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Buried paleosols in balks of Kalmykiya as a record of late Holocene nature and society interaction
Quaternary International 106–107 (2003) 103–109
Buried paleosols in balks of Kalmykiya as a record of late Holocene nature and society interaction Alexandra A. Golyevaa,*, Olga A. Chichagovaa, Yevgeny V. Tsutskinb a
Institute of Geography, Russian Academy of Science, RAN, Staramonetniy Per.29, Moscow 109017, Russia b Kalmykia Institute for Socioeconomic and Legal Studies RAS, Elista 358005, Russia
Abstract Modern and buried soils under valley sediments have been compared on the Southern Russian Plain (Kalmykiya) in the arid zone. The buried soil contains more humus and less carbonates, and pH values are lower. The humus content in this soil is comparable with that of modern Haplic Kastanozems and Gleyic Phaeozems. The comparison of differences in properties of buried soil at specific times and historical data on cultures’ functioning in these periods has allowed us to reveal the interrelation of nature and society processes development in South Kalmykia since the middle Holocene. Three stages of landscape development are recognized: (1) stable stage, at least 3000 years long (from the 2nd millennium BC until the 1st millennium AD), characterized by the formation of meadow-steppe soils; (2) dynamic stage, likely short, when deposits were accumulated, and soils were buried; and (3) modern stable stage, at least 500 years long (up to the present time), characterized by the formation of meadow-saline soils (Molli-Endogleyic Solonetz) on deposits in valleys. A strong ecological crisis was evident in the territory of modern Kalmykia about 1000 years ago, resulting from the collapse of the Khazar state. As a result, meadow-steppe soils were buried, and Saline Molli-Endogleyic soils were formed. r 2003 Elsevier Science Ltd and INQUA. All rights reserved.
1. Introduction The main aim of our research was to reconstruct the stages of nature and society interaction within the second half of the Holocene in southern Russia. The southern territories of Russia were studied by many scientists (Ivanov, 1984; Demkin et al., 1998; Spiridonova and Aleshinskaya, 1999, and others), and climatic reconstructions for the second half of the Holocene were made. For instance, Gennadiev and Puzanova (1991) pointed out that for the last 2500 years the climatic conditions were stable and comparable with the modern ones. Kiseleva (1976) made similar conclusions. Varushchenko et al. (1987) distinguished the periods at about 3000 years ago and from the 8th to 14th century AD as most favorable, i.e., less hot and more humid. Most researchers made reconstructions on the basis of studying soils under burial mounds within watershed areas. However, they did not consider possible human-induced transformations of soils. A conclusion about the environmental conditions and the *Corresponding author. E-mail address: [email protected] (A.A. Golyeva).
interaction between nature and the human society can be made mainly on the basis of analyzing natural objects without traces of human impact, for example, soils in different valleys. We share the opinion of Alexandrovskii (1996) that watershed soils allow us to reconstruct only major periods in soil and landscape evolution. Analysis of the buried soil cover in valleys is more informative: these soils make it possible to reconstruct short-term landscape events (Sycheva, 1999). Terhorst (2000), studying buried soils in southern Germany, noticed that ancient Chernozems were buried due to agriculture erosion about 5000 BP and thus preserved evidence for the degradation process. So, by studying buried soils in valleys, we may not only reconstruct ancient soils and the environmental conditions, but also the nature of the mineral deposits— natural or man-made. Such soils in Russia were studied in the central Russian Upland (Sycheva and Chichagova, 1999; Alexandrovskii, 1996). They explained the formation of colluvial deposits as a result of climate change and the cutoff of forests in the Middle Ages. However, people have lived on the Russian Plain for thousands of years. Nikolaev (1997) stated that from the
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A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
middle of the 1st millennium BP the pasture-induced degradation and deflation of soils resulted in a complete destruction of landscapes, especially the dry steppe. Similar conclusions about an intensive anthropogenic pressure on soils in the south of Russia within a period of no less than 2–3 thousand years were made by Kiseleva (1976) and Dinesman (1976). Thus, we agree with the opinion of Rosen (1995) about the combined impact of climatic and social factors on the landscapes.
2. Study area The study area is located in Kalmykia, in the south of the Russian Plain, 1500 km south of Moscow (451410 N, 441320 E), in the arid zone (Fig. 1). Modern climatic conditions are dry and warm. Mean annual precipitation is 350 mm, and mean annual temperature is 11.11C. We observed modern Molli-Endogleyic Solonetz and buried soils. These are 0.8–1.0 m below the land surface on valley bottoms and appear as Chernozem-like soils, which have not previously been reported in this region. We studied two buried soils in balks (wide flat-bottom valleys) in the dry steppe. The Mu-Scharet Valley, a dry wide valley typical of this area, was studied in detail. It has an average width of approximately 200 m and a
maximum depth of 15 m. It contains saline soil in colluvial deposits overlying Meadow–Chernozems. Archaeological objects (large scraps of Bronze Age ceramics) were found in buried soil in another valley, the Mandzhikiny balk. However, no traces of human impact were observed in the other soil in the Mu-Scharet balk. Both buried soils had dark and thick humus horizons in contrast to modern soils. Humus of both buried and modern soils was analyzed. People lived in this area since the Neolithic Age. During the Bronze Age (the 4th–3rd millennium BC), Jama and Katakomba cultures alternated. In the II millennium BC, it was Skifian and Sarmats territory. The Khazar state existed there from the 6th to 10th century AD and was destroyed by Russian prince Svyatoslav in 973–1048 AD (Artamonov, 1962). Then, this area was occupied by guzes, who kept numerous sheep flocks. Tatar–Mongolian nomads lived there in the 13–15th centuries. Kalmyks have inhabited this territory since 1657 (History of Kalmyks, 1967).
