Indications of windfall morphogenesis in soils in the blackish taiga (by the example of the interfluve between the Tom' and the Yaysk rivers)

Soils in Blackish taiga are significantly different from soils in other forest regions located in the South of Siberia. The reason of this is traditionally associated with the peculiarities of climate, vegetation, and bedrocks: the superposition of these peculiarities causes specific soil morphogenesis which is described by the normal model and its lateral modifications. However, our research showed that in Blackish taiga tree falls with uprooting (windfalls) play an important role in the soil morphogenesis and a pedoturabtion model can be developed. We have analyzed traces of windfalls in soil profiles in forest without evident windfalls and the structure of the modern windfalls and their distribution in landscape as well. We showed when edificators of Blackish taiga Abies sibirica L. and Populus tremula L. fall with uprooting, they form pits with an average depth of 60 cm that are wide spread in forests undisturbed by man. There is not a major root in the root systems of these trees; the root systems are composed of a set of medium-sized roots that are embedded in the upper part of the argic horizon. This structure leads to windfalls with a flat lower boundary from which the cylinder morphones are separated down up to 30 cm. On the basis of soil trenches and 70 soil profiles we have described the following indicators of windfalls in the soil: contours of windfall pits; multiscale morphological mosaic (“floating lumps” in the elluvial horizons, mosaics of the finest fragments of various horizons distinguishable on the slice of soil aggregates); lamellar wood coal at depths of up to 75 cm; morphones in place of plucked roots in the upper part of the argic horizons ("root wedges"); gley spots on the border with textured horizon; washed clean whitish powdery material in the pores; nuciform of "the second humus horizons"; unstructured areas in the (humus-)elluvial horizons; residual type of transition from (humus-)elluvial or "secondary humus" horizons to the textural horizons; hole-pits shape of the top border of the argic horizon; particle soil profile; etc. The paperfirst discusses the irreversible impact ofwindfalls on the structure of the in excess deep bleached soils and dark humus soils in the Blackish taiga in the interfluve between the Tom' and the Yaysk rivers. We showed that the depths of the old windfalls correspond to the depths of the modern windfalls of Abies sibirica and Populus tremula. We defined that deep windfalls increase the contrast of the boundaries between the soil components. They also contribute to the formation of sporadic-spotted elementary soil areas, lead to a clarification of the soil, deepen the upper boundary of the argic horizon and lead to the truncation of the upper boundaries of the residual humus horizons. Windfalls influence soil evolution by accelerating the underlying trend of soil formation. (Humus-)elluvial horizons with undulating lower bound in the Blackish taiga soils can be figuratively titled as "arable" thickness, and the role of "plow' to give the eversible tree roots.

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