164. Nettleton, W.D., Brasher, B.R., Baumer, O.W., Darmody, R.G., 1994. Silt flow in soils. Dev. Soil Sci. 22, 361–373. Nygard, I.J., McMiller, P.R., Hole, F.D., 1952. Characteristics of some Podzolic, Brown Forest and Chernozem soils of the northern portion of the Lake States. Soil Sci. Soc. Am. J. 16, 123–129. Parfenova, Y.I., Mochalova, E.F., Titova, N.A., 1964. Micromorphology and chemism of humus–clay new formations in Grey Forest soils. In: Jongerius, A. ŽEd.., Soil Micromorphology, Elsevier, Amsterdam, pp. 201–212. Pawluk, S., Bal, L., 1985. Micromorphology of selected mollic horizons. In: Douglas, L.A., Thompson, M.L. ŽEds.., Soil Micromorphology and Soil Classification. SSSA Spec. Publ. no. 15, 63–83. Pettapiece, W.W., 1969. The forest–grassland transition. In: Pawluk, S. ŽEd.., Pedology and Quaternary research. Symposium, University of Alberta, Edmonton, Canada, 103–113. Ponomareva, V.V., 1972. Water–soil characteristic of some vegetation types. Ecologiya 6, 35–47. Radeke, R.E., Westin, F.C., 1963. Gray Wooded soils of the Black Hills of South Dakota. Soil Sci. Soc. Am. J. 27, 573–576. Redmond, C.E., Omodt, H.D., 1967. Some till derived Chernozem soils in eastern North Dakota. Parts I and II. Soil Sci. Soc. Am. J. 31, 89–107. Rogaar, H., Lothhammer, H., van der Plas, L., Jongmans, A.G., Bor, J., 1993. Phaeozem and Luvisol development in relation to relief and climate in Southwest Rheinhessen, Germany. Mainzer Geowiss. Mitt. 22, 227–246. Rohdenburg, H., Meyer, B., 1968. Zur Datierung und Bodengeschichte mitteleuropaischer oberflachenboden ¨ ¨ ŽSchwarzerde, Parabraunerde, Kalksteinbraunlehm.: Spatglazial oder Holozan?. Gottinger Bodenkundl. ¨ ¨ ¨ Ber. 6, 127–212. Rust, R.H., 1983. Alfisols. In: Wilding, L.P., Smeck, N.E., Hall, G.F. ŽEds.., Pedogenesis and Soil Taxonomy: II. The Soil Orders. Elsevier, Amsterdam, pp. 253–281.

R. Miedema et al.r Catena 34 (1999) 315–347

347

Santos, M.C.D., Mermut, A.R., Anderson, D.W., St. Arnaud, R.J., 1985. Micromorphology of three Gray Luvisols in East-Central Saskatchewan. Can. J. Soil Sci. 65, 717–726. Severson, R.C., Arneman, H.F., 1973. Soil characteristics of the forest–prairie ecotone in Northwestern Minnesota. Soil Sci. Soc. Am. J. 26, 270–274. Sillanpaa, M., Webber, L.R., 1961. The effect of freezing–thawing and wetting–drying cycles on soil aggregation. Can. J. Soil Sci. 41, 182–187. Slager, S., Jongmans, A.G., Miedema, R., Pons, L.J., 1976. Fossil and recent soil formation in Late Pleistocene loess deposits in the southern part of the Netherlands. Neth. J. Agric. Sci. 26, 326–335. Soil Taxonomy, 1994. Keys to Soil Taxonomy Soil Conservation Service, 6th edn. USDA, 306 pp. Sokolov, V.V., 1996. Pedogenetic paradoxes of the Russian Plain and micromorphological arguments for their solution. Xth International working Meeting on Soil Micromorphology, Moscow. Abstractbook, p. St. Arnaud, R.J., Whiteside, E.P., 1964. Morphology and genesis of a Chernozemic to Podzolic sequence of soil profiles in Saskatchewan. Can. J. Soil Sci. 44, 88–99. Surmach, G.P., 1987. On plant formation and grey forest soils pattern in the forest–steppe as related to loessic sediments heterogeneity. Pochvovedenie 1, 7–16. Targulian, V.O., Birina, A.G., Kulikov, A.V., Sokolova, T.A., Tselischeva, L.K., 1974. Arrangement, composition and genesis of sod–pale podzolic soil derived from mantle loess. Morphological investigations. Xth Int. Congr. Soil Sci., Moscow, 47 pp. Van Vliet-Lanoe, ¨ 1985. Forest effects in soils. In: Boardman, J. ŽEd.., Soil and Quaternary Landscape Evolution. John, Chichester, UK, pp. 117–158. Van Vliet-Lanoe, ¨ 1990. The genesis and age of the argillic horizon in Weichselian loess in northwestern Europe. Quaternary International 5, 49–56. Velichko, A.A., Morozova, T.D., 1989. Holocene landscape-climatic changes and evolution of forest–steppe soils. Paleoclimates of the Late Glacial Period and the Holocene. Publishing House ‘Nauka’, Moscow, pp. 57–61. Velichko, A.A., Morozova, T.D., Nechaev, V.P., Porozhnyakova, O.M., 1996. Paleocryogenesis, Soil Cover and Agriculture. ‘Nauka’, Moscow, 150 pp. Walker, P.H., 1966. Postglacial environments in relation to landscape and soils on the Cary drift, Iowa. Iowa State University Res. Bulletin 549, 840–875. Weir, A.H., Catt, J.A., Madgett, P.A., 1971. Postglacial soil formation in the loess of Pegwell Bay, Kent ŽEngland.. Geoderma 5, 131–149. White, E.M., Riecken, F.F., 1955. Brunizem-Gray Brown Podzolic soil biosequences. Soil Sci. Soc. Am. J. 19, 504–509. Yakusheva, T.E., Makeev, A.O., 1996. Geography of the Upper Quaternary sediments in the center of the Russian plain. InquarISSS Paleopedology Commission Newsletter No. 12, 27.