3. Methods The present research is based on 14C dating of soil humus, soil properties, and history of the region. About
Fig. 1. Study area.
A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
3 kg soil samples from each layer were analyzed for radiocarbon data at the Institute of Geography, Russian Academy of Sciences. Humic acids from soils were extracted by the pyrophasphate method (Chichagova and Cherkinskiy, 1993). The 14C age of humic acids was obtained, using liquid scintillation counting. The radiocarbon data were calibrated using the program CAL 20 (Van der Plicht, 1993). Chemical and biomorphic analyses also were done. Colors were determined by comparison with the Munsell Soil Color Chart. Laboratory research included evaluation of pH in water, organic carbon (by oxidation with dichromate), particle size analysis by the pipette method and the content of CaCO3. For biomorph analysis (Golyeva, 2001), specimens of phytoliths and diatoms were removed from 50-g samples of morphologic horizons and mineral deposits. Light soil fractions, including the biogenic fractions, were separated from bulk soil samples and treated with 30% H2O2 to remove organic matter. The clay fraction was removed and the rest of the specimen was filled with CdJ2+KJ (specific gravity 2.3 g/cm3). After a 10-min centrifugation, the fraction concentrated in the upper part of the tube was washed with distilled water. A drop (0.5 ml) of each specimen was examined using an optical microscope at 250–300 magnifications. Phytoliths and diatoms were counted and the percentage of the main groups was calculated. The scanning electron microscope (AMRAY 1830 I) was used to see some details of phytoliths and
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diatoms. Analyses of phytoliths are included in paleoenvironmental research as an effective technique for historical reconstruction of the landscape (Rovner, 1988).
4. Results The buried soil in the Balk Mu-Scharet differs considerably from the modern soil. This soil ranges from dark grayish brown to very dark grayish brown to dark brown, and is practically decalcified. On the valley floors the displaced materials form several colluvial layers, which can be distinguished by texture, color and carbonate content. They mostly cover soils on the valley bottom and preserve decalcified Meadow-steppe Chernozem-like soil. The color of layers is grayish brown and dark grayish brown. The upper sediment is greatly mixed and has no clear boundaries with the modern soil. Buried soil contains more humus and less carbonates, and pH values are lower in comparison with the modern soil (Table 1). The humus content is greater in the upper buried horizons than in the overlying colluvium. Particle size analyses of the upper horizons of buried soil indicate a clay content of 18–20% and increase with depth to 38%. The lower brown colluvial layer (M1) has a clay content of almost 15–16%, with sand particles at 30–33%. The second brown unit (M2) has more clay (22–24%) and less sand (20–22%) particles. Clay
Table 1 Balk Mu-Scharet. Selected properties of modern and buried soils Horizon
Depth (cm)
Colour (dry) Munsell
Sand 0.05–2.0 mm (%)
Silt 0.001–0.05 mm (%)
Clay o0.001 mm (%)
CaCO3 (%)
pH, H2O
C (%)
Ag
0–3
10YR 4/3
4.0
74.7
21.3
0.09
8.65
1.60
AB
6–13
10YR 3/2
5.7
64.2
30.1
0.27
8.85
2.65
M3
17–23 30–35 40–45 50–55 60–65 70–75 80–85
10YR 10YR 10YR 10YR 10YR 10YR 10YR
16.4 13.2 20.9 22.4 22.6 32.9 30.6
59.5 57.9 56.2 55.6 53.1 50.3 46.8
24.1 28.9 22.9 22.0 24.3 16.8 14.6
1.26 1.86 1.95 1.88 2.04 1.98 2.24
8.05 8.85 8.60 8.75 8.35 8.75 8.30
0.93 0.83 0.62 0.65 0.67 0.40 0.36
II Ag
91–95
10YR 4/2
21.7
59.7
18.6
0.03
7.85
1.16
II A
95–102 102–109
10YR 3/2 10YR 3/3
21.1 24.5
59.0 57.7
19.9 17.8
0.03 0.01
7.70 7.70
1.34 1.34
II AB
109–118
10YR 4/3
22.6
59.3
18.1
0.01
7.80
1.10
II B
120–125 125–130 130–135 135–140
10YR 10YR 10YR 10YR
23.1
52.2
24.7
45.0 43.7
37.9 38.5
7.85 7.60 7.40 7.50
0.48
17.1 17.8
0.00 0.02 0.05 0.07
M2
M1
4/2 5/2 5/3 5/2.5 5/3 5/3 5/3
4/3 4.5/2 4/2 3.5/3
M3–M1=Late Holocene colluvial layers.
