ACTA BIOLOGICA SIBIRICA · VOLUME 12 (2026) · PAGES 323–343

An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia

Daria M. Kuzmina1, Anastasia A. Tkacheva1, Sergey V. Loiko1, Georgy I. Istigechev1, Sergey P. Kulizhsky1
1 Tomsk State University, 36 Lenin av., Tomsk, 634050, Russia
Corresponding author: Sergey V. Loiko — s.loyko@yandex.ru
Academic editor: R. Yakovlev Received: 11 January 2026 Accepted: 27 February 2026 Published: 5 April 2026 DOI: 10.5281/zenodo.19401011

Abstract

This study presents a morphological and analytical characterisation of a native reference soil developed under an old-growth, non-agrogenic tall herb aspen forest in the south-eastern part of Western Siberia’s forest zone. The main objective was to establish a baseline description of a Luvic Greyzemic Phaeozem, the vast majority of whose analogues in the region have been converted to arable land. Conducted at the 'Ust-Sosnovka' key site, the research employed detailed profile descriptions, morphometric analyses and a range of laboratory methods, including carbon elemental analysis, carbonate determination and sub-micromorphological investigations of carbonate pedofeatures. The results revealed a thick, well-structured and highly biogenic soil profile, characterised by a pronounced accumulative distribution of organic carbon (Corg reaching 5.2–9.9% in the 0–10 cm layer) and low bulk density (0.6–0.7 g/cm³), which is indicative of intense bioturbation. A significant stock of inorganic carbon (Cinorg) was identified in the middle and lower horizons, with neoformations showing signs of active dissolution and leaching under the humid climate. The soil is classified as prograding, with no signs of degradation or relic features. The calculated carbon stocks emphasise the importance of both the surface and deep horizons in the total carbon budget. The characterised pedon serves as a crucial reference for quantifying the direction and magnitude of centennial-scale agrogenic transformation in analogous soils. The findings emphasise the importance of conserving such native ecosystems for monitoring carbon stocks and assessing the sustainability of land management. Consequently, this soil should be included in regional soil protection registries, such as a prospective Red Book of Soils for the Kuzbass region.

Keywords

Reference soil, soil organic carbon, inorganic carbon, carbon stocks, soil morphology, old-growth forest

Introduction

Over recent centuries, the boreal belt of Europe and Asia has experienced extensive transformations of its natural environment, largely associated with the complete abandonment of traditional agricultural practices, particularly the slash-and-burn cultivation system (Henttonen et al. 2020; Tikkanen and Chernyakova 2014). The most substantial change in land use systems in Eurasia during the 20th century occurred in Russia (Henebry 2009; Lyuri et al. 2010), where almost 650,000 km² of agricultural land was abandoned over the course of a century (Lyuri et al. 2010). By 2020, the area of permanent arable land in Russia had stabilised (Rukhovich et al. 2025).

A wide spectrum of post-agrogenic ecosystems is now developing across vast expanses of the south of the forest zone (Ryzhova et al. 2020; Smirnova et al. 2017; Telesina and Zhukov 2019). Former agricultural land that is currently being reforested plays a significant role as a carbon sink (Poeplau et al. 2011; Post and Kwon 2000; Kurganova et al. 2021). Studies have shown that the influence of climate change and land use change on the carbon balance is comparable (Rolinski et al., 2021). This makes retrospective regional landscape studies pertinent in order to understand the extent to which prior land use has displaced them from equilibrium.

In the context of contemporary climate initiatives, such as carbon neutrality and the '4 per 1000' initiative, it is crucial to conduct regional assessments of the impact of historical and current land use on soil organic carbon (SOC) stocks. Effective management of SOC stocks through land use management requires an in-depth understanding of how contemporary organic matter stocks have formed under various natural and geographical conditions (Minasny et al. 2017). The southern part of the forest zone in Western Siberia is one region with a large area of fallow land. This study investigates a reference native soil, Luvic Greyzemic Phaeozem (WRB 2022), which has never been ploughed, providing a baseline to quantify agrogenic transformation over centuries.

Study area and sampling sites map
Figure 1. The study area and sampling sites.

