Rendzinas of the Russian Northwest: Diversity, Genesis, and Ecosystem Functions: A Review

Abstract

Rendzinas in the taiga zone are intrazonal soils; moreover, all of their processes occur in ways that are different from podzolic soil formation, which is typical for the zonal taiga boreal ecosystem. At the same time, the habitats of carbonate soils are known as places in which there is a concentration of biodiversity in the more southern regions, as they are drier, are insolated, and have a higher trophic state than zonal podzols. The biotopes on carbonate soils are becoming more southern and are dominated by nemoralis species of flora, including abundant calciphilous plant species. Carbonate soils regulate biogeochemical processes within their distribution and in the geochemically subordinate landscapes of Northwest Russia. They are associated with the existence of a number of specially protected natural areas, as well as the implementation of a number of important ecosystem services. Carbonate soils of the southern taiga are endangered and require special protection. The belt of the carbonate soils in the northwestern Russian and Baltic regions extends to Poland and is the basis for the formation of a special landscape–ecological framework with specific biodiverse, biogeochemical, and geographical characteristics. The intensive extraction of limestone from quarries leads to the destruction of rendzinas, which makes them increasingly rare and extremely vulnerable. The rate of recovery of rendzina soils after technogenic impacts is much slower than the regeneration of zonal podzols; therefore, they are an almost non-renewable resource. Thus, rendzinas are an important component of the Northwest Russian soil cover, where all factors of soil formation “refract” and acquire specificity, leading to radical changes not only in the soil-forming potential of the environment but in all of the components of terrestrial ecosystems. In other words, the island of alkaline rocks inherited from the ancient seas is currently pedogeochemically actualized in the soil cover of vast taiga areas.

Soil Microbiome of Abandoned Plaggic Podzol of Different-Aged Fallow Lands and Native Podzol in South Taiga (Leningrad Region)

“…In the fallow soils, we could note the processes of forest litter formation in the native podzol, thus deepening the fallowarable horizon (Ahb) and forming new horizons (Oe) at the boundary with fallow-arable horizons [42]. The transformation of fallow soils is strongly related to the time factor of soil formation [15]: with an increase in the time of the fallow state, we could observe changes in the taxonomic composition of the microbial community, as well as changes in the physico-chemical composition and morphological features of fallow soils. However, it is still an open question on how much time is needed for the formation of the natural microbiome in soils subjected to agricultural development and what processes may also contribute significantly to the change in the taxonomic composition of the microbial community.…”

“…Due to the huge area of fallow lands, it is necessary to understand the direction of transformation of these lands and the ecosystems formed on them, as these areas are richer in microbial communities, contents of biogenic elements, and plant biodiversity. Studies by Luri et al [14] show that post-agrogenic soils in the taiga zone develop in the direction of native podzols, but, depending on local lithological features, Rendzinas and Rendzic Leptosols are formed on carbonate rocks [15], and Retisols and Gleysols are formed on clayey rocks, so the process of transformation into natural soils may take different amounts of time. Thus, in podzols formed on oligomictic sands, after 20 years, signs of leaching can already be determined [12], while, in polymictic sands, the process of podzolization will develop very slowly.…”

Molecular Composition of Humic Acids of Different Aged Fallow Lands and Soils of Different Types of Use in Northwest of Russia

“…The northwestern physico-geographical region is almost entirely located in the Valdai glaciation zone [6] and is a kind of "museum" of soil-forming rocks, which leads to the development of various scenarios of post-agrogenic soil evolution, including divergence and convergence of soil morphotypes and their chemical parameters. The least fertile soils are on the eluviae of granites and other massive crystalline rocks; the most fertile soils are characteristic of carbonate loams [9].…”