0.51
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content increases but carbonate content decreases in the upper part of colluvial material (M3). The dates on buried soils from two valleys (Mu-Scharet and Mandzhikiny) are shown in Table 2. The age of humic acids from the buried soil in Mu-Scharet valley increases with depth from ca. 1000 years BP to 4000 years BP. The upper horizon of modern soil contains many diatoms (Table 3). All of them are intact, indicating in situ deposition (Fig. 2(1)). High diatom content is typical for a Molli-Endogleyic Solonetz. In the upper horizon of the buried soil there are single diatoms as well. All of these are broken in different parts (Fig. 2(2)), indicating perhaps that they were transported by wind. There are single sponge spicules throughout the profile. They are especially regular in the buried soil (Table 3). All of those spicules are strongly corroded. The content of phytoliths differs from modern and buried soils and mineral deposits (Table 3). Minimum phytolith concentrations are found in the samples from mineral deposits. The modern soil has significantly less phytoliths than the buried soil, indicating that modern
assemblages are not so rich in species (especially cereals) and total volume as in the past. The upper horizon of buried soil contains a number of different phytoliths, including steppe grasses and herbs, indicating fertile meadow-steppe soils. The upper layer of this soil has fewer phytoliths than the lower one, and has more phytoliths from xerophytic plants (Fig. 2(3)). Samples from 100–105 to 110–115 cm have maximum numbers of phytoliths, and their amounts decrease with depth. The qualitative phytolith distribution shows similar differences within the profile.
5. Discussion The age of humic acids from the buried soil in MuScharet valley shows that stable conditions of soil formation without any mineral deposits and burial processes prevailed in the area over several thousand years. This soil was buried under saline mineral material only about 1000 years ago. Differences between the age of buried soil in the Mandzhikiny balk and the age of
Table 2 14 C ages, equivalent calibrated ages and approximate archaeological ages for soils from South Kalmykia 14
Soil level, depth, (cm)
C date (yr BP)
Calibrated date (yr BP)
Age intervals (cal BP71s)
Lab. code
Archaeological age
Balk Mu-Scharet (arid zone, dry steppe) 6–14 340790 91–95 1070740 95–100 1260740 102–109 1430750 109–118 2430770 120–125 33307100 125–130 3410780 130–135 3645770 135–140 38607120
323, 381, 430 961 1174 1309 2369, 2399, 2428 3562 3635, 3677, 3680 3928, 3955, 3964 4264
293–501 936–984 1160–1262 1290–1346 2349–2711 3461–3687 3562–3810 3857–4080 4087–418
IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN
No archaeological material
Balk Mandzhikini (arid zone, dry steppe) 55–75 23307160
2342
2143–2708
IGRAN 2022
2000 2104 2107 2005 2004 2003 2108 2109 2001
Ceramics approx. 3000–4000 yr BP
Table 3 Contents of silica biomorphs (units) and distribution forms of phytolith (%) Depth (cm)
Diatoms
Spiculas
Phytoliths
1
2
0–3 6–13 17–23 30–35 91–96 100–105 105–115 115–125 125–135 135–145 145–155
12
1
1 1 2* 1*
56 53 64 100 54 66 69 44 31 50 50
31 36 18
1 1
32 53 11 1 95 154 150 32 13 6 2
21 14 12 9 — 17 —
1*
3
4
5
3 9 9
10 2 9
— — —
11 9 15 38 38 17 50
15 11 3 6 31 16 —
— — 1 3 — — —
Note. *—corroded forms; Numbers refer to different groups of plants according phytolith forms: 1—herbs; 2—meadow cereals; 3—steppe cereals; 4—dry- steppe (xeromorphic) grasses; 5—other forms (unknown and not specific).
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Fig. 2. Different forms of silica biomorphs: (1) Diatom from the upper horizon of modern soil; (2) part of the diatom from the upper horizon of buried soil; (3) phytolith from xerophyte plant; (4) phytolith from Stipa.
ceramics (approximately 3–4 thousand years BP) from this soil can be connected with one of two reasons: (1) The buried soil is located at a relatively small depth (50 cm) and is penetrated by roots of modern arid vegetation. Therefore, the rejuvenation of humus is possible; or (2) During the stable period (without erosion processes), ceramics could stay on the soil surface for a long time and become buried considerably later. In this case, the age of soil coincides with the
beginning of the dynamic stage (soil burying), and the difference between the ages of ceramics and soil is the duration of the stable stage of development. Taking into consideration the data on buried soil from the Mu-Scharet balk, we believe that the latter suggestion is most probable. The strong corrosion of spicules shows their ancient age and relic genesis. In the upper part of the profile, single spicules may have been removed with the other
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mineral material as a part of deposit. They are not as corroded, and therefore are not as old. The differences between colluvial layers indicate erosion from different places and/or at different times. Low concentrations of phytoliths in the samples from mineral deposits means that material was transported material from places without plants, or represents the lowest (mineral) parts of soil horizons, where organic material is absent. The common phytolith distribution (total mass) is not typical for soils, as it increases with depth and shows the maximum amount in the second layer from the surfaces in both cases. For the modern soil, it absolutely coincides with intensive pasturing during the last hundred years (History of Kalmyks, 1967). Under the impact of pasturing, the original vegetation was substituted by more xerophytic (drought-resistant) grasses, and the total number of species decreased. The quantitative and qualitative phytolith distribution confirms this fact. The humus content, which increases down the profile, and the change in colors suggest polygenesis of the buried soil. The buried soil is comparable with modern meadow–steppe soil, but not with the molli-endogleyic soil which is now on the surface. The phytolith profile from 100–105 to 110–115 cm is typical for meadow–steppe Chernozem-like soils, indicating that herbs and steppe cereals (for example, different Stipas (Fig. 2(4)) grew on this soil in the past.
