Legacies of historical ploughing in the soils of secondary forests, Western Siberia

The abandonment of agricultural land, followed by afforestation, is a widespread global phenomenon. This process is not always well documented. Many ecosystems carry a post-agricultural legacy that is not always obvious, but which can be identified using a series of indicators. One way to identify these indicators is to examine arable soils, the existence of which can be confirmed using archival cartographic information. This study aims to identify morphological indicators of historical ploughing in the soils of secondary forests in southern Western Siberia. The study focused on Luvic Greyzemic Phaeozems that formed on the site of documented peasant arable land abandoned approximately 120–130 years ago. A comprehensive approach combining historical map analysis, field morphological description, laboratory soil analysis and radiocarbon dating of charcoal enabled land-use history to be reconstructed and long-term indicators of former soil ploughing to be identified. These indicators include: a smooth lower boundary of the Ap horizon, its uniform colouration, the presence of agrogenic microrelief (furrows and ridges), the absence of treefall pit-and-mound topography associated with windthrow, and a specific distribution of fine earth particles. The activity of soil fauna (e.g. moles, ants, insects and earthworms) has been shown to be a leading factor in the transformation and masking of these features during post-agrogenic succession. Despite a lengthy recovery period, the soils have not completely returned to a quasi-pristine state. This work provides a methodological foundation for identifying ancient arable lands within forest landscapes in Siberia.