Materials and methods

The research was conducted at the key study site 'Ust-Sosnovka' (56°5'52" N, 84°59'25" E) in the Kemerovo region (Kuzbass). Five soil profiles were studied within an old-growth tall herb aspen forest ecosystem, which according to cartographic sources has not been cleared for agricultural use for over 230 years. Soil samples were collected down to >200 cm depth. Bulk density was determined by cutting ring method. Total carbon (Ctot) and soil organic carbon (Corg) were analysed using a Thermo Flash 2000 elemental analyser. Carbonate (Cinorg) was determined by alkalimetric method. Non-silicate Fe and Al were extracted, and exchangeable Ca/Mg, hydrolytic acidity, and mobile P/K were measured. Soil colour was determined by spectrophotometry, and particle size distribution by pipette method. Carbonate pedofeatures were studied at meso- and submicro-morphological levels.

Results and discussion

The old-growth forest ecosystem is represented by a tall aspen forest (Fig. 2) with features of prolonged forest history: uneven-aged aspen, gap-phase mosaic, windthrow pits, coarse woody debris, and diverse herb synusiae including Paeonia anomala, Aconitum septentrionale, Heracleum dissectum, etc. Canopy cover ~0.6–0.7, stand composition 9 aspen : 1 birch. Moss cover less than 5%.

Old aspen tallgrass forest
Figure 2. Old aspen tallgrass forest.

Morphological description (Profile 4): Horizon AU (0–28 cm) dark grey, granular-crumb, loose, abundant earthworm casts. Horizon AUel,b (28–36/40 cm) dark grey with brownish coatings, granular-crumb. Horizon AU/BELgl (36/40–52/57 cm) nutty structure, dark grey molehills. Horizon BTa,gl,el (52/57–60/73 cm) light brown, heavy loam, clay coatings. Horizon BCCa (119/129–144 cm) pale brown, effervesces with HCl, carbonate veinlets. Horizon ICa (144–170+ cm) yellowish-pale, loess-like loam, strong effervescence. Morphometric parameters: AU horizon thickness 19.4±6.2 cm, argic horizon with lamellae 80.4±10.3 cm, depth of effervescence 122.9±8.9 cm.

Example of studied soil profiles of Luvic Greyzemic Phaeozem
Figure 3. Example of studied soil profiles of Luvic Greyzemic Phaeozem.

Colour coordinates (CIE Lab) show L* values 2.8–4 in the top humus horizon, and increasing a*/b* down the profile reflecting illuviation features. No relic second humus horizon indicates progradation. Carbonate pedofeatures include acicular calcite, pseudomycelium, and inherited arid granular forms with etching cavities, showing active dissolution under humid climate.

Color coordinates in CIE Lab space
Figure 4. The color of the horizons of the reference pedon Luvic Greyzemic Phaeozem presented as mean values and standard deviations of color coordinates in CIE Lab space (n = 5).
Mesomorphological structure of carbonate horizons
Figure 5. Mesomorphological structure of carbonate horizons of profile US22-4. a – Large calcite crystals, horizon Ica (150-160 cm). b – Close-up of carbonate ped, horizon BCCa (128-138). c, d – Carbonate film in pores with well-defined white veins of pseudomycelium, horizon ICa(150-160).
Submicromorphological structure of soil calcite
Figure 6. Submicromorphological structure of soil calcite in the carbonate horizon US22-4. a – Rod-shaped carbonates, horizon ICa(150-160). b – Large calcite crystals, horizon ICa(150-160). c – Coating of soil mass with needle-shaped accumulation of calcite, horizon ICa(150-160). d – Carbonate crust of colloform structure with cracks and needle-shaped, rod-shaped and flocculent carbonate units on the surface, horizon BCCa(128-138); e – Accumulation of needle-shaped calcite, horizon ICa(150-160); f – The pore is covered with a crystallomorphic film, with needle-like and rod-shaped contractions on the surface, horizon ICa(150-160).

Analytical characteristics (averages, n=5): Corg accumulative distribution – top 0–10 cm 5.2–9.9%; Cinorg peak at ~150 cm depth. Bulk density 0.6–0.7 g/cm³, low density due to high faunal activity. pHwater in humus horizon slightly acidic (5.1), becoming neutral to alkaline below carbonate horizon. Carbon stocks (Fig. 8): more than half of total C stored in top 30 cm; when including inorganic carbon, 100–200 cm layer holds 76% of the stock present in 0–30 cm. This highlights importance of deep C pools. The soil shows progradation, absence of degradation, and should serve as a regional benchmark for monitoring and for the prospective Red Book of Soils of Kuzbass.