The differences of phytolith qualitative distribution might represent the factors of climate change during the time of soil development. It is possible to suppose that at the first stages the conditions were more humid, followed by a short period suitable for xerophyte plants. This age coincides with the nomads of the Katakomba culture, the period of the highest population in history of this area (Artamonov, 1962). After that, there was a long period with the typical meadow-steppe grasses on the surface of the soil until the time of the Khazar State’s development. Phytolith distribution and broken diatoms in the upper layer of buried soil may be a result of several factors: intensive grazing and the beginning of deposit accumulation. Thus, this sample has fewer phytoliths with the predominance of arid flora and diatom fragments. On the basis of comparing the results of our study of buried soils in gullies with archaeological data (Table 4), it can be assumed that deposit accumulation and soil burial were induced by certain historical events. These events are the downfall of the Khazar state (from 973 to 1048 years AD) and the subsequent invasion of guze tribes. Guzes came with large flocks of sheep. Sheep husbandry is more dangerous from an ecological point of view than cattle or horse breeding (Armand et al., 1999). As a result of their extensive pasture, the grass cover was trampled down, and desertification developed. The probability of destructive erosion processes
Table 4 History of the area and landscape development during the second half of Holocene (Balk Mu-Scharet) 14
C cal. yrs ADa, BCb (71s)
Development of the vegetation
History of the area, human impact
Landscape development
0–3
—
Degradation vegetation
Modern pasture
Molli-Endogleyic Solonetz,
6–13
1499–1657a
Meadow-solonetz plants
1657 yrAD—Kalmyk’s occupation
Stable conditions
Depth, (cm)
17–35
—
35–70 70–91
Different Mineral deposits Dynamic conditions —
—
Sparse, degradation vegetation
973–1048 yrs AD—Khazars routed, guzes tribe occupation.
91–95
966–1014a
95–102 102–109 109–118 120–125
688–790a 604–660a 399–761b 1511–1737b
Meadow-steppe
Khazar State Khazar State forming Sarmats Scyths
125–130
1612–1860b
Dry steppe
Katacomba tribe
130–135
1907–2130b
Steppe
Katacomba and Jama tribes
135–140
2137–2468b
Meadow-steppe Chernozemlike soil, Stable conditions over 3000 years
A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
occurring greatly increased. Strong winds usual in this area caused intensive wind erosion. Considerable amounts of fine mineral material were transported and accumulated in gullies.
6. Conclusion Three stages of landscape development are recognized: (1) stable stage, at least 3000 years long (from the 2nd millennium BC until the 1st millennium AD), characterized by the formation of meadow-steppe soils; (2) dynamic stage, likely short, when deposits were accumulated, and soils were buried; and (3) modern stable stage, at least 500 years long (up to the present time), characterized by the formation of meadow-saline soils (Molli-Endogleyic Solonetz) on deposits in gullies. A strong ecological crisis was evident in the territory of modern Kalmykia about 1000 years ago. The main reason was the collapse of the Khazar state. The result was the burying of fertile meadow-steppe soils and formation of saline molli-endogleyic soils. Probably, the vegetation was sparse, reflecting degradation by grazing just before burial. The data obtained do not contradict the naturalclimatic reconstructions of the region. They illustrate the significance of the anthropogenic factor for the formation of soils and landscapes in the south of Russia within the last thousands of years. Different climate changing during thousands of years were not very intensive at this area and could not change the global soil development from meadow-steppe Chernozem-like soil. However, after the human impact (intensive pasture by sheep), absolutely new soils began forming. This means that the human impact is a stronger factor than climate change in soil evolution in the second half of the Holocene in South Russia.
Acknowledgements The work was supported by the Russian Foundation for Basic Research (grants NN 01-05-64403 and 01-0680242). We thank Dr. S.N. Sedov for critically reviewing and improving the first version of the manuscript.
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References Alexandrovskii, A.L., 1996. Natural environment as seen in soil. Pochvovedenie 3, 277–287. Armand, A.D., Luri, D.J., Zherikhin, V.V., Rautian, A.C., 1999. Anatomy of crises. Moscow. Nauka, 238 p. Artamonov, M.I. 1962. History of khazar. Leningrad, Ermitazha (Hermitage Museum), 524p. Chichagova, O.A., Cherkinskiy, A.E., 1993. Problems in radiocarbon dating of soils. Radiocarbon 35 (3), 351–362. Demkin, V.A., Dergacheva, M.I., Borisov, A.V., Ryskov, Ya.G., Oleinik, S.A., 1998. Soil evolution and climate change in the semidesert zone of eastern Europe during the late Holocene. Pochvovedenie 2, 148–157. Dinesman, L.G., 1976. The History of Biogeocenoses of the Russian Plain in the Holocene. In: The History of Biogeocenoses of the USSR in the Holocene, Moscow, Nauka, 122–132. Gennadiev, A.N., Puzanova, T.A., 1991. The Holocene evolution of soil cover in the western part of Caspian lowland. Pochvovedenie. 