Forests advancements to grasslands and their influence on soil formation: Forest Steppe of the Central Russian Upland

Yu Chendev,T Sauer,S Matveev,A Gennadiev,E Terekhin

doi:10.1088/1755-1315/392/1/012003

Abstract

Natural replacement of grasslands by forests during the Late Holocene and in the modern period was observed. Soil changes as reaction to this phenomena were analyzed. Long-term transformation of steppe Chernozems into forest Phaeozems and Luvisols has been studied in archaeological landscapes in 5 key sites by comparison of paleosols buried under Early Iron Age defensive ramparts, with modern background soils of broad-leaved natural environments. Short-term changes of Chernozems covered by tree cover were studied in 3 key sites, presented by 55 yrs broad-leaved shelterbelts, planted on initially open spaces with Chernozems in agroforestry landscapes. Long-term (during the last 2800-2000 yrs) steppe Chernozems transformation into the forest categories of soils leaded to decrease of humus pools in the soil profiles more than 2 times. After 55 years of steppe Chernozems existence under a tree canopy (in shelterbelts) soil profiles exhibited an increase of humus stocks to depths 1 m in average on 13% at initial values. Stages of Chernozem evolution in response to changing land cover from forest to grassland is discussed. Natural advancement of forest over grasslands continues in the contemporary period. From 1970–2014 rates of climatically determined frontal advancement of forests edges onto grasslands, studied in 6 key sites in different regions of forest steppe, have linear connection with the hydrothermal coefficient (HTC). According to this linear trend, rate of forests advancement to grasslands in modern period declines to zero at HTC 0.75 (the index of the center of steppe zone).

Highlights

Relationships between forests and grasslands in space and time in transitional zone between forests and steppes – prairies in Eurasia and North America is one of the most discussed questions in ecological and geosciences issues over the last century
Longterm transformation of steppe Chernozems into forest Phaeozems and Luvisols has been studied in archaeological landscapes in 5 key sites by comparison of paleosols buried under Early Iron Age defensive ramparts, with modern background soils of broad-leaved natural environments
In all key sites of soil-archaeological research (Borisovka, Dmitrievka, Petropavlovka, Voronezh, Podgornoe) soils buried under the ramparts of Early Iron Age settlements at the beginning of Subatlantic period of the Holocene have been identified as dark-humus soils

Summary

Introduction

Relationships between forests and grasslands in space and time in transitional zone between forests and steppes – prairies in Eurasia and North America is one of the most discussed questions in ecological and geosciences issues over the last century. Buol et al [2] presented examples of soils transformation in different regions of North America as a result of bioclimatic changes in Middle and Late Holocene. Bettis III et al [3], used a complex of scientific approaches including the study of soil chronosequences, for Upper Missouri Valley. They reconstructed dry climatic conditions with prairie vegetation in the Middle Holocene and humid conditions with forest vegetation in the Late Holocene [3]. Eckmeier et al [6] discusses different points of views on origin and development of Chernozems in the Central Europe, and in their turn – bioclimatic changes in the Holocene as a factor of these soils development.

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