Profile analytical characteristics of the reference pedon
Figure 7. Profile analytical characteristics of the reference pedon Luvic Greyzemic Phaeozem obtained by averaging data from five individual profiles. Standard deviations are shown.
Average carbon stocks in reference Luvic Greyzemic Phaeozem
Figure 8. Average carbon stocks obtained for five profiles in the reference Luvic Greyzemic Phaeozem. A – Ctot in 0–200 cm. B – Corg in 0–200 cm. C – Corg in 0–100 cm. D – Corg in 0–30 cm. E – Cinorg in 0–200 cm.

Conclusion

This study provides a thorough morpho-analytical characterisation of a rare, well-preserved native Luvic Greyzemic Phaeozem (dark grey super-deeply bleached soil) in south-eastern Western Siberia. The old-growth tall herb aspen forest supports a thick, bioturbated profile with low bulk density and high natural fertility. The soil is prograding, with active accumulation of organic matter and down-profile translocation. Substantial carbon stocks – both organic and inorganic – emphasise the value of native reference soils for evaluating century-scale agrogenic transformation. The dynamic inorganic carbon pool, showing dissolution features under humid climate, is particularly important for the global carbon cycle. Conserving such reference pedons is critical for carbon neutrality initiatives and sustainable land management. We recommend including this unique soil in regional protection registries, such as the prospective Red Book of Soils for the Kuzbass region.

Acknowledgments

This work was supported by the Russian Science Foundation (project number 24-27-00417).

References

📚 How to cite this article (recommended citation formats)

Original citation: Kuzmina DM, Tkacheva AA, Loiko SV, Istigechev GI, Kulizhsky SP (2026) An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia. Acta Biologica Sibirica 12: 323–343. https://doi.org/10.5281/zenodo.19401011

APA 7th edition:
Kuzmina, D. M., Tkacheva, A. A., Loiko, S. V., Istigechev, G. I., & Kulizhsky, S. P. (2026). An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia. Acta Biologica Sibirica, 12, 323–343. https://doi.org/10.5281/zenodo.19401011
MLA 9th edition:
Kuzmina, Daria M., et al. "An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia." Acta Biologica Sibirica, vol. 12, 2026, pp. 323–343. DOI: 10.5281/zenodo.19401011.
Chicago 17th (author-date):
Kuzmina, Daria M., Anastasia A. Tkacheva, Sergey V. Loiko, Georgy I. Istigechev, and Sergey P. Kulizhsky. 2026. “An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia.” Acta Biologica Sibirica 12: 323–343. https://doi.org/10.5281/zenodo.19401011.
BibTeX entry:
@article{Kuzmina2026,
  author = {Kuzmina, Daria M. and Tkacheva, Anastasia A. and Loiko, Sergey V. and Istigechev, Georgy I. and Kulizhsky, Sergey P.},
  title = {An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia},
  journal = {Acta Biologica Sibirica},
  volume = {12},
  pages = {323--343},
  year = {2026},
  doi = {10.5281/zenodo.19401011}
}
RIS (EndNote, Zotero):
TY - JOUR
AU - Kuzmina, Daria M.
AU - Tkacheva, Anastasia A.
AU - Loiko, Sergey V.
AU - Istigechev, Georgy I.
AU - Kulizhsky, Sergey P.
PY - 2026
TI - An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia
JO - Acta Biologica Sibirica
VL - 12
SP - 323
EP - 343
DO - 10.5281/zenodo.19401011
ER -
Vancouver style:
Kuzmina DM, Tkacheva AA, Loiko SV, Istigechev GI, Kulizhsky SP. An unploughed reference pedon of Luvic Greyzemic Phaeozem under an old-growth forest in the long-cultivated North Pritom'e region in south-east Western Siberia. Acta Biologica Sibirica. 2026;12:323–343. doi:10.5281/zenodo.19401011.

📄 This article is permanently available under the Creative Commons license as specified by the journal. The reference pedon is a key site for monitoring carbon dynamics and agrogenic transformation in Western Siberia.

© 2026 Kuzmina et al. — Acta Biologica Sibirica | Published 5 April 2026 | DOI: 10.5281/zenodo.19401011