2, 5–15. Golyeva, A.A., 2001. Biomorphic analysis as a part of soil morphological investigations. Catena 43, 217–230. Ivanov, I.V., 1984. Soil and Environmental Change within the Steppe Zone of the USSR in the Holocene. Moscow, Nauka, 26p. History of Kalmyks (period before the October Revolution)., 1967. Moscow, Nauka, 193p. Kiseleva, N.K., 1976. Biogeocenoses in the North of the Caspian Area in the Holocene. In: The History of Biogeocenoses of the USSR in the Holocene. Moscow, Nauka, 244–260. Nikolaev, V.A., 1997. Socio-natural history of Asian steppes (from Ural to Altai). Aridnie ecosistemi 3 (6–7), 84–92. Rosen, A.M., 1995. The social response to environmental change in early Bronze age Canaan. Journal of Anthropological Archaeology, 14, 26–44. Rovner, I., 1988. Macro-and micro- ecological reconstruction using plant opal phytolith data from archaeological sediments. Geoarchaeology 3, 155–163. Spiridonova, E.A., Aleshinskaya, A.C., 1999. Periodization of the neolith-eneolith of the European Russia on the basis of palinological data. Russian Archaeology 1, 23–34. Sycheva, S.A., 1999. Cycles of soil formation and sediment accumulation in the Holocene (according to 14C data). Eurasian Soil Science 6, 688–696. Sycheva, S.A., Chichagova, O.A., 1999. Cyclic rhythms of soil formation in the central Russian upland in the Holocene. Eurasian Soil Science 8, 963–979. Terhorst, B., 2000. The influence of Pleistocene landforms on soilforming processes and soil distribution in a loess landscape of Baden-W.urttemberg (South-West Germany). Catena 41, 165–179. Van der Plicht, J., 1993. The Groningen radiocarbon calibration program. In: Stuiver, M., Long, A., Kra, R.S. (Eds)., Calibration 1993, Radiocarbon 35 (1), 231–237. Varushchenko, S.I., Varushenko, A.N., Klige, R.K., 1987. Changes in the Regimes of the Caspian Sea and Closed Water Reservoirs in Paleotime. Moscow, Nauka, 240p.
Buried paleosols in balks of Kalmykiya as a record of late Holocene nature and society interaction Alexandra A. Golyevaa,*, Olga A. Chichagovaa, Yevgeny V. Tsutskinb a
Institute of Geography, Russian Academy of Science, RAN, Staramonetniy Per.29, Moscow 109017, Russia b Kalmykia Institute for Socioeconomic and Legal Studies RAS, Elista 358005, Russia
Abstract Modern and buried soils under valley sediments have been compared on the Southern Russian Plain (Kalmykiya) in the arid zone. The buried soil contains more humus and less carbonates, and pH values are lower. The humus content in this soil is comparable with that of modern Haplic Kastanozems and Gleyic Phaeozems. The comparison of differences in properties of buried soil at specific times and historical data on cultures’ functioning in these periods has allowed us to reveal the interrelation of nature and society processes development in South Kalmykia since the middle Holocene. Three stages of landscape development are recognized: (1) stable stage, at least 3000 years long (from the 2nd millennium BC until the 1st millennium AD), characterized by the formation of meadow-steppe soils; (2) dynamic stage, likely short, when deposits were accumulated, and soils were buried; and (3) modern stable stage, at least 500 years long (up to the present time), characterized by the formation of meadow-saline soils (Molli-Endogleyic Solonetz) on deposits in valleys. A strong ecological crisis was evident in the territory of modern Kalmykia about 1000 years ago, resulting from the collapse of the Khazar state. As a result, meadow-steppe soils were buried, and Saline Molli-Endogleyic soils were formed. r 2003 Elsevier Science Ltd and INQUA. All rights reserved.
1. Introduction The main aim of our research was to reconstruct the stages of nature and society interaction within the second half of the Holocene in southern Russia. The southern territories of Russia were studied by many scientists (Ivanov, 1984; Demkin et al., 1998; Spiridonova and Aleshinskaya, 1999, and others), and climatic reconstructions for the second half of the Holocene were made. For instance, Gennadiev and Puzanova (1991) pointed out that for the last 2500 years the climatic conditions were stable and comparable with the modern ones. Kiseleva (1976) made similar conclusions. Varushchenko et al. (1987) distinguished the periods at about 3000 years ago and from the 8th to 14th century AD as most favorable, i.e., less hot and more humid. Most researchers made reconstructions on the basis of studying soils under burial mounds within watershed areas. However, they did not consider possible human-induced transformations of soils. A conclusion about the environmental conditions and the *Corresponding author. E-mail address: [email protected] (A.A. Golyeva).
interaction between nature and the human society can be made mainly on the basis of analyzing natural objects without traces of human impact, for example, soils in different valleys. We share the opinion of Alexandrovskii (1996) that watershed soils allow us to reconstruct only major periods in soil and landscape evolution. Analysis of the buried soil cover in valleys is more informative: these soils make it possible to reconstruct short-term landscape events (Sycheva, 1999). Terhorst (2000), studying buried soils in southern Germany, noticed that ancient Chernozems were buried due to agriculture erosion about 5000 BP and thus preserved evidence for the degradation process. So, by studying buried soils in valleys, we may not only reconstruct ancient soils and the environmental conditions, but also the nature of the mineral deposits— natural or man-made. Such soils in Russia were studied in the central Russian Upland (Sycheva and Chichagova, 1999; Alexandrovskii, 1996). They explained the formation of colluvial deposits as a result of climate change and the cutoff of forests in the Middle Ages. However, people have lived on the Russian Plain for thousands of years. Nikolaev (1997) stated that from the
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A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
middle of the 1st millennium BP the pasture-induced degradation and deflation of soils resulted in a complete destruction of landscapes, especially the dry steppe. Similar conclusions about an intensive anthropogenic pressure on soils in the south of Russia within a period of no less than 2–3 thousand years were made by Kiseleva (1976) and Dinesman (1976). Thus, we agree with the opinion of Rosen (1995) about the combined impact of climatic and social factors on the landscapes.
2. Study area The study area is located in Kalmykia, in the south of the Russian Plain, 1500 km south of Moscow (451410 N, 441320 E), in the arid zone (Fig. 1). Modern climatic conditions are dry and warm. Mean annual precipitation is 350 mm, and mean annual temperature is 11.11C. We observed modern Molli-Endogleyic Solonetz and buried soils. These are 0.8–1.0 m below the land surface on valley bottoms and appear as Chernozem-like soils, which have not previously been reported in this region. We studied two buried soils in balks (wide flat-bottom valleys) in the dry steppe. The Mu-Scharet Valley, a dry wide valley typical of this area, was studied in detail. It has an average width of approximately 200 m and a
maximum depth of 15 m. It contains saline soil in colluvial deposits overlying Meadow–Chernozems. Archaeological objects (large scraps of Bronze Age ceramics) were found in buried soil in another valley, the Mandzhikiny balk. However, no traces of human impact were observed in the other soil in the Mu-Scharet balk. Both buried soils had dark and thick humus horizons in contrast to modern soils. Humus of both buried and modern soils was analyzed. People lived in this area since the Neolithic Age. During the Bronze Age (the 4th–3rd millennium BC), Jama and Katakomba cultures alternated. In the II millennium BC, it was Skifian and Sarmats territory. The Khazar state existed there from the 6th to 10th century AD and was destroyed by Russian prince Svyatoslav in 973–1048 AD (Artamonov, 1962). Then, this area was occupied by guzes, who kept numerous sheep flocks. Tatar–Mongolian nomads lived there in the 13–15th centuries. Kalmyks have inhabited this territory since 1657 (History of Kalmyks, 1967).
3. Methods The present research is based on 14C dating of soil humus, soil properties, and history of the region. About
Fig. 1. Study area.
A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
3 kg soil samples from each layer were analyzed for radiocarbon data at the Institute of Geography, Russian Academy of Sciences. Humic acids from soils were extracted by the pyrophasphate method (Chichagova and Cherkinskiy, 1993). The 14C age of humic acids was obtained, using liquid scintillation counting. The radiocarbon data were calibrated using the program CAL 20 (Van der Plicht, 1993). Chemical and biomorphic analyses also were done. Colors were determined by comparison with the Munsell Soil Color Chart. Laboratory research included evaluation of pH in water, organic carbon (by oxidation with dichromate), particle size analysis by the pipette method and the content of CaCO3. For biomorph analysis (Golyeva, 2001), specimens of phytoliths and diatoms were removed from 50-g samples of morphologic horizons and mineral deposits. Light soil fractions, including the biogenic fractions, were separated from bulk soil samples and treated with 30% H2O2 to remove organic matter. The clay fraction was removed and the rest of the specimen was filled with CdJ2+KJ (specific gravity 2.3 g/cm3). After a 10-min centrifugation, the fraction concentrated in the upper part of the tube was washed with distilled water. A drop (0.5 ml) of each specimen was examined using an optical microscope at 250–300 magnifications. Phytoliths and diatoms were counted and the percentage of the main groups was calculated. The scanning electron microscope (AMRAY 1830 I) was used to see some details of phytoliths and
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diatoms. Analyses of phytoliths are included in paleoenvironmental research as an effective technique for historical reconstruction of the landscape (Rovner, 1988).
4. Results The buried soil in the Balk Mu-Scharet differs considerably from the modern soil. This soil ranges from dark grayish brown to very dark grayish brown to dark brown, and is practically decalcified. On the valley floors the displaced materials form several colluvial layers, which can be distinguished by texture, color and carbonate content. They mostly cover soils on the valley bottom and preserve decalcified Meadow-steppe Chernozem-like soil. The color of layers is grayish brown and dark grayish brown. The upper sediment is greatly mixed and has no clear boundaries with the modern soil. Buried soil contains more humus and less carbonates, and pH values are lower in comparison with the modern soil (Table 1). The humus content is greater in the upper buried horizons than in the overlying colluvium. Particle size analyses of the upper horizons of buried soil indicate a clay content of 18–20% and increase with depth to 38%. The lower brown colluvial layer (M1) has a clay content of almost 15–16%, with sand particles at 30–33%. The second brown unit (M2) has more clay (22–24%) and less sand (20–22%) particles. Clay
Table 1 Balk Mu-Scharet. Selected properties of modern and buried soils Horizon
Depth (cm)
Colour (dry) Munsell
Sand 0.05–2.0 mm (%)
Silt 0.001–0.05 mm (%)
Clay o0.001 mm (%)
CaCO3 (%)
pH, H2O
C (%)
Ag
0–3
10YR 4/3
4.0
74.7
21.3
0.09
8.65
1.60
AB
6–13
10YR 3/2
5.7
64.2
30.1
0.27
8.85
2.65
M3
17–23 30–35 40–45 50–55 60–65 70–75 80–85
10YR 10YR 10YR 10YR 10YR 10YR 10YR
16.4 13.2 20.9 22.4 22.6 32.9 30.6
59.5 57.9 56.2 55.6 53.1 50.3 46.8
24.1 28.9 22.9 22.0 24.3 16.8 14.6
1.26 1.86 1.95 1.88 2.04 1.98 2.24
8.05 8.85 8.60 8.75 8.35 8.75 8.30
0.93 0.83 0.62 0.65 0.67 0.40 0.36
II Ag
91–95
10YR 4/2
21.7
59.7
18.6
0.03
7.85
1.16
II A
95–102 102–109
10YR 3/2 10YR 3/3
21.1 24.5
59.0 57.7
19.9 17.8
0.03 0.01
7.70 7.70
1.34 1.34
II AB
109–118
10YR 4/3
22.6
59.3
18.1
0.01
7.80
1.10
II B
120–125 125–130 130–135 135–140
10YR 10YR 10YR 10YR
23.1
52.2
24.7
45.0 43.7
37.9 38.5
7.85 7.60 7.40 7.50
0.48
17.1 17.8
0.00 0.02 0.05 0.07
M2
M1
4/2 5/2 5/3 5/2.5 5/3 5/3 5/3
4/3 4.5/2 4/2 3.5/3
M3–M1=Late Holocene colluvial layers.
0.51
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content increases but carbonate content decreases in the upper part of colluvial material (M3). The dates on buried soils from two valleys (Mu-Scharet and Mandzhikiny) are shown in Table 2. The age of humic acids from the buried soil in Mu-Scharet valley increases with depth from ca. 1000 years BP to 4000 years BP. The upper horizon of modern soil contains many diatoms (Table 3). All of them are intact, indicating in situ deposition (Fig. 2(1)). High diatom content is typical for a Molli-Endogleyic Solonetz. In the upper horizon of the buried soil there are single diatoms as well. All of these are broken in different parts (Fig. 2(2)), indicating perhaps that they were transported by wind. There are single sponge spicules throughout the profile. They are especially regular in the buried soil (Table 3). All of those spicules are strongly corroded. The content of phytoliths differs from modern and buried soils and mineral deposits (Table 3). Minimum phytolith concentrations are found in the samples from mineral deposits. The modern soil has significantly less phytoliths than the buried soil, indicating that modern
assemblages are not so rich in species (especially cereals) and total volume as in the past. The upper horizon of buried soil contains a number of different phytoliths, including steppe grasses and herbs, indicating fertile meadow-steppe soils. The upper layer of this soil has fewer phytoliths than the lower one, and has more phytoliths from xerophytic plants (Fig. 2(3)). Samples from 100–105 to 110–115 cm have maximum numbers of phytoliths, and their amounts decrease with depth. The qualitative phytolith distribution shows similar differences within the profile.
5. Discussion The age of humic acids from the buried soil in MuScharet valley shows that stable conditions of soil formation without any mineral deposits and burial processes prevailed in the area over several thousand years. This soil was buried under saline mineral material only about 1000 years ago. Differences between the age of buried soil in the Mandzhikiny balk and the age of
Table 2 14 C ages, equivalent calibrated ages and approximate archaeological ages for soils from South Kalmykia 14
Soil level, depth, (cm)
C date (yr BP)
Calibrated date (yr BP)
Age intervals (cal BP71s)
Lab. code
Archaeological age
Balk Mu-Scharet (arid zone, dry steppe) 6–14 340790 91–95 1070740 95–100 1260740 102–109 1430750 109–118 2430770 120–125 33307100 125–130 3410780 130–135 3645770 135–140 38607120
323, 381, 430 961 1174 1309 2369, 2399, 2428 3562 3635, 3677, 3680 3928, 3955, 3964 4264
293–501 936–984 1160–1262 1290–1346 2349–2711 3461–3687 3562–3810 3857–4080 4087–418
IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN IGRAN
No archaeological material
Balk Mandzhikini (arid zone, dry steppe) 55–75 23307160
2342
2143–2708
IGRAN 2022
2000 2104 2107 2005 2004 2003 2108 2109 2001
Ceramics approx. 3000–4000 yr BP
Table 3 Contents of silica biomorphs (units) and distribution forms of phytolith (%) Depth (cm)
Diatoms
Spiculas
Phytoliths
1
2
0–3 6–13 17–23 30–35 91–96 100–105 105–115 115–125 125–135 135–145 145–155
12
1
1 1 2* 1*
56 53 64 100 54 66 69 44 31 50 50
31 36 18
1 1
32 53 11 1 95 154 150 32 13 6 2
21 14 12 9 — 17 —
1*
3
4
5
3 9 9
10 2 9
— — —
11 9 15 38 38 17 50
15 11 3 6 31 16 —
— — 1 3 — — —
Note. *—corroded forms; Numbers refer to different groups of plants according phytolith forms: 1—herbs; 2—meadow cereals; 3—steppe cereals; 4—dry- steppe (xeromorphic) grasses; 5—other forms (unknown and not specific).
A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
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Fig. 2. Different forms of silica biomorphs: (1) Diatom from the upper horizon of modern soil; (2) part of the diatom from the upper horizon of buried soil; (3) phytolith from xerophyte plant; (4) phytolith from Stipa.
ceramics (approximately 3–4 thousand years BP) from this soil can be connected with one of two reasons: (1) The buried soil is located at a relatively small depth (50 cm) and is penetrated by roots of modern arid vegetation. Therefore, the rejuvenation of humus is possible; or (2) During the stable period (without erosion processes), ceramics could stay on the soil surface for a long time and become buried considerably later. In this case, the age of soil coincides with the
beginning of the dynamic stage (soil burying), and the difference between the ages of ceramics and soil is the duration of the stable stage of development. Taking into consideration the data on buried soil from the Mu-Scharet balk, we believe that the latter suggestion is most probable. The strong corrosion of spicules shows their ancient age and relic genesis. In the upper part of the profile, single spicules may have been removed with the other
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mineral material as a part of deposit. They are not as corroded, and therefore are not as old. The differences between colluvial layers indicate erosion from different places and/or at different times. Low concentrations of phytoliths in the samples from mineral deposits means that material was transported material from places without plants, or represents the lowest (mineral) parts of soil horizons, where organic material is absent. The common phytolith distribution (total mass) is not typical for soils, as it increases with depth and shows the maximum amount in the second layer from the surfaces in both cases. For the modern soil, it absolutely coincides with intensive pasturing during the last hundred years (History of Kalmyks, 1967). Under the impact of pasturing, the original vegetation was substituted by more xerophytic (drought-resistant) grasses, and the total number of species decreased. The quantitative and qualitative phytolith distribution confirms this fact. The humus content, which increases down the profile, and the change in colors suggest polygenesis of the buried soil. The buried soil is comparable with modern meadow–steppe soil, but not with the molli-endogleyic soil which is now on the surface. The phytolith profile from 100–105 to 110–115 cm is typical for meadow–steppe Chernozem-like soils, indicating that herbs and steppe cereals (for example, different Stipas (Fig. 2(4)) grew on this soil in the past.
The differences of phytolith qualitative distribution might represent the factors of climate change during the time of soil development. It is possible to suppose that at the first stages the conditions were more humid, followed by a short period suitable for xerophyte plants. This age coincides with the nomads of the Katakomba culture, the period of the highest population in history of this area (Artamonov, 1962). After that, there was a long period with the typical meadow-steppe grasses on the surface of the soil until the time of the Khazar State’s development. Phytolith distribution and broken diatoms in the upper layer of buried soil may be a result of several factors: intensive grazing and the beginning of deposit accumulation. Thus, this sample has fewer phytoliths with the predominance of arid flora and diatom fragments. On the basis of comparing the results of our study of buried soils in gullies with archaeological data (Table 4), it can be assumed that deposit accumulation and soil burial were induced by certain historical events. These events are the downfall of the Khazar state (from 973 to 1048 years AD) and the subsequent invasion of guze tribes. Guzes came with large flocks of sheep. Sheep husbandry is more dangerous from an ecological point of view than cattle or horse breeding (Armand et al., 1999). As a result of their extensive pasture, the grass cover was trampled down, and desertification developed. The probability of destructive erosion processes
Table 4 History of the area and landscape development during the second half of Holocene (Balk Mu-Scharet) 14
C cal. yrs ADa, BCb (71s)
Development of the vegetation
History of the area, human impact
Landscape development
0–3
—
Degradation vegetation
Modern pasture
Molli-Endogleyic Solonetz,
6–13
1499–1657a
Meadow-solonetz plants
1657 yrAD—Kalmyk’s occupation
Stable conditions
Depth, (cm)
17–35
—
35–70 70–91
Different Mineral deposits Dynamic conditions —
—
Sparse, degradation vegetation
973–1048 yrs AD—Khazars routed, guzes tribe occupation.
91–95
966–1014a
95–102 102–109 109–118 120–125
688–790a 604–660a 399–761b 1511–1737b
Meadow-steppe
Khazar State Khazar State forming Sarmats Scyths
125–130
1612–1860b
Dry steppe
Katacomba tribe
130–135
1907–2130b
Steppe
Katacomba and Jama tribes
135–140
2137–2468b
Meadow-steppe Chernozemlike soil, Stable conditions over 3000 years
A.A. Golyeva et al. / Quaternary International 106–107 (2003) 103–109
occurring greatly increased. Strong winds usual in this area caused intensive wind erosion. Considerable amounts of fine mineral material were transported and accumulated in gullies.
6. Conclusion Three stages of landscape development are recognized: (1) stable stage, at least 3000 years long (from the 2nd millennium BC until the 1st millennium AD), characterized by the formation of meadow-steppe soils; (2) dynamic stage, likely short, when deposits were accumulated, and soils were buried; and (3) modern stable stage, at least 500 years long (up to the present time), characterized by the formation of meadow-saline soils (Molli-Endogleyic Solonetz) on deposits in gullies. A strong ecological crisis was evident in the territory of modern Kalmykia about 1000 years ago. The main reason was the collapse of the Khazar state. The result was the burying of fertile meadow-steppe soils and formation of saline molli-endogleyic soils. Probably, the vegetation was sparse, reflecting degradation by grazing just before burial. The data obtained do not contradict the naturalclimatic reconstructions of the region. They illustrate the significance of the anthropogenic factor for the formation of soils and landscapes in the south of Russia within the last thousands of years. Different climate changing during thousands of years were not very intensive at this area and could not change the global soil development from meadow-steppe Chernozem-like soil. However, after the human impact (intensive pasture by sheep), absolutely new soils began forming. This means that the human impact is a stronger factor than climate change in soil evolution in the second half of the Holocene in South Russia.
Acknowledgements The work was supported by the Russian Foundation for Basic Research (grants NN 01-05-64403 and 01-0680242). We thank Dr. S.N. Sedov for critically reviewing and improving the first version of the manuscript.
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